Читать книгу Climate Change For Dummies - Elizabeth May - Страница 87

Clean coal doesn’t exist. Options for cleaner uses of coal, however, do. Over a period of decades, many technological advances have been made to reduce pollution from burning coal. The following actions were taken to diminish pollution from coal plants:

 The first step taken to reduce pollution from coal plants was aimed at reducing nitrous oxide emissions. To do this, the coal was burned at incredibly high temperatures (around 1,500 degrees F) — this is considered a low temperature compared to the 2,500 degrees F at which coal is usually burned. At such a low temperature, nitrogen doesn’t combine with oxygen, thus no nitrogen oxide is created. This process happens during the burning process and reduces many pollutants but does nothing to reduce carbon dioxide.

 The next step in pollution reduction was when coal-fired power plants in many industrialized countries added scrubbers in the 1970s to capture the sulfur and prevent it from falling to Earth as acid rain. Scrubbers are technically called flue gas desulfurization units — devices installed right in the flue. The device sprays a specially made liquid mix of water and powdered limestone right into the emissions coming from the burning coal. The spray immediately soaks up and becomes one with the sulfur, trapping it in this new solid material.

 Another way of “cleaning” coal is called fluidized bed combustion, where the coal actually becomes liquid in the bed of the furnace. Scrubbers and fluidized bed combustion reduce emissions of nitrogen and sulfur dioxide, but not of carbon dioxide. Industries were even able to extract the sulfur and sell it, increasing their profits. Removing sulfur dioxide was a step in the right direction for solving the problem of acid rain, but these scrubbers, again, do nothing to reduce carbon dioxide, mercury, or the whole array of other pollutants.

Research and development teams are devoting a lot of time and energy to producing a type of coal that doesn’t add to GHGs. One idea suggests turning coal into a gas and stripping the carbon dioxide out of that gas, then storing the carbon dioxide in the ground. The technology to actually strip the carbon dioxide from the gas doesn’t yet exist, but the carbon-storage technology does (and parts of Europe already use it). Until the day that carbon dioxide can be stripped out of coal, conservation practices and replacing coal-fired power plants with cleaner, renewable fuels are the most effective and sustainable ways to reduce GHGs. (Flip to Chapter 13 for more on clean fuels and carbon storage.)

Coming out of COP26 in Glasgow, for the first time climate negotiators from every country on earth agreed that everyone has to phase down coal use together. Many countries, including the UK and Canada, are part of the Powering Past Coal Alliance. Increasingly, in the context of a rapidly depleting global carbon budget, governments agree coal-burning for electricity must end. The search for finding cleaner ways to burn it is replaced with the race to replace it.