1.3.3 Energy optimisation

Technology constitutes one of the main driving forces of economic growth.

The successful introduction of new environmentally sound technologies into the marketplace will depend, among other factors, of the cost-competitiveness to the existing ones.

What is renewable energy?

Energy exists freely in nature. Some of them exist infinitely (never run out, called RENEWABLE), the rest have finite amounts (they took millions of years to form, and will run out one day, called NON-RENEWABLE).

South Africa, like other transitional countries, faces the dual challenge of pursuing economic growth and environmental protection. Sustainable energy systems, based on renewable energy (RE) resources, offer the possibility of doing both. The implementation of RE technologies faces a major challenge because South Africa has large coal deposits and its electricity generated from coal is among the cheapest in the world. Currently less than 1% of the 200 000 GWh of electricity generated in the country originates from renewable sources.

Solar water heaters

The provision of hot water using SWH technologies has the benefit of providing quality local government infrastructure services, saving households money over the long term and mitigating GHG emissions associated with fossil fuel usage. SWHs are also the least expensive means of heating water for domestic use on a life-cycle cost basis because solar energy is free. South Africa experiences high levels of solar radiation, with average daily solar radiation of between 4.5 and 6.5 kWh per square metre. This resource is relatively predictable and well distributed throughout the country with some regional variations. The levels of radiation available for SWH are dependent on:

  • Geographical location within South Africa
  • The azimuth angle of the collector in relation to True North
  • The angle of tilt from the horizontal
  • Local climate and atmospheric conditions

Biodiesel

Biodiesel processing technology is relatively uncomplicated and it can be profitable on small or large scales. The fuel can be blended with petroleum diesel. In rural areas cooperatives can be set up with surrounding producers and customers and it can be produced as energy fuel in remote rural areas. Opportunities for job creation are high, in both the agricultural and production sectors. New cooperatives centred around the biodiesel production units could become development hubs for other agricultural activities as cattle feed lots.

What is biomass?

Biomass fuels come from things that once lived: wood products, dried vegetation, crop residues, aquatic plants and even garbage. It is known as ‘Natural Material’. Plants used up a lot of the sun’s energy to make their own food (photosynthesis). They stored the foods in the plants in the form of chemical energy. As the plants died, the energy is trapped in the residue. This trapped energy is usually released by burning and can be converted into biomass energy.

Wood is a biomass fuel. It is renewable. As long as we continue to plant new trees to replace those cut down, we will always have wood to burn. Just as with the fossil fuels, the energy stored in biomass fuels came originally from the Sun.

It is such a widely utilised source of energy, probably due to its low cost and indigenous nature, that it accounts for almost 15% of the world’s total energy supply and as much as 35% in developing countries, mostly for cooking and heating

How is biomass converted into energy?

  • Burning

This is a very common way of converting organic matter into energy. Burning stuff like wood, waste and other plant matter releases stored chemical energy in the form of heat, which can be used to turn shafts to produce electricity. Let us see this simple illustration of how biomass is used to generate electricity.

  • Energy from the sun is transferred and stored in plants. When the plants are cut or die, wood chips, straw and other plant matter is delivered to the bunker
    • This is burned to heat water in a boiler to release heat energy (steam).
    • The energy/power from the steam is directed to turbines with pipes
    • The steam turns a number of blades in the turbine and generators, which are made of coils and magnets.
    • The charged magnetic fields produce electricity, which is sent to homes by cables.

Other ways in which organic matter can be converted into energy include:

  • Decomposition:

Things that can rot, like garbage, human and animal waste, dead animals and the like can be left to rot, releasing a gas called biogas (also known as methane gas or landfill gas). Methane can be captured by a machine called Micro-turbine and converted into electricity. Sometimes, animal waste (poop) can also be converted into methane by a machine called ‘Anaerobic Digester’

  • Fermentation:

Ethanol can be produced from crops with lots of sugars, like corn and sugarcane. The process used to produce ethanol is called gasification.

Wind Energy

  • Wind Energy Fact Nr.1

In 1997 wind power generated only 0.1% of the world’s electricity, this increased to 1.5% in 2008 and 2.5% in 2010.

  • Wind Energy Fact Nr.2

Wind power is currently the fastest-growing source of electricity production in the world.

  • Wind Energy Fact Nr.3

A single wind turbine can power 500 homes and is one of the lowest-priced renewable energy sources.