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December 4 , 2009 VIA E - MAIL Ms. Melanie King Energy Strategies Group U. S. Environmental Protection Agency Mail Code D243 - 01 Research Triangle Park, NC 27711 Re: EMA Response to Questions Regarding Crankcase Emission Controls Dear Ms. King : On a recent conference call between your office and the Engine Manufacturers Associ at io n (EMA), you requested some info rmat io n and reco mmendat io ns fro m E MA regarding the control of crankcase vent emissio ns fro m e xist ing stationary compressio n ignit io n (CI) engines. O ur understanding is that EPA is exploring options and possible controls to reduce th e emissio ns o f ha zardous ai r pollutants (HAP), in particular metallic HAP emissio ns, fro m exist ing stationary diesel engines. EPA would adopt any p ote nt ia l control s in the upco ming fina l NESHAP for stationary CI engines to be released in February 2010. I have discussed the issue with EMA member companies that manufacture the vast majorit y of in - use and new stationary CI engines sold in the U nit ed States. EMA has the fo llo wing information and recommendations regarding the control of crankcase vent or blo w - by emissio ns. · The crankcases of all engines, including co mpressio n ig nit io n engines , mu st be vented so that pressure within the crankcase remains within tolerance levels. Wit hout vent ing, high pressures fro m co mbust io n gases that enter the crankcase th rough pi ston - cylinder gaps would quickly build to levels that exceed crankcase and crankcase seal specificat io ns. Seal failures and external oi l leaks would result. Conseque nt ly, all CI engine crankcases are vented to relieve such pressures . Hi stori cally, th e normal pract ice had been to vent the crankcase direct ly t o th e atmosphere , but many newer model engines have incorporated some mechanism to reduce blow - by emissi on s . · Th is crankcase vent ing or blow - by adds only a very small amount of ai rb orne emissio ns to the total emissi on s f rom CI engines , on the order of 0.01% of total emissio ns . However, as exhaust emissio n standards have beco me increasingly more stringent, blow - by e missio ns have beco me a larger percentage of total emissio ns, even though th ey are st ill small in abso lut e terms. Blow - by emissio ns are largely co mposed- 2 - of oil mist. It is likely that meta llic HAP are also emitted since engine lube oi l and the wearing o f sur faces in the crankcase (bearings, rings, and liner interface, etc.) are believed to be the major source of metallic com pounds in engine emissio ns. · Older CI engines are likely to have higher levels of blow - by emissio ns because increased deteriorati on and wear o f t he piston ring and liner interface over t ime increases crankcase pressure and the amount of oil emissions . This mechanism is a natural part of engine operation and can only be mitigated by engine overhaul. · More recently, e ngine manufacturers have developed open and clo sed crankcase systems to reduce the amount of oil mist escaping into the atmosphere , and therefore other com

pounds carried in the blow - by in the o il mist . Closed crankcase systems are mo re co mmo n on heavy- dut y o n - highway application s while open crankcase systems are used on larger engines. Newer CI mo bile source engines used in both on - highwa y and nonroad applicat io ns have addressed blow - by emissio ns by co llecting the oil mist and returning it to the crankcase, by direct ing the blow - by emissio ns back to the combustion chamber on naturally aspirated engines, by direct ing the blow - by emissio ns to the exhaust system , or by co llect ing the oil droplets for re - use or liquid di sposal . As you may be aware, c urrent EPA regulat io ns fo r new CI engines requi re th at blow - by emissio ns be addressed by the application o f c lo sed crankcase systems or by requiring the engine manufacturer to account for blow - by emissio ns as part of the total system- out emissi on s o f t he engine (See the EPA 2007 heavy- dut y on - highwa y emissio n regulat io ns and the Tier 4 nonroad regulations for details o f t he requirements fo r new engines). · EMA members h ave very limited direct information available on metallic const it uents contained in blow - by emissio ns. This has not been an area of focus for manufacturers nor has there been a requirement to measure tho se const it uents. However, metallic HAP cons ti

tu ents have considerably different characterist ic s co mpared to th e oil which contains and transmits the HAP. Wear metal s in lube oil are thought to be in th e 2 - 20 micron range whereas the o il mist itself is closer to 300 nano met ers. Thus wear metals are no minally 6 to 60 times larger than the o il mist. Consequent ly , since capture and return systems for the o il mist are more effic ient at capturing larger parti cles, it is reasonable to conclude that th ey would effec tively return a very high perce n ta ge of the relatively large metallic HAP parti cles to the crankcase. · In applying crankcase vent emissio ns controls to existing engines, t he options available depend on the age of the engine, th e f uel used, the size of the engine, the amount of blow - by and whether the engine is naturally aspirated or turbocharged. Control s are generally mo re difficult on turbocharged engines since blo w - by e missio ns cannot be recirculated into the intake air due to turbocharger fouling and reducti ons in performance (NOTE: For a discussion o f t hose issues, see the EMA wri tten comments on the Nonroad Tier 4 NPRM in EPA docket EPA - HQ - OAR - 2003 - 0012 , those co mmen

ts dated August 20, 2003 and submitted by Jed Mandel, Page 50).- 3 -

Considering the issues described above, and if EPA decides that blow - by emissions fro m exist ing stationary CI engines are a significant source of metallic HAP emissi ons th at requi re further control s , then a potenti al way to reduce emissio ns is to consider retrofi tting exist ing non emergency CI stati onary engines that do not have a crankcase filtrat io n control system wi th such a system . EMA believes that appropriate systems exist in the form of open crankcase o il separators that can significantly collect and reduce the oil mist in crankcase blow - by vents. Such systems are designed to ei th er return the collected oil to the crankcase or condense the oil droplets for collection and proper re - use or disposal. EMA does not believe that such systems should be applied to emergency stand - by engines because such engines operate so infrequent ly, and the addit io n o f crankcase filtrat io n systems would not be cost effect ive , in t he same manner that exha ust af tertreatment systems on emergency engines are not just ified. Open crankcase filtration systems are effect ive in reducing blow - by emissio ns but mu st be sized properly to avoid significant crankcase pressure increases that can be detrimental to the engine . In general, such systems can remo ve upwards of 60 - 80% of the oil mist and return it to th e crankcase or collect it for liquid disposa l, depending on flow rates and engine operati on . In general, the more efficient the co llect io n system, the more restri ct ive it is. A balance between removal efficiency and increased backpressure needs to be maintained. As noted above, engineering judg ment suggests that metallic HAP emissio ns would be decreased at a higher rate th an the o il flo w in general . Such systems are relat ively simple and are designed to maintain engine performance wi

thout operator intervent io n . Should EPA decide to require open crankcase filtration controls on exist ing stationar y engines, EMA recommends that such systems: · Apply to non - eme rgency engines that are not currently equipped wit h crankcase oil filtrat io n systems, · Meet a minimum perf ormance standard of 60 - 80% oil removal efficiency, · Be verified to meet the oil remo val performance standard, perhaps through EPA’s exist ing retrofi

t verificat io n process, · Be applied to both naturally aspirated and turbocharged engine s , and · Have an effect ive installat io n date at least three years af ter publication of the final regulat io n in order to allow manufacturers time to develop and verify the sy stems and owners and operators to purchase and install the systems. EMA believes that retrofitting non - emergency statio nary CI engines wit h open crankcase filtrat io n systems is a technically feasible method to reduce oil - related crankcase blow - by- 4 -

emissio n s as well as metallic HAP emissio ns fr om exist ing CI engines. Open crankcase filtrat io n systems ca n be applied to virtually all exist ing non - emergency engine s and provides a flexible so lut io n t hat can be adapted to si te - specific condit io ns. Please feel f

ree to con

tact me if you have any questions regarding the informat io n provided or EMA’s recommendat io n to address blow - by emissio ns. Sincerely, 

## Joe Suchecki Joseph L. Suchecki Di rector, Public Affairs