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  BBC Online 1 Nov 05
Concepts for a low carbon future
By Richard Black Environment Correspondent

On one side of London, the UK's environment secretary Margaret Beckett was outlining the threat of climate change to energy and environment ministers from a further 19 nations.

"There is more evidence that the oceans are warming, that a long-term reduction in Arctic ice cover is accelerating, and that the strength of hurricanes has increased in the last 30 years," she said.

Technology, she declared, would be essential in making the transition to a low carbon economy - which might ameliorate, if not eliminate, these ills.

But which technologies? This year, a welter of initiatives on climate change - the G20, the G8, the Asia-Pacific Pact - have all talked up the tech route to tackling greenhouse gas emissions, without specifying, quantifying or pricing the technologies which their architects had in mind.

Some are of course already with us and maturing nicely - wind turbines, geological carbon disposal - but others, like solar cells, need a substantial technical push, while still more are merely lightbulbs in a researcher's intuition.

Even as Mrs Beckett was urging her fellow ministers to political action, British scientists and engineers were gathering just a quick bicycle ride away to showcase and debate some of these technologies, and assess what they might contribute to a low carbon future.

"Energy is the world's biggest industry," the UK government's chief scientist Sir David King told delegates, "and over the next 30 years we'll see the biggest transformation in a century." Referring to the European Emissions Trading Scheme which opened at the beginning of the year, Sir David said: "We have market mechanisms in place which will determine the energy mix of the future; but we, as innovators, need to bring ideas into that marketplace."

Pounds win prizes

The UK government announced recently that it was increasing funding to its research councils for low carbon energy projects. The money available goes up from £40m per year currently to £70m per year in 2007/8, and will be disbursed through a number of agencies co-ordinated by the Engineering and Physical Sciences Research Council (EPSRC).

In case you thought that a "low carbon future" simply means renewable power with a bit of energy efficiency thrown in, a look around the display at the meeting would have put you right. Innovations in solar cells, biomass burning and wave power nestled alongside ideas for distributing power in a system where generation is less centralised, for assessing the total carbon footprint of industrial goods, and for storing electrical power.

The concept is that all of these things would be necessary to build the reliable, cost-effective infrastructure which could realistically break the fossil fuel habit - which is why the EPSRC's Supergen project is funding them all.

Cells for all

"What we're trying to do is find ways to make cheaper solar cells," said Ken Durose from Durham University, principal investigator for a project called Photovoltaics for the 21st Century, or PV21.

"We're not talking about just refining the engineering, but changing the physics and chemistry of solar cells, looking at new materials and new processes within those materials."

One of the materials PV21 is working with is cadmium telluride (CdTe); the maximum efficiency obtained for CdTe solar cells so far is around 16%. Professor Durose believes that could almost be doubled, though the science involved is, he says, "ambitious," involving changing the electrical properties of the boundaries between CdTe crystals.

PV21 researchers are also trying to improve on the industry standard, the silicon solar cell. One particularly neat concept involves trying to increase the amount of radiation which each cell absorbs by trapping light inside the cell, which could radically increase its efficiency.

With fancy materials and unrealistic set-ups, solar cells can already achieve high efficiencies - in June the American company Spectrolab set a world record of 39%. Cost, though, is another thing entirely; Ken Durose believes the technologies which he is working with could come in at around one euro per Watt capacity, which would make them cheaper than existing cells.

Excited states

Laurie Peter from Bath University is working on something which could eventually be cheaper still - the excitonic solar cell.

"Excitonic cells are different because they draw on processes found in plants," he told me. "Light is absorbed by molecules similar to chlorophyll; and then a second step is used to produce electricity."

The excitonic cell consists of two materials which weave in and out of each other - rather like, in Professor Peter's words, "black and white spaghetti." The chlorophyll-like molecule, put into an excited state by absorbing sunlight, deposits an electron in the black spaghetti and extracts an electron from the white stuff - creating a voltage between the two.

"The main attraction is that we can tailor components in a way which can't be done with silicon," said Laurie Peter. "So you can have something that's good at absorbing light, then something that's good at conducting electricity; and you can do it all at room temperature with technologies currently used for making plastics, so it should be dirt cheap."

Pedal to the metal

If the excitonic cell sounds more like something James Bond might be shown just before evading death at villainous hands than a cuddly planet-saving piece of plastic, the mythical Q would surely find something to appreciate in Strathclyde University's electric car.

Basically it is battery powered; well, that has been done before, and not proven hugely popular - so what's new? "You want a car to go for hundreds of miles, and that's what a battery is good for," said Peter Hall.

"What it's not good for is acceleration, because as you ask it for more current, the power output goes down. "So we combine the battery with a super-capacitor which discharges quickly and gives you a burst of super-acceleration." A super-capacitor is a large-scale version of the tiny charge-storing devices which peppered the electronic circuit boards of devices from the transistor age and which are found in their microscopic thousands in silicon chips.

Professor Hall's project is called the Energy Storage Consortium, and aims to find ways of improving batteries as well as capacitors; the scope goes way beyond cars to the national electricity network. "If your energy mix goes above 15% renewables, you have to have storage," he told me, "just as with water, you have to have a reservoir. "My vision is that in 40 or 50 years' time, every wind turbine will have a storage unit attached; no moving parts, reliable, and modular."

Cornering the market

Many of the Supergen-supported programmes are at an early stage, and are not yet attractive to industry; some may fail completely, while others could go on to global success.

The successes could assist developing countries as well as the west to achieve economic growth without soaring emissions - the very concept which Margaret Beckett was pushing down the road at Lancaster House.

Do not, though, believe that the UK government's support for Supergen is entirely altruistic. "Despite initial interest, other countries have run away with the market for wind turbines," said energy minister Malcolm Wicks in his speech to delegates.

It is clear that the government does not intend to let the same thing happen with newer technologies - it wants Britain to reap a financial reward from these seed investments.

But with some other countries spending far more than the UK, the low carbon future will not be an easy place to dominate.
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