Environmental Issues

Alternative energy sources pertain to sources that are yet to be tried or discovered. However, what is important for the foreseeable future is development of the technology and know-how that will make economically practicable the widespread commercial use of alternative sources that are already being employed experimentally or on a small scale (Brown, 2009). Energy conservation is an objective that seems to be desirable from just about any point of view It decreases production costs, conserves raw materials, as well as lessens the unfavorable impact of production on the environment. Emission of particulates into the atmosphere as a consequence of fuel burning can be to a great extent reduced, for instance, by increasing the efficiency of the burning process (Restivo, 2005). Energy-conservation measures reduce the emission of CO2 considerably and fuel substitution measures hold a large potential for emission reductions and can be efficiently done by promoting renewable energy sources for power and heat generation. If this option was fully exploited, and electricity generation became carbon-free, emissions in 2020 would be reduced by 30 per cent (Brown, 2009). The alternative energy sources to be discussed in this paper are wind turbines, hydroelectricity, geothermal electricity, solar energy technologies, biomass energy, and fusion technology.

Wind Turbines
Wind energy is utilized to generate electricity, to provide mechanical drive (as in pumping water), or to propel vessels. The latter two technologies have been in use for thousands of years, the former for a century. Most recent efforts have been directed toward improving technologies for wind electricity, although some efforts have been intended at sail-assisted ocean transport (Ehrlich  Ehrlich, 1991).

There now are more than 15,000 wind turbines operating in California, producing a total of over 1,500 megawatts of electric power. The cost of generating electricity by wind energy decreased by approximately a factor of 10 during the 1980s, and is now less than 150 the cost of generating electricity with coal-burning plants. It has been anticipated that the cost of producing electricity by wind, at least in some locations, could reduce by another 50 between the 1990s and 2020s (Bahgat, 2008).

 Almost every country in Western Europe is experimenting with the use of wind for electricity generation. Wind turbine makers in a number of countries are developing new turbine designs and studying the potentials for increased efficiency in the use of longer blades with variable-pitch capability constructed from fiber-composite materials. The development of more effective variable-speed turbines also represents an opportunity for improvement (Bahgat, 2008).

A problem with wind as an energy source is its substantial variability however, this is primarily an argument against dependence on wind as the only source and not against its use as an input into a power distribution facility that draws from other sources as well. As a supplement to a fossil-fuel burning plant, it could assist to reduce the amount of fuel that would have to be burned on the average to deliver any given amount of power over a period of time (Ruttiman  Marris, 2006).

Wind power apparently has the great advantage of not producing the atmospheric pollutants produced by many other primary energy sources. It is not completely free of environmental problems, however. One concern that has been raised is the probably unsightly effect of large windmill farms on the rural landscape. Another is the substantial noise that wind turbines can produce (Ehrlich  Ehrlich, 1991).

Hydroelectricity
Falling water has been utilized as an energy source for thousands of years and as an electricity source for a century. Hydropower is usually the cheapest source of electricity. Most of the major large dam sites have already been developed in the United States. Rising real costs of electricity have restored competitiveness to several small sites with dams and have encouraged the installation of generators at many of the nations dams that were built for other purposes. Refurbishing existing equipment often increases electricity output (Chasek, 2000).

Many utilities as well have built pumped-storage facilities. During off-peak hours, water is pumped from a lower reservoir to a higher one. After that, during times of peak demand, the stored water can be released. This capacity allows utility-based load equipment to run gradually when demand fluctuates. Ordinary hydro facilities can also be used for peak demand. Stream flow raises water in the reservoir during off-peak times, and the turbines operate at peak times as well (Bahgat, 2008).

These facilities, designed to accommodate base load coal and nuclear generating plants, will turn out to be extremely convenient for supply systems with solar-electric and wind-electric components. The reservoirs turned out to be the chief storage medium to accommodate fluctuations in output (Ottinger  Williams, 2002).

Geothermal Electricity
Geothermal steam has been used commercially to produce electricity at Laradello, Italy since 1904. Low-temperature geothermal resources are being developed quickly for space heat. Some researchers do not group this resource with other renewable energies on grounds that it is subject to depletion. However, it appears to be capable of producing heat for an indefinite period if withdrawal rates are cautiously established. Old Faithful has been releasing heat to the atmosphere for a very long time (Ehrlich  Ehrlich, 1991). Presently, most geothermal electricity comes from dry steam that drives conventional combustion turbines. This is a small fraction of the total geothermal heat resources. A large expansion of geothermal electricity supply consequently depends on technologies that use steam-hot water mixtures, or hot water alone. The resource is even larger if heat from hot, dry rocks can be tapped. Numerous plants generating electricity from hot water are now running on a pilot basis (Bahgat, 2008).

Solar Energy Technologies
The sun can be used to produce energy in various ways. The use of solar panels and heat-storage systems to heat buildings is a comparatively well- established technology. A variety of techniques are being examined for using the sun to generate electricity (Glaser, 1994). Among them are photovoltaic technology, in which photons make an electric current when absorbed in a semiconductor, and solar thermal electric technology, in which reflected solar radiation is used to heat a fluid to the point at which it can make steam that can be used to drive a turbine generator (Cairns, 2006).

Production of photovoltaic power has reduced in cost by about a factor of five to ten since the 1980s. Further cost reductions, probably by another order of magnitude, are expected in the 1990s (Glaser, 1994). Some experts think that megawatt power plants based on solar cells could be in use, and become competitive with other means of energy production, by the turn of the century. Improvements in the technology are being made along several lines, including the development of low-cost photovoltaic materials, more efficient device designs, automated manufacturing processes, and augmented reliability and durability of devices and systems (Cairns, 2006).

At present, most space satellites of the United States are powered by photovoltaic cells. Solar energy is as well being used to power such devices as calculators and watches. Solar-powered plants can now generate electricity for between 2 and 3 times the cost of producing it with fossil-fuel plants (Glaser, 1994). We ought to see much greater interest in solar technology as it becomes more cost effective, and particularly if the price of oil and natural gas were to increase significantly. Sandia National Laboratories recently developed a photovoltaic cell that uses gallium arsenide and silicon and converts 31 of incident sunlight into electricity (Glaser, 1994). This is seen as a milestone accomplishment that exceeded the expectations of many experts who doubted that photovoltaic cells could reach efficiencies comparable to those of more conventional energy sources (the average efficiency of coal- and oil-fired electric plants is 34) (Ottinger  Williams, 2002).

Researchers estimate that photovoltaic systems should be capable of meeting the majority of the electrical power requirements of the United States by the mid-2030s. They also argue that photovoltaic power has the potential to become the primary source of electricity worldwide by the end of the 21st century. Among the issues aside from cost that are likely to affect the rate at which photovoltaic technology is adopted are the large land areas required for solar arrays, the intermittency of sunlight, and the ensuing variability in the amount of power generated (Brown, 2009).

Inasmuch as vehicle emissions are among the worst sources of atmospheric pollution, the possibility of practical sun-powered vehicles is particularly attractive from an environmental point of view. Prospects for the development of automobiles that can run primarily on solar power were brightened recently when a totally sun-powered vehicle won the 1,867-mile Pentax World Solar Challenge race by going from Darwin, Australia to Adelaide in 44 hours and 54 minutes of running time at an average speed of 41.6 mph. (Ottinger  Williams, 2002).

Biomass Energy
Biomass symbolizes another large renewable resource. Biomass has been anticipated to account for about 14 of the worlds primary energy supplies, most of this coming in the form of noncommercial fuels for open-hearth combustion, particularly in developing countries. The term biomass has come into use since it is awkward to keep referring to wood, other plant-based energy sources, and organic wastes (Barnes  Floor, 1999). The principal method now used to extract energy from biomass is just to burn wood. This may change in the future, as liquid fuels to replace petroleum products will one day be needed. All plant matter can be turned into liquid fuels through a variety of chemical processes. Some plants such as crops directly yield oils similar to diesel fuel or lubricating oils (Woloski, 2006).

Methane (natural gas) is produced almost any time that decaying biomass is protected from oxygen, plus the temperature is in the right range. Swamps, landfills, and sewage plants make methane willy-nilly. Modern technology enters to control the process, maximize yields, and reduce costs (Ferrey, 2003).

As to biomass energy sources that are presently cost-effective Scraps and other wood wastes are widely used in the forest products industries for process heat (and, with cogeneration equipment, electricity). Wood use for residential heat has also increased since 1973. Small amounts of methane are now recovered economically, mostly from garbage landfills and sewage plants (Barnes  Floor, 1999). The technology exists and works to derive methane from numerous other sources  feedlot manure, dairy manure, food processing wastes, or even energy crops like water hyacinths. Commercialization awaits further increases in natural gas prices and further cost reductions in the processes (Youngquist, 1998).

Fuel alcohol (ethanol) made from sugarcane in Brazil and from corn in the United States represents the largest volume of biomass-based liquid fuel now being produced. Most observers think that the most promising large-volume liquid fuel from biomass will be methanol (wood alcohol) (Barnes  Floor, 1999). Research and development activity is aimed at increasing conversion efficiency and lowering costs. Although biomass in the forms of combustible waste, crops produced specifically for combustion, and gas produced from biomass by pyrolysis can be used also for the generation of electric power, such use has not yet reached a very significant level (Cairns, 2006).

Fusion Technology
Nuclear fusion is an attractive potential source of energy because of its relative safety and environmental advantages and the greater supply of fuel. Fusion reactors would not emit carbon dioxide or pollutants to the atmosphere, nor would they produce high-level, long-lived radioactive waste. Fusion technology, in its current state of development, is not radioactively clean because neutrons escape during the process, but there is reason to hope that the technology can be improved to the point of solving this problem (Chasek, 2000). Unfortunately, the fusion process that is most likely to be practically feasible in the foreseeable future involves deuterium and tritium, the two- and three-neutron isotopes of hydrogen further in the future is the hope of a practical deuterium-deuterium process.

Deuterium-tritium reactors are not likely to be used widely because of the limited supply and the nasty nature of tritium. Because deuterium is abundant in the oceans, successful development of the deuterium-deuterium technology would essentially solve the problem of limited resources, but this technology is at a relatively primitive stage of development (Youngquist, 1998).

Although steady progress has been made in fusion research over the past few decades, it has been slow and has been predicted that at least three more decades of research and development will be necessary before a prototype commercial fusion reactor could be operated and evaluated, and that fusion is unlikely to provide a significant fraction of electricity in the United States before the middle of the 21st century (Chasek, 2000). On the other hand, recent developments in the use of short-wavelength lasers to heat heavy hydrogen have led some scientists to speculate that it might be possible to demonstrate the feasibility of harnessing fusion power by laser by the beginning of the century (Ferrey, 2003).

The United States has been involved in a joint effort with Europe, Japan, and the (former) Soviet Union to produce a conceptual design of the International Thermonuclear Experimental Reactor (ITER), a fusion reactor with a thermal energy capacity of at least 1,000 megawatts. The conceptual design phase of this effort began under the auspices of the International Atomic Energy Agency of the United Nations in 1988 (Chasek, 2000). Some scientists have argued strongly that the international collaboration should be continued through subsequent phases of engineering design, construction, and operation. However, the future of this project is uncertain largely because of funding difficulties. It appears that the European community may be stepping up its research on nuclear fusion while the United States is retrenching (Youngquist, 1998).

The research quickly became highly controversial, however, and most experts believe that its implications for the near-term future are small or nonexistent. The possibility of cold fusion catalyzed by negative muons has been the subject of some interest for nearly 50 years. Except for a short time following the first experimental observation of muon-catalyzed fusion by Luis Alvarez in the late 1950s, when investigators thought the process might lead to inexpensive power, it has been generally believed to be too slow for practical use (Chasek, 2000). Recently, however, as a consequence of both theoretical and experimental progress, the prospects for developing muon-catalyzed fusion into an economically viable energy source have been looking somewhat better (Ruttiman  Marris, 2006).

Conclusion
If the renewable energy sources are fully exploited, then constructing new nuclear capacity and extending the lifetime of existing nuclear plants need not be brought into the climate policy. In most countries, nuclear is the least desirable alternative in the case of high environmental concern. For various reasons, however, neither coal-use restrictions nor renewables are exploited in full with the implication that the nuclear option is being utilized. Moreover, some countries need not pursue coal phase-out or renewable options in full to meet their national emission targets, while other countries will not meet their target even after a full coal phase-out and maximum use of renewables (Ferrey, 2003).

The fuel substitution is relatively important because of a notable growth in renewable, which largely replaces old and inefficient coal plants. Climate policy measures ensure by a clear margin that SO 2 targets are met for most countries. Hence, there is no need for a further reduction by mandating emission control measures to reduce SO 2 emissions, except for a few locations with high local concentration of sulphur. The fuel substitution measures alone are sufficient to fulfill the SO 2 target due to the major reductions in coal use in industry and the power sector (Restivo, 2005). For NO x, climate policy measures are not sufficient to enable the target to be reached. Although energy-conservation policies are relatively effective in curbing NO x emissions, due to the emphasis given to transport sector measures, additional emission control policies have to be installed (Woloski, 2006).