Renewable Energy was written by IEA Founding Member, Andrew Hunter
Some existing renewable energy solutions currently in use are described below. At this time, no single method for generating renewable energy is going to solve our energy problems. Unfortunately, there are usually environmental problems with most of these. But in some cases if the conditions are right in a particular location, a certain renewable energy source can be used while having minimal or no environmental concerns.
This is the energy that is released from biomass materials that contain stored energy from the sun. Biomass material is organic plant, animal and organism materials that is either living or is recently dead. Examples of biomass materials include wood, crops and garbage, but the list of all available biomass materials is long. These biomass sources are either waste materials or they are materials than can be grown relatively quickly. The many different processes of releasing the energy from biomass materials do not pollute the environment or increase global warning. That means that biomass materials meet the requirements necessary in order to qualify as a renewable energy source. In the United States in 2010, four percent of the energy used was from biomass fuels, mostly in the form of wood biomass, ethanol and municipal waste.
This is energy that comes from the heat stored in our planet. In some places on earth, the internal heat source comes into contact with water, heating the water which then moves to the surface of the earth. We can use the hot water directly to warm homes, building and greenhouses. This energy from warm water is also used directly in food hydration, gold mining and milk pasteurizing industries. The geothermal energy can also be converted into electrical energy by allowing the steam from the hot water, or dry steam directly from the earth heat source to turn power turbines on electrical generators.
This particular kind of renewable energy is captured in many clever ways. Anywhere there is naturally moving water, it is possible to harness hydroelectric energy. Hydroelectric energy accounted for six percent of all electrical energy created in the United States in 2010.
Water Dams such as the Grand Coulee Dam or the Hoover Dam create great amounts of electricity. Water passes through power turbines on electrical generators which in turn produce electricity. As impressive as these Dams are, surprisingly in the United States most dams are constructed to provide irrigation and flood control, and not to produce electricity.
Water Turbines are pretty much the same in concept as the air wind turbines we see on land to harness energy. After all, both air and water are fluids. These water turbines can be placed under water in rivers, ocean tidal fields, and in ocean water passages between land masses in which there is a strong steady current flow.
Tidal Barrages produce electric energy in a way similar to traditional water dams. In a tidal basin that has large differences in high tide and low tide (northern and southern areas), a dam is build, but with sluice gates. When tide is at its low point, the sluice gates are opened. Tide is allowed to enter the tidal basin through these gates until it reaches high tide, at which point the gates are closed. As tide heads towards low tides, the ocean water captured behind the tidal barrage is allowed to flow through power turbines to create electricity.
Wave Channels are basically two walls constructed on a land mass and out into the ocean. The walls form a funnel for waves as they head towards the land mass. At the back end of the funnel is a containing tank. As the waves pick up speed heading towards land, and as they are funneled towards the container, the waves increase greatly in size, enabling them to leap over the container wall at the back end of the funnel, and up and over into the containing tank. The contained water is then allow to flow back down into the ocean by passing through power turbines, creating electricity.
Ocean Thermal water movement is another opportunity to harness energy. The sun heats the surface of the ocean. In tropical regions the temperature in the depths below is a lot less than that at the surface that is being heated by the sun. This causes ocean currents. Placing power turbine in between allows us to generate electricity.
There are two primary ways to convert solar energy it into electrical energy that are currently in use in throughout the world. Of course, it is more practical to capture solar energy in locations that have more hours of sunlight, that have more intense sunlight, or where the cost of alternative sources of energy is more expensive.
Solar Thermal energy is simply arranging mirrors in a way that allows them to reflect and concentrate sunlight onto receivers which then covert the solar energy into heat. The heat is then used to create electrical energy by boiling water to produce pressure and steam which then drives a generator. California currently has the largest solar thermal power plants in the world.
Photovoltaic Solar energy systems use photovoltaic cells to convert sunlight directly into electricity. The photovoltaic cells are made of semiconductors which produce moving electrons when they are struck with the energy contained in sunlight. These cells are capable of creating small amounts of electricity from small cells on toy solar powered cars or a calculators, medium amounts of electricity when the larger cells are on top of homes, and large amounts of electricity when many of the cells are placed in a formation for purposes of generating larger amounts of electricity for towns or cities. It is hoped that the efficiency of photovoltaic cells will increase from 15% to 30% within the next few years.
Solar energy itself is pollutant free, however the chemicals used in manufacturing mirrors and photovoltaic cells are harmful. Solar energy can be captured in ways that can minimize visual negative visual impact. Generally though, the downside is that capturing solar energy in large scale power plants does require great areas of land which then has a negative impact on the environment, both visual and by displacing wildlife. The focused energy created in generating solar thermal energy can also kill insects and birds.
It is possible to have the benefits of solar energy in buildings without any of the negative environmental issues and with no recurring cost. Some architecture companies put considerable thought into passive building designs. These designs allow sunlight to enter the building in ways that will provide natural lighting when needed, and allow solar energy to heat a building when it is needed, and not allow solar energy to heat a building when it is not needed.
The power of wind can be used to turn large wind turbines, converting the power of the wind into electrical power. When a great many of these large wind turbines (perhaps hundreds) are arranged together, this is called a wind farm. There are already large wind farms in place throughout the world. Some are on land, and some are in the water with bases anchored to sea bottom or placed on floating devices.
In theory the total amount of electricity that can be extracted from all the wind in the world is more than our current electricity use. The amount of electrical energy produced from wind each year all around the world is increasing exponentially. Some countries such as Denmark and Portugal produce twenty percent of their electrical energy using wind. In 2010, about 2.5% of the electricity produced in the world was with wind. That is up from ten years before when it was only one tenth of one percent.
One technical difficulty with wind is that it is variable. Studies show that as long as we only rely on the wind for about twenty percent of our electrical energy needs, this variation is not a large problem. Such problems would include power storage, reducing demand during times of low wind, and backup power supplies. Environmental impact is that the farms use large areas of land or water, and the use of natural resources to manufacture the turbines.
For small isolated places, there are small wind generation systems that can produce up to 50 kw of electrical power. This would allow someone to decrease their dependency on traditional power sources, or even eliminate these other sources.
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