The pros and cons of solar power

Maggie Ayre, BBC Radio 4 Costing the Earth 7 Feb 08;

Even in grey, overcast Britain, some householders are managing to use solar power to meet their energy needs.

But there are far more ambitious plans for Europe to import solar power from huge installations in North Africa.

Johannes Gleede installed a solar thermal panel in the roof of his semi-detached house in south west London ten years ago and paid around £1,500 for it.

From a flat plate solar collector slotted into his roof, water is conducted into a cylinder where it heats. You don't need direct sunlight, just light. And when we visited Johannes' on a December afternoon, the water was certainly hot enough for a shower.

It was an ideal time for Johannes to invest, because he needed to replace the boiler so the total cost was around £5,000 in total.

"I wanted to see if it worked," says Johannes."You have to dare to be crazy." It did work and has cut his electricity bills by 50%.

Most householders should expect to pay upwards of £3,000 for installation depending on the type of house, says David Mathews, Chief Executive of the Solar Trade Association. The cost will also go up if you have to upgrade other parts of your central heating system.

It takes a number of years to get that investment back. But the most recent government figures (2006) state 78,470 UK homes have solar thermal, making domestic water heating by far the biggest area for the use of solar power in Britain.

Expensive option

It is far more expensive to generate electricity from solar power. For a typical British house, this requires a rooftop solar collector in order to provide enough silicon cells to generate sufficient electricity.

The technology is proven, but the costs for a single house are £12,000 to £14,000 according to the British Photovoltaic Association. So far this has been installed in about 1300 homes. But it is also being used in some commercial buildings and public buildings such as schools.

More electricity can be generated in summer and less when we need it most - on dark winter evenings. And at present there is no mechanism for storing electricity generated on long summer days for use in winter.

Dr Thomas Markvart from the University of Southampton says photovoltaics could provide a substantial amount of the electricity Britain needs but fears we risk losing our expertise to countries like Germany and Spain where the industry is booming.

"We need to have the stimulus for manufacturing in this country, and that comes partially from government. Otherwise it will go abroad. Companies like BP are going to Spain where there is government support"

Last year, Spain inaugurated the world's first commercial solar plant near to Seville. But much of the engineering expertise in solar power has been nurtured in Germany where solar power has really taken off.

Saharan plants

An ambitious plan to build massive plants in the Sahara desert using concentrated solar power (CSP) was unveiled by German engineers last year.

The Desertec organisation supported by Prince Hassan of Jordan wants to use giant parabolic mirrors in the desert to track the Sun and absorb heat in a central receiver which is cooled with water to produce steam. The steam drives a turbine and produces electricity.

Hang on, you're thinking, there is no water in the Sahara desert. True, but the plants are to be placed near the Mediterranean coast so water can be pumped in and be desalinated in the process.

Franz Trieb of the German Aerospace Center (DLR) who carried out the feasibility studies into the Desertec idea sees it as a win-win scenario creating energy, water and income for the Middle East and North Africa.

"Yes you are creating shade in the desert, but shade in the desert is a good thing. It will create communities. And when I see that there will be 300 million more people in the Middle East-North Africa region in 30 years, we are going to need more water," he says.

Prince Hassan goes as far as to call it an industrial revolution for the southern Mediterranean that will create further stability in the region.

Trading dependence?

Trieb says a method of storing heat overnight using tanks of molten salt has been developed, and electricity will be exported to mainland Europe via high voltage direct cables under the Mediterranean right up to northern Europe.

Germany and Algeria have already reportedly signed a deal to lay cables stretching as far north as Aachen on the German-Belgian border.

BBC Radio 4's Costing the Earth visited Egypt where a £30m pilot plant is being built south of Cairo. Rows of parabolic troughs 50-60m wide will cover an area of 130,000 sq m. Initially it will provide electricity for 200,000 Egyptian homes. Further plants are planned or in progress in Libya, Algeria, Israel and Morocco.

In Britain, the idea of importing solar energy has been received with cautious optimism. Energy Minister Malcolm Wicks calls it "an exciting 21st century idea" and says "We have to think in revolutionary terms if we are to move away from a carbon intensive society".

But he is wary of the costs of establishing a European "supergrid" and concerned about energy security. Could it be that we would simply be trading our dependence on the Middle East for oil for a dependence on sunshine?

However, enthusiasts of the Desertec concept say there is around 8,000 times more energy than we need to be harnessed from the Sun, an unlimited renewable resource. Perhaps the sun over the Sahara could indeed be the future super generator of our electricity.