As society advances, we are discovering more pollutants that are contributing to negative climate change effects and global warming. Many of these pollutants come from our manufacturing and power generating industries, and no matter how much they are minimized, there are always going to some pollutants that will enter our atmosphere. Thermal power plants are known for producing a wide range of pollutants that are released into our atmosphere, and in this article, we look at these different types of pollutants.
A thermal power plant is a power station that converts heat energy into electric power. These power plants do this by primarily heating fossil fuels, which heats up water into steam. The steam moves through a turbine, which generates the electricity, and then it is condensed and recycled back to its pre-heated starting point. Whilst thermal power plants give out a lot of gases that are harmful to the environment, they also give out what is known as thermal pollution. Thermal pollution is the degradation of the local environment, in particular the localized waterways, that are changed by the discharge of waste water from the power plant.
Impact on the Atmosphere
Thermal power plants are known to pump out a lot of greenhouse gases and ash, which are by-products of burning the fossil fuels. Whilst some thermal power plants do use solar or nuclear energy, they are heavily reliant on fossil fuels.
Carbon dioxide is one of the main gases that is released from the burning of the fossil fuels and is known to be a greenhouse gas and a contributor of global warming. Out of all the gases released from a thermal power plant, carbon dioxide is the main one, and thermal power plants are one of the main contributors to the increased carbon dioxide levels throughout the world.
Sulfur dioxide is another gas that is released from power plants. Whilst it is technically not a greenhouse gas, it is known to have indirect effects to the atmosphere because it can affect the scattering of incoming sunlight, the formation of clouds and precipitation patterns. So, in many cases, it is considered an indirect greenhouse gas. Sulfur dioxide forms sulphuric acid in the atmosphere.This can then return to Earth as acid rain and impact various ecosystems. The level of sulfur dioxide released from thermal power plants depends on the amount of sulfur in the coal that is used—where the coal used has on average between 0.1 and 3.5% sulphur depending on which type is used. Thermal power plants are also the largest emitters of sulfur dioxide worldwide.
Nitrogen oxides are another set of gases that are released to the atmosphere by thermal power plants. Thermal power plants are also one of the biggest contributors to the global nitrogen oxide levels. Unlike nitrous oxides, nitrogen oxides are again not technically greenhouse gases, but they do have an indirect effect on the atmosphere. Nitrogen oxides are known to present visibility and respiratory issues, and they can also combine with other atmospheric gases and moisture to form acid rain and smog.
The other big pollutant to the atmosphere is ash. Ash often contains harmful particulate matter, as well as heavy metals. Ash can have multiple effects; it can get into waterways and soil wherever it falls (it doesn’t have to be the local environment) and change the alkalinity of the soil/water, which can render the soil unusable for agricultural purposes and the water undrinkable, and it can cause visibility issues. Ash, and the particulate matter contained within are also a major cause of smog—which is being seen in many cities around the world on a much more frequent and hazardous scale.
Ash contains particulate matter known as PM 2.5, which are particles of 2.5 micron or less in diameter. These particles are hazardous to humans because they are small enough to enter the lungs and cause respiratory problems. Cities worldwide are seeing high levels of PM 2.5 through frequent bouts of smog, and the problem is significantly worse over in Asia, where the levels can easily reach up to 10-20 times the recommended daily safe limit, and over 5 times the safe limit for a limited time exposure.
Impact on the Local Environment
Thermal pollution is one of the biggest issues on local environments. When the water in a power plant is no longer usable, it often gets discharged into a local waterway. This wastewater generally has a higher temperature than the local natural water, so it can increase the temperature of the water, which in turn can have a negative impact on the local ecosystem. Moreover, this wastewater often contains metals and metalloids which have dissolved—such as boron, arsenic and mercury—which can also affect the balance of the local ecosystem.
However, it is not just the discharge of water that affects the local environment. Even though ash is discharged through a flue, the affects of its release can enter the local environment near the power plant. Whilst the ash itself can be problematic, it is often what is contained within the ash that affects the local ecosystem. The discharged ash can once again contain metal ions that can escape into the local ecosystem, but it can also contain radioactive nuclides (radionuclides). Whilst a lot of radionuclides remain within the power plant, some can escape, and because they are radioactive, they can affect many aspects of the local environment—from the waterways, to the soil, vegetation, and any human and animals living in the local vicinity of the plant. The ash, and the constituents contained within, can also leach into water systems that are used for human consumption, and this can make the local water unpotable for the surrounding community.
Whilst the release of certain pollutants affects the flora and fauna within the localized environment, the land required to build these power plants has a significant effect on the local habitats before the power plant processes even begin—and can destroy many habitats, local ecosystems and local food chains without even releasing any pollutants.
Overall, with the generation of power plants, and their subsequent processes, the habitats that do remain are altered in a negative way and the effluents from the plant can have a significant impact on the local ecosystem. From a global perspective, many greenhouse gases are now released into the atmosphere and have become a major man-made contributor of climate change and global warming. Whilst measures have been put in place in many power plants to reduce the emissions to the environment, it might be a case of too little too late, as a significant amount of damage has already been done to the environment.
Sources and Further Reading