China’s Going Supercritical — A Critical Test for China and World?

by Bill Chameides | June 9th, 2010
posted by Erica Rowell (Editor)

Permalink | 5 comments

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
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  1. gao
    Jun 18, 2010

    Why Fahrenheit for turbines? Brace the SI!

    • Bill Chameides
      Jun 25, 2010

      Just trying to push my non-geek cred.

  2. Jim
    Jun 9, 2010

    I just don’t think going ultra-critical with coal will get the job done. I’m glad they are trying, but it will take a lot more than what they are proposing. As to people that say that AGW is a hoax, they tend to want to politicize it and have no understanding of the science. If someone says AGW is a hoax, I say “have you looked at the science”, then they says it was invented by Al Gore, then I says “have you looked at the science”, then they say it’s a conspiracy, then I say… People just don’t get it that AGW is a scientific issue and not a political one and they can’t separate the two. The fact is that there is not enough resources or land on the earth for everyone to live like an American with current means of energy production, agriculture, consumption, etc., not even close. I like to think that everyone could have a safe, reliable home with access to food and health care and education, but it will take some major changes both technically and as a society for this to happen. In the meantime we will keep pursuing the consumption of resources to the point of collapse.

    • Ken Towe
      Jun 12, 2010

      “…have you looked at the science”? Not a hoax, Jim, nor a conspiracy. Remember, it’s not just the evidence for a warming trend, it’s the direct connection of the trend to mankind’s “pollution” that is critical. A good question was asked of Dr. Michael Oppenheimer on CNN by Campbell Brown (Dec. 7, 2009)… BROWN: “You say that even if you throw out all those damning e-mails, you take them completely out of the equation. You still say the evidence is overwhelming. So what is the most persuasive piece of evidence to you?” MICHAEL OPPENHEIMER, PRINCETON UNIVERSITY: “Well, to be clear about it, the connection between greenhouse gases like CO2, carbon dioxide and global warming is as solid as the link between smoking and lung cancer. It’s that simple.” This answer is, of course, not EVIDENCE. I wrote to Oppenheimer and received this e-mail reply: 1. The geographic pattern of warming over the past 150 years matches computer simulations of what the warming should have been, given the buildup of greenhouse gases. 2. In addition, the time evolution of the observed warming is consistent with the simulated time evolution. 3. Indirect inferences of temperature in the northern hemisphere over the millennium indicate that the recent warming is unique. 4. Many responses to warming, such as collapsing ice shelves, are occurring, accompanied by evidence that such changes are unique for at least a period of thousands of years. So, may I ask you, Jim, after looking at the science, what YOU find to be THE most persuasive or compelling EVIDENCE that connects the A to the GW in AGW?

  3. MattN
    Jun 9, 2010

    – ” Especially since so many Americans think global warming is a hoax perpetrated by the Chinese and other developing-worlders to steal jobs from us.” Absolutely no one thinks that. I am well read in the “who thinks what” game of global warming and I’m telling you no one thinks that, with the possible exception of very unintelligent and uninformed people. Anyone who spends 5 minutes reaserching this can easily conclude China is not perpetuating a AGW-hoax. Just absurd. – “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.” I really think this whole “carbon intensity” speak is nothing more than a hand-waving shell game and fancy spread-sheet accounting. Are they or are they not going to reduce the total number of CO2 molecules they emit by 2020? I will bet a large sum of money they will not. 2.5 billion tons of coal produces the same CO2 no matter how efficient you make it. You can generate more electricity with your ultra-super-critical process, sure, but you’re still burning 2.5 billion tons of coal…

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