For better air, we need efficient air conditioners

Sep 13th, 2010 | By | Category: Energy Efficiency

Karl Wagener, the executive director of the Council on Environmental Quality, writes that last week’s air quality was the state’s worst in years. For better air quality, he says, we need efficient air conditioners.

HARTFORD – The air in Connecticut last week was the most polluted of the summer and, for many towns, the worst in more than two years. Part of the problem was a big demand for electricity caused by the large number of inefficient air conditioners in the state, according to the Council on Environmental Quality (CEQ).

The CEQ explained that as the temperature goes up and people start their air conditioners, seldom-used power plants are called upon by ISO New England – the company that oversees the regional electricity supply – to start generating electricity to meet the peak demand. Some of these so-called “peaking plants” are more expensive to operate and produce more pollution on an hourly basis when compared to regularly-operating power plants.

As an example, the CEQ noted that the “South Meadow Jets” facility in Hartford, which is used only rarely, was called upon to produce electricity last Thursday (Sept. 2) to help meet the heightened demand. According to recent CEQ research, the South Meadows facility – which is essentially eight aging turbine engines that burn jet fuel – puts out more particulate matter on an hourly basis than almost any other power plant in the state.

The South Meadows Station is owned by the Connecticut Resources and Recovery Authority (CRRA). Aside from the occasional load of wood chips several years ago, the plant has used nothing but municipal solid waste as fuel since the late 1990s, according to CRRA’s Paul Nonnenmacher.

Hartford Electric Light Company (HELCO) corrected smoke problems at the South Meadows plant by converting from coal to oil in 1967. In 1970 CL&P installed four internal combustion jet-fueled turbines each with a nominal rating of 46 MW for peaking capacity at the South Meadows station. These units are classified as “black start” which means they have the capability to be started and brought to full capacity in minutes in the event of a power failure. In 1987 and 1988 the two abandoned coal-fueled steam generators constructed in the late 1940s at CL&P’s South Meadows Station were reactivated by the Connecticut Resources and Recover Authority and CL&P as a trash-to-energy facility with a total capacity of 64 MW of electricity. CL&P currently owns no generating facilities. Today the company is “strictly poles and wires.”

According to the CEQ, the added pollution from these peaking plants is not an inevitable consequence of hot weather.

“Our choice is not between keeping cool and sweltering,” said CEQ Chair Barbara Wagner. “Our choice is between cooling our homes in an efficient way or in an inefficient way.”

More information from CRRA about their peaking power plant:

CRRA owns a peaking power plant which is adjacent to the Mid-Connecticut Project trash-to-energy facility in Hartford’s South Meadows.

The peaking plant is activated remotely by the Connecticut Valley Electric Exchange and can reach the maximum wattage of 160 MW in less than 15 minutes.

Although the peaking plant is less efficient than the units at base-load power plants, the peaking plant operates only a few hours per year. The peaking plant is operated in full compliance with all applicable permits, orders and regulations, including a Title V Air Operating Permit issued by the Connecticut Department of Environmental Protection. DEP has issued CRRA a trading order, allowing it to buy credits to offset any exceedances of emissions limits.

DEP has also ordered CRRA to determine the steps necessary to bring the peaking plant into compliance with emissions regulations and the costs of those steps. A report is due in 2011.
 
The peaking plant consists of four electric generator sets, each capable of producing 40 megawatts (MW) of electricity. Each generator set consists of two Pratt & Whitney FT4A-9 jet engines typically used for aircraft applications on Boeing 707 and B-52 aircraft. The FT4A-9s run on jet fuel.

Compared with base-load power plants that run continuously, peaking power plants are only run when demand for electricity nears its peak – hence the term “peaking plant.” As demand increases, the Independent System Opeerator-New England (ISO-NE), which operates the regional power grid, brings peaking units online.

ISO-NE – not CRRA – determines when to activate the peaking units and for how long.
 
Recently, ISO activated this peaking plant on Sept. 2 and Sept. 4 to meet an unusually high demand for power. The “jets,” as they are known, ran for about three and a half hours at a time. Although the jets have the ability to run around the clock, in the past few years they have averaged about 12 to 18 hours of service per year.

Hartford’s peaking plant went into commercial operation on June 1, 1970. CRRA acquired the plant in 2001 from Connecticut Light & Power (CL&P) after legislation restructuring Connecticut’s electric utility industry required CL&P to sell its generation assets. At the same time, CRRA acquired the electric generating portion of the adjacent trash-to-energy plant.

A 5 million-gallon jet fuel storage tank is adjacent to the peaking plant and the site includes a common maintenance shop and office building. The tank was installed in 1945 and needs to be replaced, so starting in the fall of 2010 CRRA will remove the existing fuel tank and replace it with a 550,000-gallon tank – almost 90 percent smaller – which ISO agreed will be sufficient for the peaking plant’s limited hours of operation.

The complete news release from CEQ can be found at http://www.ct.gov/ceq/lib/ceq/September_2010_IOTM_Release.pdf or it may be viewed on the CEQ’s website at http://www.ct.gov/ceq.

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