Eskom and SAREC (South African Renewable Energy Council) are still debating the future of renewable energy in South Africa, with Eskom still insisting renewable energy is too expensive and SAREC replying that Eskom is not taking all factors into consideration. Eskom is capable of generating 34 000 MW. This includes all coal-fire, a nuclear and two hydroelectric power stations, with the main generation coming from coal-fire based power stations. So the question is… how do we move from the electricity grid we have, to a fully renewable energy grid?
At the moment, South Africa has invested money into renewable energies such as solar and wind. As most people know, the snag in these renewable energies are that the wind doesn’t always blow and we can only get solar power when the sun is out. To use renewable energy more effective, the excess power that is generated needs to be stored in such a way that it can be used at a point in time where a renewable energy source is not available, in other words a grid scale storage for renewable energy.
There are many ways energy can be stored. The most commonly known form of storage is a battery. Batteries only have a life expectancy of 10 years. For a renewable energy grid to exist, we need to look at energy storage of a massive scale which is not required to be replaced over short periods of time. Although there are many forms of energy storage, three are considered to be viable options for grid scale energy storage. These are Chemical Energy Storage, Compressed Air Storage and Pumped Hydro.
Pumped Hydro and Compressed Air Storage basically work with the same concept. Renewable energy can be used to pump water from a low to a high position, or used to compress air. Water would then use gravity feed to flow to a lower position to rotate a turbine, like a hydroelectric plant. The same with compressed air. The pressure build up from compressing air can be released and the flow of air will rotate a turbine and thus begin generating electricity. Chemical Energy Storage works on the principle of using renewable energy, to generate hydrogen. The hydrogen can be stored and used later to create methane gas or be used in fuels cells.
Projects researching alternative energy storage, as mentioned above, are already in progress with countries such as Germany, America and Australia making big contributions. Although these technologies are still expensive and far from being implemented as grid storage, if countries such as Germany, who has been responsible for the price of solar panels dropping by 80% in the last few years, are investing in development, the cost of energy storage will be going down in the near future.