A Fresh Look at Coal
A large number of coal-fired power plants will be shut down over the next two years.
Many applaud this as progress, though real progress would have been to build ultra-supercritical coal-fired power plants in a planned program to replace old plants.
With the current very low price for natural gas, it’s reasonable to conclude that we can afford to shut down old coal-fired power plants and replace them with natural gas combined cycle (NGCC) plants and not worry about ultra-supercritical coal-fired power plants.
An earlier article established that 167 old coal-fired power plants could be shut down without endangering our supply of electricity – providing they weren’t closed too quickly.
During the next few years the price of natural gas will rise, to the point where coal would again be competitive.
It would then be wise to consider building ultra-supercritical coal-fired power plants, and allow market forces to make the determination.
Old coal-fired power plants had a thermal efficiency of only 32% HHV, and emitted SOx, NOx, particulates and mercury, though emission controls allowed them to meet required regulations.
Ultra-supercritical coal-fired plants have a thermal efficiency of around 45% HHV, which represents a 40% improvement over old coal-fired plants.
This translates into 40% fewer emissions of SOx, NOx, particulates and mercury, permitting lower cost methods for cutting emissions by 90% or more. They would meet new mercury emission regulations. Interestingly CO2 emissions would be nearly as low as from NGCC plants.
Ultra-supercritical coal-fired power plants deserve the title “clean coal”.
We have over a 200-year supply of coal which is a national resource that should be put to good use by allowing market forces to decide the mix between coal and natural gas.
Ultra-supercritical plants operate at very high temperatures and pressures. Advances in metallurgy have allowed the use of higher temperatures and pressures in boilers and turbines. Continuing research is aimed at further improvements and the building of advanced ultra-supercritical coal-fired plants.
The United States has one ultra-supercritical plant under construction in Arkansas, while China and Europe are moving ahead with many more units. With the closing of nuclear plants in Germany, it’s very likely that Germany will turn to coal and ultra-supercritical plants for new power generation.
Real science should allow us to make good choices, and allow the construction of ultra-supercritical coal-fired power plants.
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