1 

### Technical Support Document: Net Ener gy Output Monitoring and Reporting

Draft 4/8/2014

Table of Contents Background

............................................................................................................................... .................... 2 Monitoring of Electric Generation

................................................................................................................ 3 Equipment standards

............................................................................................................................... .. 3 Specification and frequency of quality assurance testing

......................................................................... 4 Proposed definition of net electric output

................................................................................................. 4 Default apportionment of parasitic loads to multiple units

....................................................................... 5 Monitoring of Non-electric Output at CHP units

.......................................................................................... 5 Reporting of Net Electric Generation and CHP Net Energy Output

............................................................ 6 Reporting of Monitoring Plan Data and Quality Assurance Testing Data

.................................................... 72 Background This document provides additional inform ation relating to the proposed Emission
Guidelines for Greenhouse Gas Emissions from Ex isting Stationary Sources: Electric Utility Generating Units. It is intended to discuss topics regarding th e monitoring and reporting of net output energy at electric generating units (EGUs) for which the agency is seeking comments in the proposal.

The proposed emission guidelines would establ ish a rate based emissions performance goal for each state on a net energy output basis. A state could meet th is goal by establishing greenhouse gas emissions rate standards for E GUs for which EGUs would need to monitor emissions and net energy output. Emissions and net energy output data would be monitored and reported under 40 CFR Part 75 and would be repo rted via the Agency’s Emissions Collection and Monitoring Plan System (ECMPS).

Currently, reporting under 40 CFR Part 75 unde r the Acid Rain Program requires the reporting of gross load (either electric or st eam) for the main purpose of apportioning emissions
to units that are monitored at a common stack an d establishing load bins for data substitution procedures. Currently, under Part 75 reporting, there are no quality assurance requirements for gross load because it is presumed that the op erator of an EGU would have the accurate monitoring of generation in its best interest a nd because the Acid Rain Program and other cap and trade programs require compliance on a mass basis and not a rate basis, so generation data is not necessary for compliance purposes.

Under the proposed emission guidelines, repor ted energy output data would be used for compliance purposes. Therefore, quality assurance of output data is as important as quality assurance of emissions data. The EPA is propos ing and taking comment on requiring states to use net energy output as the measure for any ra te based emission standards. A rate-based standard, whether gross or net, would necessita te quality assurance of output data above and beyond what is currently required un der Part 75 to ensure that all output data are of the same quality.3 Monitoring of Electric Generation Electricity is used at power pl ants for a variety of purposes and is commonly described as auxiliary or parasitic load. The EPA understands that electric ge neration and para sitic loads are universally measured at EGUs. These parasitic lo ads can include any of the following: electric motors used for pumps, fans, air compressors, coal handing equipment (such as conveyor belts and pulverizers), gas turbine starters, air pollu tion control equipment (s uch as electrostatic precipitators), and buildi ng use (such as lighting, air conditioni ng, computer systems, etc.). Gross generation is measured at the generator terminal s (via current and potential transformers) enroute to the unit high voltage step up transformer, plant HV switchyard, and transmission into the electric grid. A unit auxiliary transformer typi cally steps down generator voltage to provide separately measured medium voltage electricity to in plant auxiliary/parasitic loads. Station service transformers typically provide separately measured electricity from the grid to plant auxiliary loads when the EGU is not in opera tion or is starting up. The EPA understands that steam boiler based plants typically have stati on service transformers, while combustion turbine based plants commonly do not have separate station service tran sformers and back feed through unit and unit auxiliary transforme rs to measured aux loads when the EGU is not operating or is starting up. Given these measurements commonly occur at EGUs, the EPA understands that the equipment needed to convert gross generation to net generation on an hourly basis exists at all
EGUs.

Equipment standards
The EPA understands that there are several equipment standards including those that require 0.2 accuracy meters and 0.5 accuracy mete rs. The American national Standards Institute (ANSI) published an American Na tional Standard for Electricity Meters – 0.2 and 0.5 Accuracy Classes (ANSI C12.20-2010) and published a C ode for Electricity Metering: ANSI C12.1-2008. The EPA is seeking comment on the proposed requi rement that would specify 0.2 accuracy class meters to determine net electric output (or gro ss electric output). The EPA is seeking comment on the use of ANSI C12.20 to specify the minimum accuracy of equipment that would be used to measure net electric output under the proposed emissions guidelines. The EPA is seeking comments on the use of equipment standards that would ensure a level playing field regarding the minimum acceptable accuracy of equipment us ed to measure net electric generation while4 minimizing any additional burde n of upgrading equipment used to measure net electric generation.

Specification and frequency of quality assurance testing The EPA understands that, on a regular basi s, EGUs typically perform checks on their electricity meters to ensure that the equipm ent is operating as designed. The EPA is seeking comments on the specifications of such checks an d the frequency at which they are typically performed. The EPA is seeking comments on indus try’s best practices that would ensure adequate net electricity measurement accuracy while minimizing additional burden of quality assurance testing procedures.

Proposed definition of net electric output The EPA is proposing the following definition:

Net-electric output means the amount of gr oss generation the generator(s) produce (including, but not limited to, output from st eam turbine(s), combustion turbine(s), and gas expander(s)), as measured at the generato r terminals, less the electricity used to operate the plant (i.e., auxili ary loads); such uses include fuel handling equipment, pumps, fans, pollution control equipment, othe r electricity needs, and transformer losses
as measured at the transmission side of the step up transformer (e.g., the point of sale). For hours or partial hours when there is no gross generation, net el ectric output shall be zero. Measurements must be performed us ing 0.2 accuracy class electricity metering instrumentation and calibration procedur es as specified under ANSI Standards No.
C12.20.
The EPA is seeking comment on this definiti on, especially regarding the specification of the 0.2 accuracy class meters. The EPA is also seeking comment on the tr eatment of externally provided electricity when the unit is not operating or begins to start up in the determination of net electric output. Under this de finition, grid supplied electricit y (or other externally provided electricity) that is used at the station when the EGU has no gross generation, (such as when the EGU is not operating or when the EGU is beginni ng to start up) would not be subtracted from the zero gross generation, which would prevent net generation from being negative. This would5 effectively only subtract electricity that is used by the plant and that is derived from unit from gross generation.

Default apportionment of parasitic loads to multiple units For plants that have more than one unit, apportionment of parasitic loads that share common auxiliary transformers would be nece ssary. The EPA is taking comment on a default system of apportioning parasitic loads among multiple EGUs. The proposed default apportionment, as mentioned in the preamble of the proposal, would be to apportion net generation to each unit at a facil ity that shares common auxiliary transformers or a common bus to the grid by the gross generation of each of th e generators. For combined cycle units, the gross generation of the steam turbine would be apportioned to each combustion turbine by the gross load of each combustion turbine, as currently prescribed in the Part 75 Emissions Monitoring Policy Manual, question 17.2. There may be unique tr ansformer and parasitic load configurations at a plant with multiple units that would make the default apportionment of net generation to each unit problematic. For example, if two un its share a common steam header and a common generator, there are not two gross generation va lues to apportion the ne t electric generation. Also, for example, if two units have parasitic load s that are on a shared auxiliary transformer and if the equipment that serves one of the units typi cally uses a lot more electricity than the other, then the default apportionment of net generati on to each of the units could be problematic. Therefore, as mentioned in the preamble to th e proposal, the EPA intends to allow owners and operators of affected EGUs to propose alte rnative apportionment procedures for the EPA approval given unique plant configurations. The EPA welcomes comment regarding this default apportionment procedure.

Monitoring of Non-electr ic Output at CHP units
For affected EGUs that are combined h eat and power (CHP) units (also known as cogeneration units), the combustion of fuel is used to provide bot h electric generation and other useful energy. Commonly, waste heat is captured and useful thermal output is provided for onsite use or sale. Thermal energy from CHP units can be used in direct process applications or indirectly to produce steam, hot water, hot air for drying, or chilled water for process cooling. Under the proposed rule, a CHP unit would demons trate compliance with a rate based system on a net energy output basis: both net electric out put and useful thermal output (converted into6 MWh equivalent) would be combined into net energy output. Therefore, for CHP units to demonstrate compliance with a rate based standar d, the measurement of both net electric output and useful thermal output would be required. Mechanical energy fr om turbines can be used to drive rotating equipment, such as compressors, pu mps and fans, and the exhaust of which may be routed through a heat recovery steam generator to generate elec tricity. Combustion turbines used for mechanical drive applications are typically used in the oil and gas industry. There may be a few such systems that meet the applicability requi rements of the rule that would need to measure mechanical energy produced for net energy outpu t. The EPA is seeking comment regarding the equipment used to measure and record mechan ical output on an hourly basis for reporting

purposes.
The measurement of useful thermal output in the form of steam involves the monitoring of steam pressure and steam flow (and in the case of superheated steam, steam temperature). However, there are several potential methods depending on whether the heat content of
condensate or steam return is measured and ot her considerations. Please refer to “Developing and Updating Output-Based NO x Allowance Allocations: Guidance for States Joining the NO x Budget Trading Program under the NOx SIP Call” 1 for more details, specifically section VI: Monitoring locations: Where could facil ities monitor electric and thermal output and subsection
D. How could sources monitor electric and thermal output at a cogeneration facility . The EPA presumes that a CHP unit that sells useful ther mal output would already be using equipment to measure the saleable product. The operation a nd calibration equipment that measure pressure, temperate and steam flow leaving the unit and that measure the temperate and flow or returning condensate or the pressure, temper ature and steam flow of returning steam would be needed. The EPA is seeking comment on the best practices for the measurement and recording of useful thermal output and the best practices regarding qu ality assurance protocols for such equipment.

Reporting of Net Electric Genera tion and CHP Net Energy Output

In order to facilitate compliance with a rate based sta ndard, The EPA is proposing that an affected EGU could report hourly net electri c generation under 40 CFR Part 75 via ECMPS, which would be included in emissions reports submitted quarterly. A CHP unit would

1 http://www.epa.gov/airmarkets/progsre gs/nox/docs/finaloutputguidanc.pdf7 additionally report net energy outpu t as calculated from net elect ric generation, useful thermal output and any other useful mechanical output. Even if a rate based standard is based on gross electric output (rather than net), then an affected EGU would need to report gross electric output, and if a CHP unit, would need to also report energy output considering useful thermal output.

Reporting of Monitoring Plan Data and Quality Assurance Testing Data The EPA is seeking comment about including equipment used to measure net electric output (and net energy output for CHP units) in an EGU’s monitoring plan under 40 CFR Part 75, as currently being reported via ECMPS. Th e EPA is also seeking comment on the reporting of the performance of tests on equipment used to measure net electric generation and net energy output for the purpose of determining whether the equipment is accurate or is operating as designed. Even if a rate based standard is based on gross electric output (rather than net), then monitor plan and quality assurance information would need to be submitted. The EPA invites comments regarding the quality assurance testin g data that would be useful for reporting.