Electricity Generation: Air Pollution And Its Types

Electricity is a clean and relatively safe form of energy, but electricity generation and transmission affect the environment. All forms of electricity generation have some environmental impact, but coal-fired power is the dirtiest. Fossil fuel-fired power plants are a leading source of air, water, and land pollution, affecting communities worldwide. Burning fossil fuels like coal, oil, or gas releases harmful pollutants, including carbon dioxide, nitrous oxide, and nitrogen dioxide, contributing to global warming and climate change. These emissions harm human health, with children and the elderly being particularly vulnerable. Additionally, the extraction, transport, and storage of fossil fuels can create further air pollution and health risks. While renewable energy sources like wind and solar power emit little to no greenhouse gases or pollutants, the production of solar panels creates some pollution.

Burning fossil fuels

The burning of fossil fuels releases nitrogen oxides, which contribute to the formation of smog and acid rain. These emissions affect not only the air but also the land and water. Additionally, the combustion of fossil fuels releases greenhouse gases, primarily carbon dioxide (CO2) and nitrous oxide (N2O), which intensify the greenhouse effect, leading to increased average air temperatures on Earth. These gases can remain in the atmosphere for decades to centuries.

Coal-fired power plants are a significant contributor to air pollution, with their emissions directly impacting the health of nearby residents and those living hundreds of miles downwind. To reduce emissions, some coal-fired power plants burn low-sulfur-content coal or cofire wood chips with coal. Pretreating and processing coal can also minimize undesirable compounds in combustion gases, and particulate emission control devices can capture hazardous materials before they exit the power plant.

The transportation and storage of fossil fuels also contribute to air pollution. For example, diesel locomotives used to transport coal emit pollutants, and leaks from pipelines and storage facilities distributing oil and gas can drive health risks and worsen climate change. The extraction and mining of fuels can likewise harm nearby communities and workers.

The impact of burning fossil fuels on human health is significant. Air pollution from fossil fuel combustion has been linked to respiratory diseases, including asthma, chronic bronchitis, emphysema, and lung cancer. It is also a leading environmental threat to pediatric health, with children bearing a disproportionate burden of disease and developmental impairment. Exposure to air pollutants during pregnancy has been associated with an increased risk of preterm birth and low birth weight, which are risk factors for neurodevelopmental disorders.

To address the air pollution caused by burning fossil fuels, a transition to renewable energy sources is necessary. Renewable energy technologies, such as wind and solar power, emit little to no greenhouse gases or pollutants and are becoming increasingly affordable. Energy conservation measures, such as improving energy efficiency and reducing electricity consumption, can also help minimize air pollution and its associated health and environmental risks.

Greenhouse gases

According to the United Nations, generating electricity and heat by burning fossil fuels accounts for a large proportion of greenhouse gas emissions. While renewable sources like wind and solar power are gaining traction, most electricity is still generated by burning fossil fuels. In 2022, power plants burning fossil fuels or materials derived from them were responsible for about 31% of total US energy-related CO2 emissions. Additionally, the extraction, transport, and refining of fossil fuels contribute to air pollution and pose risks to workers and communities nearby.

The health impacts of air pollution from electricity generation are significant, particularly for those living near power plants. The emissions released, including sulfur dioxide, nitrogen dioxide, carbon monoxide, and hazardous pollutants like mercury and fine particulate matter (PM), can cause respiratory issues such as asthma, chronic bronchitis, emphysema, and lung cancer. The World Health Organization (WHO) reported in 2018 that 93% of the world's children breathe toxic air daily, with 1.8 billion children at serious risk due to air pollution.

To address these concerns, organizations like the American Lung Association advocate for policies promoting a transition to zero-emission sources of electricity. Additionally, the UN Environment's Share the Road Programme aims to reduce greenhouse gases and air pollution by encouraging walking and cycling as alternative modes of transportation.

It is worth noting that all electricity generation technologies, including nuclear and renewable sources, emit greenhouse gases at some point in their life cycle. However, renewable energy technologies are becoming increasingly affordable, making them the most cost-effective source of power today.

Nitrogen oxides

NOx emissions contribute to air pollution and have harmful effects on human health and the environment. They are a particular concern for people living near power plants, but they can also impact those hundreds of miles downwind. The emissions from fossil fuel combustion, including NOx, have been linked to respiratory issues such as asthma and chronic bronchitis, especially in children and the elderly. Additionally, NOx plays a role in the formation of photochemical ozone, which further contributes to air pollution.

In the atmosphere, NO is oxidized by ozone, converting it into NO2. In rural areas, away from sources of NO, nitrogen oxides are predominantly found in the form of NO2. Eventually, NO2 is oxidized to form nitric acid (HNO3) vapour, which is then absorbed by surfaces such as the ground, vegetation, or cloud droplets. It can also be converted into nitrate-containing particles or dissolved in cloud droplets. At night, different oxidation processes convert NO2 into nitrates.

The emissions of nitrogen oxides have been addressed through various strategies. For example, the U.S. Clean Air Act regulates air pollutant emissions from power plants, and the Environmental Protection Agency (EPA) sets emissions standards. Older electricity-generating units, which tend to have higher emissions, are being phased out in favour of newer units with better emission controls. Additionally, technologies such as flue gas treatment can reduce NOx emissions by converting them into less harmful compounds.

Mercury emissions

Mercury is a heavy metal that is hazardous to human and animal health. It is a naturally occurring element found in the earth's crust and in coal and other fossil fuels. When these fuels are burned to generate electricity, the mercury becomes airborne and is released into the atmosphere as a pollutant.

In the upper atmosphere, mercury is relatively harmless to humans. However, it can undergo a chemical reaction with sunlight and other elements such as oxygen, sulfur, and bromine, forming a type of salt that dissolves in water vapour. This salt falls to the earth as rain, soaking into the soil and washing into waterways. In aquatic ecosystems, bacteria can convert mercury to methylmercury, which can easily pass through the blood-brain and placental barriers and accumulate in the bodies of animals and humans.

Methylmercury contamination often starts with microscopic organisms, such as plankton, which are then consumed by larger organisms and eventually by humans. This is known as bioaccumulation, where the mercury travels up the food chain, accumulating in larger quantities at each step. For example, top predators in the Arctic, such as polar bears and seals, tend to have very high mercury levels, as do the Indigenous communities that rely on them for food.

The burning of coal for electricity generation is a significant source of mercury emissions. In the United States, coal-fired power plants are the largest source of mercury emissions, accounting for about 44% of all man-made mercury emissions. While most coal-burning power plants emit around 5 kilograms of mercury per year, there are clusters of plants with much higher emissions, exceeding 100 kilograms annually.

To address this issue, the U.S. Environmental Protection Agency (EPA) has proposed regulations to tighten mercury emissions from coal-burning power plants. The new standards aim to lower mercury emissions from lignite coal plants by 70%, benefiting the health of those living near the power plants, especially vulnerable communities and children. The EPA has also implemented a cap-and-trade system to control mercury emissions from existing and new utility sources. While the system aims for a 70% reduction by 2018, it may take until 2030 to achieve due to emissions banking and trading.

Climate change

The burning of fossil fuels to generate electricity is a major contributor to climate change. Fossil fuels include coal, oil, natural gas, and other carbon-based fuels. When these fuels are burned, they release carbon dioxide (CO2) and other greenhouse gases into the atmosphere, leading to an increase in global temperatures and causing climate change. This phenomenon is known as the greenhouse effect, where certain gases in the Earth's atmosphere trap long-wave thermal radiation, resulting in a warmer climate.

Electric power plants that burn fossil fuels are a significant source of CO2 emissions. In 2022, about 31% of total US energy-related CO2 emissions came from the electric power sector, and about 35% of the world's electricity was generated by burning coal. Coal-fired power plants are of particular concern due to their high emissions of hazardous pollutants, such as sulfur dioxide, nitrogen dioxide, carbon monoxide, and heavy metals like mercury. These emissions have detrimental effects on human health, especially for those living near power plants and downwind, contributing to respiratory issues and an increased risk of lung cancer.

To mitigate the impacts of climate change, a transition to cleaner and renewable sources of energy is essential. This includes sources such as wind, solar, hydropower, geothermal, and nuclear power. Canada, for example, generates about 66% of its electricity from renewable sources, including hydropower, wind, and solar, with nuclear power contributing an additional 15%. The cost of renewable energy technologies is decreasing, making them the most affordable source of power today.

In addition to transitioning to renewable energy sources, other measures can be taken to reduce the impact of climate change. This includes improving energy efficiency, reducing electricity consumption, and participating in carbon offsetting programs. By implementing these measures, we can work towards a cleaner and more sustainable future, reducing the health and environmental impacts of air pollution caused by electricity generation.

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