- July 28, 2012
- Posted by: essay
- Category: Sample essay papers
Contemporary processes – like rapid exhaustion of fossil fuels supplies (first of all, oil and gas), the use of which is also related to serious pollution of environment (including thermal contamination, and threatening climatic consequences of increase of atmospheric carbonic acid’s level), limitation of uranium supplies (energetic usage of which causes dangerous radio-active wastes) and indistinctness of both conditions and ecological consequences of the industrial use of thermonuclear energy ”“ makes the society pay greater attention to the searches of effective utilization possibilities and of ecologically friendly energy sources.
Growing requirements to environmental protection demand the new approach to energetics. Nowadays more and more scientists and engineers of the world are engaged in searches of new, nontraditional energy sources which would undertake at least a part of cares on providing humanity with energy. Nontraditional renewable energy sources include solar, wind, geothermal and hydrothermal energy, energy of biomass and World ocean energy.
In fact, the use of just 0.0125 % of the Sun’s energy could cover all the needs of world energetics, and the use 0.5 % of it ”“ all the long term needs. However, one of the most serious obstacles is low intensity of solar emission. So in order to make solar radiation accumulators annually collect the quantity of solar radiation, which would be enough for all humanity’s necessities satisfaction, we need to place them on the territory of 130 000 km2 (Kreith 21-9).
A necessity to use the collectors of enormous sizes, in addition, causes considerable financial expenses. According to calculations, production of solar radiation accumulators in area of 1 km2 requires about 104 tons of aluminium. The world supplies of this metal are estimated in 1.17*109 tons (“Renewables 2007: Global Status Report”).
The greatest success in the area of solar energy usage was achieved by Loose Industries (USA). In December 1989 the solar-gas station of 80 MWe power was put into operation. Later, in 1994 in California 480 MWe of electric power were also put, thus, cost of 1 kWh of energy was only 7-8 cents. At night and in winter the energy is produced by gas, and in summer and in day-time ”“ by the Sun. Power-station in California showed that gas and sun are able to match each other effectively (Sherwood 48). So a conclusion is not surprising, that different types of liquid or gas fuel should accompany solar energy. The most credible variant is hydrogen (“Renewables 2007: Global Status Report”).
Fast development of the solar power engineering became possible due to the decline of photo-electric accumulators cost and to the increase of their efficiency index. Decrease of solar watt cost up to 50 cents will allow solar station to compete with other autonomous energy sources (Sherwood 50).
One of leaders in solar energy practical usage is Switzerland. In frames of “Solar-91” Program about 2600 solar generators of 1-1000 kW and solar collector devices for getting thermal energy were built. Operation experience showed that the Sun is ready to cover energy demand of at least all dwellings buildings in the country (Kreith 21-18).
There also exist some other directions of solar energy usage. One of the large directions in solar energetics is the development of transport vehicles using solar energy; the concept of solar mobile appears (“Renewables 2007: Global Status Report”). Moreover, there’s the direction of photosynthesizing ability of plants usage. In laboratory conditions photobiochemical systems, where the energy of quantum of light is used for the electrons transfer, are already created and successfully work. They are the prototypes of effective transformers using principles of natural photosynthesis (Kreith 19-1).
So far electric energy produced by the sun costs much more than the one got by traditional methods. However, scientists hope that experiments they carry out on the experimental stations will help to solve not only technical but also economical problems.
The supplies of wind energy are bigger, than the supplies of hydropower of all rivers of planet in more than one hundred times. Wind blows everywhere – on land and at the seaside. However, the important disadvantage of wind energy is its changeability in time, but it can be solved due to the location of wind machines (Ucar 466). If a few dozens of large wind machines are united, their average power will be permanent (“Renewables 2007: Global Status Report”). And, finally, it is possible to get mechanical energy directly from a windmill.
Due to the efforts of scientists and engineers the most various constructions of the modern wind settings are created.
The principle of all windmills’ action is the same: a wind wheel with vanes is rotated under pressure of wind, passing a twisting moment through the transmission system to the billow of generator, producing electric power, aquatic pump. The more diameter of a wind wheel is, the greater is air stream it takes and the more energy is produces (Ucar 471).
According to the company Boeing prognoses in a current century the length of windmills’ vanes will not exceed 60 meters, which will allow creating wind machines of traditional arrangement with the power of 7 MWe (“Renewables 2007: Global Status Report”). Today the largest of them are twice weaker. In the serious wind energetics it is possible to count, that 1 kWh price will go down to 10 cents, only at the conditions of mass building. Nowadays, wind engines cover only 0,001 of world need in energy (Kreith 19-31).
Eruption power of even comparatively small volcano is huge; it exceeds the power of the largest energy station created by man (“Future of Geothermal Energy” 30). However, there’s no talk about the direct use of volcanic eruptions energy, while people have no possibilities to control this rebellious element, and, fortunately, eruptions are rare enough events. But it is a display of energy hidden in the earth, when only the tiny part of this inexhaustible energy finds an output through the craters of volcanoes.
Iceland fully provides itself with tomatoes, apples and bananas using geothermal energy. The numerous hothouses of Iceland get energy from the heat of the earth; there are practically no other local energy sources in Iceland. But this country is very rich on thermal springs and famous geysers-fountains of hot water, which get out from under the earth with the exactness of chronometer. And although priority in the use of heat of earth sources belongs not to the Icelanders, the population of this Northern country intensively exploits an underground boiler. Reykjavik, which is inhabited by the half the country’s population, gets heating only due to geothermal sources (“Renewables 2007: Global Status Report”).
But people get the energy from the earth not only for heating. Power-stations using thermal underground springs work for many years already. First of such power stations, a low-powered one, was built in 1904 years in a small Italian town Larderello, name after the French engineer Larderelli, who in 1827 years made a project of the use of numerous thermal springs in this district. Energy of the power-station grew gradually, all new aggregates entered into a line-up, the new sources of hot water were used, and in our days power of the station reached the imposing rate of 360 tsd of kilowatts (“Future of Geothermal Energy” 41). In New Zealand there also exists such a power-station; its power is 160 tsd kW. In 120km from San Francisco, USA, the geothermal station produces electric power of 500tsd kW (Kreith 26-18).
INLAND WATER ENERGY
The enormous supplies of energy are hidden in the running water of inland waters. Historically, first people learned to use the energy of rivers. Advantages of the hydroelectric power stations are obvious: the constantly renewable nature energies, simplicity of exploitation, absence of environmental pollution. However, building of a dam for a large hydroelectric power station is a difficult task; in order to drive powerful hydro-turbines to the rotation, it is needed to collect the enormous supply of water (Kreith 27-1). Therefore at the beginning of the 20th century only few hydroelectric power stations were built.
For example, the state policy of Russia resulted in the fact that the system of powerful hydroelectric stations is developed in Russia even more than in any other country of the world; they give plenty of energy and become the centers of powerful industrial complexes developed around them. Energy setting on the Rance River (Brittany), consisting of 24 reversible turbine generators and having launch power of 240 MW, is one of the most powerful hydroelectric power stations in France, and fully supplies two cities with electricity (“Renewables 2007: Global Status Report”).
The basic indexes, allowing to estimate hydroenergetic potential of regions and potential power of the work of water on a territory, where building of a hydroelectric power station is planned, are river’s rate of stream flow and presence of considerable overfalls of relief elevations (Kreith 4-2).
The hydroelectric power stations are the most economically advantageous energy source, but at the same time have a number of the serious disadvantages, related to the necessity of energy transporting on large distances (often the users of energy are located far from the rivers). While transporting electric power through the electricity transmission lines up to 30% of the energy gets lost and an ecologically dangerous electromagnetic radiation is created. In addition, deforestation has to be conducted in order to put those lines, which also affects ecology (Kreith 8-1).
By present moment, only a small part of hydroenergetic potential of the Earth serves people. Annually enormous streams of waters formed from rains and melting snow flow down in seas without being used. If we succeeded to hold them by dams, humanity would get the huge amount of energy additionally.
ENERGY OF THE WORLD OCEAN
The World ocean, making 71% of the planet’s surface, hides different types of energy: tidal energy, energy of ocean currents, thermal energy, etc.
Tidal Energy. The most obvious method of the use of ocean energy is building of tidal power stations. Beacons and lighthouses, using energy of waves have already filled coast waters of Japan. For many years beacons, which are the whistles of coastguard in the USA, are operating due to wave vibrations. In the mouth of the river of Rance in France a tidal power station is working on tide flows of up to 13 meters with the power of 240 tsd kW and with an annual return of 540 tsd kWh (“Renewables 2007: Global Status Report”).
Energy of Ocean Currents. Kinetic energy of ocean currents is estimated in 1018 J. In 1974 National Oceanic and Atmospheric Research Administration in Miami reported, that oceanic propellers would be able to generate electricity, extracting energy from Gulf-stream, which carries its waters near the coast of Florida at a speed of 5 miles per hour (“Renewables 2007: Global Status Report”).
Thermal Energy of the Ocean. Great attention is now concentrated on ocean thermal energy conversion, which actually means obtainment of electric power due to the difference of temperatures between superficial and deep ocean waters, sucked in a pump at the use of such liquids as propane, freon or ammonium. There are energy supplies in surface water, which in 10 tsd times exceed world demand in it. According to J.Isaacs’s estimations, modern technology will allow to create energy settings which would produce electricity in two times more than whole world’s contemporary consumption (Kreith 26-15).
Energy of Oceanic Biomass. Ocean has favourable environment for living, which includes nutritives, salts and other minerals. In the middle of 1970s with the support of US Navy the first world ocean energetic farm was created on 40 feet depth, where the giant Californian brown algae were grown. Up to 50 % of their energy can be converted into natural methane. Ocean farms of brown algae of 100tsd acres area will be able to give enough energy to satisfy the needs of cities with the population of 50 thousand people (Kreith 25-37).
Internal Energy of Water Molecules. The hydrogen extracted from water can be burned as a fuel and used not only to set different transport in motion but also for the obtainment of electric power. The prospectivity of hydrogen energetics is in the fact, that the obtained hydrogen is comfortable to keep in the any state (compressed gas, condensated, and solid state) and is easily transported. One of the most perspective methods to get hydrogen is the electrolysis of water. In 60s the NASA specialists succeeded to carry out the process of electrolysis of water and so effectively collected hydrogen, that this hydrogen was used during the flights of the Apollo program. (“Renewables 2007: Global Status Report”)
Obtainment of Energy Due to Differences of Chemical Composition of Water. The enormous amount of salts is dissolved in the World ocean. Salinity can be used as an energy source. Researchers consider that in order to obtain plenty of energy it’s possible to construct batteries, in which reactions between salty and unsalted water would take place.
Thus, at the modern rates of scientific and technical progress, substantial changes in ocean energy should happen in the nearest decades. Some of the offered ocean power settings can be realized, and become cost-effective.
ENERGY OF BIOMASS
In addition to abovementioned water-plants, biomass includes wastes of agrarian production and plant biomass, which becomes useless, as for example, the products of animals’ vital functions (Kreith 24-1). In developing countries this type of energy resources makes on the average 20%. In a number of African countries the use of biomass for power aims is 60% of general energy consumption, in Asian countries – 40%, in a number of European countries, in Mideast and North Africa – up to 10%. The resource is especially important in the countries with tropical climate and in large cities, where the problem of liquidation and energetic utilization of wastes plays a significant role (“Renewables 2007: Global Status Report”).
For the last decade only three countries (the USA, Denmark and Sweden) led the production of electric power on settings using biomass of wastes to 400 MWe (Salo 31). And a power-plant projected in Finland, which operated on chicken dung, burned 120 tsd tons of chicken dung in heatings annually, producing 75 mln kWh of energy (Kreith 24-2).
Processing of biomass based on the processes of gasification and oil-fuels obtainments got considerable development. Since 1980 the annual production of ethanol attained, e.g. in Brazil, reached 10 mln liters (Kreith 2-36). The solution of garbage utilization problem is found in the use of solidphase digestion technology with the obtainment of biogas (Salo 33; Kreith 25-2).
A biogas can be with high efficiency transformed into other types of energy; its efficiency coefficient as a fuel in gas generators can make 83%. The production of biogas in some countries already occupied leading positions in power balance of agricultural production (“Renewables 2007: Global Status Report”).
During the existence of our civilization the change of traditional sources to new and more perfect took place for many times. Now the new and significant stage of earth energetics begins; and it should be built to care of already strongly damaged biosphere. Energetics accumulates very quickly, assimilates, and absorbs the all newest ideas, inventions, and achievements of science. So we should believe that we are on the way to the Era of Energetic Abundance, and that all obstacles, barriers and difficulties will be overcome. The alternative forms of energy possess endless supplies, but that is so with the condition, that we will develop effective and economic methods for their usage.