Patent Publication Number: US-2011071721-A1

Title: Systems and methods for obtaining emissions offset credits

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of priority to U.S. Provisional Patent Application Ser. No. 61/032,968, filed Mar. 1, 2008, which is incorporated herein by reference. 
    
    
     BACKGROUND 
     Modern society generates large amounts of undesired emissions that harm human health and/or the environment. For example, vehicles and electric power plants collectively generate large amounts of undesired emissions such as carbon dioxide, methane, nitrous oxide, sulfur hexafluoride, benzene, and volatile organic compounds such as hydrocarbons, which include but are not limited to, hydrofluorocarbons and perfluorocarbons. As another example, hazardous liquid wastes, such as used engine coolant and motor oil, are produced in large quantities and present a waste disposal problem. 
     In many instances, the costs associated with reducing emissions discourage making such reductions. For example, absent government regulations, a power plant owner may elect to not install scrubbing equipment to reduce the plant&#39;s emissions due to the equipment&#39;s high cost. As another example, although a vehicle&#39;s owner may desire to reduce emissions resulting from a defective component on the vehicle, the owner may not be able to afford the costs associated with replacing the component. Accordingly, many opportunities to reduce emissions are missed due to the lack of economic incentive to make such reductions. 
     Emissions Trading Systems 
     It is known to use an emissions trading system to encourage emissions reductions in a manner that presents among the lowest overall costs to society. An authority, such as a governmental authority or a private entity, sets a maximum limit or cap on the total amount of one or more emissions types that may be collectively generated in a given area by all emitters subject to the cap. 
     The authority issues allowances or credits equal to the cap. Credits allow a holder to emit emissions up to the amount of credits that they hold. Each emitter subject to the cap must hold at least enough credits to cover the maximum amount of emissions that it produces over an allowed amount. In some situations, the allowed amount may be zero. 
     Markets permitting free trade of credits among emitters and speculators may be provided for the emissions trading systems. Market allocation helps distribute credits to the emitters that value the credits most, which in turn helps achieve emission reductions at an overall lowest cost to society. The markets effectively assign a monetary value to the credits through trading. Credits may be exchanged at prevailing market prices. An emitter that needs to increase its emissions will need to purchase additional credits to offset the increase. Conversely, a party that has excess credits can sell them. 
     The Kyoto Protocol is an international agreement that sets binding targets for reducing greenhouse gas (GHG) emissions. Participating countries voluntarily agree to comply with an emissions trading system for the following six greenhouse gases: carbon dioxide, methane, nitrous oxide, sulfur hexafluoride, hydrocarbons, and perfluorocarbons. Under the Treaty, countries must meet their targets primarily through national measures. However, the Kyoto Protocol offers them an additional market-based means of meeting their targets. Each participating country agrees to respective emission caps, and during a five year compliance period, a country that emits less than its cap will be able to sell emission credits to countries that exceed their cap. 
     The Chicago Climate Exchange (CCX) is an example of an emissions trading system. The CCX is a voluntary exchange where members contract to reduce emissions of the six greenhouse gases regulated under the Kyoto protocol. Specifically, CCX members contract to meet annual greenhouse gas reduction targets. Members that reduce their emissions below their target levels earn emission credits or allowances, and members who produce emissions in excess of their targets buy allowances from other CCX members. The CCX also includes offset projects. The CCX issues tradable contracts to owners of eligible projects on the basis of sequestration, destruction, or reduction of greenhouse gas emissions. Offset providers do not have significant GHG emissions. 
     Other examples of emissions trading systems include, but are not limited to, the European Union Emission Trading Scheme, the Montreal Climate Exchange, the Western Climate Initiative, the Regional Greenhouse Gas Initiative in northeast United States, and systems instituted in regional air quality districts. 
     Many emissions trading systems enable a party to earn, and subsequently sell or hold, credits by the sequestration, destruction, or reduction of emissions, such as greenhouse gase emissions. Such sequestration, destruction, or reduction achieves an emissions reduction that would not have occurred but for the party&#39;s actions. Such earned emissions credits are sometimes referred to as emission reduction credits, emission reduction offsets, or carbon offset credits. For example, the CCX may issue contracts from qualifying greenhouse gas sequestration, destruction, or reduction projects that are not part of a cap and trade system. The amount of a greenhouse gas sequestered, destroyed, or reduced is commonly represented for trading purposes by its carbon dioxide equivalent (CO 2 e), where the carbon dioxide equivalent corresponds to an amount of carbon dioxide having the same global warming potential as the greenhouse gas. 
     The specific requirements to earn emissions offset credits may vary among emissions trading systems. The following is one example of specific requirements that must be met in order for a party to earn emissions offset credits. First, the party must show that the emissions reduction is surplus—that is the emissions reduction must be in addition to any reduction that would otherwise be obtained. Such requirement is sometimes referred to as the “additionality” requirement. Additionality is sometimes shown by demonstrating that the party&#39;s emissions reduction action would not occur without the availability of emission offset credits. 
     Second, the party must quantify the emissions reduction and have such reduction verified, such as by an independent third party. Third, the party must show that the emissions reduction is “real”—this is, the emissions reduction is not offset by an emissions increase elsewhere. Fourth, the party must show the emissions reduction to be permanent, that is sustained for a specified time period. 
     Fuel Filler Caps 
     Fuel tanks are extremely pervasive in modern society. For example, most automobiles include a fuel tank for storing a liquid fuel, such as gasoline, diesel fuel, and liquefied petroleum, used to fuel the automobile. Fuel tanks are also widely found, for example, on motorcycles and on airplanes, as well as in gardening, maintenance, and construction equipment such as lawn mowers, edgers, snow blowers, air compressors, and portable generators. Furthermore, fuel tanks are commonly found on recreation equipment such as snowmobiles, all terrain vehicles, boats, jet skis, dune buggies, etc. Moreover, fuel tanks are sometimes stand alone portable fuel containers that are used to transport fuel from a fuel point to a device or tank disposed elsewhere—one example of a portable fuel container is a portable “fuel can” used to fill fuel tanks on equipment such as lawn mowers, snow blowers, etc. 
     Fuel tanks are generally designed to be replenished when their stored fuel level is low. For example, a vehicle&#39;s fuel tank must be periodically replenished because the vehicle consumes fuel from the tank as the vehicle operates. Accordingly, many fuel tanks include an opening, sometimes referred to as a fuel filler neck, to allow fuel to be added to the tank. 
     It is desirable to seal the fuel filler neck when it is not being used to add fuel to the fuel tank. One reason to seal the fuel filler neck is to keep contaminants, such as dirt and water, from entering the fuel tank. Another reason to seal the fuel filler neck is to prevent fuel and fuel vapors, such as from gasoline or diesel fuel, from escaping from the fuel tank. Not only do escaping fuel vapors constitute undesired emissions, evaporation of fuel also results in waste of the fuel. 
     A fuel filler cap is used to seal a fuel filler neck when it is not in use. The cap includes a seal to seal the opening of the fuel filler neck, and the cap frequently additionally includes one or more vents to help maintain a desired pressure within the fuel tank. One example of a fuel filler cap is a gas cap used to seal the fuel filler neck of a gasoline storage tank. Unfortunately, the fuel filler cap&#39;s seal and/or vents commonly degrade over time and eventually no longer provide a tight seal, thereby allowing fuel vapors to escape from the fuel tank. Additionally, a fuel filler cap may leak because it is not properly installed, such as not adequately tightened. Furthermore, a fuel filler cap may be completely missing from the fuel filler neck due to the user misplacing the cap. 
     Engine Oil 
     Many engines include a lubrication system that uses motor oil to lubricate the engine. The lubrication system commonly includes an oil filter to remove contaminants from the system&#39;s motor oil. Nevertheless, even with the oil filter&#39;s presence, the motor oil eventually becomes sufficiently contaminated such that it is no longer suitable for lubricating the engine. In particular, engine damage can result from operating the engine with contaminated oil. Furthermore, motor oil additives designed to protect the engine and/or increase engine performance may also degrade over time to the point that they are ineffective. Accordingly, motor oil generally must be replaced or “changed” from time to time. 
     Engine Coolant 
     An engine produces heat as it operates. This waste heat must be removed from the engine, or engine damage will result. Some engines are “air cooled”—that is, the engine is cooled by directing air across heat exchanging surfaces of the engine, and heat is transferred from the engine to the air. However, many engines are “water cooled” where a cooling system circulates a liquid, commonly referred to as coolant, along heat exchanging surfaces of the engine. Heat is transferred from the engine to the coolant, and the coolant is subsequently cooled, such as by transferring heat from the coolant to the environment using a radiator. 
     Engine coolant commonly consists of water and antifreeze. As its name implies, antifreeze helps prevent coolant from freezing. But, antifreeze may perform other useful functions. For example, antifreeze may raise the coolant&#39;s boiling point and may include additives to help minimize cooling system wear (e.g., help reduce rust and corrosion). 
     Engine coolant eventually becomes contaminated such that it no longer serves its intended purpose. For example, coolant may become contaminated with rust, scale, metals, and sludge. Accordingly, engine coolant generally must be replaced from time to time. 
     SUMMARY 
     In an embodiment, a method for reducing emissions from a fuel filler cap includes valuating a cost of replacing the fuel filler cap, calculating an amount of emissions that corresponds to an emissions offset credit having a monetary value equal to the cost, estimating an emissions threshold that an object having a fuel container would have to reach to meet the amount of emissions, measuring a leakage amount of the fuel filler cap, and replacing the fuel filler cap when the measured leakage amount exceeds the emissions threshold. 
     In an embodiment, a method for obtaining emissions offset credits by testing a population of fuel tanks that includes instances of both leaking and non-leaking fuel filler caps includes testing each fuel filler cap for leakage. The fuel filler cap is determined to pass when the fuel filler cap&#39;s leakage is below a threshold amount. The fuel filler cap is determined to fail when the fuel filler cap&#39;s leakage is above the threshold amount. When the fuel filler cap fails, the fuel filler cap is replaced, and emissions offset credits are obtained for emissions reductions resulting from replacing the fuel filler cap. 
     In an embodiment, a method for obtaining emissions offset credits by testing a population of fuel tanks that includes instances of missing fuel filler caps includes checking whether each fuel filler neck of the population of fuel tanks has a missing fuel filler cap. When the fuel filler neck has a missing fuel filler cap, a replacement fuel filler cap is provided, and emissions offset credits are obtained for emissions reductions resulting from replacing the missing fuel filler cap. 
     In an embodiment, a method for obtaining carbon offset credits includes testing the integrity of a gas cap on a vehicle that is not subject to having its gas cap tested on a periodic basis, determining that the integrity of the gas cap is acceptable when the gas cap&#39;s leakage is below a threshold, determining that the integrity of the gas cap is unacceptable when the gas cap&#39;s leakage is above the threshold, replacing the gas cap when its integrity is unacceptable, and obtaining a carbon offset credit when the gas cap is replaced. 
     In an embodiment, a method for obtaining emissions offset credits by reducing use of motor oil includes the following steps: (1) upon a request to change motor oil of an engine, testing a condition of the motor oil; (2) determining whether the condition is acceptable; (3) changing the motor oil solely when the condition is unacceptable; and (4) when the condition is acceptable, obtaining emissions offset credits for emissions reductions resulting from not changing the motor oil. 
     In an embodiment, a method for obtaining emissions offset credits by reducing use of antifreeze includes the following steps: (1) upon a request to change coolant in an engine cooling system, testing a condition of the coolant; (2) determining whether the condition is acceptable; (3) changing the coolant solely when the condition is unacceptable; and (4) when the condition is acceptable, obtaining emissions offset credits for emissions reductions resulting from not changing the coolant. 
     In an embodiment, a method for obtaining emissions offset credits by reducing evaporation of fuel from a portable fuel container includes replacing a leak prone portable fuel container with a low leak portable fuel container, and obtaining emissions offset credits for emissions reductions resulting from preventing evaporation of fuel from the leak prone portable fuel container. 
     In an embodiment, a method for obtaining emissions offset credits includes repairing an engine emissions control system, and obtaining emissions offset credits for emissions reductions resulting from repairing the emissions control system. 
     In an embodiment, a method for obtaining emissions offset credits includes installing an electronic catalytic converter in series with a fuel intake line of an internal combustion engine, and obtaining emissions offset credits for emissions reductions resulting from installing the electronic catalytic converter. 
     In an embodiment, a method for obtaining emissions offset credits includes performing an activity selected from the group consisting of implementing an energy conservation measure and installing a renewable energy source, and obtaining emissions offset credits for emissions reductions resulting from performing the activity. 
     In an embodiment, an interface system for gathering emissions reduction data and for converting the emissions reduction data into emissions trading data includes at least one tester for generating the emissions reduction data, at least one local computer for gathering the emissions reduction data from the at least one tester, and a central computer for converting the emissions reduction data gathered by the at least one local computer into the emissions trading data. 
     In an embodiment, a computer program for obtaining emissions offset credits by testing a population of fuel tanks that includes instances of both leaking and non-leaking fuel filler caps is stored on a computer readable medium. The computer program includes instructions, which, when executed by a computer, perform the following steps: (1) testing each fuel filler cap for leakage; (2) determining that the fuel filler cap passes when the fuel filler cap&#39;s leakage is below a threshold amount; (3) determining that the fuel filler cap fails when the fuel filler cap&#39;s leakage is above the threshold amount; and (4) when the fuel filler cap fails, obtaining emissions offset credits for emissions reductions resulting from replacing the fuel filler cap. 
     In an embodiment, a method for obtaining emissions offset credits by replacing a leaking fuel filler cap of a vehicle includes testing the fuel filler cap for leakage. The fuel filler cap is replaced with a replacement fuel filler cap, and a difference in leakage between the fuel filler cap and the replacement fuel filler cap is calculated. An emissions reduction of the vehicle based on the difference in leakage is estimated, and emissions offset credits for the emissions reduction are applied for. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows one method of obtaining emissions offset credits by testing fuel filler caps of a population of fuel tanks that includes instances of both leaking and non-leaking fuel filler caps, according to an embodiment. 
         FIG. 2  shows one method of obtaining emissions offset credits by testing fuel filler caps of a population of fuel tanks that includes instances of both leaking and non-leaking fuel filler caps, according to an embodiment. 
         FIG. 3  shows one method of quantifying the reduction in hydrocarbon emissions achieved by executing the methods of  FIG. 1  or  2 , according to an embodiment. 
         FIG. 4  shows one method of quantifying the reduction in carbon dioxide emissions achieved by executing the methods of  FIG. 1  or  2 , according to an embodiment. 
         FIG. 5  shows one method of quantifying the fuel savings achieved by executing the methods of  FIG. 1  or  2 , according to an embodiment. 
         FIG. 6  shows one method of quantifying the reduction in greenhouse gas emissions achieved by executing the methods of  FIG. 1  or  2 , according to an embodiment. 
         FIG. 7  shows one method of obtaining emissions offset credits by reducing use of engine motor oil, according to an embodiment. 
         FIG. 8  shows one method of obtaining emissions offset credits by reducing use of antifreeze, according to an embodiment. 
         FIG. 9  shows one method of obtaining emissions offset credits by reducing evaporation of fuel from portable fuel containers, according to an embodiment. 
         FIG. 10  shows one method of obtaining emissions offset credits by repairing an engine&#39;s emission control system, according to an embodiment. 
         FIG. 11  shows one method of obtaining emissions offset credits by installing an electronic catalytic converter in series with the fuel intake line of an internal combustion engine, according to an embodiment. 
         FIG. 12  shows one method of obtaining emissions offset credits by implementing an energy conservation measure and/or by installing a renewable energy source, according to an embodiment. 
         FIG. 13  shows one interface system for gathering emissions reduction data and converting the data into emissions trading data, according to an embodiment. 
         FIG. 14  shows one interface system for gathering emissions reduction data and converting the data into emissions trading data, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     It is noted that, for purposes of illustrative clarity, certain elements in the drawings may not be drawn to scale. Specific instances of an item may be referred to by use of a numeral in parentheses (e.g., tester  1402 ( 1 )) while numerals without parentheses refer to any such item (e.g., testers  1402 ). 
     As discussed above, many opportunities to reduce emissions are missed due to the lack of economic incentive to make such reductions. However, novel methods and systems discussed herein may advantageously reduce emissions and generate a corresponding monetary return, thereby potentially helping to overcome the lack of economic incentives to reduce emissions. For example, emissions reduction systems and/or processes may be made economically viable by obtaining emissions offset credits for emissions reductions achieved by implementing such systems and/or by executing such processes. 
       FIG. 1  shows one method  100  of obtaining emissions offset credits by testing fuel filler caps of a population of fuel tanks that includes instances of both leaking and non-leaking fuel filler caps. The population of fuel tanks includes, for example, fuel tanks of one or more of the following: vehicles such as cars, trucks, and motorcycles; airplanes; helicopters; watercraft such as boats and jet skis; construction equipment such as earth moving equipment, air compressors, and portable generators; gardening, maintenance, and landscaping equipment such as lawnmowers, edgers, snow blowers, and string trimmers; recreation equipment such as snow mobiles and dune buggies; fuel transport and storage equipment such as portable fuel containers; and any other object including a fuel tank. 
     In some embodiments of method  100 , the population of fuel tanks is limited to fuel tanks that would likely not have their fuel filler caps tested but for execution of method  100 . For example, method  100  may be used to test fuel filler caps of a population of vehicles that are operated in areas without mandatory physical testing of fuel filler caps for leakage. Method  100  may also be used, for example, to test fuel filler caps of some or all vehicles brought to a service center, such as a tire store, for maintenance or repairs unrelated to the vehicles&#39; fuel filler caps, thereby resulting in testing of fuel filler caps that would likely not otherwise be physically tested. As yet another example, method  100  may be used to test the fuel filler caps of community members who voluntarily submit their fuel filler caps for leakage testing. Some embodiments of method  100  could also replace or supplement an existing and/or a proposed emissions inspection and maintenance program. 
     Method  100  begins with step  102  where a fuel filler cap from the population is tested for leakage. Stated differently, the fuel filler cap&#39;s integrity is tested in step  102 . Step  102  includes, for example, testing the cap&#39;s seal and/or vents for leakage. It should be noted that in some embodiments of step  102 , solely the fuel filler cap is tested for leakage. For example, in the case of a vehicle, the fuel filler cap, and not the vehicle&#39;s entire emissions control system, is tested for leaks in some embodiments of step  102 . 
     Step  102  preferably includes removing the fuel filler cap from its respective fuel filler neck and testing the cap&#39;s leakage with an external test instrument. The external test instrument is, for example, certified by a governmental agency for testing fuel filler caps. 
     One example of step  102  is removing a fuel filler cap and testing it with a Waekon Corporation FPT2600E Handheld Fuel Cap Tester. The FPT2600E provides a pass/fail test result—if the cap&#39;s leakage is below a threshold amount, the cap passes; if the cap&#39;s leakage is above the threshold amount, the cap fails. The FPT2600E also indicates whether a passing cap is leaking, which means that the cap has a leakage of greater than zero, but less than the threshold amount. 
     Another example of step  102  is removing a fuel filler cap and testing it with a Waekon FPT27 Electronic Fuel Cap Tester. The FPT27 includes communication interfaces for communicating with an external subsystem, such as an Emission Inspection System (“EIS”) test center computer that uses the BAR-97 standard. The FPT27 is operable to send test data to an external computer which is connected thereto. The external computer, for example, executes software operable to process test data from the FPT27. In some embodiments of step  102 , the FPT27 is wirelessly connected to a computer, and the FPT27 is operable to wireless transmit test data to the computer. 
     In some embodiments of step  102 , the fuel filler cap is tested for leakage with the aid of diagnostic equipment residing on the equipment hosting the fuel filler cap. For example, a vehicle&#39;s fuel filler cap could be tested in step  102  with the help of the vehicle&#39;s on-board diagnostic equipment, such as OBD-I, OBD-II, or OBD-III on-board diagnostic equipment. A technician may access the on-board diagnostic equipment, such as by coupling a test instrument with the equipment, to obtain diagnostic data that may be useful in evaluating the fuel filler cap&#39;s integrity. 
     On-board diagnostic data may also be obtained for use in some embodiments of step  102  without a technician&#39;s assistance. For example, a vehicle&#39;s on-board diagnostic equipment may automatically transmit diagnostic data to an external system, such as a communications network, and a party executing one or more steps of method  100  directly or indirectly accesses the diagnostic data from the external system. This automatic transmission of diagnostic data occurs, for example, via radio-frequency, cellular, satellite, optical, or wi-fi communication. 
     Another example of accessing on-board diagnostic data for use in some embodiments of step  102  is monitoring a vehicle&#39;s on-board diagnostic equipment via a data logger. The data logger, which is coupled with the vehicle&#39;s on-board diagnostic equipment, records on-board diagnostic data. A party executing one or more steps of method  100  subsequently accesses the diagnostic data from the data logger. In some embodiments, the data logger is removably coupled to the vehicle&#39;s on-board diagnostic equipment, such as via an electrical connector, and the data logger is periodically decoupled for accessing diagnostic data stored therein. 
     Yet another example of accessing on-board diagnostic data is a vehicle owner driving an on-board diagnostic equipment equipped vehicle to a self service test kiosk. The vehicle&#39;s on-board diagnostic equipment is coupled with the kiosk, such as via a cable or wireless communication, and diagnostic data is transmitted from the on-board diagnostic equipment to the kiosk. A party implementing one or more steps of method  100  directly or indirectly obtains the diagnostic data from the kiosk. 
     If on-board diagnostic equipment indicates a problem (e.g., an emissions control system problem) in embodiments of step  102  utilizing on-board diagnostic data, the fuel filler cap can then be directly or indirectly tested to determine whether the cap is the source of the problem. For example, the fuel filler cap can be indirectly tested by replacing it on the fuel filler neck with a known non-leaking cap to determine whether the fuel filler cap is the source of the leak. However, an external test instrument may provide more accurate test results than on-board diagnostic equipment, and such increased accuracy may result in obtaining more emissions offset credits. For example, an external test instrument may be able to detect a leak as small as 60 cubic centimeters, while on-board diagnostic equipment may not be able to detect a leak smaller than 600 cubic centimeters. Furthermore, an external test instrument may provide leakage information that is specific to the fuel filler cap, while on-board diagnostic equipment may only be able to provide system level leakage information, such as whether there is a leak somewhere in an emissions control system. 
     In decision step  104 , the test results of step  102  are considered to determine whether the fuel filler cap passes or fails. A cap with an acceptable leakage is considered to pass, and a cap with an unacceptable leakage is considered to fail. An example of step  104  is comparing numerical leakage values obtained in step  102 , which represent seal and/or vent leakage, to a threshold amount, such as a predetermined measure of vapor effluent. The cap is deemed to pass if the leakage value is below the threshold. Conversely, the cap is deemed to fail if the leakage value is above the threshold. The threshold amount may be a regulated threshold specified by a regulating entity, such as a governmental entity. For example, the regulated threshold may be 60 cubic centimeters. As another example, if the test of step  102  merely provides a pass/fail result (as opposed to a numerical leakage value), such result is adopted in step  104  as the decision on whether the cap passes or fails. 
     As yet another example of step  104 , if a Waekon FPT27 Electronic Fuel Cap Tester connected to a computer is used in step  102  to test a fuel filler cap, the FPT27 may transfer test data to the computer which electronically records the test data. The computer compares the test data to the threshold amount to determine whether the cap passes. The computer may further be operable to generate reports showing test statistics such as how many caps have been tested, how many caps have passed, how many caps have failed, etc. 
     If the cap passes in decision step  104 , method  100  ends. Otherwise, method  100  proceeds from decision step  104  to step  106 . The results of step  104  may be recorded, such as in a computer system, and/or on paper. 
     In step  106 , the failing fuel filler cap is replaced with a passing cap, such as a new cap or a reconditioned cap. In some embodiments, the failing cap is replaced with a passing cap on the spot. The passing cap is, for example, a cap certified for use as a replacement fuel filler cap and may be a zero leak fuel filler cap. In the context of this patent application and corresponding claims, a zero leak fuel filler cap has negligible leakage. The replacement cap may also be a “touchless” cap, which allows for refueling without removing the cap. Utilizing a touchless replacement cap may advantageously allow earning of additional offset credits due to a user not having to remove and reinstall the cap on a regular basis, which reduces the likelihood that the cap will be incorrectly installed and thereby leak. 
     In some embodiments, the replacement cap is certified to have an acceptable integrity for a long period of time, such as in the case of a vehicle, the lesser of 15 years or 150,000 miles, thereby enabling earning of additional emissions offset credits. The passing cap may even have a lifetime warranty, which may enable earning of yet additional emissions offset credits. The passing cap is optionally secured to the equipment hosting the fuel tank, or the fuel tank itself, with a tether to prevent loss of the fuel filler cap. For example, a vehicle&#39;s fuel filler cap may be secured to the vehicle using a tether. The failing fuel filler cap may be retained, such as for a year, for auditing purposes. The failing fuel filler cap may also be recycled after it is no longer needed for auditing and/or verification purposes. Additional emissions offset credits for emissions reductions resulting from recycling the cap may be obtained. 
     In alternative embodiments of step  106 , a community member is provided an economic incentive to replace the failing cap with a passing cap. An example of such economic incentive is providing the community member a voucher enabling the member to obtain a passing cap at a reduced price or at no cost. 
     In optional step  108 , the fact that the fuel filler cap fails is verified. Such verification may be required to obtain emissions offset credits and may need to be performed by a party unrelated to the party (or parties) executing the remainder of method  100  to ensure the verification is considered unbiased. Additionally, the optional retesting in step  108  may be useful in confirming the accuracy of the testing of step  102 . One example of performing step  108  is to send the failing fuel filler caps to a third party verifier. The third party verifier in turn, re-tests the failing fuel filler cap to determine whether its leakage value is above the threshold value. The third party&#39;s test results may optionally be adjusted to compensate for resetting of defective vents during the shipment of the failing fuel filler caps to the third party verifier. Such adjustment may be desirable because shipment of failing caps may subject the caps to rough handling, and the rough handling may temporarily reset failed vents and cause erroneous verification results, such as a false determination that a failing fuel filler cap is passing. In some embodiments of method  100  where a plurality of fuel filler caps are tested, only a subset of the failing fuel filler caps are sent to the third party verifier. For example, one percent of failing fuel filler caps may be sent to the third party verifier. As another example, some portion of failing fuel filler caps may be sent to the third party verifier in the early stages of execution of method  100 , and such verification may be reduced or eliminated after confidence in the testing of method  100  is established. 
     In addition to or as an alternate to sending a failing fuel filler cap to a third party verifier, a failing fuel filler cap can be re-tested in optional step  108 , such as at the same location where step  102  is performed. For example, if method  100  is performed on vehicles brought to an automotive service facility, a cap determined to fail in step  104  can be retested at the automotive service facility, such as by using a different test instrument than was used in step  102 . Furthermore, the identification of the apparatus hosting the failing fuel filler cap may be manually or automatically recorded, such as by a computer connected to an external test instrument. For example, if the failing fuel filler cap is from a vehicle, the vehicle&#39;s identification number may be recorded. 
     In step  110 , emissions offset credits are obtained for replacing the failing fuel filler cap in step  106 . Such credits may be used, for example, to make method  100  economically feasible. Examples of the offset credits include hydrocarbon emissions offset credits, carbon dioxide emissions offset credits, or carbon dioxide equivalent emissions offset credits. 
     The offset credits may correspond to the emissions reductions achieved by replacing the failing cap with a passing cap. Such emissions reductions may include direct and/or indirect emissions reductions. One example of indirect emissions reductions are reductions achieved by preventing emissions generation during the “fuel cycle”. The fuel cycle represents energy required to provide a unit of fuel to the end user, accounting for activites such as exploring, drilling, refining, transporting, storing, and delivering. The fuel cycle has been estimated to be around 50%—accordingly, for every unit of fuel provided to an end user, approxiately another half unit of fuel is consumed in providing the unit of fuel to the end user. Accordingly, emissions are generated when providing fuel to an end user. Therefore, preventing fuel from evaporating from a leaking fuel filler cap not only prevents direct evaporative emissions, but also prevents the need to replace the fuel evaporating from the leaking cap. By preventing the need to provide replacement fuel, emissions that would result from providing the replacement fuel are eliminated. 
     The emissions reductions achieved by replacing the failing cap with a passing cap are, for example, estimated, such as by using one or more or methods  300 ,  400 , or  600 , discussed below. As another example, leakage of the passing cap may be measured, and emissions reductions achieved by replacing the failing cap with a passing cap may be deemed equal to or based on a difference in the leakage of the failing cap and the leakage of the passing cap. Furthermore, the emissions reductions achieved by replacing the failing cap with a passing cap can be calculated, for example, by considering a parameter of the fuel tank and/or equipment hosting the fuel tank. For example, in the case of a vehicle, the emissions reduction achieved by replacing the failing cap with a passing cap can be calculated based on one or more of the vehicle&#39;s location, the vehicle&#39;s fuel efficiency, the vehicle&#39;s age, the vehicle&#39;s make, the size of the vehicle&#39;s fuel tank, and weather at the vehicle&#39;s location. 
     The offset credits obtained in step  110  may be obtained from an authority of an emissions trading system, including but not limited to, the Chicago Climate Exchange and the Montreal Climate Exchange. The offset credits may be tradable via an exchange. Accordingly, a party may execute some embodiments of method  100  to obtain an economic return. Alternately, the credits obtained in step  110  may be useable to offset emissions, such as by an emissions emitter subject to a regulatory schema. Thus, some embodiments of method  100  may be executed solely to offset emissions, such as to offset new emissions. For example, if an electrical utility subject to emissions regulations needs to offset emissions from a new power plant, the utility may execute an embodiment of method  100  to offset the power plant&#39;s emissions, thereby potentially enabling the utility to build and/or to operate the power plant. 
     Method  100  is performed for each member of the population of fuel tanks. However, in some embodiments of method  100 , steps  102 - 108  are performed as needed for each fuel tank, and step  110  of obtaining credits is performed once after completion of testing of all of the population&#39;s fuel tanks. In other embodiments of method  100 , steps  102 - 108  are performed as needed for each fuel tank, and step  110  of obtaining credits is performed at set intervals, such as at set times or after a predetermined number of fuel filler caps are tested. 
     As discussed above, step  110  optionally includes obtaining emissions offset credits from the authority of an emissions trading system. Accordingly, step  110  optionally includes obtaining a certification from an emissions trading system authority that execution of method  100  meets the authority&#39;s requirements to obtain emissions offset credits. Such certification may be in part or in whole electronically gathered and transmitted. The following is one example of how it could be shown that some embodiments of method  100  meet an authority&#39;s requirements to obtain offset credits. 
     First, as discussed above, in some embodiments of method  100 , the fuel filler caps tested in step  102  are limited to fuel filler caps that would not likely otherwise be subject to leakage testing. For example, a party could execute method  100  in an area not currently subject to fuel filler cap testing, such as at a reduced or no cost to the public and/or a responsible government authority. Furthermore, some embodiment of method  100  may be costly to execute. Such costs include, for example, costs of acquiring, installing, and maintaining test equipment, costs of training operators to use the test equipment, labor costs associated with testing fuel filler caps, verification costs, cost of obtaining emissions offset credits, and costs of replacing defective fuel filler caps. Thus, some embodiments of method  100  would likely not be financially viable but for availability of emissions offset credits. Accordingly, such embodiments of method  100  satisfy the additionality requirement. 
     Second, the emissions reductions achieved by execution of some embodiments of method  100  can be quantified and verified. Specifically, the amount of emissions reductions achieved by replacing failing fuel filler caps can be quantified, and such reductions can be verified, such as via optional step  108 . 
     Third, causing a failing fuel filler cap to be replaced in step  106  will not result in a generation of corresponding additional emissions elsewhere. Thus, the emissions reductions resulting from execution of some embodiments of method  100  are real. 
     Fourth, as noted above, in some embodiments, a failing fuel filler cap is replaced with a passing cap that is certified to retain its integrity for a specified time period. Thus, execution of such embodiments of method  100  results in permanent emissions reductions. 
     The exact amount of credits obtained in step  110  may vary based upon factors including the expected life of the replacement good cap, the level of verification performed at step  108 , the identity of the equipment (e.g., vehicle such a car or lawnmower) hosting the defective fuel filler cap, etc. 
     In some embodiments of step  104 , a community member may be informed that their fuel filler cap is leaking when the cap passes but has a leakage value between zero and the threshold amount. The community member further can be educated that the passing but leaking fuel filler cap is wasting fuel and thereby wasting money, and that the leaking fuel filler cap is contributing to undesired emissions. For example, the community member may be educated that even a small leak may result in loss of significant amount of fuel, and that a small leak will generally result in as much fuel loss as a large leak over time. The community member may elect to replace the passing but leaking cap to eliminate the negative consequences of the leaking cap. In such case, steps  106 - 110  are subsequently executed even though the cap passes, such that the cap is replaced and emissions offset credits are obtained. 
       FIG. 2  shows one method  200  of obtaining emissions offset credits by testing fuel filler caps of a population of fuel tanks that includes instances of both leaking and non-leaking fuel filler caps. Method  200  is an embodiment of method  100 ,  FIG. 1 , and method  200  includes steps in addition to those of method  100 . Specifically, as discussed below, method  200  includes steps  212 - 216  and/or steps  218 - 222  in addition to steps  102 - 110 . 
     Method  200  optionally includes steps  212 - 216 . If method  200  includes such steps, method  200  begins with decision step  212  of determining whether a fuel filler cap is installed on a fuel filler neck of a fuel tank of the population. For example, a vehicle&#39;s fuel filler neck is checked to see if a fuel filler cap is installed thereon. Additionally, some embodiments of method  200  include determining whether a compatible fuel filler cap is installed on the fuel filler neck. A compatible fuel filler cap is one having a design that allows the cap to adequatey seal the fuel filler neck. In the case of a vehicle, a compatible fuel filler cap is, for example, a cap intended for use with the particular vehicle. 
     If the fuel filler cap is missing or incompatible, method  200  proceeds to step  214  where an effective fuel filler cap, such as a new or refurbished fuel filler cap, is provided. For example, in step  214 , the user may be provided a zero-leak gas cap, which optionally has a lifetime warranty. Alternately, in step  214 , the user may be provided an economic incentive, such as a voucher for a new cap, to obtain a replacement fuel filler cap. Additionally, in some embodiments of step  214 , the user is questioned as to why the fuel filler cap is missing. If the user answers that he or she finds it difficult to install the cap, the user is provided a tool, such as a wrench, to help the user install the cap. 
     Method  200  proceeds from step  214  to step  216  where emissions offset credits are obtained in a manner similar to that of step  110 ,  FIG. 1 . The offset credits obtained in step  216  may correspond to the emissions reductions achieved by replacing a missing or incompatible fuel filler cap with a passing fuel filler cap. Additionally, in some embodiments of step  216 , additional emissions offsets are obtained if the user is provided a tool to help install the fuel filler cap in step  214 . 
     Method  200  includes steps  218 - 222  in addition to or as an alternative to steps  212 - 216 . If method  200  includes steps  218 - 222 , method begins with decision step  218  if decision step  212  is not included. Alternately, method  200  reaches decision step  218  if decision step  212  is executed and when the result of decision step  212  is that a compatible fuel filler cap is installed. In step  218 , it is determined whether the fuel filler cap is correctly installed. A correctly installed fuel filler cap is, for example, properly threaded and properly torqued. Proper installation may be checked, for example, by visually inspecting the fuel filler cap&#39;s installation and/or by physically checking the fuel filler cap&#39;s installation. If the cap is incorrectly installed, a remedial action is performed in step  220 . Such remedial action includes, for example, asking the user why the fuel filler cap is incorrectly installed, and the depending on the user&#39;s answer, instructing the user on the importance of properly installing the fuel filler cap, instructing the user on how to properly install the fuel filler cap, and/or a providing the user a tool, such as a wrench, to aid the user in properly installing the cap. Method  200  proceeds to step  222  where emissions offset credits are obtained in a manner similar to that of step  110 . The offset credits obtained in step  222  may correspond to the emissions reductions achieved by henceforth correctly installing a fuel filler cap that was previously incorrectly installed. 
     If it is determined in decision step  218  that the fuel filler cap is correctly installed or after execution of step  222  or  212 , method  200  proceeds to steps  102 - 110  in the same manner as in method  100 ,  FIG. 1 . 
     Method  200  is performed for each member of the population of fuel tanks. However, in some embodiments of method  200 , one or more of the steps of obtaining offset credits  110 ,  216 ,  222  are executed once after the completion of testing of all of the population&#39;s fuel tanks or after a predetermined interval. Additionally, although steps  110 ,  216 , and  222  are shown as discrete steps, two or more of these steps could be combined into a single step. For example, all applicable offset credits could be obtained in a single, final step of method  200 . 
     Each step of method  100  or  200  may be performed by a single party. Alternately, the steps of method  100  or  200  may be performed by two or more parties. For example, in method  100 , step  110  may be performed by a first party, and steps  102 - 108  may be performed by a second party. Similarly, in method  200 , steps  110 ,  216 , and  222  may be performed by a first party, and the remaining steps may be performed by a second party. The second party may perform its respective steps of method  100  or  200  for the first party, such as pursuant to a contract with the first party. The second party is, for example, a retail store or service center that has agreed to test fuel filler caps for the first party, or a non-profit organization that has agreed to test fuel filler caps for the first party in order to achieve environmental benefits resulting from reducing emissions from fuel filler caps. 
     As discussed above, in some embodiments of method  100  or  200 , at least one failing fuel filler cap is transferred or sent to a third party verifier in optional step  108 . Such transfer may be accomplished by a party that is different from the party that obtains emissions offset credits in step  110 , thereby increasing confidence that the testing of method  100  or  200  is unbiased. For example, if a first party obtains emissions offset credits in step  110  and a second party performs the remainder of the steps in method  100 , the second party may directly send a failing fuel filler cap to the third party verifier in optional step  108  without the first party handling the defective cap. Alternately, a failing fuel filler cap may be sent to the third party verifier by the first party. 
     Methods  100  and  200  each include step  110  of obtaining emissions offset credits. As discussed above, emissions reductions generally must be quantified in order to obtain corresponding offset credits.  FIG. 3  shows one method  300  of quantifying hydrocarbon reductions for use in step  110  of method  100  or  200 . However, hydrocarbon reductions resulting from execution of method  100  or  200  may be quantified using other methods. Method  300  is performed, for example, by a computer executing a software product including instructions, stored on computer readable media, where the instructions, when executed by the computer, perform the steps of method  300 . The software product optionally is operable to allow assumptions used in calculations to be manually and/or automatically changed. For example, the software product may be operable to allow a user to manually change the value of constant Evap discussed below, such as by using a keyboard, a touch screen, a voice recongition system, a mouse, and/or a trackball. Some embodiments of the software product are operable to automatically generate and/or submit an application to obtain emissions offset credits, such as hydrocarbon emissions offset credits. 
     Method  300  begins with step  302  of inputting the quantity of failing fuel filler caps replaced by executing step  106 . Step  302  is performed, for example, by a human entering the quantity into a computer configured to execute method  300 . As another example, step  302  may be performed by a computer executing method  300  automatically obtaining the quantity from equipment associated with one or more test centers, such as vehicle service facilities, where method  100  or  200  is performed. As yet another example, step  302  may be performed by a computer executing method  300  automatically determining the quantity from test data, where the computer obtains the test data via a temporary or permanent connection to test equipment or from computer readible media physically transferred from test equipment to the computer. 
     In step  304 , the mass or weight of the hydrocarbon reduction achieved by replacing defective fuel filler caps is calculated using EQN. 1 as follows: 
       HC reduction =(Density)(Comp)(Evap)(Quantity)(Conv)  EQN. 1
 
     where HC reduction  is the amount of hydrocarbon reduction, in metric tons per year for example, resulting from execution of method  100  or  200 . Density is the density of the fuel, such as 0.74 kilograms per Litre in the case of gasoline. Comp is the portion of a unit of measure of the fuel that contains hydrocarbons. If the fuel is gasoline, Comp is for example 86.6%. 
     Evap is an estimated amount of fuel that evaporates on average each year from a leaking fuel filler cap. Evap may be obtained, for example, from published literature, such a 1997 M. J. Bradley and Associates Study entitled “Protocol for Determination of VOC Reductions from the Replacement of Gas Caps on Light Duty Gasoline Vehicles.” For example, Evap may be estimated at 102.2 Litres in the case of a gasoline powered vehicle&#39;s fuel filler cap. 
     Quantity is the number of caps from step  302 , and Cony is an optional conversion factor to obtain desired units. For example, Cony may be equal to 0.001 metric tons per kilogram such that HC reduction  is expressed in metric tons per year. 
     In optional step  306 , the value of the hydrocarbon reduction calculated in step  304  may determined by multiplying the market price for hydrocarbon offset credits by the value of HC reduction  determined in step  304 . For example, if the market value of hydrocarbon offset credits is $8,000 per metric ton—year and the amount of hydrocarbon reduction from step  304  is 692.80 metric tons per year, the value of the hydrocarbon offsets is $5,542,400. 
     Method  300  may also be adapted to quantify the hydrocarbon reduction achieved by replacing a missing or incompatible fuel filler cap in step  214 ,  FIG. 2 . In such case, Evap would be an estimated amount of fuel that evaporates per year as a result of a missing or incompatible fuel filler cap, and Quantity would be the number of times that step  214  is executed. Furthermore, method  300  may be adapted to determine the amount of hydrocarbon reduction achieved in step  220  by instructing a user how to properly install a fuel filler cap and/or providing a wrench to the user in step  220 ,  FIG. 2 . In such case, Evap would be an estimated amount of fuel that evaporates each year as a result of an incorrectly installed fuel filler cap, and Quantity would be equal to the number of times that step  220  is executed. 
     The value of HC reduction  determined in EQN. 1 may optionally be adjusted to account for losses due to the fuel cycle in addition to direct evaporative losses by multiplying HC reduction  by an appropriate scaling factor, such as 1.5. Additionally, HC reduction  may optionally be converted to carbon dioxide equivalents by multiplying HC reduction  by an appropriate scaling factor, such as 3.7. 
       FIG. 4  shows one method  400  of quantifying carbon dioxide offset credits resulting from savings in the fuel cycle for use in step  110  of method  100  or  200 . However, carbon dioxide reductions resulting from execution of method  100  or  200  may be quantified using other methods. Method  400  is performed, for example, by a computer executing a software product including instructions, stored on computer readable media, where the instructions, when executed by the computer, perform the steps of method  400 . The software product optionally is operable to allow assumptions used in calculations to be manually and/or automatically changed. For example, the software product may be operable to allow a user to manually change the value of constant FC discussed below, such as by using a keyboard, a touch screen, a voice recognition system, a mouse, and/or a trackball. Some embodiments of the software product are operable to automatically generate and/or submit an application to obtain emissions offset credits, such as carbon dioxide emissions offset credits. 
     Method  400  begins with step  402  of inputting the quantity of failing fuel filler caps replaced in step  106 . Step  402  is performed, for example, by a human entering the quantity of caps into a computer configured to executed method  400 . As another example, step  402  may be performed by a computer automatically obtaining the quantity of caps from equipment associated with one or more test centers, such as vehicle service facilities, where method  100  or  200  is executed. As yet another example, step  402  may be performed by a computer executing method  400  automatically determining the quantity from test data, where the computer obtains the test data via a temporary or permanent connection to test equipment or from computer readible media physically transferred from test equipment to the computer. 
     In step  404 , the mass or weight of the carbon dioxide reduction is calculated using EQN. 2 as follows: 
       CO2 reduction =(Evap)( P )(FC)(Quantity)(Conv)  EQN. 2
 
     where CO2 reduction  is amount of carbon dioxide reduction, such as in metric tons per year, resulting from replacing leaking fuel filler caps in step  110  of method  100  or  200 . Evap is an estimated amount of fuel that evaporates each year from a leaking fuel filler cap, as in method  300  of  FIG. 3 . Quantity is the number of fuel filler caps inputted in step  402 . P is the estimated amount of carbon dioxide produced by producing one measure of fuel. For example, if the fuel is gasoline, P may be 2.33 kilograms per Litre. 
     FC is the fuel cycle cost. As discussed above, the fuel cycle accounts for energy expenditures associated with exploring, drilling, refining, transporting, storing, and delivering a unit of fuel to an end user. For example, in the case of gasoline, FC may be estimated to be 50%. Accordingly, for each Litre of gasoline provided, an additional half Litre is effectively consumed, such as by exploring, drilling, refining, transporting, storing, and delivering, in order to provide the Litre of gasoline. Thus, as can be observed from EQN. 2, CO2 reduction  represents carbon dioxide emissions solely due to savings in the fuel cycle. 
     As in method  300 , Cony is an optional conversion factor to obtain desired units. For example, Cony may be equal to 0.001 metric tons per kilogram such that CO2 reduction  is expressed in metric tons per year. 
     In optional step  406 , the value of the carbon dioxide reduction credits calculated in step  404  may be determined by multiplying the market price for carbon dioxide offset credits by the value of CO2 reduction  determined in step  404 . For example, if the market value of carbon dioxide offset credits is $25 per metric ton-year and the amount of carbon dioxide reduction from step  404  is determined to be 1,256.40 metric tons/year, the value of the carbon dioxide offsets is $31,410. 
     In a similar manner to that of method  300 , method  400  may also be adapted to quantify the carbon dioxide reduction achieved by replacing a missing or incompatible fuel filler cap in step  214 ,  FIG. 2 . In such case, Evap would be an estimated amount of fuel that evaporates per year as a result of a missing or incompatible fuel filler cap, and Quantity would be the number of times that step  214  is executed. Furthermore, method  400  may be adapted to determine the amount of carbon dioxide reduction achieved by instructing a user how to properly install a fuel filler cap and/or providing a wrench to user in step  220 ,  FIG. 2 . In such case, Evap would be an estimated amount of fuel that evaporates each year as a result of an incorrectly installed fuel filler cap, and Quantity would be equal to the number of times that step  220  is executed. 
       FIG. 5  shows one method  500  of quantifying the fuel savings achieved by causing replacement of failing fuel filler caps in step  106  of method  100  or  200 . Method  500  begins with step  502  of inputting the quantity of defective fuel filler caps caused to be replaced in step  106 . Step  502  is performed, for example, by a human entering the quantity of caps into a computer configured to execute method  500 . As another example, step  502  may be performed by a computer automatically obtaining the quantity of caps from equipment associated with one or more test centers, such as vehicle service facilities, where method  100  or  200  is executed. As another example, step  502  may be performed by a computer executing method  500  automatically determining the quantity from test data, where the computer obtains the test data via a temporary or permanent connection to test equipment or from computer readible media physically transferred from test equipment to the computer. 
     In step  504 , the amount of fuel saved is calculated using EQN. 3 as follows: 
       Fuel_Saved=(Evap)(Quantity)  EQN. 3
 
     where Fuel_Saved is the amount of fuel saved by executing step  106  of method  100  or  200 . As in methods  300  and  400 , Evap is an estimated amount of fuel that evaporates each year from a leaking fuel filler cap. Quantity is the number of times that step  106  is executed from step  502 . 
     In step  506 , the monetary value of the fuel saved by executing step  106  is calculated by multiplying Fuel_Saved from step  504  by the market value of fuel, such as in dollars per Litre. 
     In a similar manner to that of method  300  or  400 , method  500  may also be adapted to quantify the fuel saved by replacing a missing or incompatible fuel filler cap in step  214 ,  FIG. 2 . In such case, Evap would be an estimated amount of fuel that evaporates per year as a result of a missing or incompatible fuel filler cap, and Quantity would be the number of times that step  214  is executed. Furthermore, method  500  may be adapted to determine the amount of fuel saved by instructing a user how to properly install a fuel filler cap and/or providing a wrench to user in step  220 ,  FIG. 2 . In such case, Evap would be an estimated amount of fuel that evaporates each year as a result of an incorrectly installed fuel filler cap, and Quantity would be equal to the number of times that step  220  is executed. 
       FIG. 6  shows one method  600  of quantifying greenhouse gas emissions reductions for use in step  110  of method  100  or  200  when the population of fuel tanks are vehicle fuel tanks, such as light duty passenger vehicle fuel tanks. However, greenhouse gale reductions resulting from execution of method  100  or  200  may be quantified using other methods. Method  600  is performed, for example, by a computer executing a software product including instructions, stored on computer readable media, where the instructions, when executed by the computer, perform the steps of method  600 . The software product optionally is operable to allow assumptions used in calculations to be manually and/or automatically changed. For example, the software product may be operable to allow a user to manually change the value of constant V discussed below, such as by using a keyboard, a touch screen, a voice recongition system, a mouse, and/or a trackball. Some embodiments of the software product are operable to automatically generate and/or submit an application to obtain emissions offset credits, such as greenhouse gas emissions offset credits. 
     Method  600  begins with step  602  of estimating the amount of hydrocarbons lost due to a leaking fuel filler cap using the following expression: 
     
       
         
           
             
               
                 
                   G 
                   = 
                   
                     454 
                      
                     
                         
                     
                      
                     
                       W 
                        
                       
                         [ 
                         
                           520 
                           
                             690 
                             - 
                             
                               4 
                                
                               
                                   
                               
                                
                               M 
                             
                           
                         
                         ] 
                       
                     
                      
                     
                         
                       
                         
                           [ 
                           
                             
                               P 
                               va 
                             
                             
                               
                                 P 
                                 a 
                               
                               - 
                               
                                 P 
                                 va 
                               
                             
                           
                           ] 
                         
                         [ 
                         
                             
                         
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                             ( 
                             
                               
                                 
                                   
                                     ( 
                                     
                                       
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                           - 
                           
                             
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                   EQN 
                   . 
                   
                       
                   
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                   4 
                 
               
             
           
         
       
     
     where G is the amount of hydrocarbons lost in grams due to a leaking fuel filler cap. W is the liquid density of gasoline in pounds per gallon, M is the molecular weight of gasoline in pounds per pound-mole, P va  is the average true vapor pressure in pounds per square inch, P a  is the ambient pressure in pounds per square inch, P 1  is the initial true vapor pressure in pounds per square inch, P 2  is the final true vapor pressure in pounds per square inch, T 1  is the initial temperature in degrees Rankine, T 2  is the final temperature in degrees Rankine, and V is equal to 2.46062-0.02139 (PF), where PF is the percent fill of the fuel tank. 
     Method  600  proceeds from step  602  to step  604  where hot soak emissions are determined using EQN. 5 below. Hot soak emissions result from hot emission control and fuel systems heating the fuel tank after the vehicle is turned off at the end of a trip. 
         G   h =4 G/VKT− 5%  EQN. 5
 
     In EQN. 5, G h  is the hot soak emissions in grams per kilometer, G is determined using EQN. 4 above with values appropriate for hot soak emissions, and VKT is vehicle travel distance per day in kilometers. EQN. 5 assumes four trip ends per day as specified by the constant four. However, EQN. 5 may be modified assume a different number of trip ends per day by replacing the constant four with another constant. EQN. 5 includes a five percent correction factor to account for a portion of the emissions that would normally be controlled by the vehicle&#39;s carbon canister. 
     In step  606 , diurnal emissions are determined using EQN. 6 below. Diurnal emissions result from heating of the fuel tank due to rising temperatures of a typical day. 
         G   d   =G/VKT   EQN. 6
 
     In EQN. 6, G d  is diurnal emissions in grams per kilometer, G is determined using EQN. 4 above with values appropriate for diurnal emissions, and VKT is vehicle travel distance per day in kilometers. 
     Running emissions are determined in step  608  using EQN. 7 below. Running emissions result from heat transfer to and from the fuel tank during the vehicle&#39;s operation. 
         G   r   =G/ 1.609344  EQN. 7
 
     In EQN. 7 above, G r  is running emissions in grams per kilometer, and G is determined using EQN. 4 above with values appropriate for running emissions. 
     Method  600  proceeds from step  608  to step  610  where total hydrocarbon loss is determined using EQN. 8 as follows: 
         G   T =( G   h   G   d   G   r ) VKT− 5%  EQN. 8
 
     where G T  is total hydrocarbon lost in grams per year, G h  is deter lined from EQN. 5 above, G d  is determined from EQN. 6 above, and G r  is determined from EQN. 7 above. VKT is vehicle travel distance per year in kilometers. 
     In step  612 , the greenhouse gas reduction resulting from replacing a defective fuel filler cap is determined using the following expression: 
     
       
         
           
             
               
                 
                   
                     C 
                      
                     
                         
                     
                      
                     
                       O 
                       
                         2 
                          
                         
                             
                         
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                         e 
                       
                     
                   
                   = 
                   
                     
                       
                         [ 
                         
                           
                             44 
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                               n 
                               voc 
                             
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                               G 
                               TA 
                             
                           
                           
                             MW 
                             voc 
                           
                         
                         ] 
                       
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                         10 
                         
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                           6 
                         
                       
                     
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                     PE 
                     + 
                     ML 
                   
                 
               
               
                 
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                   . 
                   
                       
                   
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                   9 
                 
               
             
           
         
       
     
     where CO 2 e is the carbon dioxide equivalent greenhouse gas reduction in tonnes per gas leaking gas cap replaced per year due to secondary contributions. G TA  is the total hydrocarbon lost per year from EQN. 8 above, n voc  is the number of carbon atoms in a molecule of the hydrocarbon or volatile organic compound (8 for gasoline), MW voc  is the hydrocarbon&#39;s or volatile organic compound&#39;s molecular weight (105 grams per mole for gasoline), PE is processing emissions of gasoline (e.g., average of 0.275 tonnes of CO 2 e for each tonne of CO 2  emission), and ML is equal to 3.15G TA /1,000,000. 
     The value of CO 2 e determined in step  612  can be used to apply for greenhouse gas emissions offset credits. It should be noted that EQNS. 4-9 may be modified to allow for use of different units. For example, the equations could be modified such that CO 2 e determined in EQN. 9 represents the greenhouse gas reduction in tonnes per gas leaking gas cap replaced per day. 
     As discussed above, engine oil must be changed from time to time. However, many engine owners change their engine&#39;s motor oil more frequently than necessary. Indeed, in the case of vehicles, it has been estimated that approximately 70% of motorists in North America change their vehicle&#39;s oil more frequently than needed. Businesses that engage in changing oil frequently recommend that engine motor oil be replaced at specific time or use intervals. For example, in the case of vehicles, it is often recommended that motor oil be changed every three months or every three thousand miles, whichever comes first. However, the effective life of engine motor oil is affected by factors besides time and use. For example, in the case of a vehicle&#39;s engine, motor oil lifetime is governed by factors including (1) the type of driving, such as city or highway, (2) the load being moved by the vehicle, (3) road conditions, (4) environmental terrain, (5) weather, (6) vehicle mechanical condition, and/or (7) the driver&#39;s practices. Accordingly, if an individual changes their engine&#39;s oil based on a specific time or use intervals, there is a good chance that the oil is being replaced more frequently than needed, resulting in undesired emissions and waste of resources. 
     Some vehicles include indicator lights that notify a driver when the vehicle&#39;s engine oil needs to be changed. However, notification is commonly triggered by logarithmic programs that have little to do with the motor oil&#39;s actual condition. Accordingly, if a vehicle&#39;s driver relies on the vehicle&#39;s indicator light to determine when to change the vehicle&#39;s motor oil, there is a good chance that the driver will change the oil more frequently than needed, resulting in undesired emissions and waste of resources. 
     Waste motor oil, which is motor oil removed from an engine when changing the engine&#39;s oil, is generally considered hazardous waste. For example, waste motor oil may include one or more of the following substances: (1) degraded base oil chemicals, (2) heavy metals such as Barium, Chromium, and Zinc, (3) wear metals from the engine, (4) residual and degraded oil additives, and (5) combustion by-products such as polycyclic aromatic hydrocarbon. Motor oil can greatly harm the environment, and it can pose a threat to human health. Therefore, it would be desirable to reduce the amount of waste motor oil resulting from unnecessary oil changes. 
     Furthermore, unnecessary oil changes may increase demand for motor oil. Producing motor oil generates emissions, such as hydrocarbons and carbon dioxide. For example, it is estimated that production of a quart of motor oil generates more than 15 pounds of carbon dioxide. Therefore, reducing unnecessary oil changes reduces emissions. 
       FIG. 7  shows one method  700  of obtaining emissions offset credits by reducing use of engine motor oil. Method  700  begins with step  702  with the test of the motor oil&#39;s condition in response to a request to change the engine&#39;s motor oil. Such condition includes, for example, the oil&#39;s sludge content. An example of step  702  is upon a request to change an engine&#39;s oil, dipping a diagnostic test strip in the oil and comparing the strip to a chart to determine the oil&#39;s condition. Another example of step  702  is transferring the engine oil onto paper of a diagnostic kit to evaluate the oil&#39;s condition. Yet another example of step  702  is evaluating the engine oil&#39;s condition using a mass spectrometer. 
     In decision step  704 , it is determined whether the motor oil passes or fails. The motor oil passes if its condition is acceptable, and the motor fails if its condition is unacceptable. An example of step  704  is evaluating the test results from step  702  to determine whether the oil passes or fails. If the motor oil passes, the engine&#39;s motor oil is not changed, and operation proceeds to step  710  whereby an unnecessary oil change is thereby avoided. 
     If the motor oil fails, the motor oil needs changing, and method  700  proceeds to step  706 . In step  706 , contaminated motor oil is removed from the engine, such as by draining the oil. In an embodiment, compressed air is used to help remove the contaminated motor oil in step  706 . Use of compressed air helps remove contaminated oil that would not otherwise be removed when relying on gravity alone to drain the oil. Contaminated oil remaining in the engine will partially contaminate clean oil that is subsequently added to the engine, thereby decreasing the clean oil&#39;s life. Accordingly, using compressed air to remove contaminated oil in step  706  advantageously increases the life of the clean replacement oil, thereby helping to reduce the frequency of oil changes and associated consumption of motor oil. One example of an apparatus that may be used to help remove contaminated oil using compressed air is disclosed in U.S. Pat. No. 6,298,947 to Flynn, which is incorporated herein by reference. 
     In step  708 , clean motor oil is added to the engine. In the event compressed air was used to flush contaminated oil from the engine in step  706 , some motor oil is injected into the engine using compressed air to prevent a “dry start”, which is an engine start with insufficient motor oil. In embodiments of method  700 , the clean oil is reconditioned motor oil. Such reconditioned motor oil is obtained, for example, by reconditioning the contaminated motor oil removed in step  706 . 
     In step  710 , emissions offset credits are obtained from the emissions reductions resulting from the reduction in motor oil consumption achieved by executing method  700 . In particular, emission reductions may be achieved by preventing unnecessary oil changes resulting from executing method  700 . Additionally, emissions reductions may be achieved by using compressed air in step  706 , thereby reducing the frequency of required oil changes. Furthermore, emissions offset credits may be obtained for emissions reductions resulting from using reconditioned as opposed to new motor oil in step  708 . Examples of the offset credits include hydrocarbon emissions offset credits, carbon dioxide emissions offset credits, carbon dioxide equivalent emissions offset credits, and/or volatile organic compound emissions offset credits. 
     In some embodiments of method  700 , test history data is recorded in step  704  to create an oil change history database for the engine. The test history data includes, for example, the engine&#39;s identity, the decision from step  704  as to whether the engine&#39;s oil passes or fails, and information identifying when method  700  was executed, such as the date or the engine&#39;s mileage upon execution of method  700 . For example, in the case of a vehicle, every time method  700  is performed on the vehicle, the vehicle&#39;s identification number, the test results of step  704 , and the vehicle&#39;s mileage may optionally be recorded in step  704  to create an oil test history for the vehicle. An operator may manually create the oil change history database, or a computer may create the oil change history database by automatically obtaining the test history data, such as from test equipment in communication with the computer. The oil change history database can then be evaluated, such as by a computer, to predict when the engine&#39;s oil needs to be changed. Because the prediction of when the engine&#39;s oil needs to be changed is based upon actual testing of the engine&#39;s oil in step  702 , the prediction may be more accurate than predictions based upon other factors such as time accrued and/or mileage accrued since the engine&#39;s last oil change. 
     Method  700  may be executed on each engine of a population of engines. However, in some embodiments, steps  702 - 708  are performed as needed for each engine, and step  710  is performed once after the completion of testing, and replacement if necessary, of the motor oil of all of the population&#39;s engines. In yet other embodiments, steps  702 - 708  are performed as needed for each engine, and step  710  is performed at predetermined intervals. 
     Each step of method  700  may be performed by a single party. Alternately, method  700  may be performed by a number of parties. For example, step  710  may be performed by a first party, and the remaining steps may be performed by a second party. The second party may perform its respective steps for the first party, such as pursuant to a contract with the first party. The second party is, for example, a vehicle service center. 
     As discussed above, engine coolant must be replaced from time to time. In the case of vehicles, it is often recommend that coolant be replaced every two years or 30,000 miles, whichever comes first. However, coolant&#39;s actual service life is a function of variables in addition to time and use. Accordingly, many engine users replace their coolant more frequently than needed. 
     Similar to motor oil, waste engine coolant is considered hazardous waste. Furthermore, production of antifreeze for coolant produces emissions and consumes resources (e.g., natural gas). Accordingly, it would be desirable to reduce unnecessary coolant changes to reduce emissions and resource consumption. 
       FIG. 8  shows one method  800  of obtaining emissions offset credits by reducing consumption of antifreeze. Method  800  begins with step  802  where the condition of an engine&#39;s coolant is tested upon a request to change the coolant in the engine&#39;s cooling system. An example of step  802  is dipping a diagnostic strip into coolant to determine properties of the coolant, such as the coolant&#39;s freezing point, boiling point, and/or corrosion protection capability. Another example of step  802  is transferring the coolant onto paper of a diagnostic kit and evaluating the coolant&#39;s condition. Yet another example of step  802  is evaluating the coolant&#39;s condition using a mass spectrometer. 
     In decision step  804 , it is determined whether the coolant passes or fails. The coolant passes if its condition is acceptable. Conversely, the coolant fails if its condition is unacceptable. If the coolant passes, the coolant does not need changing, and method  800  proceeds to step  814 , thereby preventing an unnecessary coolant change. 
     If the coolant is determined to fail in step  804 , the coolant needs to be changed, and method  800  proceeds from decision step  804  to optional step  806 . In step  806 , the engine&#39;s cooling system is cleaned, such as by using a cleaning solution that does not require neutralization. Cleaning the cooling system may remove rust, scale, and/or sludge, thereby potentially improving cooling system and engine performance. 
     Optional step  808  follows optional step  806 . In step  808 , the coolant is filtered to remove particles, such as particles dislodged during step  806 , to facilitate recycling or reconditioning of the coolant. Particles remaining in the coolant may clog a recycling machine&#39;s filters, thereby impeding recycling. 
     Step  810  follows step  804 ,  806 , or  808 , depending on whether one or both of optional steps  806  or  808  are performed. In step  810 , coolant is removed or drained from the cooling system. Compressed air is optionally used to remove coolant in step  810 , thereby increasing the amount of coolant removed from the cooling system. In a manner similar to that discussed above with respect to method  700 , contaminated coolant remaining in the cooling system can contaminate replacement, clean coolant, and thereby shorten the replacement coolant&#39;s life. Accordingly, using compressed air to remove coolant in step  810  may increase the life of clean, replacement coolant, thereby reducing consumption of antifreeze. 
     In step  812 , replacement, clean coolant is added to the engine. In some embodiments, the replacement coolant includes reconditioned antifreeze. The reconditioned antifreeze is, for example, obtained by reconditioning antifreeze from the coolant that was removed from the engine in step  810 . Using reconditioned antifreeze further reduces the need to produce new antifreeze and may enable obtaining additional emissions offset credits. It has been estimated that every gallon of coolant that is reused prevents the production of 15 pounds of carbon dioxide. 
     In step  814 , emissions offset credits are obtained for emissions reductions resulting from executing method  800 . Such reductions, for example, result from preventing unneeded coolant changes by executing method  800 , use of reconditioned as opposed to new antifreeze, and/or extending the time interval between coolant changes by using compressed air in step  810 . Examples of the offset credits include hydrocarbon emissions offset credits, carbon dioxide emissions offset credits, carbon dioxide equivalent emissions offset credits, and/or volatile organic compound emissions offset credits. 
     In some embodiments of method  800 , test history data is recorded in step  804  to create a coolant change history database for the engine. The test history data includes, for example, the engine&#39;s identity, the decision from step  804  as to whether the engine&#39;s coolant passes or fails, and information identifying when method  800  was executed, such as the date or the engine&#39;s mileage upon execution of method  800 . For example, in the case of a vehicle, every time method  800  is performed on the vehicle, the vehicle&#39;s identification number, the test results of step  804 , and the vehicle&#39;s mileage may optionally be recorded in step  804  to create a coolant test history for the vehicle. An operator may manually create the coolant change history database, or a computer may create the coolant change history database by automatically obtaining the test history data, such as from test equipment in communication with the computer. The coolant change history database can then be evaluated, such as by a computer, to predict when the engine&#39;s coolant needs to be changed. Because the prediction of when the engine&#39;s coolant needs to be changed is based upon actual testing of the engine&#39;s coolant in step  802 , the prediction may be more accurate than predictions based upon other factors such as time accrued and/or mileage accrued since the engine&#39;s last coolant change. 
     Method  800  may be executed on each engine of a population of engines. However, in some embodiments, steps  802 - 812  are performed as needed for each engine, and step  814  is performed once after the completion of testing, and replacement if necessary, of the coolant of all of the population&#39;s engines. In yet other embodiments, steps  802 - 812  are performed as needed for each engine, and step  814  is performed at predetermined intervals. 
     Each step of method  800  may be performed by a single party. Alternately, method  800  may be formed by a number of parties. For example, step  814  may be performed by a first party, and the remaining steps may be performed by a second party. The second party may perform its respective steps for the first party, such as pursuant to a contract with the first party. The second party is, for example, a vehicle service center. 
     As discussed above, portable fuel containers are widely used to transport and store fuel. One common example of a portable fuel container is a fuel can used for fueling equipment such as lawn mowers, string trimmers, edgers, blowers, snow blowers, and generators. However, portable fuel containers are generally prone to leak vapors of the fuel stored therein, and thereby cause evaporation of the fuel. The evaporated fuel constitutes undesired emissions. Additionally, fuel evaporation results in waste of fuel and generation of emissions from the fuel cycle when producing additional fuel to replace the fuel lost due to evaporation. 
       FIG. 9  shows one method  900  of obtaining emissions offset credits by reducing evaporation of fuel from portable fuel containers. Method  900  begins with step  902  where a leak prone portable fuel container that would likely not otherwise be replaced is replaced with a low leak fuel container. A low leak fuel container has negligible leakage, and may be certified to substantially prohibit evaporation for a certain amount of time. An example of step  902  is establishing a program where fuel container owners can exchange their leak-prone fuel containers with low leak fuel containers at reduced or no cost. Another example of step  902  is providing a low leak fuel container at no charge with the purchase of an apparatus, such as a lawnmower, requiring use of a portable fuel container. 
     In step  904 , emissions offset credits are obtained from the emissions reductions resulting from replacing leak prone fuel containers that would likely not otherwise be replaced with low leak fuel containers. Such replacements prevent emissions that would otherwise result from continued use of the leak prone fuel containers. Examples of the offset credits include hydrocarbon emissions offset credits, carbon dioxide emissions offset credits, or carbon dioxide equivalent emissions offset credits. In embodiments of method  900 , step  902  is performed a plurality of times, and step  904  is periodically performed at predetermined intervals or after the conclusion of performing all instances of step  902 . 
     Many engines include an emissions system or an emissions control system to reduce emissions generated from the engine. For example, most modern passenger vehicles have an emissions control system including components such as a catalytic converter and an oxygen sensor to reduce emissions generated from the engine. However, components of emissions control systems generally fail over time. Accordingly, an engine may be generating more emissions than necessary due to failure of one or more components of its emissions control system. 
       FIG. 10  shows one method  1000  of obtaining emissions offset credits by repairing an engine&#39;s emissions control system. An engine&#39;s emissions control system includes, for example, components such as a fuel filler cap, hoses, gaskets, fittings, valves, canisters, fuel tanks, etc. Method  1000  begins with step  1002  where the engine&#39;s emission control system is tested. Step  1002  is, for example, performed only on an emission control system that would likely not otherwise be tested but for execution of method  1000 . 
     In some embodiments of step  1002 , the emission control system is tested by a technician. For example, a technician may test the integrity of the engine&#39;s evaporative emissions control system using a pressure test instrument. Evaporative emissions control systems commonly include components such as hoses, gaskets, fittings, valves, canisters, etc. that can leak. For example, statistical data from the California Bureau of Automotive Repairs shows that a high percentage of certain tested vehicles have a leaking emissions control system hose. The pressure test instrument, for example, pressurizes the evaporative emissions control system with a gas, such as nitrogen or air. The pressure test instrument may optionally inject a gas that can be detected by a technician, such as smoke, to assist in detecting leaks. In some embodiments of step  1002 , pressurized gas is introduced into an emission control system via an opening in a zero leak fuel filler cap installed on the engine&#39;s fuel filler neck. 
     In some embodiments of step  1002 , the engine&#39;s emission control system is tested with the aid of diagnostic equipment residing on the equipment hosting the engine. For example, a vehicle&#39;s emission control system could be tested in step  1002  with the help of the vehicle&#39;s on-board diagnostic equipment, such as OBD-I, OBD-II, or OBD-III on-board diagnostic equipment. A technician may access the on-board diagnostic equipment, such as by coupling a test instrument with the equipment, to obtain diagnostic data that may be useful in evaluating the emission control system&#39;s status. 
     Some embodiments of step  1002  include obtaining on-board diagnostic system data without a technician&#39;s assistance. For example, in manners similar to that discussed above with respect to  FIG. 1 , a vehicle&#39;s on-board diagnostic equipment may automatically transmit diagnostic data to an external system, on-board diagnostic equipment may be monitored via a data logger, or diagnostic data may be obtained via a self service test kiosk. 
     If an engine&#39;s emission control system is determined to be leaking in step  1002 , the engine&#39;s fuel filler cap can optionally be replaced with a plug (e.g., a zero leak fuel filler cap known not to leak) to help determine the source of the leak. If testing subsequently shows that there is no longer a leak after replacing the cap with a plug, it can be concluded that the fuel filler cap was the source of the leak. Conversely, if testing subsequently show there is still a leak after replacing the cap with a plug, it can be concluded that there is a leak in the emissions control system unrelated to the fuel filler cap. 
     Operation proceeds from step  1002  to decision step  1004  where the results from step  1002  are evaluated to determine whether the emissions control system passes. An example of step  1004  is a pressure test instrument used in step  1002  indicating whether an evaporative emissions control system passed or failed. If the emission control system passes, method  1000  ends. Otherwise, method  1000  proceeds to step  1006 . 
     In step  1006 , the defective emissions control system is repaired, or a party (e.g., engine owner) is provided an incentive to have the emissions control system repaired. An example of step  1006  is replacing a leaking hose in an engine&#39;s evaporative emissions control system. Another example of step  1006  is providing an economic incentive to an owner of engine having a defective emissions control system to have the system repaired. 
     In step  1008 , emissions offset credits are obtained from the emissions reductions resulting from repairing emissions control systems that would likely not otherwise be repaired but for execution of method  1000 . Repair of the emissions control systems prevents generation of emissions that would result if the emission control systems were not repaired. Examples of the offset credits include hydrocarbon emissions offset credits, carbon dioxide emissions offset credits, or carbon dioxide equivalent emissions offset credits. In some embodiments of method  1000 , steps  1002 - 1006  are performed a plurality of times, and step  1008  is periodically performed at predetermined intervals or after the conclusion of performing all instances of steps  1002 - 1006 . 
     It should be noted that method  1000  need not necessarily include steps  1002  and  1004 . In particular, method  1000  could be modified to repair or caused to be repaired emissions control systems that are already known to be defective and obtain corresponding emissions offset credits. For example, in an embodiment of method  1000 , steps  1002  and  1004  are omitted, and step  1006  includes providing an economic incentive to an owner of engine that has failed a regulatory required emissions test to conduct emissions control system repairs beyond those required by regulations. 
     Method  1000  could, for example, be executed by a party in an area where engine emission control systems are or are not otherwise likely to be subject to testing. For example, a party could offer to perform method  1000  (or a subset of method  1000 ) in an area where engine emission control systems are not otherwise subject to mandatory testing at a reduced cost or at no cost to the public and/or a responsible governmental authority. As another example, a party could offer to replace an existing emissions control system test program with all or part of method  1000  at a reduced cost or at no cost to the public and/or a responsible governmental authority. 
       FIG. 11  shows one method  1100  of obtaining emissions offset credits by installing an electronic catalytic converter in series with the fuel intake line of an internal combustion engine. Method  1100  begins with step  1102  of installing an electronic catalytic converters in series with the fuel intake lines of an internal combustion engine that likely would not have an electronic catalytic converter installed thereon but for execution of method  1100 . An example of step  1102  is providing an economic incentive for an engine owner to install an electronic catalytic converter in the fuel intake line of their engine. 
     Installing an electronic catalytic converter in series with an engine&#39;s fuel intake line increases the efficiency and/or reduces emissions generated by the engine. In step  1104 , emissions offset credits are obtained from the emissions reductions corresponding to the efficiency increase and/or emissions reduction resulting from installing the electronic catalytic converter in step  1102 . Examples of the offset credits include hydrocarbon emissions offset credits, carbon dioxide emissions offset credits, or carbon dioxide equivalent emissions offset credits. In embodiments of method  1100 , step  1102  is performed a plurality of times, and step  1104  is periodically performed at predetermined intervals or after the conclusion of performing all instances of step  1102 . 
       FIG. 12  shows one method  1200  of obtaining emissions offset credits by implementing an energy conservation measure and/or by installing a renewable energy source. Method  1200  begins with step  1202  of implementing an energy conservation measure and/or installing a renewable energy source. An example of step  1202  is retrofitting a building&#39;s incandescent lighting with compact fluorescent lighting. Another example of step  1202  is installing photovoltaic cells or a wind turbine to provide electric power to a building. Yet another example of step  1202  is replacing a building&#39;s relatively inefficient gas fired furnace with a high efficiency gas fired furnace. 
     In step  1204 , emissions offset credits are obtained from the emissions reductions corresponding to the implementation of an energy conservation measure and/or installing a renewable energy source in step  1202 . Examples of the offset credits include hydrocarbon emissions offset credits, carbon dioxide emissions offset credits, or carbon dioxide equivalent emissions offset credits. For example, if a 5.2 killowatt phovoltaic electric generation system is installed on a house, it may be estimated that the system prevents the emissions of 353,213 pounds of carbon dioxide as well as 2,034 pounds of nitrous oxides and sulfur oxides, and corresponding emissions offset credits may be obtained. In embodiments of method  1200 , step  1202  is performed a plurality of times, and step  1204  is periodically performed at predetermined intervals or after the conclusion of performing all instances of step  1202 . 
     A number of methods of obtaining emissions offset credits are discussed above. Each of these methods includes a step of obtaining emissions offset credits. In order to obtain such credits, specific data generally must be presented to an emissions trading system authority. Additionally, the authority may further require the data to be formatted in a specific manner. For example, an emissions trading system authority may require an emissions offset credit application to include information such the emissions reduction specified as a carbon dioxide equivalent reduction, geographic location of the emissions reduction, and the date in which the emissions reduction occurred. 
       FIG. 13  shows one interface system  1300  that can be used to facilitate obtaining emissions offset credits by providing required data in a form needed to obtain credits from an emissions trading system authority. In particular, system  1300  gathers emissions reduction data  1302  (e.g., fuel filler cap test data, test data concerning other components of an emissions control system, and/or number of leaking fuel filler caps replaced) from one or more sources and converts or transforms the data into emissions trading data  1304  that is suitable for use in obtaining emissions offset credits. Emissions trading data  1304  includes, for example, data required to be included in an emissions offset credit application. Emissions trading data  1304  may optionally be in the form of a credit exchange report which can be submitted (e.g., electronically) to an emissions trading system authority in order to obtain emissions offset credits. 
       FIG. 13  shows system  1300  receiving emissions reduction data  1302  from a number of sources. Each source, for example, represents a different test site, such as a site where one or more of methods  100 ,  200 ,  700 ,  800 ,  900 ,  1000 ,  1100 , or  1200  are performed. However, some embodiments of system  1300  obtain data from only a single source. Additionally, although  FIG. 13  shows system  1300  providing a single set of emissions trading data  1304 , some embodiments of system  1300  provide a number of sets of emissions trading data  1304 , such as a respective set for each of a number of different emissions trading system authorities. 
       FIG. 14  shows one interface system  1400  for gathering emissions reduction data and converting the data into emissions trading data. System  1400 , which is an embodiment of system  1300  of  FIG. 13 , gathers emissions reduction data from testers  1402  and generates corresponding credit exchange reports  1416  that may be submitted to an emissions trading system authority in order to obtain emissions offset credits. Additionally, some embodiments of system  1400  are operable to perform one or more of the following processes: (1) auditing of test data, (2) quality checking of test data, and (3) dissemination of test data. 
     System  1400  includes one or more local computers  1408  for gathering and optionally storing emissions reduction data from testers  1402 , as well as a central computer  1414  for generating credit exchange reports. Central computer  1414  optionally additionally consolidates and stores test data from local computers  1408 . Although only one local computer  1408  is shown in  FIG. 14 , system  1400  may have any number of local computers. Local computers  1408  are, for example, located at respective test sites, such as automobile service facilities. Central computer  1414  is, for example, located at a central site, such as a company&#39;s head office or data center. 
     Local computers  1408  are, for example, personal computers and/or servers each including a processor, memory, data storage (e.g., hard drive, tape drive), and an input/output system. As another example, local computers  1408  may be specially designed for use in system  1400 . Local computers  1408  optionally include software allowing a user to maintain and/or report gathered test data, and in some embodiments, predict or forecast future test results. 
     Testers  1402  generate emissions reduction test data characterizing an emissions reduction activity. For example, testers  1402  may include fuel filler cap test equipment, such as the Waekon Corporation FPT2600E Handheld Fuel Cap Tester and/or the Waekon FPT27 Electronic Fuel Cap tester discussed above with respect to  FIG. 1 . In such case, test data may include fuel filler cap integrity data (e.g., whether the cap passes or fails or a numerical cap leakage value), information on the number of times a cap has been tested, identity of equipment hosting the fuel filler cap (e.g., make, model, and year of a vehicle), and/or geographic location of the test. 
     As another example, testers  1402  may include a vehicle&#39;s on-board diagnostic equipment discussed above with respect to  FIG. 10 . The vehicle&#39;s on-board diagnostic equipment may be directly coupled with a local computer  1408  to transfer test data to the local computer  1408 . Additionally or alternately, the on-board diagnostic equipment may transfer test data to an external system, such as via remote transmission, a data logger, and/or a self-service test kiosk, as discussed above. The external system, in turn transfers the test data to local computer  1408  and/or central computer  1414  for use as emissions reduction data. As yet another example, testers  1402  may include a pressure test instrument discussed above with respect to  FIG. 10 . 
     One or more testers  1402  are optionally communicatively coupled with local computer  1408  via a respective interface  1410 . Each interface  1410  is a system for transmitting data as known in the art, such as a universal serial bus connection, a RS 232 serial connection, a wired Ethernet connection, or a wi-fi connection. Coupling of testers  1402  with local computer  1408  advantageously allows for transfer of emissions reduction data from testers  1402  to local computer  1408 . Such transfer is automatic in some embodiments. For example, local computer  1408  may periodically poll testers  1402  for new emissions reduction data and download new data as it is identified. As another example, emissions reduction data may be automatically transferred from testers  1402  to local computer  1408  on a periodic basis and/or after accumulation of a threshold amount of data in a respective local storage  1406  of a tester  1402 . 
     Testers  1402  and local computers  1408  that are communicatively coupled each include appropriate software to facilitate data transfer via an interface  1410 . For example, an embodiment of tester  1402  may include software operable to store emissions reduction data in internal storage  1406 , convert the stored data to a form compatible with local computer  1408 , and transfer the stored data via an interface  1410 . Local computer  1408  may include, for example, software operable to transfer data via interface  1410  using industry standard protocols with optional data verification and redundancy checks. Local computer  1408  may also include software for converting emissions reduction data from testers  1402  into a form amenable for storage, manipulation, and/or reporting. 
     In some embodiments of system  1400 , data and/or commands may be transferred from local computer  1408  to testers  1402  via interfaces  1410 . For example, local computer  1408  may transmit upgraded software or calibration information to testers  1402 . As another example, local computer  1408  may transmit commands requesting a tester to start a test or to stop a test, thereby enabling local computer  1408  to control at least some aspects of one or more testers  1402 , such as to perform one or more of methods  100 ,  200 ,  700 ,  800 ,  900 ,  1000 ,  1100 , or  1200  discussed above. In particular, in some embodiments of system  1400 , one or more of testers  1402 , local computers  1408 , or central computer  1414  are operable to execute a computer program stored on a computer readable medium to perform at least some steps of one or more of methods  100 ,  200 ,  700 ,  800 ,  900 ,  1000 ,  1100 , or  1200 . 
     In some embodiments of system  1400 , at least some emissions reduction data is transferred from one or more testers  1402  to local computer  1408  without the use of an interface  1410 . For example, a user may manually enter emissions reduction data (e.g., whether a fuel filler cap passes or fails) into local computer  1408 , such as via a keyboard or mouse. As another example, local computer  1408  may have voice recognition capability enabling local computer  1408  to record test data spoken by a human (e.g., a technician conducting a test). Furthermore, some embodiments of system  1400  may include a optical character recognition device coupled to local computer  1408  enabling local computer  1408  to read test data from a written test report, such as generated by a printer  1404  coupled to a tester. As yet another example, one or more testers  1402  may encode test data on a medium, such as using bar code, radio frequency identification, or magnetic storage techniques, and local computer  1408  may read the medium to obtain the test data. 
     Each local computer  1408  is coupled to central computer  1414  via a respective interface  1412 . Central computer  1414  may be a server located at a central facility. However, central computer  1414  may include a number of computers, which may be located at a common location or geographically dispersed. For example, central computer  1414  may be embodied by a network of computers connected via the internet. Central computer  1414  includes a processor, memory, storage, and an I/O system. 
     Interfaces  1412  may be communications systems or methods for transmitting data as known in the art, such as for transmitting data over long distances. For example, an interface  1412  may represent a dedicated a T1 circuit, a virtual private network operating on the internet, a wireless data connection (e.g., cellular or satellite), a batch transfer of data over a temporary connection (e.g., via a telephone modem or an internet file transfer protocol session). Alternately, an interface  1412  may represent physical transfer of a medium embodying test data, such as shipment of a printed test report or magnetic tape. Each local computer  1408  and central computer  1414  include, for example, software facilitating secure communication therebetween. 
     Central computer  1414  generates credit exchange reports  1416  from emissions reduction data from local computers  1408 . Data included on credit exchange reports  1416  is, for example, determined at least in part by one or more of methods  300 ,  400 ,  500 , or  600  discussed above. Credit exchange reports  1416  may include information such as the quantity of emissions reduction achieved, location of the emissions reduction, and the date of the emissions reduction. Some embodiments of system  1400  are operable to produce a number of credit exchange reports  1416 , each having appropriate data and being appropriately formatted for submission to a respective emissions trading system authority. As discussed above, central computer  1414  may optionally be operable to consolidate and store emissions reduction data from local computers  1408 . 
     In some embodiments of system  1400 , central computer  1414  further has the capability to perform at least one of the following processes: (a) manipulation of consolidated test data, (b) reporting of test data, (c) generation of all necessary documentation to support emissions offset credit processing with an emissions trading system authority, (d) support of remote access  1418 , such as to allow a third party (e.g., an auditing entity or a government entity) access to data, and (e) automatically apply for emissions offset credits from an emissions trading system authority, such as via an interface  1420 . 
     Some embodiments of system  1400  advantageously include functionality to facilitate calibration of testers  1402 . For example, software included on one or more of testers  1402 , local computers  1408 , or central computer  1414  may track and/or maintain calibration results for testers  1402  in order to help ensure testing accuracy. Further, in some embodiments of system  1400  that are configured and arranged to be used with method  100  or  200 , such embodiments are operable to track and report specific fuel filler caps that were replaced. In these embodiments, test data may be tied to specific fuel filler caps and used to obtain emissions offset credits from an emissions trading system authority. 
     Although system  1400  has been described above with certain functions being performed by each of testers  1402 , local computers  1408 , and central computer  1414 , functionality may be distributed among the elements of system  1400  in a different manner. For example, at least some aspects of generating emissions trading data may be performed on local computers  1408  and/or testers  1402  instead of central computer  1414 . Indeed, all required functional of central computer  1414  may be integrated into local computers  1408  and/or testers  1402  such that central computer  1414  can be omitted. Conversely, functionality of local computers  1408  may be incorporated into testers  1402  and/or central computer  1414  such that local computers  1408  can be omitted. In such embodiments, testers  1402  could for example directly generate credit exchange reports  1416  and/or communicate with an emissions trading system authority. 
     It is envisioned that two or more of the methods of obtaining emissions offset credits discussed herein may be executed together as part of a common program or procedure. For example, method  100  or  200  may be performed whenever method  700  or  800  is performed. Additionally, one or more of the methods of obtaining emissions offset credits discussed herein may be performed when performing an activity other than those discussed herein. For example, an automotive service facility may execute method  100  or  200  on any vehicle brought to the facility for a tire rotation or an oil change. Furthermore, emissions offset credits can be obtained by performing additional emissions reductions activities, such as checking a vehicle&#39;s emission system, tire pressure, air filter, and/or brake system. Such additional emissions reduction activities could be performed while executing one of the methods (e.g.,  100 ,  200 ,  700 ,  800 ,  900 ,  1000 ,  1100 ,  1200 ) discussed herein. 
     Furthermore, it should be noted that one or more of the methods of obtaining emissions offset credits discussed herein may be adopted such that they are executed only if they are economical. For example, a method may be executed only in the case where the value of emissions offset credits to be earned from the method exceeds the cost of executing the method. 
     As a particular example, method  100  could be modified as follows. First, the cost of replacing the fuel filler cap is valuated. Such cost includes, for example, the cost of providing a fuel filler cap, costs associated with testing and replacing the cap, and/or overhead associated with testing and replacing the cap. Next, an amount of emissions that corresponds to an emissions offset credit having a monetary value equal to the cost of replacing the fuel filler cap is calculated. An emissions threshold that an object having a fuel container (e.g., a motor vehicle, a portable fuel container, a lawn mower, an airplane) would have to reach to meet the amount of emissions is estimated. The fuel filler cap&#39;s leakage is measured, where the leakage does not necessarily have to include an amount required to open a fuel filler vent in the case of a pressure overload. The fuel filler cap (good or bad) is replaced only if its measured leakage exceeds the emissions threshold. Accordingly, the fuel filler cap is replaced only if the value of emissions offset credits to be earned by replacing the cap exceeds the cost of replacing the cap. This modification of method  100  may advantageously result in replacing a leaking fuel filler cap whenever it is economical to do so, regardless of whether the fuel filler cap has a leakage that exceeds a particular standard. 
     Emissions can also be reduced and corresponding emissions offsets can be obtained by causing a fuel powered machine (e.g., a gasoline or diesel fuel powered motor vehicle) to operate more efficiently. For example, an engine&#39;s fuel system can be cleaned, such as by using a cleaning instrument and/or a cleaning solution, to cause the engine to operate more efficiently. Emissions offset credits corresponding to the resulting increase in efficiency can subsequently be obtained. As another example, a vehicle&#39;s differential, manual transmission, and/or power steering system can be cleaned such that the vehicle operates more efficiently. Emissions offset credits corresponding to the resulting increase in the vehicle&#39;s efficiency can be obtained. 
     Changes may be made in the above methods and systems without departing from the scope hereof. It should thus be noted that the matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover generic and specific features described herein, as well as all statements of the scope of the present method and system, which, as a matter of language, might be said to fall therebetween.