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Key facts

Although renewable energy is becoming more common, there are still big issues to overcome if we are to move away from completely.

Many energy sources (wind, wave, solar) rely on the weather, which is unpredictable. It is not always possible to produce a reliable supply of energy. Storing energy might help solve this problem.

Energy storage is also important to make renewable energy more portable.

A hydrogen fuel cell car refuels with hydrogen at an H2 hydrogen filling station, Herten, Germany.
Image caption,
A hydrogen fuel cell car refuels with hydrogen at an H2 hydrogen filling station, Herten, Germany.

New renewables and their impact

Find out about some of the newer types of renewable energy generation.

Pumped storage

Cruachan Power Station, Dalmally, Argyll
Image caption,
Cruachan Power Station, Dalmally, Argyll

Pumped storage is not a new idea but it could be developed more to add to our energy storage capacity.

Large amounts of energy can be stored in pumped storage systems like at Cruachan Hydroelectric Power Station.

Water held in an upper reservoir has a lot of potential energy.

When energy is needed, the water is released and flows down through and into the lower reservoir. This converts kinetic energy into electrical energy.

When there is a surplus of electricity, Cruachan can use some of this spare energy to pump water back up to the upper reservoir, ready to flow back down again.

Cruachan Power Station, Dalmally, Argyll
Image caption,
Cruachan Power Station, Dalmally, Argyll

Gravity storage

Gravitricity gravity storage facility, Leith, Scotland.Image source, Courtesy of Gravitricity/ Peter Dibdin
Image caption,
Gravitricity gravity storage facility, Leith, Scotland.
A mine shaft
Image caption,
Disused mine shafts could be used as sites for gravity storage.

Gravity storage is a newer system that uses the same principle as pumped storage.聽Instead of water the idea is to raise and lower huge weights in a deep shaft of up to 1500m.

When more electricity is being generated than is being used, some of this extra energy can be used to raise the weights. This builds up their gravitational potential energy.

Releasing the weights so that they are lowered converts this potential energy to kinetic energy. Turbines and generators turn this into electrical energy - kinetic energy converted to electrical energy.聽By letting the weights fall at different speeds, the amount of electricity generated can be controlled to meet different levels of demand.

A mine shaft
Image caption,
Disused mine shafts could be used as sites for gravity storage.

Renewable energy for transport

Electric cars

Electric cars being charged up in a UK street.
Image caption,
Electric cars being charged up in a UK street.

Electric cars are great for short trips however the battery size limits how far you can travel before you need to recharge.

Longer lasting batteries will need to be invented that provide the same amount of electricity, are a similar size but also are quicker to recharge.

Some cars have hybrid systems which use both petrol and batteries. The car uses energy created on braking to recharge the battery, which can be used to power the car at moderate speeds.

Fuel cells

A hydrogen fuel cell in a car.
Image caption,
A hydrogen fuel cell in a car.

Another solution to providing portable energy stores for transport is hydrogen fuel cells.

These react hydrogen and oxygen to producing usable electrical energy. There are very clean as no carbon dioxide is produced; only water.

  1. Stored hydrogen enters the fuel cell.
  2. A catalyst splits hydrogen molecules into protons and electrons
  3. The protons travel through an electrolyte from the positive electrode to the negative electrode
  4. The electrons travel through an external circuit from the positive electrode to the negative electrode, creating a flow of electricity.
  5. At the negative electrode the protons combine with the electrons and oxygen to form water.

But hydrogen fuel cells are expensive and need to be much bigger than a conventional petrol tank. They鈥檙e currently more suitable for lorries and buses than family cars.

Renewable ways to heat our homes

As gas-powered combination boilers are phased out, air source heat pumps will become more common.
Image caption,
As gas-powered combination boilers are phased out, air source heat pumps will become more common.

Most homes in Scotland have gas boilers to provide heat. Since natural gas is a fossil fuel, we will need a better solution.

One alternative is air source heat pumps. These take in air from outside your home and compress it. This concentrates the heat energy from the air so that even cold air can be used to warm your central heating system.

But these can鈥檛 supply as heat at such high temperatures as a gas boiler, so bigger radiators or underfloor heating are needed to keep your house as warm. This also means that many of our homes will need to have much better insulation for heat pump systems to work well.

As gas-powered combination boilers are phased out, air source heat pumps will become more common.
Image caption,
As gas-powered combination boilers are phased out, air source heat pumps will become more common.

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