Alternate energy sources

 

Alternative energy is a term used for an energy source that is an alternative to using fossil fuels. Generally, it indicates energies that are non-traditional and have low environmental impact. The term alternative is used to contrast with fossil fuels according to some sources. By most definitions alternative energy doesn’t harm the environment, a distinction which separates it from renewable energy which may or may not have significant environmental impact.

Renewable energy is energy that is generated from natural processes that are continuously replenished. This includes sunlight, geothermal heat, wind, tides, water, and various forms of biomass. This energy cannot be exhausted and is constantly renewed.

The world currently relies heavily on coal, oil, and natural gas for its energy. Fossil fuels are non-renewable, that is, they draw on finite resources that will eventually dwindle, becoming too expensive or too environmentally damaging to retrieve. In contrast, the many types of renewable energy resources-such as wind and solar energy-are constantly replenished and will never run out.

The Solar energy

Solar energy—power from the sun—is a vast and inexhaustible resource. Solar energy is one the most resourceful sources of energy for the future. One of the reasons for this is that the total energy we recieve each year from the sun is around 35,000 times the total energy used by man. However, about 1/3 of this energy is either absorbed by the outer atmosphere or reflected back into space. Solar energy is presently being used on a smaller scale in furnaces for homes and to heat up swimming pools. On a larger scale use, solar energy could be used to run cars, power plants, and space ships

Once a system is in place to convert it into useful energy, the fuel is free and will never be subject to the ups and downs of energy markets. Furthermore, it represents a clean alternative to the fossil fuels that currently pollute our air and water, threaten our public health, and contribute to global warming. Given the abundance and the appeal of solar energy, this resource is poised to play a prominent role in our energy future.

Wind power

Wind turbines harness air currents and convert them to emissions-free power. Plentiful and inexhaustible in the United States and around the world, wind power is one of the fastest growing renewable technologies and has the potential to provide a significant portion of our electricity needs.

How Wind Energy Works

Harnessing the wind is one of the cleanest, most sustainable ways to generate electricity. Wind power produces no toxic emissions and none of the heat-trapping emissions that contribute to global warming. This, and the fact that wind power is one of the most abundant and increasingly cost-competitive energy resources, makes it a viable alternative to the fossil fuels that harm our health and threaten the environment.

Wind energy is the fastest growing source of electricity in the world. In 2012, nearly 45,000 megawatts (MW) of new capacity were installed worldwide. This stands as a 10 percent increase in annual additions compared with 2011.

The Wind Resource

The wind resource — how fast it blows, how often, and when — plays a significant role in its power generation cost. The power output from a wind turbine rises as a cube of wind speed. In other words, if wind speed doubles, the power output increases eight times. Therefore, higher-speed winds are more easily and inexpensively captured.

Wind speeds are divided into seven classes — with class one being the lowest and class seven being the highest. A wind resource assessment evaluates the average wind speeds above a section of land (e.g. 50 meters high), and assigns that area a wind class. Wind turbines operate over a limited range of wind speeds. If the wind is too slow, they won’t be able to turn, and if too fast, they shut down to avoid being damaged. Wind speeds in classes three (6.7 – 7.4 meters per second (m/s)) and above are typically needed to economically generate power. Ideally, a wind turbine should be matched to the speed and frequency of the resource to maximize power production.

Biomass

Biomass—plant material and animal waste—is one of the oldest sources of renewable energy, used since our ancestors learned the secret of fire. Now we have the technology to efficiently convert it to electricity.

How Biomass Energy Works

To many people, the most familiar forms of renewable energy are the wind and the sun. But biomass (plant material and animal waste) is the oldest source of renewable energy, used since our ancestors learned the secret of fire.

Until recently, biomass supplied far more renewable electricity—or “biopower”—than wind and solar power combined.

If developed properly, biomass can and should supply increasing amounts of biopower. In fact, in numerous analyses of how America can transition to a clean energy future, sustainable biomass is a critical renewable resource.

Sustainable, low-carbon biomass can provide a significant fraction of the new renewable energy we need to reduce our emissions of heat-trapping gases like carbon dioxide to levels that scientists say will avoid the worst impacts of global warming. Without sustainable, low-carbon biopower, it will likely be more expensive and take longer to transform to a clean energy economy.

But like all our energy sources, biopower has environmental risks that need to be mitigated. If not managed carefully, biomass for energy can be harvested at unsustainable rates, damage ecosystems, produce harmful air pollution, consume large amounts of water, and produce net greenhouse emissions.

Hydrogen

also can be found in many organic compounds, as well as water. It’s the most abundant element on the Earth. But it doesn’t occur naturally as a gas. It’s always combined with other elements, such as with oxygen to make water. Once separated from another element, hydrogen can be burned as a fuel or converted into electricity.

Geothermal energy

taps the Earth’s internal heat for a variety of uses, including electric power production, and the heating and cooling of buildings. And the energy of the ocean’s tides come from the gravitational pull of the moon and the sun upon the Earth.

Ocean energy

 comes from a number of sources. In addition to tidal energy, there’s the energy of the ocean’s waves, which are driven by both the tides and the winds. The sun also warms the surface of the ocean more than the ocean depths, creating a temperature difference that can be used as an energy source. All these forms of ocean energy can be used to produce electricity.