The third method for capturing solar energy is with solar cells, also known as photovoltaic. Solar cells are devices that convert the sun's energy directly into electricity. Until recently, solar cells were not a realistic option for most consumers because of their high cost and low efficiency. The manufacture of solar cells is a complicated, expensive process requiring the expenditure of much energy. However, great strides have been made in designing more efficient and cost-effective solar cells.
The main problem with solar-energy systems is that they require sunny weather to work. Only few regions can count on extended periods of clear skies. Places that have the right kind of weather (e.g. deserts) are generally far from population centers, meaning that this source of energy isn’t suitable for all members of the society, because of the places they live. Additionally, there is only so much energy that can be extracted from a given amount of sunlit surface. To meet the electricity needs of even a small city would require covering hundreds of acres with expensive solar cells. Then, even in optimum weather, the system would work for only a few hours a day. Backup generators would be needed to supply electricity during "off hours." But nevertheless, solar energy remains the friendliest form of energy, because its pollution free, renewable, and there’s lots of it. During the collecting process, no fuels are used and so no harmful gases are emitted into the atmosphere. Another advantage of not using fuels is that “its price would not be affected by the supply and demand of fuels.”
Another source of energy is the wind. Wind is an indirect form of solar energy. The sun heat's the Earth's surface, unevenly, putting the atmosphere into turbulent motion. Tremendous energy is contained in the wind. This energy can be captured with a turbine that is connected to an electric generator. A windmill is an example of a device that captures the energy of wind.
The technology of wind generators is well developed, and the cost of wind-generated electricity is lower than the cost of electricity produced by some other sources and its capital cost is decreasing. The chief disadvantage of wind energy is that few regions have winds strong or consistent enough to make wind generators economical. And there are other disadvantages: Large commercial wind generators may not be attractive additions to the landscape. At full speed they can be very noisy. This proves to be a major problem in communities who depend on tourists as their main source of income, because such problems usually drive tourists, who want to relax and enjoy their holiday, away. Although in some places, like in Holland, Windmills are part of the scenery and many tourists pay to see them. A further disadvantage is that the blades of large wind generators can often interfere with microwave communications. While wind energy may never be a major source of energy, it is a practical alternative in some areas.
Other energy providers are the hydroelectric power plants. Thousands of years ago, humans learned to harness the energy of falling water. Today water is used to generate electricity. The water must fall a considerable distance to have enough energy to push a heavy turbine and a generator (fig. to the left). Dams provide this vertical distance. Water power has several advantages. It is clean and renewable, and it leaves no waste. There are indirect benefits as well. The reservoirs that form behind hydroelectric dams offer recreational opportunities which helps the local economy. Furthermore, they can provide drinking water for the local community. But more importantly, they also control flooding.
On the other hand, hydroelectricity has some disadvantages. When a dam is constructed, the water forms a reservoir that disrupts the river ecosystem and displaces the local habitats, and the people that have been driven away will probably never get to see the energy that is produced, only the people living further away who will not have to move. Furthermore, the cost of dam construction has soared. Finally, hydroelectricity is an option limited to only areas that have rivers and streams.
The interior of the Earth is a very hot place. In some places, the heat lies very close to the surface. Such places are sources of geothermal energy (the heat inside the Earth). This heat can be used to drive electric generators, similar to the way in which fossil fuels and nuclear energy drive electric generators. The major problem with geothermal energy is that Earth processes replace the heat very slowly. In some locations, large-scale geothermal operations can quickly use up the available geothermal energy. In New Zealand, for example, most electricity was once generated with geothermal energy, but excessive use of the resource depleted it. Another disadvantage is that geothermal energy can be tapped in only a few places, so its availability is limited, meaning that it is only available to a limited amount of people.
Another form of energy is nuclear power, however it is a very controversial topic, because many environmentalists say that nuclear energy is harmful and should therefore be banned. They rest their case by talking about a major nuclear waste problem facing society caused by nuclear power plants, which is the cleanup of decommissioned nuclear power plants. A reactor has a predicted useful lifespan of 30 to 40 years. During its operation, it becomes contaminated and in most cases, the concrete containment structure around the reactor also becomes contaminated. When it is decommissioned, it must either be dismantled, with the removal of all radioactive parts to the waste disposal facility, “entombed” in concrete or steel. Although both methods are extremely costly. Many nuclear weapon plants suffer from the same problem. The release of radioactivity into the environment would contaminate large expanses of soil and water. If humans are exposed to such radiation, they could suffer from all types of cancers from leukemia to brain cancer, lung cancer and other devastating problems. Even if facilities cease such practices, an enormous and technologically difficult cleanup is needed to prevent people from additional exposure to the harmful wastes. In the United States, estimates for cleaning up this type of pollution would cost over 200 billion dollars. Personally, I feel that if society would cut down on their energy use, and develop means to use energy more efficiently, maybe by installing better insulation or using more modern heating systems, then the need of building more nuclear power would become unnecessary. Who knows, we might eventually be able to replace nuclear energy with a safer and more efficient form of energy.
But, to make matters worse, due to modern technology it has become possible to convert the uranium used in power plants to provide electricity to the people’s homes, giving them light, heat and other necessities for life, into weapons of destruction. Society was against the use of nuclear weapons from the start. Using such a wonderful source of energy that served many towns, to create weapons of destruction just didn’t appeal to the ethical beliefs of many people. Unfortunately, the governments of many countries permitted the usage of nuclear weapons, which made it harder for people to protest against it.
However, many economists and business men argue and say that it is a wonderful source of energy, not only because it will outlast non-renewable fuels but also because the production of energy is smoke-free. It is also a more reliable source of energy, because it isn’t vulnerable to strikes or natural disasters like some other energy providers are, such as dams which produce hydroelectric power are very vulnerable to earthquakes and would be destroyed if such a disaster were to take place. It is also the most efficient form of energy, “one ton of uranium produces more energy than is produced by several million tons of coal or several million barrels of oil.”
The government does not force the people to get energy only from a particular source of energy. In today’s world there are many different forms of energy from which people can choose. We have the freedom to decide for ourselves whether we want our electricity to come from nuclear plants or from windmills and I feel that this is the way it should stay. If there are people who do not mind where their electricity comes from, then the government can decide which form of energy is most suitable for them. Like I said before, there are many forms of energy out there that can improve the current situation of the world, they just need to be utilized properly and this can only be done if we work together for a better future.
Bibliography:
Book(s):
Usborne Dictionary of Science
Internet:
http://www.altenergy.org/
library.thinkquest.org/26366/ text/alternative/solar.html
www.austinschools.org/kealing/energy/ reports/present/rephydro.html
jiskha.com/social_studies/world_issues/ nuclear_energy.html
library.thinkquest.org/3471/nuclear_energy_body.html
Other:
My Chemistry Essay, The Environmental, Social and Ethical Consequences of mining,
processing and using Uranium
Pictures:
Just from Google…