Coal-fired power generation is the largest, fastest growing contributor to global warming.
China is at the center of the coal problem. It built one large coal plant every other day in 2006. These plants will run until at least 2046. Between now and 2030, China will build more new electric power plants than the United States now has, and most of them will be coal fired. In 2007, China passed the United States as the most prolific emitter of carbon dioxide (CO2). India is behind both but is following a similar path; by 2050, India is projected to have a larger population than China.
Here in the United States, the Department of Energy predicts, coal-produced electricity will grow eight times more slowly between 2010 and 2030 than it will in China, but thirty times faster than electricity from renewable energy sources.
Although the coal problem is difficult, one somewhat new technology holds promise. Producers can capture CO2 from power plants, pump it underground, and store it there almost permanently. No one has yet done this, although commercial operations have tested all the pieces of the system. But the question remains: Is this a viable solution to the coal problem? [...]
If you’ve downloaded Google Earth, which is free online, you can take a virtual flight over the only operating synfuel plant in the United States. To do so, copy the following address into the Fly To box and click on the little magnifying glass:
[...] The Great Plains Synfuels Plant is now the largest example of carbon capture and storage in the world. The North Dakota plant compresses most of its CO2 under 5,000 pounds of pressure and pumps it through a two-foot diameter pipe for 205 miles to Weyburn, Saskatchewan. There the CO2 is injected almost a mile underground to help breathe new life into an old oil field by thinning out whatever thick oil is left so producers can pump it out. And there the CO2 will stay for thousands of years. Investigators are closely monitoring the gas field for geological leaks and so far have not detected any.
But this isn’t quite a “clean-coal” plant. The natural gas it makes from coal contains carbon, and when it is burned, it releases CO2. The whole process is no better, from a global warming perspective, than using natural gas. [...]
Once the CO2 is captured and compressed, the cost of transporting it is only about $1.50 per hundred miles per ton of CO2. Typically it is pumped 3,000 feet below ground and trapped for thousands of years, dissolved, for example, in brackish water. It might seem like the CO2 would leak out, but remember that the natural gas you use to cook with was trapped underground for more than a hundred million years. Geologists believe there is likely to be plenty of room underground for all the CO2 we need to store, but we need more research concerning storage locations.
You might think the tricky part of clean coal is learning to store the CO2 underground, but oil companies have been doing it for thirty years. Just as the Great Plains Synfuels Plant does, oil producers have pumped CO2 down into old oil fields, not to get rid of the CO2, but as a form of “enhanced oil recovery.” In fact oil-recovery projects usually make extra CO2 just for this purpose. The CO2 dissolves in the remaining thick oil, making it thin enough to pump out. In the process, a lot of the CO2 becomes trapped. Producers can recycle what does come out with the oil, pumping it back in again, just as the operators of the Saskatchewan oil field do with Great Plains’ CO2.
The benefits of clean-coal power plants are twofold: They can capture and store 90 percent or more of the CO2. And they remove other pollutants, such as mercury, more cheaply and more completely. The disadvantage is cost. At present, that cost is uncertain, which is why we need a demonstration plant. A typical estimate is that it would raise the cost of coal-fired electricity by about three cents a kilowatt-hour. Compare that with a national average retail price of about nine cents per kilowatt-hour. Of course, it will take many years to make the switch, and as clean coal technology improves, the costs may come down.[...]
Because of the high financial risk involved in building the first plant based on a new technology, new clean-coal power plants should be at the top of the list in the energy research budget. An interdisciplinary team at the Massachusetts Institute of Technology (MIT) agrees.
In 2007, MIT published the team’s comprehensive study, called “The Future of Coal,” which recommends steps that could put clean coal on track. Because several approaches to carbon capture and storage are possible, the MIT team recommends three to five demonstration projects, one for each of the technologies. These should be commercial-scale projects, according to the researchers. They also recommend three to five projects testing CO2 storage in various geological formations.
The team recommends a sensible, market-based approach to subsidizing these projects. The group suggests that the government pay only for CO2 actually stored. Companies that wish to gain this subsidy by building a demonstration project would bid on a certain subsidy rate. The bidder who offers to build the project for the lowest subsidy wins the project and the subsidy. If the project fails, it will capture and store no CO2, and the government will owe the bidder no money. This will force bidders to be realistic in their bids, and the process will select the project with the best chance of success as well as the lowest cost to the government.
Carbon capture and storage will add to the cost of producing electricity, so the MIT team considers a charge of $25 per ton of CO2 emitted as an incentive to the proposal’s adoption. If the proposal went into effect in 2015 and increased carbon capture and storage by 4 percent per year, the MIT group predicts that 60 percent of coal use would be subject to carbon capture by 2050. In spite of the increased cost, the researchers predict that coal use would expand 20 percent to 60 percent. The only amendment I would make to the MIT group’s recommendations is that the carbon charge be an untax—that is, all revenues should be returned to consumers to compensate them for higher electricity costs.
Coal has now passed oil as the largest source of CO2 emissions, and it will pull further ahead in the years to come. Because coal is used mainly to produce electricity, coal-fired generation of electricity has become the number-one greenhouse gas problem. Fortunately, coal plants don’t have wheels, so they stay in one place, making it possible to capture their CO2 and store it underground permanently.
The cost of doing so effectively doubles the price of coal, but coal is still several times cheaper than oil per unit of energy produced. Requiring new coal power plants to capture their carbon would eventually cost the United States about 0.2 percent of GDP—two-thousandths of the value of what we produce as a nation. [...] Clean coal technology may not be the best answer, but it is almost certainly one solution to a critical problem. It deserves a high-priority, federally sponsored research program, starting immediately.
These are excerpts from chapter 12 of my forthcoming book Carbonomics.