China’s Going Supercritical — A Critical Test for China and World?
by Bill Chameides | June 9th, 2010
posted by Erica Rowell (Editor)
China aims to lead the way in high-efficiency power generation from coal.
China has pledged to reduce its greenhouse gas emissions per unit of gross domestic product (or carbon intensity) by 40 to 45 percent by 2020. Yet about 70 percent of its electricity comes from coal, the most carbon-intense of fossil fuels, and the country’s use of coal is growing by leaps and bounds. In 2008, China’s coal consumption had increased by 129 percent from the year 2000 to an estimated three billion short tons, which is almost 40 percent of the world’s total coal consumption.
How is China going to meet its emissions goal if it keeps depending upon coal to fuel an ever-expanding economy?
I posed that question to a faculty member from Shanghai Jiao Tong University last night over dinner at the university’s faculty club. The answer was “ultra-supercritical.”
Subcritical, Supercritical and Ultra-Supercritical Coal-Fired Power
A coal-fired power plant operates by boiling water to create a high-pressure steam that drives a turbine which produces electricity by moving an electrical wire through a magnetic field. (For a fuller explanation, watch the video below.)
A conventional (or subcritical) plant typically operates at temperatures up to 1050 degrees Fahrenheit and has an efficiency of between 33 and 39 percent. Operating a plant at higher temperatures and pressures can increase its efficiency, potentially lowering emissions of carbon dioxide (CO2) in the process.
A so-called supercritical plant operates at sufficiently high pressures and temperatures (between 1000 and 1075 degrees Fahrenheit) such that the water and steam become indistinguishable (the critical point of a liquid), allowing efficiency rates to reach 42 percent. An ultra-supercritical plant operates at temperatures of 1075 degrees Fahrenheit and above and can achieve efficiencies of more than 42 percent.
(A quick caveat here — keep in mind that even with these efficiency boosts, coal still produces roughly twice as much CO2 emissions as a natural gas plant and adding carbon-capture technologies one day may negate most if not all of the efficiency gains. But coal doesn’t look to be going away any time soon, either, so making plants more efficient is you might say critical.)
Ultra-Supercritical Coal-Fired Power Plants Figure in China’s Energy Plans
My dinner companion explained that part of China’s strategy to meet its greenhouse gas commitment is to continue full steam ahead converting its coal-fired power plant fleet from a conventional one to an ultra-supercritical one — a move that will decrease its energy intensity from coal-generated power by more than 20 percent.
By all accounts China has jumped into the ultra-supercritical game with both feet. It is busy building supercritical and ultra-supercritical power plants at an astonishing rate — a whole lot faster, by the way, than we are here in the United States. And China’s ultra-supercritical power plant that went online in Yuhuan in 2006 reportedly holds the record as “the world’s cleanest, most efficient and most advanced ultra-supercritical units” with an efficiency of 46 percent.
My dinner companion explained that the key to making further advances in ultra-supercritical technology “depends on materials,” the development of new alloys for boilers that can withstand the extreme conditions of ultra-supercritical coal-fired power plants. He opined that the R&D race for developing these new alloys is currently being led by the United States, where high-temperature material engineers are working on nickel-based alloys capable of operating at 1400 degrees Fahrenheit and yielding efficiencies of more than 50 percent.
China also has a healthy R&D program in coal-fired power plants, some of which is being carried out right here at Shanghai Jiao Tong University. But much of its focus is taking discovery to application — in the case of advanced coal-fired plants, that means developing cost-effective systems for manufacturing the new generation of high temperature- and high pressure-ready boilers. He thinks that the United States will likely win the race for the development of advanced alloys, but lots of ultra-supercritical power plants will be built in China.
Reality Check on China’s Coal Moves
All this effort to make coal more efficient (and more environmentally palatable) is impressive, no question. I admitted as much to my dinner companion, but went on to point out that a 20 percent increase in efficiency does not get you a 40 percent reduction in carbon intensity.
He agreed wholeheartedly and said that the government had other plans including beefing up nuclear, solar, and wind projects. I asked him what Beijing intended to do with all the old, conventional plants already online, and he said government plans call for shutting down the really inefficient ones and upgrading the rest. “It is going to be difficult,” he said, “but I think we can get the job done.” (See here and here.)
I am not sure I buy his conclusion, but such optimism and belief in the government were at least refreshing — a far cry from the sentiments routinely expressed in the United States.
But Then Global Warming Was Mentioned …
He said, “You know, many people in China do not believe in global warming. Last year, in Beijing, the temperatures were lower than normal, and an archeologist claims that 300 years ago, carbon dioxide concentrations were higher than today.”
He explained that many Chinese think that the whole global warming thing is a hoax fostered by Americans to keep China from developing economically.
It’s an interesting viewpoint. Especially since so many Americans think global warming is a hoax perpetrated by the Chinese and other developing-worlders to steal jobs from us.
So who’s right? I don’t mean to be super critical, but maybe, just maybe they’re both wrong.filed under: carbon dioxide emissions, climate change, coal, energy, energy efficiency, faculty, fossil fuels, global warming
and: carbon intensity, China, Copenhagen Accord, electricity, greenhouse gas emissions, supercritical power plant, ultra-supercritical power plant