Energy from the Sun
- Most of our energy resources on the Earth come from the Sun:
- The Sun heats up the atmosphere, creating wind and producing waves
- Water evaporated by the Sun falls as rain, filling up reservoirs
- Plants grown using sunlight form the basis for fuels – both biofuels and fossil fuels
- Some forms of energy, however, do not come from the Sun, these include:
- Geothermal – this comes from heat produced in the Earth’s core
- Nuclear – this comes from elements which make up a small proportion of the Earth’s crust
- Tidal – this comes (mainly) from the gravitational attraction of the Moon
Solar Radiation
- The energy from the Sun that falls on the Earth is transferred by radiation
- This is mostly visible light and infrared radiation
- The amount of energy transferred from the Sun to the Earth each hour is equal to the energy use of the world in one year
- Therefore, scientists are working hard to find methods of harnessing this energy
- Solar energy has a low energy density, which means large collecting devices are required
- Collecting solar energy is expensive (due to the equipment required) and inefficient
Solar Cells
- Solar cells transfer energy from sunlight electrically producing a current, and therefore generating electricity
- Solar cells, sometimes called photovoltaic cells, are made of semiconducting materials
- A number of cells connected together can supply electricity to homes, small-scale businesses, communication devices and satellites
- Energy generated from solar cells can be stored in batteries for later use
Field of Solar Cells
Solar cells use energy from sunlight to produce electricity
Solar Panels
- Solar panels transfer energy from sunlight to the thermal store of the solar panels
- This can be used to heat water in pipes for domestic water supplies
- This can reduce the cost of producing hot water since it is heated partially by the solar panel
Function of a Solar Panel
Solar panels use energy from sunlight to heat water
Solar Furnaces
- Solar furnaces consist of large curved mirrors that focus the Sun's rays onto a small area
- These can be used to heat water to generate steam which can turn turbines and generate electricity in a power station
- Water is stored in a water tank and pumped through small pipes running through the solar panel
- Infrared radiation from the Sun heats the water in the pipes as it flows through them
- The water returns to the tank at a higher temperature
- Water may still need to be heated further to reach the desired temperature (e.g. for a shower)
Advantages of Solar Energy
- Solar energy is a renewable resource
- In many places on Earth, sunlight is a reliable energy resource (i.e. places where the Sun shines most of the time)
- Solar farms produce no greenhouse gases or pollution
- Solar energy can be generated in remote places and in individual homes
- Solar panels are cheaper to produce and maintain than other energy sources
Disadvantages of Solar Energy
- Solar farms need to be large scale to produce large amounts of electricity and this requires vast areas of land
- People often don't like the appearance of large solar farms, this is known as visual pollution
- In many places on Earth, sunlight is not a reliable energy resource (i.e. places where there is a lot of cloud cover)