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Units of energy consumption are usually expressed in terms amount of energy used over a certain period – the standard term for this is kilowatt hours or kWh i.e. the amount of energy consumed over an hour. The 1.5kW heater if left on for an hour with a constant electrical supply will therefore consume 1.5kWh of energy. Electricity is sold by the kWh, which equals 1 unit of electricity. The current average domestic tariff is around 14p per kWh, therefore keeping the electric heater on for 1 hour will consume 1.5 units of electricity and cost 21p.

Understanding some renewable energy basics will help you to work through what may be possible for your community. Below are some typical questions that arise as people seek to understand how renewable energy works and why they should consider using it.

In general, renewable energy sources are less energy dense then fossil sources. This has two practical implications: more space to store or extract the energy source is required and it takes longer to harness an equivalent amount of useful energy.

Fossil fuels have limited reserves estimated to last between 50 and 120 years based on their current and projected consumption. Renewable energy is limitless and, as its name suggests, is renewable and at least one of its forms is available anywhere in the world.

In the long-term, the on-going cost of renewable energy based systems is likely to be lower than those based on fossil sources with fossil fuels widely expected to increase in cost as global demand increases. In addition, as the use of renewable systems increase, economies of scale will mean installation costs will become more competitive with traditional sources.