Environment

Carbon sequestration - How to clean coal

Renewable energies won’t be able to fully substitute fossil fuels for years to come. Can “clean coal” be a reliable solution to climate change?
 \tA flexible CO2-tube at the mini coal power plant \'Schwarze Pumpe\' in Spremberg, Germany. The .../ Credits: Reuters
The smokestacks of the Schwarze Pumpe coal power plant in eastern Germany are an impressive sight. This giant plant towers over the surrounding fields and villages, supplying 1,600 Megawatts of energy for the region.

If you're concerned about global warming, however, you might be less impressed. The towers belch out around 36,000 tons of carbon dioxide every day–one of thousands of coal-fired plants worldwide that together produce around 20 percent of all greenhouse gas emissions and over 40 percent of carbon dioxide (CO2) emissions.

But hope is near, just hundreds of meters away, engineers are experimenting with what could be the future of the coal industry–carbon capture and storage (CCS). This technology traps carbon dioxide that would otherwise be released into the atmosphere when burning coal. Instead of lingering in the atmosphere for centuries, the captured CO2 can be liquefied and stored in places like depleted oil and gas fields.

Here at Schwarze Pumpe (literally, “black pump”), Swedish utility Vatenfall has established the world's first operational CCS pilot plant. The 30-Megawatt facility went online in September, and will test the technology and economic feasibility of oxyfuel combustion–one of a few ways by which carbon dioxide can be captured. Oxfuel burns coal in pure oxygen, which produces a nearly pure stream of CO2.

Small scale, high hopes

Although the pilot project is very small in scale (50 times smaller than the neighboring coal power plant), hopes are high about the technology’s potential to curb carbon dioxide emissions globally, particularly because global dependence on coal continues to grow rapidly. Worldwide coal consumption is expected to increase by 65 percent by 2030, with most of growing demand coming from India and China.

Eileen Claussen, president of the Pew Center on Global Climate Change, calls CCS the "best hope" for adapting the coal industry for a climate-conscious world.

"Coal is cheap and plentiful, and the United States is going to use it for the foreseeable future," Claussen told U.S. Congress in 2007. "Even if we did not, China and India would, so rapid development and deployment of climate-friendly technologies is essential."

UK economist Nicholas Stern also believes CCS is worth developing, as does U.S. President Barack Obama. He supports "clean coal", a blanket term used to refer to CCS and other processes designed to reduce the environmental damage caused by burning coal. Some U.S. lawmakers have even proposed putting a moratorium on all new coal-fired power plants that do not have CCS facilities, despite the fact that the technology is probably at least a decade away from maturity.

Solving or postponing the CO2 problem?

Aside from further technical development, the other major obstacle to widespread use of CCS is its high cost. Utility Vatenfall wants to have a commercial CCS plant running by 2020, and aims to cut costs to 20 euros per ton of captured and stored CO2. But McKinsey & Company estimates current cost at between 60 and 90 euros–well above the current price of a ton of CO2 on the global carbon market. CCS technology also consumes energy and thus raises the cost of energy production.

Several environmental advocacy organizations have also voiced concerns about the environmental impacts of injecting liquefied CO2 underground and deep into the oceans. There is also little knowledge about how long the CO2 will stay underground. The World Wide Fund for Nature (WWF) says that before investing billions of dollars, governments should be certain that stored CO2 will not leak for at least 100,000 years. After all, the aim is to solve–not merely delay–the CO2 problem.

But the industry seems confident about the leakage question. Oil companies have long been pumping CO2 into depleted oil and gas fields to maximize recovery, while Norwegian gas company StatoilHydro has been stripping CO2 of natural gas and pumping it deep below the North Sea for over a decade now.

"If natural gas stays down below the earth with high pressure for several hundred million years, why shouldn't CO2 stay down there?," says Daniel Kosel, an engineer who works at the Schwarze Pumpe facility.

The prospect of safe, cheap, and industrial-scale CCS offers an interesting perspective, particularly for countries that are most reliant on coal. Coal-rich countries like Canada, Australia, and the United States have already planned or launched pilot CCS projects. The U.S. alone has between 250 and 500 years of coal reserves and enough underground capacity to store its entire CO2 emissions for another three centuries.

Long the nemesis of climate advocates, the coal industry may still find its key to survival in the low-carbon economy of the future. It’s now up to governments to decide whether to support this technology, or if in fact “no coal” is better than “clean coal.”


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