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optionnox -- Optional Reduced NOx Emission Standards for Heavy-Duty Engines
Posted: 09 Dec 2014 17:10:08
Proposed Optional Reduced Emission Standards for Heavy-Duty Engines are now in effect. On Friday, December 5, 2014, the Office of Administrative Law approved the Proposal for Optional Reduced Emission Standards for Heavy-Duty Engines. The new regulation, which the Board approved for adoption on December 12, 2013, establishes three optional oxides of nitrogen (NOx) emission standards for heavy-duty engines: 0.1 grams per brake horsepower-hour (g/bhp-hr), 0.05 g/bhp-hr, and 0.02 g/bhp-hr. These optional standards are 50 to 90 percent lower than the current standard of 0.2 g/bhp-hr. The formal regulatory documents are posted on the Heavy-Duty GHG Phase 1 2013 webpage. Background Since 1990, the NOx exhaust emission standards for heavy-duty on-road engines have significantly increased in stringency, from 6.0 g/bhp-hr to the current 0.2 g/bhp-hr standard, which was phased in beginning in 2007. In addition to these NOx standards, ARB has also established several generations of optional, lower NOx standards over the past 15 years. From 1998 to 2003, optional NOx standards ranged from 2.5 g/bhp-hr to 0.5 g/bhp-hr, in 0.5 g/bhp-hr increments, which were much lower than the, then current, 4.0 g/bhp-hr standard. Starting in 2004, engine manufacturers could choose to certify to optional NOx + non-methane hydrocarbon (NMHC) standards ranging from 1.8 g/bhp-hr to 0.3 g/bhp-hr, in 0.3 g/bhp-hr increments, which were significantly below the, then current, 2.4 g/bhp-hr NOx+NMHC standard. Such optional standards allowed local air districts and ARB to preferentially provide incentive funding to the purchasers of cleaner trucks, which encouraged the development of cleaner engines. California is in a drought emergency. Visit www.SaveOurH2O.org for water conservation tips.