California’s first natural-gas plant to make use of Siemens rapid-start technology that reduces CO2 emissions broke ground in Lodi this month. A small utility, the Northern California Power Agency started building a $375 million, 280 MW natural gas combined-cycle plant that is able to ramp up to capacity quickly in responses to changes in load on both the supply and demand sides.
The technology is 57% efficient, using a power train that uses a gas-fired turbine at the front end to generate electricity, but then reuses waste heat from the gas turbine to produce steam that is run through a steam turbine at the back-end to generate more electricity.
Fast-start technology addresses CO2 emissions. The start-up period when a gas plant is fired up is responsible for 80% of greenhouse gas emissions while turbines are warming up. Normally that takes up to an hour. Siemens fast-start technology reduces start-up time to 20 minutes, which reduces emissions.
Combined cycle technology has already lower CO2 emissions: 6 parts per million. With this cutting edge new Siemens technology, that goes further. CO2 emissions are reduced 60% and NOx emissions are reduced 30% to 2ppm each.
With CO2 emissions of 800 lbs per megawatt hour, the plant is well under California’s emissions performance standard of 1,100 pounds met by natural gas-fired plants in the state.
The emissions standard rules out any coal-fired power in the state because coal emits around 2,100 lbs per megawatt hour, and the few remaining Southern California coal power contracts from out of state are about to expire. About one third of the power will go to The Department of Water Resources, to replace an expiring coal contract that must be replaced by 2013.
Other than reducing greenhouse gas emissions directly, the rapid-start technology also facilitates the addition of more intermittent renewable energy, indirectly helping to reduce greenhouse gas emissions. Because many of California’s wind farms are sited within a relatively small region – most are in Tecachapi – they are more subject to local wind speed than are wind farms that encompass multiple wind speeds because they are spread out over a larger region.
As California looks to bring in intermittent renewable resources, such as wind and solar power for its 33% by 2020 renewable energy standards, and readies itself for smart-grid technologies, a rapid-start (and rapid-stop) relatively harmless fossil energy plant can be one useful intermediary for putting additional wind power on the grid.
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Source: Energy prospects