CWLP’s Generation Portfolio
Before the new unit was built, CWLP’s generating capacity was provided by three coal-fired steam turbine generators at Dallman (372 MW), one dual-fuel natural gas – and oil-fired combustion turbine (128 MW), two oil-fired combustion turbines (totaling 38 MW), three oil-fired diesel generating units (totaling 6 MW), and two coal-fired Lakeside units (76 MW total). CWLP’s total summer maximum net generating capability was 620 MW before adding Dallman 4’s contribution and subtracting the recently decommissioned Lakeside units.
The two 1960s-vintage units at the adjacent Lakeside Power Station were shuttered with the completion of Dallman 4 (which also sits adjacent to the existing Dallman units) as part of the Sierra Club agreement. Lakeside Power Station was CWLP’s original generating facility, constructed in the mid-1930s on the shore of the utility’s then-new manmade Lake Springfield. By the mid-1960s, Lakeside consisted of eight coal-fired boilers and seven turbine-generators, only two of which — boilers 7 and 8 and turbine units 6 and 7 — were operating when the plant was shut down.
Dallman consists of Dallman 31, an 86-MW unit installed in 1968; the 87-MW Unit 32, installed in 1972; and the 199-MW Unit 33, placed into service in 1978. In spite of being decades old, these units continue to operate economically. In fact, in 2008, the existing Dallman station’s net fuel cost was $19.87 per MWh. All of the Dallman units are designed to burn 100% Illinois high-sulfur coal with an approximate heat content of 10,500 Btu per pound. Coal for all the units is trucked from the Viper Mine in Elkhart, Ill., to the coal-receiving yard for both Dallman plants.
Particulate emissions from the existing Dallman units are controlled by electrostatic precipitators. In addition, the Dallman units are equipped with wet scrubbers to control SO2 emissions. The scrubber for Dallman Unit 33 was installed in 1980; a second scrubber, serving the two older units, was put into operation in June 2001.
Each of the Dallman units has also been equipped with a selective catalytic reduction (SCR) system placed in service in May 2003, which operates during the entire year. All three Dallman units use once-through condenser cooling water from Lake Springfield.
Becoming Energy Self-Sufficient
In 2008, CWLP generated about 1.752 million MWh and purchased 410 thousand MWh for total consumption of 2.163 million MWh. CWLP’s summer peak demand of 420 MW was set on Monday, August 4 at 5 p.m., outstripping the economic production capacity of the existing plants and requiring market electricity purchases. With the addition of Dallman 4, CWLP will be able to easily meet Springfield’s summer peak demand and still have plenty of capacity available to sell into the electricity market.
Not only does Springfield no longer need to purchase expensive electricity from the open market, but it also now could very well be one of the lower-priced suppliers in that market. The foresight of CWLP and city leaders in building in that extra capacity will literally pay dividends to Springfield’s residents for many years to come.
The 200-MW net Dallman 4 project is a prime example of technological advancement and innovation that works in concert with Springfield residents’ keen desire to be environmentally progressive. Dallman 4 satisfies those desires by being one of the cleanest subcritical pulverized coal units in the nation. Its flue gas cleaning processes will remove 99% of the SO2, 95% of the NOx formed when burning high-sulfur Illinois coal, as well as 90% of the mercury in the stack gas. Carbon emissions are also reduced because Dallman 4 is 34% more efficient than the Lakeside units it replaced and shuttered in April.
The design specs of Dallman 4 also send the message that Springfield is dedicated to buying locally whenever possible. The plant burns high-sulfur Illinois coal — going against the grain of most other new coal-fired plants, which routinely select Powder River Basin coal.
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