Solar cell speeds hydrogen production

A solar cell that mimics photosynthesis has been used to make hydrogen directly from water. The prototype is inefficient, but the researchers who built it believe they can boost its efficiency, perhaps leading to a viable source of hydrogen to fuel cars and other vehicles.

The device, built by Thomas Mallouk of Pennsylvania State University and colleagues, works much like a solar cell called a Grätzel cell, using sunlight to knock electrons off dye molecules. But instead of being used to create a current, as in the Grätzel cell, the electrons are shuttled away from the dye and into a catalyst, where they split water molecules into oxygen and hydrogen ions in a reaction similar to one stage of natural photosynthesis.

Other dye-based approaches to splitting water haven't worked very well because the electrons often recombine with the dye before they can be used. Mallouk says that the problem was a matter of arranging the molecular circuitry to channel the electrons effectively, avoiding such “short circuits”.

His solution is to attach ruthenium-based dye molecules to a catalyst particle, clinging so closely that any electrons knocked out of the dye are directed into the catalyst. "The key thing is to get everything small and individually packaged," Mallouk told New Scientist.

In the new device, water is split a thousand times faster than in other dye-based cells.

Elegant and original
“The attractive feature of the work is that the dye is wrapped around the iridium oxide nanoparticles. This is a very elegant and original approach,” says Michael Grätzel of the Federal Institute of Technology in Lausanne, Switzerland, inventor of the Grätzel cell.

The approach may also be more promising than semiconductor approaches, which are incredibly complex, says James Durrant of Imperial College, London, UK.

Mallouk admits that so far the cell is very inefficient, as only around 1% of the light energy falling on it goes into splitting water, but he says that with some optimisation of the geometry and the molecules the efficiency could rise to 10% per cent. “Because we understand the relationship between intermolecular distances and electron transfer rates, we can in principle improve our system by changing the linking groups between molecules.”

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Biofuels 'need strict standards'

Biofuels should only be produced if they meet strict environmental standards, an international group of lawmakers have concluded.

The legislators said the fuels also had to deliver significant savings of greenhouse gas emissions.

If such criteria were met, they said there should be an urgent review of the tariffs that currently block imports into markets such as the EU and US.

The forum was hosted by Brazil, one of the world's biggest biofuel producers.

Biofuels have become a highly controversial issue, with claims that the rapid expansion of energy crops could threaten global food security, and add further pressure to sensitive ecosystems including rainforests.

It is also argued that in some cases the benefits to the climate of burning plant material instead of fossil fuels are outweighed by the energy needed to produce and transport biofuels, and by the release of carbon from soils by changes in land use.

The supporters of Brazilian ethanol argue, however, that huge areas of degraded cattle pasture are available to grow the crop, and that expansion of biofuel production does not require significant conversion of native ecosystems.

The meeting also failed to agree a framework for a new global agreement on measures to tackle climate change beyond 2012, with the Chinese delegation apparently reluctant to pre-empt the position of its government in forthcoming negotiations.

Lord Jay, the former head of the British Foreign Office, who had led the efforts to agree the framework, said there had been consensus over his claim that a massive increase was needed in the funds available to poorer countries to cope with the impacts of climate change.
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The £15,000 three-wheeled electric car that can go faster than a Porsche

A car manufacturer has announced they are on the verge of creating a three-wheeled electric sports car that can travel faster than a Porsche.

The enviromentally friendly Zap Alias will cost just £15,000 and does 0 to 60mph in just 5.7 seconds with a top speed of 156mph.
The futuristic looking two-seater is being developed with the help of British car company Lotus. It should go on sale next year though speculation is rife that the launch of the vehicle will be delayed.

It is powered by two electric wheel motors, one driving each of the car's front wheels. Unlike a Reliant Robin the single wheel is at the back. Together the Alias's motors generate an impressive 321.85 horse power - as much as a Porsche 911 Carrera which costs £60,000.
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The hypersonic plane

he project is part of an EU drive to push forward the boundaries of air travel. Scientists were asked to find out if it was possible to build a commercial plane that used the sort of technology more closely associated with travel to the edge of space and beyond.

Oxfordshire-based Reaction Engines designs and develops space transport and hi-tech propulsion systems. Its directors are experts in fields ranging from space rockets and weapons systems to nuclear power. One of the firm's main projects is the development of Skylon, an unpiloted reusable spaceplane intended to provide inexpensive and reliable access to space, which is expected to take approximately 10 years to develop and be capable of transporting 12 tonnes of cargo into space.
Reaction Engines estimates that the cost of the flight would be similar to a current first class fare. Moreover, the company claims, the plane would not leave much of a carbon footprint.
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