A solar-thermal power plant near Seville, Spain. (Denis Doyle/Getty Images)There is a race afoot between two energy sources that are, in essence, different forms of concentrated sunlight. Coal, of course, is one, forged from the baked, compressed remains of ancient plant life. And coal has a centuries-long head start over the newcomer, capturing the heat of the sun with arrays of mirrors and turning it into electricity.
Coal is definitely winning. A story by Roger Harrabin of the BBC yesterday provided the latest of many estimates that China's explosively growing use of coal for electric power had vaulted it past the United States into world leadership in emissions of carbon dioxide.
Hot molten salt stores solar energy so that electricity can be generated when needed most. (The New York Times)But, as Matt Wald reports in The Times today, so-called solar thermal power plants are steadily improving, in part because of new techniques for storing solar energy as heat so that electricity can be generated when it is needed most. Some use molten salt as a kind of thermal battery.
One line in Matt's story explains the benefits of having power when you need it:
At Black & Veatch, a builder of power plants, Larry Stoddard, the manager of renewable energy consulting, said that with a molten salt design, "your turbine is totally buffered from the vagaries of the sun." By contrast, "if I've got a 50 megawatt photovoltaic plant, covering 300 acres or so, and a large cloud comes over, I lose 50 megawatts in something like 100 to 120 seconds," he said, adding, "That strikes fear into the hearts of utility dispatchers."
[UPDATE 3/15:] More on "mirrors in the desert" — concentrated solar power — can be found in a nice, and enthusiastic, overview of the technology by Joe Romm in Salon.
Photovoltaic panels are catching on, as well, mostly where governments offer rebates or other incentives or wealthy individuals are willing to make a substantial investment up front for benefits that will take decades to accrue. But here and there, photovoltaics are already paying their own way. I recently visited the Army's Schofield Barracks on Oahu, where more than 5,300 homes for military personnel and families are being built with solar hot water systems and photovoltaic panels feeding into the local grid.
Housing for military families in Hawaii has solar panels on garage roofs. (Actus Lend Lease)When the project is done, it will be the world's largest solar community (with about 15 percent of its electricity coming from the panels). The developer, Actus Lend Lease, which also built the solar-powered Olympic Village in Sydney, Australia, says this is the "first time a grid-connected project has been able to be profitable enough to install PV solar panels without subsidies."
One reason is the high cost of electricity in Hawaii, where 93 percent of electricity is generated by burning imported oil. The developer says the solar installations will save about 18,000 barrels of oil a year.
Various solar technologies have come and gone in the past as the cost of other energy choices has fluctuated. This time, though, it seems the growth in solar energy is here to stay. Matt Wald got an explanation for what has changed from Terry Murphy, the president and chief executive of SolarReserve, a company that has a design for a solar-thermal "power tower" plant capable of generating 250 megawatts of electricity, enough to run a small city:
Mr. Murphy helped build a power tower at a plant in Barstow, Calif., sponsored by the Energy Department in the late '90s. It ran well, he said, but natural gas, a competing fuel, collapsed in price, and the state had few requirements for renewable power.
"There were not renewable portfolio standards," Mr. Murphy said. "Nobody cared about global warming, and we weren't killing people in Iraq."
Rising energy prices and concerns about energy security and climate may be driving a change to renewable energy options in rich countries. But, as Matt and I wrote last year, solar is climbing from a tiny base. At the same time, the trends in China imply that any curbs in emissions in the United States, Europe, Japan and other already-wealthy places won't matter unless the coal tide in Asia can be stemmed by transfers of non-polluting technology.
In the BBC report, Mr. Harrabin's sources sounded quite glum on that front. The piece focuses on a study coming next month from Max Auffhammer and others at the University of California, Berkeley, which concludes that growth in China's coal use and emissions had been underestimated and would easily outpace any gains from efficiency or other shifts in industrialized countries.
Dr. Auffhammer told the BBC that China's energy push was all about pulling people out of poverty. Any diversion to new technologies would have to be facilitated by the world's established powers, he said: "The only solution is for a massive transfer of technology and wealth from the West."
How can that happen? No one knows.
Late this week, the countries responsible for more than 80 percent of global carbon dioxide emissions will meet in Paris in the third round of climate and energy discussions organized by the Bush administration, aimed ostensibly at finding a common long-term goal for emissions limits. Will it be more talk, talk, talk, talk, talk?
No comments:
Post a Comment