New rules mostly miss AEL&P's diesel plants

The U.S. Environmental Protection Agency released new standards for limiting the emission of mercury and other hazardous pollutants from coal- and oil-fired power plants.


The EPA’s Mercury and Air Toxics Standards puts new limits on power plant emissions of mercury, arsenic, acid gas, nickel, selenium and cyanide. These emissions are considered toxic pollutants, according to the 1990 Clean Air Act Amendments.

The new standards focus on power plants, or electric generation units, because other large sources of mercury, medical waste incinerators and municipal waste combustors have already reduced mercury emissions by more than 90 percent in the last 15 years, according to EPA’s website. Power plants must reduce emissions by 10 percent, from 59 tons of mercury a year down to 53 tons annually.

Sen. Lisa Murkowski, ranking Member on the U.S. Senate Committee on Energy and Natural Resources, said in a release Wednesday she was concerned about the effect EPA’s new standards might have on the reliability of the nation’s electrical grid.

“Based on the analysis we’ve seen so far — and the information that EPA either would not or could not provide — I continue to be concerned about the potential threat this rule poses to the reliability of the nation’s electric grid,” Murkowski said. “Now that the rule has been released, I will be reviewing it closely with my staff and, when Congress returns in January, will continue to consider the need for legislation.”

How will this affect Juneau’s electric utility?

Only utilities with coal- and oil-fired plants 25 megawatts or larger must comply to national emission standards for hazardous air pollutants, also known as maximum achievable control technology standards, according to EPA documents.

Since Alaska Electric Light & Power’s largest diesel generator is 23MW, the utility will not be affected by the new standards. Most of the utility’s generators are two-megawatt units.

Scott Willis, power generation engineer for AEL&P, said EPA’s mercury standards are also limited to steam-generating units. AEL&P’s diesel back-up generators use reciprocating internal combustion engines.

“Just a big diesel engine,” Willis said.

Much larger electric generation units use boilers to produce steam that spins a turbine generator.

“A steam plant is kind of complex,” Willis said. “If you want a 1,000-megawatt plant, you need steam power.”

AEL&P won’t escape all of the EPA’s recent air quality regulations.

Though AEL&P will slip under EPA mercury standards, an EPA rule that limits carbon monoxide emissions will require the utility to make $1.5 million in upgrades to it’s back-up generation system by 2013, Willis said. The National Emission Standards for Hazardous Air Pollutants for Reciprocating Internal Combustion Engines, passed in 2010, will affect 10 of AEL&P’s generators — some of its generators are diesel turbines.

The air quality standards will require a 70 percent reduction in carbon monoxide emissions, Willis said. Other hazardous pollutants occur with carbon monoxide, so a limit on CO will limit these other pollutants as well.

Many of AEL&P’s generators are powered by Electro Motive Diesel engines, Willis said. These diesels are widely used for railroad locomotives, but can be used in marine applications and energy generation.

Willis said he worked with EMD on a solution. EMD recommended attaching what Willis said is essentially a catalytic converter — a device in the exhaust system that converts pollutant gases into less harmful gases.

The EPA also requires installation of a computer system to continually monitor emissions.

The project will cost $150,000 per generator, and Willis said his crew will be able to do most of the work. However, the utility will contract one experienced person from the maker of the catalytic converter. The work will be done during the 2012 calendar year.

Willis said the work is budgeted for 2012 and the costs are within AEL&P’s normal budget and normal investments.

“If the money was not spent on this project, we would have spent it on other improvements,” he said.

Willis also said $1.5 million is not a huge investment for the utility.

According to Willis, ratepayers will see a rate change similar to what they would see with any other investment.

“Every dollar AEL&P spends comes from the ratepayer.”

Willis said the utility will raise rates at the next rate increase, coming a few years from now.

“So there is not an effect immediately, but ultimately the costs are recovered from the ratepayers,” Willis said.

These air quality regulations reveal advantages to Juneau’s predominant reliance on lake-tap hydroelectric power from Lake Snettisham and Lake Dorothy.

Diesel generation makes up only about 2 percent of AEL&P generation; the rest comes from hydro, which has no hazardous emissions, Willis said.

“These costs for pollution controls that really affect other utilities don’t affect us,” he said.

However, Willis said, it’s a little bit frustrating for the EPA to include the utility in its carbon monoxide regulations, “because we use these units so rarely,” he said.

• Contact reporter Russell Stigall at 523-2276 or at


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