Each system has some advantages and disadvantages, but advantages and disadvantages of environmental impact assessment pdf of them pose environmental concerns. The amount of water usage is often of great concern for electricity generating systems as populations increase and droughts become a concern.
Likely future trends in water consumption are covered here. General numbers for fresh water usage of different power sources are shown below. Coal- and gas-fired boilers can produce high steam temperatures and so are more efficient, and require less cooling water relative to output. Nuclear boilers are limited in steam temperature by material constraints, and solar is limited by concentration of the energy source. Such a site will not have cooling towers and will be much less limited by environmental concerns of the discharge temperature since dumping heat will have very little effect on water temperatures.
This will also not deplete the water available for other uses. If dry cooling systems are used, significant water from the water table will not be used. Hydroelectricity’s main cause of water usage is both evaporation and seepage into the water table. EPRI data and other sources. Adapted from US Department Of Energy, Energy Demand on Water Resources. Water Requirements for Existing and Emerging Thermoelectric Plant Technologies. US Department Of Energy, National Energy Technology Laboratory, August 2008.
Such systems allow electricity to be generated where it is needed, since fossil fuels can readily be transported. The world’s supply of fossil fuels is large, but finite. New sources of fossil fuels keep being discovered, although the rate of discovery is slowing while the difficulty of extraction simultaneously increases. The estimated CO2 emission from the world’s electrical power industry is 10 billion tonnes yearly.
The linkage between increased carbon dioxide and global warming is well accepted, though fossil-fuel producers vigorously contest these findings. Depending on the particular fossil fuel and the method of burning, other emissions may be produced as well. While this helps reduce local contamination, it does not help at all with global issues. While a substantial inventory of mercury exists in the environment, as other man-made emissions of mercury become better controlled, power plant emissions become a significant fraction of the remaining emissions.
Power plant designers can fit equipment to power stations to reduce emissions. The electricity sector is unique among industrial sectors in its very large contribution to emissions associated with nearly all air issues. Electricity generation produces a large share of Canadian nitrogen oxides and sulphur dioxide emissions, which contribute to smog and acid rain and the formation of fine particulate matter. It is the largest uncontrolled industrial source of mercury emissions in Canada. Fossil fuel-fired electric power plants also emit carbon dioxide, which may contribute to climate change.
In addition, the sector has significant impacts on water and habitat and species. In particular, hydro dams and transmission lines have significant effects on water and biodiversity. Mill tailings are left out bare and have been leached into local rivers and resulted in most or all of the rivers in coal producing areas to run red year round with sulfuric acid that kills all life in the rivers. Process steam can be extracted from steam turbines. By combining electric power production and heating, less fuel is consumed, thereby reducing the environmental effects compared with separate heat and power systems.