To the editor:
There are some misleading discussions going on about clean coal. Through various chemical processes a portion of the coal can be turned into gas and liquid fuels. There’s quite a lot of waste, so it’s not exactly clean, but at least it’s not released to the atmosphere — yet. Basically, the goal is to produce methane, natural gas, which we already have in abundant and cheap supply, but never mind that for the moment. Let’s focus on stopping the release of carbon dioxide from burning methane. For this, the clean-coal camp proposes the Allam cycle. It uses pure oxygen in combustion, which avoids the production of nitrous oxides and other pollutants from combusting with air. Then, it uses a liquid-CO2 thermal engine (Allam cycle), which is more efficient than the steam turbines typically used in thermal coal power plants. It has to be to produce enough electricity to offset the cost of oxygen-producing equipment. It’s a closed system, so it ends with the CO2 in a pipe, but then what to do with that? The CO2 is not consumed, which is part of the misinformation going around. Clean-coal proponents suggest that there are industrial uses for CO2, but many of those simply end up releasing the greenhouse gas to the environment. There would be about 70 times too much of it anyway. It’s much cheaper and easier to build wind and solar, and these create more jobs too.