Dec 15 2009

Renewable Power Superstars

Posted by: Jonathan Marshall

Driving the transition from fossil fuels to renewable energy will require a lot more than gee-whiz technology. As two of PG&E's clean energy suppliers can testify, it takes a rigorous focus on execution and operational excellence to cut costs and stay competitive.

The latest issue of Power magazine honors six "top plants" in the North American renewable power industry that exemplify those attributes. Two of the six are under contract to PG&E, which must say something about our energy procurement team. One is Sempra Generation's El Dorado Energy solar photovoltaic (PV) plant in Boulder, City, Nev.; the other is the Rio Bravo Rocklin Power Station, a biomass-fired facility in Lincoln, Calif.

The 10 MW El Dorado plant, said to be the largest thin-film PV plant in the United States, was built in only six months, an astonishingly short time. One reason is that Sempra wisely chose to locate the project on the site of an existing gas-fired plant, slashing the cost of land, permits, transmission and operations.

But Power magazine also praises Sempra (working with supplier First Solar) for coming up with a "finely tuned and standardized" design for 1 MW increments of PV that can be combined as needed to reach almost any power level (land and sun permitting). "Sempra has quickly established perhaps the most rational development program for PV technology development in the U.S.," the magazine enthuses.

Sempra plans to replicate that model in its next proposed plant--a 48 MW expansion at the same site. In July, PG&E announced that it will buy the entire output of this Copper Mountain Solar facility when built. (The contract is subject to approval by the California Public Utilities Commission.)

The magazine also offered kudos to a decidely older and less sexy power plant: the Rio Bravo Rocklin plant, which has been burning waste wood products to generate 25 MW of power since 1989. It's owned by Constellation Energy and North American Power Group, Ltd.

California has plenty of waste wood, which is better burned in power generators than in forest fires. Currently, agricultural or forest waste provides fuel to biomass-fired plants in the state totaling about 400 MW of capacity.

The challenge for operators of these plants is preventing wear and corrosion of major components, including the combustor and heat transfer tubes. Fuel ash and contaminants like sand shorten plant life and can lead to expensive outages for maintenance.

At Rocklin, according to the magazine, these problem pushed the plant to the brink of closure until plant management took a discipline approach to upgrading fuel supplies, improving maintenance practices and motivating workers. As a result, the forced outage rate fell to less than 1 percent and employee turnover dropped from 30 percent annually to "almost zero."

"For keeping the plant in California's renewable resource mix for many years to come," the magazine concludes, "all Californians should send their congratulations for a job well done."

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