Kinetic energy of the flowing water is used to produce the electricity. This type of systems is called hydro power systems. The net energy of these systems is quite high. The cost of producing energy is low and also untapped energy is quite high. These systems are eco-friendly and the carbon dioxide emission is also very low. The main disadvantage is that land disruption is very large. The decay in biomass causes rapid emission of methane gas. Aquatic ecosystem and life style is also affected.
Wind energy is also very promising due to high net energy yield. The scope of wind energy is very wide. It has very low cost involved. There is no effect on the environment and these systems can be expanded easily. The disadvantages are that energy output is intermittent and requires back up. Noise pollution is caused by the large turbines and blades. Due to improper design may cause the death of some birds and bats.
Solid biomass can be used to get energy by burning directly. These are widely available and low cost involved with these plants. These also have no effect on the environment. But this system can lead to deforestation. Improper burning can cause air pollution and major problem is related to land erosion. It causes the soil erosion, water pollution and which in turns affects the wildlife.
Liquid bio-fuels are also having very low carbon dioxide emissions. This can be used to reduce the greenhouse gases. Net energy yield is also very high. Some of liquid bio-fuels causes low net energy yield and corn ethanol causes air pollution.
Ethanol is a renewable form of energy and produced from sugar cane. It does not affect the environment. It has lower heat of combustion and also large land mass required to produce it. Therefore, it causes land disruption. Wastage of ethanol causes pollution. Heat stored in rocks, soil and underground fluids can be used to explore the energy and this is called as geothermal energy. It is also a renewable energy resource. It has low cost involved at favorable sites.
Net energy yield is also very high and there is little effect on the environment. But these systems are less efficient and large cost is involved. There are very less favorable sites and thus cannot be a promising source of energy. Hydrogen can be used to produce the energy and also it is a abundant chemical on the earth. It can be produced from water and also there is very less carbon dioxide emission. Efficiency of such system is also very high. Net energy yield is very low. High cost and storage problems make it difficult to use.
a) Coal is one of the most abundant fossil fuel on earth. The process of exploration of coal is much polluted. It is presented in the form of rocks and it is exploited without pollution control devices and thus many dangerous gases such as mercury and sulfur get mixed with air and water. This makes the air much more polluted. Coal on burning also gives some of the radioactive materials and carbon dioxide. For now China is one of the countries which has much more carbon dioxide gases from burning of coal. Therefore, coal is very dirty fuel and a major polluter.
b) The process by which natural gas is exploited is very harmful for the groundwater. Natural gas is present along with the toxic materials inside the earth in the rocks. High pressure is used to free the gas from the rocks. When high pressure is applied then the high pressure causes the toxic materials also to come out in the form of slurry which mixes with the ground water and makes it toxic. Natural gas that is methane is a major green house gas along with carbon dioxide. Studies show that methane is deposited over the oil reserve. When it is burned then it produces much of carbon dioxide gas which is dangerous and this states that natural gas is not low in its carbon content.
c) Nuclear power reduces the carbon emission. It is one of the methods to produce the energy which is not affecting the carbon dioxide levels in the environment. Nuclear power plant is far more dangerous because of its radioactivity and dangerous radiation emission. A study shows that used fuel rods of nuclear reactor can kill a 39 inches away standing person in less than 3 minutes. Therefore, nuclear waste is a very big question mark around it. Many disasters happened due to nuclear power plants and these affect the environment on a larger area. Therefore, it is not a safe source for energy production.
Renewable energy resources are the future because of their characteristics. Energy efficiency is one of the major issues today. The most of the resources on which the countries are relaying have very low net rate of energy. Therefore, energy efficiency is very important.
It is good to promote the use of the efficient energy and therefore it is good to provide the fund from the fees levied on high efficient vehicles. This will encourage the use of the highly fuel efficient vehicles and along with this there must be taxes on the use of oil and coal.