Sunday, September 07, 2008

Clean Coal Technologies Breathe New Life Into an Ancient Fossil Fuel

Coal contains a lot of pollutants such as mercury. Burning coal tends to release the pollutants into the air where it can damage numerous ecosystems, including human bodies. Better coal to energy technologies hold the promise of extracting the energy from coal, but separating the pollutants where they can be safely stored away from living systems. That is clean coal.

Other types of coal powerplant technologies are also called "clean coal." These technologies go further, and separate the CO2 from the exhaust gases of a coal burn. The CO2 is then either used for productive uses, or is sequestered underground or undersea. A modified Swedish owned plant in Germany is trying to learn the best ways of sequestering CO2 from exhaust.
The U.S. produces half its electricity from burning coal—and pumps out more than 40 percent of its carbon dioxide (CO2) emissions in the process. Vattenfall—the enormous Swedish electric company—has a similar problem, though it sources most of its electricity in that Nordic country from dams and nuclear power plants.

The company also owns a slew of dirty, old coal-fired power plants in the former East Germany. These plants burn the dirtiest form of coal, lignite (a.k.a. brown coal), which is soft because it’s still damp and produces much more polluting soot when burned.

With the onset of a new CO2 emissions trading scheme in the European Union, Vattenfall decided to build a demonstration project at its lignite-burning power plant in Schwarze Pumpe. The technology is called oxyfuel, and it basically relies on burning coal in pure oxygen and CO2 rather than normal air.

By stripping out the nitrogen and other gases, the burning coal produces mostly water vapor and nearly pure carbon dioxide. After condensing the water, the CO2 can be bottled and pumped underground (in this case, into an old natural gas field to get even more methane out of the ground).
Okay, so it isn't the most elegant way of separting CO2 from exhaust. It costs energy to produce the pure O2 in the first place, so it is not actually economical at this point. Not without absurd carbon trading scams so prevalent in Europe these days.

Eventually an economical way of separating CO2 from exhaust will be developed, just as economical ways of separating other useful materials from exhaust, waste, garbage, and castoffs will be developed. Best stop wasting all those valuables, humans.

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