A solar thermal plant being developed in Seville, Spain, will produce 300MW of power at a projected cost of E1,200bn, or R11,6 billion. That’s an installed cost of R4-billion per 100MW. A prototype 11MW plant is already up and running; it’s almost a thing of beauty – take a look here or here. (The rays you see in the atmosphere have not been added to the photograph – they’re not illustrated but real, created by the intense illumination of the solar array hitting atmospheric dust and moisture.)
Eskom’s (our parastatal national electricity provider) prototype Pebble Bed Modular Reactor (PBMR) is likely to cost R25 billion. The projected output is 120MW. By my admittedly rough calculations, that makes the cost of building the PMBR approximately FIVE times more expensive than solar thermal. Even using the figures Eskom prefers to use, which are of course far lower than R25-billion, the PBMR remains much expensive than solar thermal. (The PBMR has also been judged an economic non-starter for South Africa, by PriceWaterhouseCoopers, according to documents Eskom accidentally sent to Earthlife Africa.)
Of course, no organisation is monolithic. Perhaps it is saner folk at Eskom who are working on a proposal for a solar plant for the Northern Cape, where the cost of 100MW of capacity was estimated in 2003 at R2-billion, quite a lot lower than the figure from Seville (but of course, these figures are four years old). No final decision on whether to proceed with this plant has yet been taken.
So how much would it cost to build a solar power station the size of the Medupi greenfield coal-fired station Eskom has begun constructing in Limpopo? Medupi’s projected output is 4500MW. To build a solar thermal plant the same size would cost at least R90-billion (though this estimate ignores likely economies of scale), quite a lot more expensive than Medupi at R70-billion.
But this does not take into account running costs, financial and environmental: Medupi will burn hundreds of thousands of tons of ever-more expensive coal each year, while pouring CO2 and pollutants into the atmosphere. While at an equivalent solar power station … ? Well, they’ll be kept quite busy cleaning all those mirrors, a rather less costly procedure.
Of course, another incredibly important factor in all this is that both coal and nuclear power are relatively mature technologies. Whereas solar thermal power is in its infancy. There is no reason not to be absolutely certain that as the technology matures, costs will drop, making it far more
But what happens at night?
Of course, a solar plant does not operate at night. The plant in Seville has capacity for storage of heat that allows generation to continue an hour after sunset. Even a modest extention in this capacity would help with Eskom’s second peak period of demand 17h00 to 21h00. but not sufficiently. But solar innovators are determined to crack this problem. One Californian company, Ausra, proposes a steam storage solution that would make solar energy a round-the-clock solution. Another untested solution proposes using daytime electricity to split water into hydrogen and oxygen. The two gases are then burnt at night to produce heat for power generation.
Even before a storage solution makes solar power feasible round the clock, it could already help in reducing the daytime use of coal power.
The decision to continue with coal power is absolutely insane. It ignores:
- the costs of global warming
- the finite supply of coal (even if we are at present a long way from running out)
- the direct impacts of other pollutants from coal – sulphur and particulates, and 30 million tons of coal ash
- and the fact that there is already some risk of coal shortages, and coal prices are already rising.
The decision to continue with nuclear also ignores the unsolved problem of nuclear waste storage, and the inherent dangers of the technology (which are often misunderstood, but that’s another post).
This entire discussion, of course, is limited by the fact that it assumes that we should be relying on extremely centralised power generation. This model has considerable limitations – waste of energy in the course of long-distance transmission, high vulnerability to disruption, But there are now a multitude of technologies that could be used for local and domestic power generation, wind, solar and appropriate biomass (Imagine turning all the invasive, water-sucking plant species that have invaded our biome into power – Port Jackson, hakea, black wattle, eucalyptus — and the incredible employment opportunities this would create.)