The energy that is used today comes from fossil fuels, which is a nonrenewable limited resource that will eventually be used up. Alternative energy sources such as solar, hydroelectric, geothermal and wind energies can be used, to conserve the planets limited natural resources. Alternative energy is the use of another energy without the burning of fossil fuels and break up on atoms. Solar energy can be used to operate cars and provide electricity for homes and businesses. Hydroelectric energy can be used to provide electric power to small towns and cities.

Geothermal energy can be used to heat buildings or water and to power turbines to make power. Wind energy can be used to pump water and generate electricity. Solar energy is of the most resourceful sources of alternative energy. It is the most important of the non-conventional sources of energy, because it does not pollute the earth. "One of the reasons for this is that the total energy we receive each year from the sun is around 35, 000 times the total energy used by man." (Alternative energy sources) Solar energy can be converted directly or indirectly into alternative forms of energy.

People use solar energy for many things, but most of it is used for heating, cooling, transportation and the generation of electricity. When the sun's rays are transformed into electricity, it is called photovoltaic energy. This is a simple way to get electricity. Photovoltaic panels can be put on the roof of a house to provide electricity or can be used in remote places where there is not electricity from other sources. Solar energy also powers cars without the use of gasoline which is made from the fossil fuel oil. Solar-powered vehicles (SPV's), such as cars, boats, bicycles, and even airplanes, use solar energy to either power an electric motor directly, and / or use solar energy to charge a battery, which powers the motor.

They use an array of solar photovoltaic (PV) cells (or modules made of cells) that convert sunlight into electricity. The electricity either goes directly to an electric motor powering the vehicle, or to a special storage battery. The PV array can be built (integrated) onto the vehicle body itself, or fixed on a building or a vehicle shelter to charge an electric vehicle (EV) battery when it is parked. (Green nature) Next, "Hydroelectric power is the largest source of renewable electricity in the world and in the United States." (Union of Concerned Scientists) This energy comes from water that is moving with ample speed and volume to turn a generator. The most common type of hydroelectric power comes from using a dam on a river or lake. Water is discharged from the reservoir, which spins the turbine, which activates a generator to get electricity.

Hydroelectric power does not require a large dam. Some hydroelectric power plants just use a small canal to channel the river water through a turbine. (Union of Concerned Scientists) Third, geothermal energy is heat from the earth that is used directly as hot water or steam, or used to produce electricity. Geothermal energy is contained in underground reservoirs of steam, hot water, hot dry rocks and hot spots. Geothermal hot spots are volcanic features which are found all around the world. Basically a hot spot is an area of reduced thickness in the mantle which transmits excess internal heat from the interior of the earth to the outer crust.

These hot spots are well known for their unique effects on the surface, such as the volcanic islands of Hawaii, the mineral deposits and geysers in Yellowstone National Park, or the hot springs in Iceland. These geothermal hot spots can easily be used to generate electricity. (Alternative Energy Sources) They are used at electric generating facilities, hot water or steam extracted from geothermal reservoirs in the Earth's crust is supplied to steam turbines at electric utilities that drive generators to produce electricity. Moderate to low temperature geothermal resources are used for direct use applications such as district and space heating. Lower temperature, shallow ground, geothermal resources are used by geothermal heat pumps to heat and cool buildings. (World Bank Group) Another energy is wind energy," Wind can be used to do work.

The kinetic energy of the wind can be changed into other forms of energy, either mechanical energy or electrical energy." (Energy Story) Blowing wind spins the blades on a wind turbine just like a large toy pinwheel. This device is called a wind turbine and not a windmill. Windmills grind or mill grain, or they can be used to pump water. The blades of the turbine are attached to a hub that is mounted on a turning shaft. The shaft goes through a gear transmission box where the turning speed is increased. The transmission is attached to a high speed shaft which turns a generator that makes electricity.

If the wind gets too high, the turbine has a brake that will keep the blades from turning too fast and being damaged. (Energy Story) Once electricity is made by the turbine, the electricity from the entire wind farm is collected together and sent through a transformer. There the voltage is increased to send it long distances over high power lines. In order for a wind turbine to work efficiently, wind speeds usually must be above 12 to 14 miles per hour. Wind has to be this speed to turn the turbines fast enough to generate electricity. The turbines usually produce about 50 to 300 kilowatts of electricity each.

A kilowatt is 1, 000 watts (kilo means 1, 000). You can light ten 100 watt light bulbs with 1, 000 watts. So, a 300 kilowatt (300, 000 watts) wind turbine could light up 3, 000 light bulbs that use 100 watts (Energy Story) Even though you can only use windmills in areas that are fairly windy they are still an effective way to produce without burning fossil fuels. Luckily, there are many means alternative energy sources to conserve the earths limited natural resources. Solar, hydroelectric, wind and geothermal energies are the alternative energy sources that will be used in the feature, so that consumers won't rely on the earth's natural resources as much they do now.

As the world continues to grow and have need for energy, applied science will and discover more alternate energy sources to be used in the feature. Works Cited Energy Story. Wind Energy, 15 April 2005 web Green Nature. Solar Powered Vehicles 25 April 2005 green nature. com / article 101. html The World Bank Group.

Geothermal Energy, 19 April 2005 web Tran P... Alternative Energy Sources, 19 April 2005 web Union of Concerned Scientists. How Hydroelectric Energy Works, 25 April 2005 web energy / renewable energy / page. cf m? page ID = 82.