Sources of electricity

Wind:
The kinetic energy of the rotating wind turbine helps to harness wind energy which is one of the easiest sources of renewable energy available in plenty of amounts. It is less expensive in comparison with other energy sources because it is easily available everywhere, especially in seabed, seashores, and hilly areas. This source of energy doesn't produce pollution however negligible amounts of water or air pollution may happen during the time of maintenance. The turbine used in recent times is more lucrative as compared to the age-old windmill because of its sturdiness, power, and noiselessness. Producing electricity energy by using wind power is limited to windy areas because the set-up cannot be installed everywhere, particularly on those areas where speed of wind is very slow.

Solar:
Sun is the main source of energy on earth. The sun's rays can be easily used in the form of solar energy to minimize the problem of electricity. One of the benefits is that this energy can easily be converted into electrical energy with the help of photovoltaic cells which have the characteristic to produce electric current when sunlight strikes on to their surface. These PV cells are totally made up of silicon which is the second most abundant element found on earth. PVs don't produce pollution and require less maintenance. After the life of PVs, they are recyclable and don't create environmental pollution. One limitation of PVs is that these cells generate electric current when sun is shining. They cannot work in rainy season, snowfall and cloudy weather. Moreover, the integrating intermittent PV-generated electricity provides fewer difficulties while using higher levels of solar power on large scales.

Biomass:
It is a cost-effective source of energy. It helps to generate electricity by wood, harvest residues, crops, urban refuse, and methane gas which are known as Biomass. This source requires less investment as compared with wind turbines and PV cells. Another reason for using biomass is that it is a convenient medium to store energy that produces electricity on-demand. This type of energy doesn't produce enough carbon dioxide if it is used on small-scale. But, a large scale use might cause significant influence to the environment. In case of commercial uses, the demands for electricity rise to higher levels. The vast lands are required to grow more trees or crops that can be used as biomass-fuels. Likewise, these trees will require another source of energy (or i.e. water), which can be used for other purposes. The combustion of wood is not favourable at all times, especially because of increasing pollution. Waste is not a good option for producing large-scale electricity. It is not considered as the true source of renewable energy.

Hydroelectricity:
Water is available in plenty of amounts on earth. The kinetic energy of flowing water can be used to rotate turbines that on the other hand produce hydroelectricity. It is an eco-friendly process of generating electricity which doesn't pollute environment and produces electricity on-demand. The construction of dams has deep influence on the ecological system, especially in up and downstream. At present, there are around 5.500 dams in the United State producing up to 9% of the nation's electricity. Moreover, the capacity of electricity produced depends on size of the dams which are either large or small hydroelectric projects. A large hydroelectric project involves building a huge dam on a river, which in turn requires storing (or flooding) river basin to make a big reservoir. The small hydroelectric project produces less than 30 megawatts of electricity in comparison with large project. It has fewer environmental impacts in compared to large dam. The small dam is not able to produce on-demand electricity. Another limitation is that it has uneven flow of water.

Nuclear:
The solar energy is directly (or inversely) related to other sources of energy. In case of nuclear power, the energy is harnessed by the power that constrains in the nuclei of the atoms. At first instance nuclear power seems more appealing because of low emissions and less land uses. However, many limitations came into light after thoroughly studying its major health risks and safety concerns. The nuclear lifecycle involves the mining of uranium ore, releasing radon, and producing large amounts of radioactive waste rock. Since uranium ore cannot be used directly therefore it goes through highly energy-intensive process that fabricates it into fuel rods. The energy in nuclear power plants is produced through either fission reactions or fusion reactions. In both of the cases, a huge amount of heat is generated that helps to create steam which in turn rotates turbines and produces electricity. One drawback is that it produces harmful radiation which is life-threatening and extremely dangerous to health. It may cause cancer, genetic mutations, acute illness or even death at high doses. It is non- biodegradable and stays in the atmosphere for thousands of years. No easy method of decomposing nuclear waste is available these days. Much of the waste is added in the environment because of decommissioning of the old nuclear power plants.

Natural Gas:
The story of natural gas leads back to thousands of years when buried organic matters had to go through very high pressures and temperatures. As compared to rate of formation, the process of extracting natural gas is very slow. Therefore, it is always considered as a non-renewable source of energy. This kind of fuel can be found with oil, coal or even alone. In recent times, offshore drilling has become more prevalent because of easy availability on offshore sites. Since this gas cannot be used directly, it is refined. This refined gas is used to create steam which in turn rotates turbines to produce electricity. Natural gas is a cheap source of energy and produces fewer pollutants such as particulates, sulphur dioxide and nitrogen oxide. One advantage is that it produces electricity on-demand.

Coal:
It is a cheap source of energy found in plenty of amounts on earth. It is widely used because of its ability to produce electricity on-demand. After 1950s, coal has become a major source of fuel to generate electricity in the United States. Although, it is available in abundant amounts, but a big disadvantage is that coal mining has deep impact on aquatic and terrestrial ecosystems. At times, whole mountains are removed from their place and valleys are refilled by waste rocks. The mountain top removal, open pit, and underground mining are a big cause of concern because many times rain water filter through coal mine and tailings. Sulphur dissolves into water and causes acid mine drainage which can influence thousands of miles from one to another country. Furthermore, the combustion of coal also produces gaseous waste such as sulphur dioxide, nitrogen dioxide, and carbon monoxide etc.