Six senators this week urged U.S. EPA to reconsider a proposal that eases regulatory requirements for dirty backup electricity generators.

At issue is a June proposal to amend the National Emission Standards for Hazardous Air Pollutants (NESHAP) for reciprocating internal combustion engines, or RICE, which are typically used during emergency situations to keep power flowing and prevent blackouts.

EPA's proposal, which it issued as part of a settlement agreement, would allow demand response operators to use the diesel-fueled generators for 100 hours per year without installing any emissions control technology -- significantly more than the current cap of 15 hours.

The senators, five Democrats and Independent Joe Lieberman of Connecticut, said in a letter to EPA Administrator Lisa Jackson earlier this week that they "are concerned that the current proposal would significantly expand the number of hours that these backup generators would be allowed to operate without any emissions control technology, even in non-emergency conditions."

"We urge you to finalize a rule that ensures Americans are not breathing dirty air," they added.

The RICE NESHAP has become a top concern for public health advocates as President Obama begins his second term. EPA is expected to finalize the proposal by Dec. 14.

The proposal also allows the generators to be used for up to 50 hours per year during high-demand periods, or "peak shaving," and other nonemergency situations through August 2017.

Lieberman, along with Democratic Sens. Frank Lautenberg and Robert Menendez of New Jersey, Sheldon Whitehouse of Rhode Island, Kirsten Gillibrand of New York and Ben Cardin of Maryland, said that provision is "troubling."

"Operating an uncontrolled diesel generator instead of drawing power from the electricity grid is simply shifting energy demand from the grid to a more polluting on-site generator," they wrote. "If emergency generators wish to participate in electricity markets, they should be required to compete on a level playing field by meeting emissions limits that protect public health."

Utilities have said that demand-response companies want the standard eased so they can avoid installing emissions control technologies.

Electric Power Supply Association (EPSA) President John Shelk applauded the letter yesterday.

"EPSA hopes that as the Dec. 14, 2012 deadline for a decision nears that this congressional input will have an impact as EPA carefully addresses the concerns many of us have raised," Shelk said in a statement.

On the other hand, Boston-based power marketer EnerNOC has said that the 15-hour limit was arbitrary and that the generators should be available for longer periods of time (Greenwire, May 29).

Click here to read the letter.