environmental sciences

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Burning Of Coal As An Energy Source Environmental Sciences Essay

This investigation is about whether we can cope without the combustion of coal as an energy source. It has been selected because carbon is an important element because it can be used to produce energy for generation of electricity, heat and also industrial purposes such as refining metals. There are several concerns tough for the burning of coal, for governments and companies who desire to set up environmentally friendly energy producing processes. There are a few main concerns for this as coal burning cause many environmental and health effects due to its emissions.

Chemical background

About 100 to 400 million years ago, parts of the Earth were covered with vast swampy forests. The plant remains during that time forms into fossil fuel, coal (Engineering-resource n.d). Since it forms after millions of years, it is categorized as a nonrenewable energy source. Plants absorbed energy from the sun millions of years ago. That energy absorbed became the energy that we get from coal today (Lepisto,C 2012). The plants do this through the process of photosynthesis.

6CO2 +6H2O  C6H12O6 + 6O2 (equation for photosynthesis)

Primarily, coal is comprised of carbon and other variable elements. Coal varies in its composition. Typically, it consists of six rings of carbon atoms that are joined together. It is a very complex structure, as it also has hydrogen, oxygen and nitrogen too. But it also has sulphur, which is an environmental pollutant.

There are two aspects when trying to understand the chemical composition of coal. One is its proximate analysis and the other is its elemental analysis. Proximate analyses are parameters like moisture, ash and fixed carbon. Elemental analysis is the quantitative values of carbon, hydrogen sulphur, oxygen and nitrogen within the coal itself. Typical coal has a heating value of 6.67 kWh per kilogram, and this coal usually has a carbon content of 80% (Fisher 2003).

When trying to find the carbon content or intensity in coal, we get

= kmol

What happens is carbon mixes with oxygen in the air during combustion. This produces carbon dioxide:

C + O2  CO2 (equation for combustion of carbon)

Carbon dioxide has an atomic mass of 44 kg/kmol, as (12 + (16 x 2)). When we calculate the carbon dioxide released into the air for every kilogram of combusted coal,

kmol x = kg = 2.93 kg

The value above the can be used for calculating the emission factor of carbon dioxide for the combustion of coal. The useful energy output of coal is generally around 31% of the 6.67 kWh per kilogram we can calculate that the combustion of 1 kg of coal releases around 2kWh of electrical energy. Since we know that 1kg of coal releases 2.93 kg of carbon dioxide, CO2 emissions are about 1.47 kg/kWh.

And this value seems to have significantly increased, as a report by the CO2 Carbon Dioxide Emissions from the (Generation of Electric Power in the United States, DOE, EPA 1999) reported a CO2 emission of 0.963 kg/kWh. But when compared to carbon dioxide emissions from other sources, coal carbon dioxide emission is the highest. Oil power had a CO2 emission value of 0.881 kg/kWh and natural gas had a value of 0.569 kg/kWh. The estimates of carbon dioxide emissions of other energy sources like nuclear power, hydro, and wind energy are reported to be 100 times lower.

A (direct testimony of James E. Hansen) stated the adverse effects of coal burning plants. It would be a major problem as it would become a huge contributor to the enhanced greenhouse effect which will lead to global warming and the rising of the sea level due to the melting of the polar ice caps. But there are also other negative effects of coal-burning plants.

Social and Environmental Issues

There are a few reasons why the coal is a suitable energy source.

Coal is found on every continent in over 70 countries, and the biggest reserves are in the USA, Russia, China and India (Green world investor 2011). This shows that coal is found in abundance. Coal has economical recoverable reserves of about 264 billion short tons, which can last almost 234 years. Oil reserves have about 29.4 million barrels, which can last 11.1 years and natural gas reserves have about 186.9 trillion cubic feet which can last about 9.8 years (Opposing views n.d). This shows that there are plenty of coal reserves, which can last much longer than other non-renewable energy sources.

Coal is also a reliable source of power. The energy potential of coal is enormous compared to other fossil fuels like oil and natural gas (Green World Investor 2011). Coal is continuous and predictable. Compared to wind and solar energy, coal based energy can be generated at any time. Solar and wind energy occur at irregular intervals in nature, making them less reliable.

The cost of coal is very low. It is very much cheaper than nuclear, natural gas, oil. According to (http://www.coaleducation.org/), in India, coal can be obtained at just $20/ton. Coal based electricity is generated at only 2-4c/KWh. This shows that coal is the cheapest electricity source available.

` There are several environmental problems of the burning of coal as an energy source.

Burning coal releases harmful greenhouse emissions such as carbon dioxide, sulphur dioxide, nitrogen oxides, and sulphuric acids. Coal burning emits almost twice as much carbon dioxide to produce the same level of heat when compared to natural gas. This will increase the amount of harmful greenhouse gases released into the earth’s atmosphere. This will contribute to the Enhanced Greenhouse Effect and global warming.

High sulphur content in coal will cause acid rain. Acid rain will cause leaching of minerals from the soil, corrosion of statues and many more.

Coal-based power plants emit mercury, selenium and even arsenic, and these three chemicals are detrimental to human health (World Coal Association n.d).

Coal burning causes the devastation of natural habitats near the coal mines. Animals and plants that make the place their home will lose their natural habitat (Fossil Fuel 2007). This will cause the extinction of many plants and animals if this persists. Also, it leads to deforestation, air and water pollution in areas near the mines. Not only does this cause noise and air pollution, but soil erosion as well.

Explanation of solutions for coal-burning power plants that could minimize risk of chemical pollution to the environment:

Coal power plants should have tall smoke-stacks. This will help disperse the gases, will reduce the risk of chemical pollution to the environment.

A solution from (http://www.engineerlive.com) states that the process of gasification could be used; after turning coal into gas, the impurities from the gas can be removed before it is released into the environment.

In my opinion, the burning of coal as an energy source cannot be stopped entirely. Although there are many bad environmental effects, it still can be minimized. But the important fact is that coal burning still a very much needed source because of its advantages, which are far better than other sources of energy, like oil, natural gas, solar and wind. That is why for the time being, we still cannot cope without the burning of coal.


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