...derived from natural processes that are replenished constantly. In its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, and biofuels and hydrogen derived from renewable resources.

Sustainable or renewable energy is energy generated from natural resources - such as sunlight, wind, rain, tides and geothermal heat. Climate change concerns coupled with high energy prices, resource depletion and geopolitical risk impinging on energy security are causing the increased adoption of renewable energy legislation and growth in the renewable energy industry. As an example, one of the more ambitious global sustainable energy targets is that of the European Union which reached an agreement in principle in March 2007 to produce 20% of its energy requirements from renewable fuels by 2020, as part of its drive to cut emissions of greenhouse gases.

In South Africa, most electricity is generated by coal-fired power stations. According to ESKOM, South Africa's main electricity supplier, each kilowatt-hour (unit) of electricity generated consumes 560 grams of coal and 1.44 litres of water. In turn, 1 kilogram of the greenhouse gas, carbon dioxide, is released into the atmosphere. South Africa's heavy dependence on coal puts it within the top fifteen emitters of greenhouse gases in the world. There is no doubt that pressure will be brought to bear on South Africa over the coming decades to reduce its emissions and turn towards more sustainable energy sources.

Apart from the environmental benefits of adopting renewable energy systems, there are also social and economic benefits in that renewable energy systems lend themselves to being decentralised and are thus more inclusive. These include job creation benefits which coincide with South Africa's development and poverty reduction goals.

The South Africa Governement's Department of Minerals and Energy (DME) has produced a White Paper on Renewable Energy (2003) which sets a target of 10 000GWh of energy to be produced from renewable energy sources (mainly from biomass, wind, solar and small-scale hydro) by 2013. This is approximately 4% of the projected electricity demand for that year. The DME has also formulated a Biofuels Industrial Strategy (2007) outlining policy, regulation and incentives for the production of biofuels.

The ESKOM Solar Water Heating (SWH) programme in which rebates are given to consumers who purchase a solar water heating system is also a government initiative that will alleviate some of the strain on the electricity supply whilst contributing significantly (up to 23%) of the 2013 renewable energy target. Solar water heating along with energy efficiency measures such as the use of energy efficient appliances are some of the immediate steps that organisations, families and individuals can take towards a sustainable energy future.