Renewable energy

SDG Ensure access to affordable, reliable, sustainable and modern energy for all

The sun is the ultimate source of most of our energy either directly through light and heat or indirectly through wind and waves. In addition there are tides created by the rotation of the moon around the earth or geothermal heating from the cooling of the earth’s core. The other source of energy is the conversion of light by photosynthesis into nutrients to enable the growth of plants and trees generally known as biomass.

These sources are renewable, abundant and inexhaustible. Their usage creates little or no pollutants and could be generated or produced on a micro-scale at point of use saving transmission and distribution losses. They have met our energy needs in previous eras and there is no reason why they could not meet our needs today.

One hundred years ago all energy production was localised – electricity was generated at point of use primarily by wind turbines whilst oil and paraffin was available in containers. Windmills or watermills were also used to grind wheat to produce flour.

Windmill		Watermill

Description

Renewable energy sources arise directly or indirectly from sunlight and involve five major processes

• absorption of heat from sunlight to produce hot water (solar water heaters)
• conversion of sunlight directly into electricity (photovoltaic or solar cells)
• conversion of air movement (wind) into electricity (wind turbines)
• conversion of sunlight into food which enables plant materials and trees to grow (biomass)
• concentration of low-grade heat stored within the thermal mass of the earth (heat pumps)