African solar farms to solve energy crisis?
Here comes the sun
Ashley Seager
Guardian Weekly /Guardian Unlimited, Friday December 1 2006
Source:
http://www.guardian.co.uk/guardianweekly/story/0,,1959898,00.html
In the Sahara desert is a vast source of energy that can promise a carbon-free, nuclear-free electrical future for all Europe, if not the world. We are not talking about the vast oil and gas deposits beneath Algeria and Libya, or uranium for nuclear plants, but something far simpler – the sun. Every year it pours down the equivalent of 1.5m barrels of oil of energy for every square kilometre.
Most people think of solar power as a few panels on the roof of a house producing hot water or a bit of electricity. But according to two reports prepared for the German government, Europe, the Middle East and North Africa should be building vast solar farms in North Africa’s deserts using a simple technology that more resembles using a magnifying glass to burn a hole in a piece of paper than any space age technology.
Two German scientists, Dr Gerhard Knies and Dr Franz Trieb, calculate that covering just 0.5% of the world’s hot deserts with a technology called concentrated solar power (CSP) would provide the world’s entire electricity needs, with desalinated water for desert regions as a valuable byproduct, as well as air-conditioning for nearby cities.
Focusing on Europe, North Africa and the Middle East, they say, Europe should build a new high-voltage direct current electricity grid to allow the easy transport of electricity from a variety of alternative sources. Britain could put in wind power, Norway hydro, and central Europe biomass and geo-thermal. Together the region could provide all its electricity needs by 2050 with barely any fossil fuels and no nuclear power. This would allow a 70% reduction in carbon dioxide emissions from electricity production over the period.
CSP technology is not new. There has been a plant in the Mojave desert in California for 15 years. Others are being built in Nevada, Spain and Australia. There are different forms of CSP, but all share the use of mirrors to concentrate the sun’s rays on a pipe or vessel containing some sort of gas or liquid that heats up to about 400C and is used to power conventional steam turbines.
The large mirrors create shaded areas that can be used for horticulture irrigated by desalinated water generated by the plants. Cold water produced for air conditioning means there are three benefits. “It is this triple use of the energy which really boosts the overall energy efficiency of these kinds of plants up to 80% to 90%,” says Dr Knies.
This form of solar power is also attractive because the hot liquid can be stored in large vessels, which can keep the turbines running for hours after the sun has gone down.
The German reports put an approximate cost on power derived from CSP. This is now about $50 per barrel of oil equivalent for the cost of building a plant. That cost is likely to fall sharply, to about $20, as production of the mirrors reaches industrial levels. It is about half the equivalent cost of using the photovoltaic cells that people have on their roofs. So CSP is competitive with oil, currently priced at about $60 a barrel.
Dr Knies says CSP is not yet competitive with natural gas for producing electricity alone. But if desalination and air conditioning are added, CSP undercuts gas, without taking into account the cost of the carbon emissions from fossil fuels. Desert land is cheap and there is roughly three times as much sunlight in hot deserts as in northern Europe. This is why the reports recommend a collaboration between countries of Europe, the Middle East and Africa to construct a high-voltage direct current (HVDC) grid for sharing carbon-free energy.
Alternating current cables, which form the main electricity grids in Europe, are not suitable for long-distance transport of electricity because too much is lost on the way. Dr Trieb, of the German Air and Space Agency, says the advantage of DC cables is that loss in transport is only about 3% per 1,000 kilometres. “Contrary to what is commonly supposed, it is entirely feasible, and cost-effective, to transmit solar electricity over long distances.” He added: “CSP imports would be much less vulnerable to interruption than are current imports of gas, oil and uranium.”
The two reports make it clear that an HVDC grid around Europe and North Africa could provide enough electricity by 2050 to make it possible to phase out nuclear power and hugely reduce use of fossil fuels. An umbrella group of scientists has been formed across the region called the Trans-Mediterranean Renewable Energy Cooperation (Trec) but the idea has yet to excite the imagination of governments. Neil Crumpton, renewables specialist at Friends of the Earth, said: “Most politicians on the world stage, particularly Tony Blair and George Bush, appear to have little or no awareness of CSP’s potential, let alone a strategic vision for using it to help build global energy and climate security.”
The Trec scientists hope the German chancellor, Angela Merkel, will use next year’s joint presidency of the EU and Group of Eight leading economies to push for an agreement on a European DC grid and the launch of a widespread CSP programme.
The outlook is not promising. More than 30 countries last week agreed to spend $13.5bn on an experimental fusion reactor in France that critics say will not produce any electricity for 50 years, if at all. Dan Lewis, energy expert at the Economic Research Council, calculates that CSP costs $3m-$5m per installed megawatt, a fifth of the cost of fusion. “Fusion is basically a job-creation scheme for plasma physicists.”
Mr Crumpton agreed: “Nuclear power accounts for just 3.1% of global energy supply and would be hard-pushed to provide more. Yet CSP could supply 30% or 300% of future energy demand far more simply, safely and cost-effectively. In the wake of the Stern report, the enlightened investment is on hot deserts, not uranium mines or oil wells.”