AQA Environmental Science – Renewable Energy

What is solar power?

Solar power uses energy from the Sun to generate useful energy, mainly electricity or heat. It harnesses sunlight through technologies like solar panels and solar thermal systems, making it a clean and sustainable energy source.

How does photovoltaic (PV) solar power work?

Photovoltaic cells convert solar radiation directly into electrical energy. The amount of electricity generated depends partly on the intensity of sunlight. When sunlight hits the PV cells, it excites electrons, creating an electric current that can be harnessed for power.

What is photothermal solar power?

Photothermal systems use solar radiation to heat a fluid, which can then be used for heating or to generate electricity. These systems typically involve collectors that absorb sunlight and transfer the heat to a working fluid, then use that heat in power generation through steam turbines or for direct heating applications.

Advantages of solar power?

• Renewable and effectively inexhaustible on human timescales.

• No fuel is burned during electricity generation.

• Very low operational greenhouse gas emissions.

• Can be installed at different scales, including buildings.

Disadvantages of solar power?

• Intermittent because sunlight varies during the day and with weather.

• Less effective at night and during periods of low insolation.

• Large-scale solar farms require significant land.

• Manufacturing panels requires energy and raw materials.

What technologies improve solar power?

AQA includes multi-junction photovoltaic cells, anti-reflective surfaces and Concentrating Solar Power (CSP).

How does HEP generate electricity?

Water stored at height has gravitational potential energy. As water flows downhill, this energy is converted into kinetic energy, which turns turbines connected to generators.

What is the main advantage of HEP?

HEP can provide a reliable source of electricity and can respond relatively quickly to changes in demand.

What are the disadvantages of HEP?

• Dams can flood large areas of land.

• Habitats may be destroyed or fragmented.

• River flow and sediment movement can be altered.

• Fish migration can be disrupted.

• Large construction projects have high environmental impacts.

What technologies improve HEP?

AQA specifically identifies low-head turbines and helical turbines.

What is pumped-storage HEP?

Water is pumped to a higher reservoir when electricity demand is low. It can then be released through turbines when demand is high, helping to store energy and balance the electricity supply.

How does wind power work?

Wind causes turbine blades to rotate. The rotational kinetic energy is transferred through the turbine to a generator, producing electricity.

Why is wind power renewable?

Wind is continuously produced by atmospheric circulation, which is ultimately driven largely by solar energy.

Advantages of wind power?

• Renewable resource.

• No fuel is burned during operation.

• Low greenhouse gas emissions during operation.

• Can generate significant amounts of electricity.

Disadvantages of wind power?

• Wind is intermittent, so electricity output varies.

• Turbines require suitable locations with sufficient wind speeds.

• Can cause noise pollution.

• Can affect landscapes and habitats.

• Construction and manufacture require energy and materials.

What technologies does AQA identify for wind power?

Horizontal Axis Wind Turbines (HAWTs) and Vertical Axis Wind Turbines (VAWTs), as well as wind-assisted ships.

How does wave power generate electricity?

Wave movement contains kinetic energy. Wave-energy devices convert the movement of waves into mechanical energy and then electrical energy.

Advantages of wave power?

• Renewable.

• No fuel is burned.

• Low operational greenhouse gas emissions.

• Waves are a potentially large source of energy.

Disadvantages of wave power?

• Wave energy varies with weather and sea conditions.

• Technology can be expensive to install and maintain.

• Equipment is exposed to corrosion and extreme weather.

• Devices may affect marine ecosystems and habitats.

What does AQA say about wave technology?

AQA expects students to understand new developments in wave power technology and evaluate their potential contribution to future energy supplies.

What are biofuels?

Biofuels are fuels produced from biological material, or biomass, such as crops, plant material or microorganisms.

Why are biofuels renewable?

Plants can be regrown, meaning the biological material used to produce biofuels can be replaced

Advantages of biofuels?

• Renewable if biomass is managed sustainably.

• Can replace some fossil fuels in transport.

• Biomass can store carbon through photosynthesis.

• Can potentially make use of waste biological material.

Disadvantages of biofuels?

• Growing biofuel crops can compete with food production.

• Large-scale production can require significant land.

• Habitat loss can occur if natural ecosystems are converted to crops.

• Fertilisers and pesticides can cause pollution.

• Burning biofuels releases carbon dioxide.

What biofuel technologies does AQA identify?

AQA includes biofuel crops, hydrogen from algae and biofuels from microorganisms.

What is geothermal energy?

Geothermal energy is heat from within the Earth. This heat can be used directly or to generate electricity.

How can geothermal energy generate electricity?

Heat from underground can heat water and produce steam. The steam can drive a turbine connected to a generator.

Advantages of geothermal power?

• Renewable when managed sustainably.

• Can provide a relatively reliable energy supply.

• Not dependent on sunlight or wind.

• Can be used for heating as well as electricity generation.

Disadvantages of geothermal power?

• Suitable sites are geographically limited.

• Drilling and infrastructure can be expensive.

• Underground fluids can contain minerals and gases that need management.

• Developing geothermal sites can have local environmental impacts.

What geothermal technologies does AQA identify?

AQA includes low-temperature fluids and district heating systems

What causes tides?

Tides are mainly caused by the gravitational effects of the Moon and Sun acting on Earth's oceans.

How can tidal power generate electricity?

The movement of seawater caused by tides can drive turbines, which turn generators to produce electricity.

Advantages of tidal power?

• Renewable.

• Tidal cycles are highly predictable.

• No fuel is burned during electricity generation.

• Can provide a reliable source of energy when tidal conditions are suitable.

Disadvantages of tidal power?

• Construction can be expensive.

• Suitable locations are limited.

• Tidal schemes can alter coastal and marine ecosystems.

• Barrages can affect sediment movement and habitats.

• Can interfere with some marine organisms and human activities.

What tidal technologies does AQA identify?

AQA includes tidal barrages, tidal lagoons and in-stream turbines.

What does intermittency mean?

Intermittency means that an energy resource does not provide a constant supply of energy. Wind and solar are examples because their output changes depending on environmental conditions.

What is energy density?

Energy density is the amount of energy available from a given amount or area of a resource.

What are locational constraints?

Locational constraints are factors that restrict where an energy resource can be developed, such as suitable wind speeds, sunlight, geology or tidal conditions.

Why is energy storage important for renewable energy?

Some renewable resources are intermittent. Energy storage allows excess electricity to be stored when supply is high and released when demand is greater than supply.

What energy-storage technologies does AQA identify?

• Pumped-storage HEP

• Rechargeable batteries

• Fuel cells

• Compressed gas

• Thermal storage

• Vehicle-to-grid (V2G)

• Power-to-gas (P2G)

• The hydrogen economy