On Feb. 25, 2009, EPA proposed a NESHAP for reciprocating internal combustion engines (RICE) located at areas sources. The rule, that will become part of 40 CFR Part 63, Subpart ZZZZ, affects units with a site rating of less than or equal to 500 horsepower (HP) located at major sources, existing non-emergency CI engines with a site rating >500 HP at major sources, and existing stationary RICE of any power rating located at area sources. The promulgation of these regulations means that many previously unregulated smaller engines, including those designated for emergency use, may soon be subject to federal regulation, emissions standards, and associated control requirements.
Under this proposal, owners/operators of affected engines will be required to install control equipment to limit air toxics emissions by up to 90%, conduct emissions tests to demonstrate compliance, and burn ultra-low sulfur diesel fuel in non-emergency engines with a site rating greater than 300 HP. EPA anticipates that sources will meet the new emissions standards by installing "aftertreatment" controls to engine exhaust streams. For existing "rich burn" engines, non-selective catalytic reduction (NSCR) is the expected control approach. For existing diesel engines, a combination of oxidation catalysts (OC) and catalyzed diesel particulate filters (CDFP) may be required.
This proposal is expected to have wide-reaching affects due to the prevalence of the affected units. Sources with existing engines engines should carefully review the proposed rule to determine the feasibility of complying with the standards. EPA is receiving comments on the proposed rule for 60 days from official publication in the Federal Register.