What are the sources of green energy?

Green energy, there is any source of power that is sustainable and not excessively harmful to human health or the environment. A strict definition would include water, wind and solar power. A more expensive definition would include nuclear power, biofuels and biogas.

Hydro power:

Some scientists have suggested that we use hydrogen gas (H₇) to fuel cars, heat homes, and provide hot water when oil and natural gas run out. Hydrogen gas does not occur in significant quantities in nature. However, it can be produced by chemical processes from nonrenewable coal or natural gas or by using heat, electricity, or perhaps sunlight to decompose fresh water or seawater.

Hydrogen gas can be burned in a reaction with oxygen gas in a power plant, a specially designed automobile engine, or a fuel cell that converts the chemical energy produced by the reaction into direct- current electricity. Fuel cells running on a mixture of hydrogen and air have efficiencies of 60% to 80%.

Wind Power:

Humans have been utilizing wind power for thousands of years for such applications as wind- mills and sailing ships. In the first quarter of the twentieth century, wind-powered irrigation pumps were very common in many countries (India, USA, Japan, Austria), but their use gradually declined as inexpensive oil and gas become more readily available.

Despite its drawbacks, wind power capacity continues to expand. In 1990 the global wind energy- generating capacity was a mere 10 megawatts; by 2004 it has grown to 3710 megawatts, and the growth shows no signs of abating.

In the United States, wind power received a boost from the passage of the National Energy Policy Act of 1992, which includes a tax credit of 1.5 cents per kilowatt-hour of wind- generated electricity.

The United States and Ukraine are discussing a cooperative venture to build a 500-megawatt wind farm to replace power currently supplied by one of the Chernobyl nuclear reactors. All told, the immediate future of wind power looks very bright.

Solar energy:

The largest, mostly untapped sources of energy for all countries are perpetual and renewable energy from the sun, wind, flowing water, biomass, and the earth’s internal heat (geothermal energy).

Currently India gets about 21% of its energy from perpetual and renewable energy resources but could easily get much more using available technology. California currently gets roughly 30% of its electricity from perpetual and renewable sources of energy; by the year 2009 this figure could rise to 50%.

According to the Department of Energy, reserves and potential supplies of perpetual and renewable energy sources in India make up 93% of the country’s total energy resources. Developing these untapped resources could meet up to 80% of the country’s projected energy needs by 2010 and virtually all energy needs if coupled with improvements in energy efficiency.

Doing this would save money, eliminate the need for oil imports, produce less pollution and environmental degradation per unit of energy used, and increase economic environmental and military security. The rest of this chapter evaluates the various perpetual and renewable energy resources available to us.