Wednesday, March 27, 2013

Carbon capture and storage can lead to less CO2 emissions

Burning fossil fuels releases large quantities of carbon dioxide, a harmful greenhouse gas which is held mostly responsible for climate change and global warming. This is the main reason why fossil fuels are labeled as the "dirty fuels", and why so many people around the globe want to see them being replaced with renewable energy source such as solar and wind energy. Fossil fuels are oil, carbon and natural gas.

However, there is still a significant number of energy experts who believe in carbon capture and storage technology (CCS) as the key technology in reducing the amount of carbon emissions from fossil fuel fired power plants, and thus making fossil fuels usage less damaging to our environment. In the ideal scenario, carbon capture and storage technology would even lead to CO2-free power plants, though this scenario is still far from reality.

Carbone capture technology sounds excellent in theory but scientists have plenty of work ahead of them in order to find solutions that would make this technology efficient and commercially viable. Greatly increased operational costs have been the most frequent result of currently tested CCS solutions, and this is something that science will need to improve in years to come before this technology can be implemented on global scale.

Scientists are currently researching several different CCS technologies, and currently most intriguing CCS project is the pilot fossil fuel plant at the TU Darmstadt's Institute for Energy Systems and Technology that is being utilized for investigating two brand new methods for CO2 capture. If successful these new CCS methods will allow nearly totally eliminating CO2 emissions and require virtually no additional energy input and entail only slight increases in operating costs. Both of these methods employ natural substances and reduce the energy presently required for CO2 capture by more than half.

The first method is called "carbonate looping" method, and the working principle of this method is based on utilizing the naturally occurring limestone to initially bind CO2 from the stream of flue gases transiting power plants' stacks in a first-stage reactor. The resultant pure CO2 gets reliberated in a second reactor and can then be stored. The main advantage of the carbonate-looping method is that even existing power plants can be retrofitted with this new method.

The other method is called "chemical looping" method. This method should allow capturing CO2 with hardly any loss of energy efficiency. Under this method, a dual-stage, flameless, combustion yields a stream of exhaust gases containing only CO2 and water vapor. The CO2 can then be captured and stored.

The pilot plant has already demonstrated its ability to bind CO2 in conjunction with initial trial runs. The further investigation of these two methods should be done over the next couple of years.

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