7.14 - 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.

Solar heating systems use the Sun's energy to heat water

Solar heating systems use the Sun's energy directly to heat water, rather than generating an electric current.

Solar water heating panels

• A solar water heating panel consists of black water pipes inside a glass box.
• The glass lets the Sun's energy in and the black pipes absorb it, which heats the water flowing through them.
• The hot water can then be fed into a building's heating or hot water system.
• The panels are renewable and almost free to run, though they have an upfront installation cost.