Climate Change For Dummies. Elizabeth MayЧитать онлайн книгу.
alt="Photo depicts how fossil fuel is created."/>
© John Wiley & Sons, Inc.
FIGURE 4-1: How fossil fuel is created.
Examining the Different Types of Fossil Fuels
Coal, oil, and natural gas are all fossil fuels, but they’re not all the same. They differ in how they’re used, how much they’re used, the GHGs that they release when they’re burned, and even where they come from.
When land plants, such as trees, decomposed hundreds of millions of years ago, they pressed together into a solid form known as coal. Plants and animals in the oceans decomposed in a similar way — sinking to the bottom of the ocean, getting buried under sediments, forming peat, and eventually being compressed into fossil fuels such as oil.
Each type of fossil fuel has a different amount of carbon in it, so it puts a different amount of carbon dioxide into the air when it’s burned. Coal releases the most carbon dioxide when burned, natural gas the least. In the following sections, we take a closer look at the different types of fossil fuels, starting with the largest contributor, coal, and working our way down to natural gas.
Coal
You may think that coal was king forever ago, but about a quarter of the world’s energy still comes from this fossil fuel. Coal was the first fossil fuel that humans burned for energy — in fact, the use of coal predates written history. Here we delve deeper into what’s in coal and what’s been done to decrease pollution from coal.
Dissecting coal — What is it?
Coal is a very dirty fuel in terms of releasing GHGs as well as a witch’s brew of nasties. Toxic substances like arsenic and mercury along with cancer-causing chemicals are all released when burning coal.
Because it’s essentially carbon, it releases carbon dioxide when burned, along with many other dangerous pollutants. In December 1952, to cite one dreadful example, a massive lull in air circulation trapped the coal smoke from tens of thousands of London homes over the English city, creating a blanket of pollution. In four days, the deadly smog (the name comes from combining smoke and fog) killed upward of 4,000 people directly, with 8,000 more succumbing to respiratory illnesses later.
Lowering pollution from coal plants
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.
Oil
Today, oil provides about 33 percent of the world’s energy. People use it each time they fill up their cars, get on a plane, or turn on an oil furnace. Oil is also the key raw material used for manufacturing a wide variety of very common products, including plastics (from food containers to toys), artificial fibers, and a host of other goods such as hair gels, shampoo, deodorant, and dishwashing liquid.
HOW MUCH OIL IS LEFT?
Cheap oil has been the lifeblood of the post–World War II economic boom.
Climate change activists have been urging people to reduce their fossil fuel consumption because of the impact on global warming, but another compelling reason to cut back on oil use exists: It’s running out. There are