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US EPA relaxes PM emission requirements for generators in remote Alaska

30 October 2019

On October 4, 2019, president Trump signed Senate Bill 163, the “Alaska Remote Generator Reliability and Protection Act” that relaxes US EPA Tier 4 PM emission requirements for generators used in remote areas of Alaska. Today, the US Environmental Protection Agency (EPA) finalized these PM emission amendments [4562]. This follows the relaxation of the Tier 4 requirements for NOx emissions for this engine category in 2011, under president Obama administration.

Under the prior (post-2011) regulations, stationary non-emergency CI engines in remote areas of Alaska were allowed to meet emission standards for emergency engines (effectively, Tier 3), except they had to be fitted with PM control devices to reduce PM emissions by 85%, or by 60% in engines above 30 L/cylinder. The Alaska Remote Generator Reliability and Protection Act directed the EPA to change the New Source Performance Standards (NSPS) for Stationary Compression Ignition (CI) Internal Combustion Engines by removing these PM requirements, and to allow engines certified to Tier 3 PM standards in remote Alaska.

In 2011, the EPA revised the NSPS rule to remove the requirement for these engines to meet Tier 4 standards for NOx and other pollutants except PM. With the newly adopted relaxation of PM requirements, the emission requirements for generator set engines in remote Alaska have been fully downgraded from Tier 4 to Tier 3.

In remote areas of Alaska, nearly 100% of the electricity used in villages is supplied by diesel-fueled generator sets, with many villages relying on diesel generators that are between 10 and 30 years old. Many small utilities are looking for ways they can purchase new generator sets to improve efficiency and reduce the maintenance costs of worn out engines. However, emission control technologies such as particulate filters are having difficulties working in remote areas of Alaska. If the generator shuts down in remote Alaska, qualified service technicians are at least one to two days out and extremely expensive, said US Congressman Don Young who is the sponsor of H.R. 422, companion legislation to S. 163.

Source: Senate Bill 163 | US EPA NSPS amendments