Researchers at Sandia National Laboratory are developing a new gas turbine to increase the efficiency of conventional electrical power plants with a generation system that could increase the thermal-to-electric conversion efficiency by 40 to 50 percent.
Electrical generation is an especially dirty process when coal is being used as the fuel source. It's not too efficient, either, with only about 1/3 of the energy from the burned coal being turned into useful electricity. Research is currently being done on two test assemblies which use supercritical carbon dioxide (S-CO2), rather than water and steam as the working medium, and a system using the Brayton cycle with equipment more akin to a jet engine than a conventional steam turbine.
While most coal-fired electrical plants could see benefits from this new method, other kinds of power generation would also be able to apply these developments. Nuclear power, biomass, and solar thermal power plants also could be improved through adoption of S-CO2 Brayton generation.
The S-CO2 Brayton equipment is also much more compact than equivalent power generating conventional turbines, which helps to reduce installation costs. This should also serve to make retrofitting of existing power plants easier, since available space for the conversion would be easier to allocate. A small, 4 cubic meter (about 141 cubic feet) system could replace more than 120 cubic meters (about 4,238 cubic feet) of equipment and produce the same amount of power.
Furthermore, while special materials are needed for conventional Rankine cycle turbines, because steam is corrosive at the temperatures and pressures involved, this is not an issue with S-CO2 Brayton equipment, which can be fabricated from simple stainless steel.
With efficiency increases like that, old, outmoded coal plants could be retired, and swapping in new, more efficient equipment could replace the need for building new coal plants altogether.
image via Wikimedia
written by tim, February 29, 2012
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