Renewables
Consumption of renewable sources of energy has been slowly, but progressively increasing. With CO 2 in the atmosphere at its highest levels ever (and a strong likelihood of even higher levels very soon), the melting of polar ice, destructive weather-related events, and the rising of the average temperatures, world governments and leaders, environmentalists and industries, have been taking the lead in developing new technologies to make renewables more accessible and less costly.
An approach that keeps gaining momentum is the organization of local projects at the individual or cooperative levels that take advantage of the renewable energy sources at hand to power their communities. This enterprise spirit has already seen some successes in Willits, California; Toronto, Ontario; Burlington, Vermont; Gainesville, Florida; Newburyport, Massachusetts; and Wildpoldsried, Germany. 26
As shown in the table above, energy consumption of renewable sources in the US has a presence and, year after year, there's a small but significant increase. These sources include biomass, hydropower, geothermal, wind and solar energy. This unit will only focus on solar and wind power.
Solar power
Photosynthesis has proved to be an effective process for harvesting the sun's energy for more than 2 billion years. The solar radiation that reaches the Earth does not only have to be only utilized by plants but can be, and has been, used to create heat and electricity. There are two ways of converting the Sun's light into electrical power: in photovoltaic devices (PVs) or "solar cells" sunlight is directly converted in electricity; and in Solar Thermal Power Plants, the concentrated solar energy heats a fluid to produce steam which in turn powers a generator; these can be found in California, Arizona and Nevada.
We can draw on solar energy passively as when buildings are designed to use most of the sun light; or actively, when PVs are used, or by installing panels that produce heat for solar domestic hot water (SDHW). 27 Solar energy output and devices do not pollute the air or emit CO 2; their impact on the environment is minimal when they are located on buildings. The main problems with this renewable energy is, as indicated previously, the unevenness with which the sunlight reaches the Earth's surface which means a large area is needed to collect energy at useful rates. A second concern relates to some toxic materials and chemicals employed in the manufacturing of PVs.
Wind power
Wind power is one the most rapidly growing technologies in the world of renewables. 28 It uses highly developed machines called turbines, gathered in "wind farms", to generate electricity. When wind turbines were originally utilized as early as 1891, they could only produce a few kilowatts (kW) of energy, able to power a couple of houses; now, technological improvements have made them able to generate electricity for whole communities. The new turbines can produce over 1.65 megawatts (MW) with blades measuring as long as the wingspan of a Boeing 747. 29 Turbines are becoming less expensive to make and, since they don't require fuel, generate solid waste, or use water, the world wind power capacity has been increasing double fold every three years. 30
Some of the controversies that arise with wind power generation are similar to those related to solar energy: wind is not a constant energy, and wind farms need large areas for installing enough turbines to create sustainable rates of energy. They can also be perceived as an eyesore, and animal-right activists allege they kill birds (some researchers maintain that tall buildings kill even more birds). 31 A final argument is that when compared to the solar installation at home, solar energy is a more efficient renewable.
The development of the wind power industry has been especially strong in Europe, specifically Denmark. The Danish government and farm-based communities have been powerful advocates of energy independence financing and taking charge of their wind projects. In the US, Oklahoma has seen a sustained increase in their wind-energy production. It was reported in April of 2013 that the state had climbed to the fourth place in the nation with a wind power generation of 1,127 MW –Texas, first in the nation, generated 1,826 MW in the same period. 32
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