All forms of electricity generation have an environmental impact on our air, water and land, but it varies. Of the total energy consumed in the United States, about 40% is used to generate electricity, making electricity use an important part of each person’s environmental footprint.
Producing and using electricity more efficiently reduces both the amount of fuel needed to generate electricity and the amount of greenhouse gases and other air pollution emitted as a result.
Over the past century, the main energy sources used for generating electricity have been fossil fuels, hydroelectricity and, since the 1950s, nuclear energy.
Coal, gas and oil
Fossil fuel power plants burn coal or oil to create heat which is in turn used to generate steam to drive turbines which generate electricity. In gas plants hot gases drive a turbine to generate electricity, whereas a combined cycle gas turbine (CCGT) plant also uses a steam generator to increase the amount of electricity produced. In 2017, fossil fuels generated 64.5% of electricity worldwide. These plants generate electricity reliably over long periods of time, and are generally cheap to build. However, burning carbon-based fuels produces large amounts of carbon dioxide, which drives climate change. These plants also produce other pollutants, such as oxides of Sulfur and nitrogen, which cause acid rain.
The burning of fossil fuels for energy causes considerable numbers of deaths due to air pollution. For instance, it is estimated that in China alone 670,000 people die prematurely – every year due to the use of coal. Fossil fuel plants require very large quantities of coal, oil or gas. In many cases these fuels need to be transported over long distances, which can result in potential supply issues. The price of the fuels has historically been volatile and can rise sharply at times of shortages or geopolitical instability, which can result in unstable generation costs and higher consumer prices.
Nuclear power reactors use the heat produced from splitting atoms to generate steam to drive a turbine. No greenhouse gases are produced in the fission process, and only very small amounts are produced across the whole nuclear life- cycle. Nuclear power is an environmentally friendly form of electricity generation and does not contribute to air pollution. In 2018, nuclear power generated 10.5% of the world’s electricity.
Nuclear power plants, like fossil-fueled power plants, are very reliable, and can run for many months without interruption, providing large amounts of clean electricity, regardless of the time of day, the weather or the season. Nuclear fuel can be used in a reactor for several years, thanks to the immense amount of energy contained in uranium. The power from one kilogram of uranium is about the same as 1 ton of coal. As a result, a correspondingly small amount of waste is generated. On average, a reactor supplying a person’s electricity needs for a year creates about 500 grams of waste – it would fit inside a soda can. Just 5 grams of this amount is used nuclear fuel – the equivalent of a sheet of paper. There are several management strategies available for the used fuel, such as direct disposal or recycling in reactors to generate more low-carbon electricity.
Biomass A biomass plant operates in a very similar way to gas- and coal-fired power plants. Instead of burning gas or coal, the plant is fueled by different forms of biomass (such as purpose-grown trees, wood chips, domestic waste, or ‘bio gas’). In 2017, biomass generated 2.3% of the world’s electricity.
Biomass production can require a lot of energy, both in terms of production of biomass itself and in terms of transport. Due to this, the energy required can be greater than the energy value in the final fuel, and the greenhouse gas emissions can be as high, or even greater, than those from equivalent fossil fuels. Additionally, it can take more than 100 years for the emitted carbon dioxide to be absorbed, which leads to a short-term emissions increase. Other environmental impacts related to land use and ecological sustainability can be considerable. Additionally, as with coal, the use of biomass can contribute to air pollution, and thus has negative health impacts for populations local to biomass plants.
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Written By: Laila El Azhary