Solar energy is obtained from sunlight.
Solar energy has been used by humans for a long time for uses such as heating, cooking food, removing salt from seawater and drying clothes.
These days it is also used to create electricity. As technology has improved, solar power costs have decreased and it has become a more viable alternative, competing with energy sources such as coal and oil.
While solar power is becoming more efficient, it only provides a small fraction of the world’s energy supply.
Solar cells convert light energy into electricity.
Solar cells are also called photovoltaic cells.
Wind power involves turning energy from the wind into other forms of useful energy.
Wind power can be harnessed in a number of different ways. For example, windmills create mechanical energy, sails move boats and wind turbines generate electricity.
Windmills have been around for a long time, they were used in Persia (Iran) as far back as 200 B.C.
Wind energy is clean and renewable.
Large groups of wind turbines are called wind farms.
Geothermal energy is made inside the Earth.
The world geothermal comes from Greek words meaning ‘Earth’ (geo) and ‘heat’ (thermos).
The technology behind geothermal electricity generation has improved substantially but it still only provides a fraction of world electricity generation.
Geothermal power is clean, reliable and cost effective but its availability is often limited to areas near tectonic plate boundaries.
Geothermal power plants in the Philippines and Iceland contribute around 30% of their electricity production. In the USA it is less than 1%.
Nuclear power uses fission (splitting atom nuclei) to produce energy.
Nuclear fusion (joining atom nuclei) also has potential for energy production.
Around 6% of the world’s energy and 14% of the world’s electricity is produced by nuclear power.
There are over 400 nuclear power reactors in use around the world.
Around 30 different countries have operational nuclear reactors.
Hydropower uses the energy of moving water for a variety of useful applications.
Hydroelectricity generates electricity by harnessing the gravitational force of falling water.
In 2006, hydroelectricity supplied around 20% of the world’s electricity.
Most hydroelectric power stations use water held in dams to drive turbines and generators which turn mechanical energy into electrical energy.
The largest hydroelectric power station in the world is the Three Gorges Dam in China.
- Almost half of the renewable energy produced in the United States comes from biomass sources, like wood and paper products.
- In Iowa and Wisconsin, biomass energy from landfills and dairy farms is being used to make electricity.
- In southern Iowa, a power plant is using a crop called switchgrass to make electricity.
- The word "biomass" means natural material.
- If you've ever been near a campfire or a fireplace, you've witnessed biomass energy through the burning of wood.
- Biomass has been around since the beginning of time when man burned wood for heating and cooking.