8.5 - Wind & Solar

Wind turbines generate electricity

• Wind turbines are built in exposed places where the wind is strong - moors, coasts, or out at sea.
• They can stand singly or be grouped into a wind farm.

How a wind turbine works

• Each turbine has a generator inside it.
• Moving air turns the blades, which turn the generator to produce electricity.
• The energy comes from the kinetic energy of the wind, so no fuel is burned.

Advantages

• No pollution while running (some is produced during manufacture).
• The wind is free, so there are no fuel costs and low running costs.
• Renewable - The wind won't run out.
• No permanent damage to the landscape.

Disadvantages

• High initial cost to build, especially out at sea.
• A very large number of turbines is needed to replace one conventional power station, taking up a lot of space and affecting views.
• Turbines can be noisy, annoying people living nearby.
• The supply is unreliable - they only work when it's windy, and output can't be increased to meet extra demand.

Solar cells generate electricity directly from sunlight

• Solar cells generate electricity directly from sunlight, with no moving parts and no burning of fuel.
• Individual cells join together to form solar panels, and multiple panels form a solar farm.

What they are used for

• Powering small, low-power devices such as calculators and watches.
• Providing electricity in remote places - satellites, road signs, and homes far from the mains grid.
• Small-scale generation on home rooftops.

Advantages

• No pollution while working.
• The Sun's energy is free and running costs are almost zero once installed.
• Renewable and very reliable in sunny countries.

Disadvantages

• High initial cost to manufacture and install.
• They only generate in the daytime, and the supply can't be increased to meet extra demand.
• They produce relatively little power for the area they take up.