ENERGY bines and back pressure steam turbines. With a combined capacity of 184.6 megawatts (MW). Adkins Energy is one of a handful of plants that installed CHP when first built in 2002. Plant Manager Jason Townsend says electrical rates in the region at the time made generating the plant’s own electricity an economic decision. The rationale for CHP has changed over the years. “For a time, we were watching the electric market and turning the turbine off and on based on electrical pricing,” he says. “For the past several years, we’ve been running it 100% of the time. Part of that is electrical reliability. We would have had quite a few power outages if we had relied upon the grid.” Adding the steam from the natural gas turbine to the supply coming from the boilers also enabled running the plant at full capacity. As the facility expanded to 60 MMgy and added another dryer, the increased electrical load led Adkins to install a second
CHP PIONEER: Adkins Energy LLC, in Lena, Illinois, installed CHP when the plant was built in 2002. When the facility later expanded, Adkins installed a second turbine that generates power from high pressure steam coming off the plant’s evaporators. PHOTO: ADKINS ENERGY
turbine that generates power from the high pressure steam coming off the evaporators that needs to be reduced for use elsewhere in the process. Rather than wasting the energy as the steam passes over a pressure reducing valve, it now generates electricity in a let-down or back-pressure steam turbine. “We’re able to generate a little over a megawatt of electricity now for very low cost,” Townsend says.
Evolving Strategies
Whether investing in a let-down steam turbine would pay was a straightforward equation when he started at ICM in 2007, says Jeff Scharping, ICM director of sales. Only if electrical rates were over 7 cents a kilowatt hour would the capital investment for a steam turbine make sense. Today, the value of the potential carbon intensity reduction is changing the equation. But even in the earlier years, there were
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