A Fossil-fuel-free future by Gavin Lloyd
Following on from the Sundays@Belmont debate on Renewing the Earth, members expressed interest in the prospects for renewable energy in South Africa. The challenge is considerable since South Africa currently has one of the world’s worst per capita consumptions of fossil fuel, being a car-mad country with generally poor public transport and vast quantities of mainly low-quality coal. However, it is possible within the next fifty years for us to change our patterns of energy production completely so that we become substantially fossil fuel-free. But this must be achieved without bankrupting our economy, which is where most reports on the matter become senseless. The inherent difficulty with renewable energy forms like wind, wave, tidal and solar is that they are either inconsistent or cyclical. All four of these forms have a load factor of between 16 and 20%, which makes them ultimately expensive and unsuitable for base load power unless generally prohibitively more money is spent on some form of energy storage. So capital spent on these forms of renewable energy is generally window dressing, making you feel better but actually pushing up the cost of electricity unnecessarily. Worldwide, the cheapest form of electricity production remains the hydro-electric extraction of electricity from fast-flowing water. It does seem that the well-known evils of major dams are no longer a necessary ecological negative. There have been new developments using low-head turbines that deliver a similar quantum of power using multiple weirs in combination in order to lower the environmental impact and avoid the siltation problems of high walled dams, this being particularly problematic in Africa. Africa happens to have the finest hydro-electric site in the world, namely the Inga Rapids just 150 km from the coast in the Democratic Republic of the Congo. The Congo is the second largest river in the world with the world’s highest average flow and it plunges from an elevation of 260m to 100m over just 20 km of L-shaped rapids. Were this potential to be fully developed, Africa would benefit from cheap renewable electricity for the remainder of this century, but there are severe political difficulties that have recently caused all further Feasibility Studies to halt indefinitely. Hopefully these difficulties will be overcome in the next 25 years. South Africa does not have any significant hydro-electric potential on land but we do have an exceptional offshore site along our Wild Coast. A combination of factors cause the Agulhas Current to rapidly increase velocity and press against the coastline from Port Shepstone down to Port Elizabeth at a distance of between 5 and 15 km offshore. The Current reaches velocities of up to 2m/sec making it one of the fastest ocean currents in the world. If we could harness just 1% of this energy, we would be able to power most of South Africa in a marine-life-friendly way. ESKOM has undertaken fundamental research since 2003 on the Current’s behaviour and together with technology being developed in France, USA and Scotland, there is reasonable hope that we will have pilot projects in the sea within 5 to 10 years. It is still too early to establish a production cost. However, Eskom’s main effort in renewable energy will be focussed on Concentrated Solar Power (CSP), a novel technology that uses sun-tracking helio-stat mirrors to focus heat on a 190-m high central tower where molten salt is heated to over 800 °C. The salt is then stored in underground tanks from which steam is created to power a turbine continuously. Eskom is hoping to build a standardized 100 MW CSP unit covering 12 square km (model shown here). As yet, no units of this size have been constructed in the world so the initial costs will be relatively high (probably four times our current electricity production cost). Nevertheless, it is appropriate technology for SA, although dry-cooling may have to be introduced and unit prices should fall within the range of coal within 10 years. There is also the possibility that photo-voltaic cells can be combined with the helio-stats to improve overall efficiency. So, in the context of SA, we have an approximately 10-year technology gap that no current renewable technology can reasonably fill without severely raising the unit cost of electricity in the country. Nuclear power has to step into this gap and the newest designs coming from Europe and the USA are promising very advanced levels of efficiency, safety and longevity. It is probably that these reactors will have a South African unit price that is about 30% higher than that of coal (nuclear costs are comparable to that of coal in Europe). This will provide the time window to allow the more expensive CSP and Marine Current technologies to reduce in price. We therefore need to accept that in the interests of quickly reducing our per capita carbon output, we now need to build another three or four nuclear power stations rather than a third or fourth coal-fired power station (two more are already in construction). However, some programmes that indicate 20 nuclear power plants seem very excessive and unnecessary in the long term. Staying with nuclear power, SA has spent a great deal of research money to develop its own Pebble Bed Reactor after purchasing critical patents in the early 1990s. These reactors produce much higher temperatures (up to 900 °C) and are inherently safer than Pressure Water Reactors. However, an important design shift happened at the end of 2008 and the Reactor is now being redesigned as a smaller unit to deliver process heat as well as steam at various take-off temperatures. The first pilot plant will still be built at Koeberg to be operational by 2018. Such plants could be used in a very efficient way ultimately to save substantial quantities of carbon emissions by industry worldwide. Lastly, we should expect at least four fully electric cars, specifically designed for the urban commuter, to appear on the market in the next three years and many more thereafter. Not only will they be substantially cheaper to run (about 14% of the current running costs of a vehicle) but in using off-peak power, they will help to reduce the average cost of electricity since power stations will start to run more efficiently. Battery development is progressing at a frantic pace worldwide; however, the long-term solution to energy storage may just be the simple capacitor in a super dense form since it can be recharged virtually instantaneously. SA is developing its own very attractive electric 5-seater car called the Joule which is due to go into mass production in East London in 2012. There is therefore considerable hope that the world will be largely free of the infernal internal combustion engine within the next decade except for long haulage and heavy vehicles where the power density contained in diesel is hard to beat. To summarise, SA’s natural assets in solar and ocean current power place us in an advantageous position to become at least 60% renewable in the next 50 years (even more if Grand Inga in the DRC is built). Probably about 20% will remain nuclear and the remainder will be from coal-fired power stations serving out their life span unless there is a breakthrough in safe carbon sequestration. All homes will have solar geysers by law and fossil-fuelled cars will be heavily taxed. Bio-diesel will be commonly produced from waste organic matter for industry. Hopefully, too, SA will have a vibrant nuclear industry manufacturing components for PBMRs for the world marker. The average suburbanite can make a big difference now by installing a solar-powered geyser as soon as possible (the latest technologies using vacuum tubes are very efficient and cheaper than you think) and then budgeting for an electric car within the next four years. In that way you will help considerably in gaining that ten years of developmental time needed to roll out CSPs and also reduce valuable capital expenditure on nuclear power. As Christians, we should pray for world leaders in December at the critical Copenhagen meeting on Global Warming-countering strategies as well as for African leaders to take decisive steps to harness our continent’s natural assets to best effect through regional energy-sharing agreements.
As there is much poorly understood press on renewable energy technology, as witnessed by letters to the editor in the daily newspapers, I think it is worthwhile to look ahead realistically to foresee what could be achieved in the next fifty years on our sub-continent.
