August 9, 2011 at 6:00 pm #2172
Petro-powered Hanford plant shutting down
Written by Ben Keller
Monday, 08 August 2011 08:24
A 20-year-old power plant in Hanford powered by a gasoline byproduct is shutting down this month.
Originally designed as a coal-fired facility on the same site, the 25-megawatt Hanford L.P. Cogeneration Power Plant is now one of only eight power plants in the state, and the only one in the Central Valley, producing steam and energy by burning petroleum coke.
But given Californias greenhouse gas regulations, including AB 32, the plants are nearing the end of their practical life.
Riley Jones, spokesperson for Pittsburg, Calif.-based owner GWF Energy, LLC, said with the Hanford plants power purchase agreement with Pacific Gas & Electric Co. ending this summer, operations are expected to cease late August while the other plants are set to shut down in the first quarter of 2012.
Our plants were built in 1991, when alternative fuels such as pet coke were supported by California energy policies, and now that is not the case, Jones said. We’re looking at alternatives. We don’t understand yet what those will be.
A byproduct of the oil refining process, petroleum coke is derived from the heavier, solid sediments that settle in the bottom of the tank after crude oil has been distilled into products such as kerosene, diesel fuel, gasoline or asphalt.
The power plant once produced steam for neighboring tire manufacturer Pirelli Armstrong Tire before that factory closed down in 2002. The plant hasnt been producing as much steam since due to no demand.
The Hanford plant also produces approximately 6,000 tons of synthetic gypsum used in cement manufacturing in the regional area. Combined, GWFs six petroleum coke power plants generate around 110 megawatts of electricity, enough to power 110,000 homes and businesses.
Petroleum coke was chosen for the plant more than 20 years ago since original plans for a coal-fired plant were challenged in court by local environmental groups following its approval by the city of Hanford in 1988. The city council later adopted a moratorium banning the use of coal in new power plants. Petroleum coke is responsible for scarcely more than 0.3 percent of Californias energy generating capacity. Besides GWFs six cogeneration plants, Constellation Energy operates a 33-megawatt petroleum coke-fired facility in Bakersfield while Air Products Energy Enterprise uses the fuel in its 60-megawatt plant in Stockton.
Many still consider the fuel a large step up from coal, producing comparatively very little ash, sludge and other toxic chemicals.
Easier to ship and burn than coal, petroleum coke generates around 14,000 BTU (British thermal units) of energy per pound, compared to 8,000 to 13,500 BTU/pound associated with coal.
The sulfur content from petroleum coke, on the other hand, is usually much higher at 1.5 to 3 percent or more to coals 1 percent, and actually emits slightly more carbon dioxide (CO2).
In 2008, the Hanford plant reported 219,000 metric tons of CO2-equivalent greenhouse gases. According to Jones, however, much has been done thus far at the facility to reduce harmful pollutants, especially in light of impending regulations like cap-and-trade emission auctions stemming from Californias Global Warming Solutions Act of 2006.
There are injections in the process where the fuel is burned to eliminate, to the most extent possible, all the sulfur dioxides, he said. We put limestone in to eliminate that, and we also use other injections in the combustors to prevent other emissions that are harmful to the environment. We have an excellent record with air district as far as emissions are concerned.
Nevertheless, petroleum coke is increasingly viewed as a fuel born of an era littered with smokestacks spewing black smoke, producing around 225 pounds of CO2 per million BTUs compared to 161 pounds of CO2 per million BTUs for oil and 117 pounds of CO2 per million BTUs for natural gas.
The plant relies on fluid bed technology that suspends solid fuels on upward-blowing air jets during combustion, resulting in a tumbling mix of gas and solids that provides a more effective chemical reaction and heat transfer, also reducing the amount of sulfur emissions.
Since 1989, the GWF family of companies have constructed, owned and operated nine power plants in California with a combined generation capacity of more than 500 megawatts.
In addition to its petroleum coke facilities, the company also operates natural-gas peaker power plants in Hanford, Tracy and Lemoore. All three are now in the process of converting into a combined-cycle system that will use air condensers to convert steam back into liquid for reuse.
The work is expected to boost the plants efficiency another 20 percent or more while increasing generating capacity from 95 to 120 megawatts in Hanford and Lemoore and 169 to 315 megawatts in Tracy.
Out of 389 natural-gas-fired power plants in California, there are only 23 combined-cycle plants in operation with a total capacity of 3,766 megawatts of energy.
GWF was also approved by Kings County for a 125-megawatt solar farm near the Naval Air Station in Lemoore. The proposed solar farm would be the largest in the county, which has a handful of solar array in the works.
Photo above by Ben Keller
The Hanford L.P. Cogeneration Power Plant is stops production this month with the expiration of its power purchase agreement with Pacific Gas & Electric Co. It is the only plant in the Central Valley fired with petroleum coke, a byproduct of oil refining.
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