In the United States and around the world, electricity is needed. The electric power needed is generated from other sources of primary energy. The energy from the primary source is then used to create the electricity delivered to consumers. In this blog, I will discuss 3 ways electricity is generated-coal-fired, natural gas, and nuclear power plants.

Coal:

According to eia.gov in 2013, about 67% of the electricity generated was from fossil fuels and 39% was from coal. Coal-fired electricity is the process of turning water into steam and the steam drives the turbine generators to produce

electricity. The coal needs to be turned in order to turn the water into steam. Before the coal is burned, it is turned into a fine powder. It is mixed with hot air and is thrown into the firebox of a boiler. The firebox is a chamber in the boiler fuel is burned to heat the boiler’s water to steam. Water is pumped through pipes in the boiler and is turned to steam by the coal burning. The steam has a huge amount of pressure and it is used to push against large turbine blades. The turbines are connected to the generator. In the generator, magnets are spun with wire coils to produce electricity.

After the steam has done its job, it is turned back into water. Cool water from a river or lake is pumped through tubes and it converts the steam back into water. The water can be used over and over again without contaminating the source of the water.

Natural Gas:

The next highest contributor to electricity generation is natural gas. Reliance on electricity generated

through natural gas has increased over time. Burning fossil fuels such as coal is cheaper then natural gas, however, it also releases high levels of pollutant into the air. The environmental damage fossil fuels have caused has forced electric generators to switch to alternative methods such as natural gas.

Natural gas is pumped into a gas turbine. It is mixed with hot air, like the coal, and converted into heat energy. Burning the natural gas also produces combustion gas. Mixed with heat, the combustion gas expands and builds pressure in the turbine. This process is similar to the coal-burning because the enormous amount of pressure drives the blades of the gas turbine to spin. However with natural gas, the spinning converts some heat energy into mechanical energy. A shaft connects the turbine to a generator. As the blades spin, the generator uses an electromagnetic field to convert the mechanical energy into electrical energy.

The combustion gas is piped to the heat recovery steam generator. Just like coal, the pipes are used to turn water into steam. The combustion gas goes up through the exhaust stack. The exhaust stack is built very tall so the gas can disperse without touching the ground. Unlike coal-burning, this does not affect the quality of the air around the station. Just like coal, water from the sea is pumped through the pipes to convert the steam into water again. The water is then pumped back into the sea to be reused.

Nuclear Power Plants:

Electricity generated through nuclear power plants totals to about 19% of the electricity generation. Like coal and natural gas, in a nuclear-fueled power plant, water is turned into steam and the steam pressure is used to drive the turbine generators to produce electricity. However, the source of heat is different and there is no combustion. The heat to make the steam at a nuclear power plant is created when uranium atoms split. This process is called fission.

The first nuclear reactor is the Pressurized Water Reactor (PWR). This process keeps water under pressure so it heats but doesn’t boil. The heated water is pumped through pipes in a steam generator. The water going through the steam generator turns into steam and then drives the turbine generators. The heated water from the reactor and the steam never mix because they are kept in separate systems. The other nuclear reactor is the Boiling Water Reactor(BWR). The water is heated by fission and turns into steam. The steam is then used to drive the turbines. In both reactors, the water used can be pumped back into the river or lake and reused.

 

 

Conclusion:

While coal-burning the cheapest form of generating electricity, it does ruin the air quality by releasing greenhouse gases and pollutants that are harmful to humans and wildlife. Natural gas has been the go-to for many companies especially because of the environmental impact. Natural gas is the cleanest of all the fossil fuels. It creates less greenhouse gas emissions than coal. Nuclear energy, on the other hand, uses uranium, which is a nonrenewable source that cannot be replaced by humans. While nuclear power plants do not emit pollutants into the air while generating electricity, fossil fuel emissions can be emitted into the air during uranium extraction from mining. All three ways use large amounts of water to turn into steam which could affect the aquatic life. The good thing about these ways is that the water can be reused. I hope companies have seen the environmental impacts these three ways have, good and bad, and make a good decision as to what to use to generate our electricity.

References:

http://www.duke-energy.com/about-energy/generating-electricity/coal-fired-how.asp

http://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3

http://www.edfenergy.com/energyfuture/generation-gas

http://www.duke-energy.com/about-energy/generating-electricity/nuclear-how.asp

http://naturalgasnb.com/cms/en/home/whatisnaturalgas/theenvironment/environmentalimpact.aspx

http://www.epa.gov/cleanenergy/energy-and-you/affect/nuclear.html