Features > If not biofuels, what?
If not biofuels, what?
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Clare Dwyer Hogg looks at other alternatives to fossil fuels
HYDROGEN
Any day now, a select group of Californians will be able to drive the first commercially produced fuel-cell cars. Honda's FCX Clarity combines hydrogen with oxygen to create electricity; the electricity powers an electric motor which enables the car to work. The only emission is water vapour, the only by-product heat. The technology for such vehicles has been theoretically possible for many years, but there have been difficulties: not just in making it affordable but in making it safe. Hydrogen is highly explosive, and has to be stored at extremely low temperatures - as little as -250C. Detractors also point out that it takes energy to produce hydrogen, and if that energy isn't created through renewable means, it may not be as "green" as we think. But the main problem is that, although fuel-cell cars are around twice as efficient as cars that run on fossil fuel, they can only be refuelled at special hydrogen fuel stations, which remain scarce. Britain currently has just one hydrogen filling station, opened in April at Birmingham University as part of a feasibility study. This will allow an experimental fleet of 70 hydrogen-powered vehicles, commissioned by Transport for London, to be brough into operation next year. It is estimated that by 2010 there will be 12 hydrogen-filling stations in the UK. Iceland, meanwhile, is hoping to become the world's first hydrogen economy by 2050.
SOLAR
An increasingly familiar and effective alternative, but still costly to install. The commonest way to capture solar power is by a photovoltaic (PV) system, often placed on roofs, which takes energy from the sun to generate electricity, as with GM's Zaragoza plant, soon to be home to the biggest roof-top solar power station. The benefit of this is that it doesn't matter if it's overcast: PV cells need daylight, not direct sunlight. A southfacing roof in Britain will get about 1.000 kilowatt hours (kWh) of radiation per square metre per year, while the average home uses around 3,500kWh a year, so a household using a solar power system could cut down on 1.2 tonnes of CO2 a year and slash about £230 off a typical electricity bill. But capturing solar energy on a much larger scale (for example, for power stations that might provide energy for millions of electric cars) remains problematic in the UK. Hence, perhaps, Gordon Brown's support for an ambitious plan by scientists from the European Commission's Institute for Energy to use a 450bn network of "solar farms" to "harvest" 0.3 per cent of the sunlight that shines on in the Sahara - and so provide Europe with all the energy it needs. Meanwhile, the obvious attractions of solar power - it is inexhaustible and releases no by-product - mean that humanity will continue to seek better ways of harnessing it.
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ALGAE
Scientists at Massey University in New Zealand estimate that algae - not just from sewage ponds (see above) - could potentially produce nearly 100,000 litres of biodiesel per hectate per year, compared with 6,000 litres per hectare with palm oil. There is no shortage of algae (the world's most plentiful lifeform) and a San Diego company called Sapphire recently announced that it had raised $50m of investment in a project to produce a green equivalent of crude oil from which fuel for cars and aeroplanes could be extracted. Will it work? It remains to be seen. But many feel that algae (which are highly efficient at converting sunlight and CO2 into energy) could be the best of all possible solutions to our energy problems.
WIND POWER
There is no shortage of wind in the UK. As with solar power, however, it's a question of how fast and cheaply the technology for harvesting this entirely free source of energy can be developed and installed. Britain got its first wind farm in November 1991, and currently boasts 176 such farms, which means that 2,033 wind turbines are now operational in the UK. These generate 2,546.775 megawatts (MW) - which provides the equivalent of 1,424,027 homes with electricity, and slashes CO2 emissions by 5,755,915 tonnes. There are also two offshore wind farms too (North Hoyle, which contributes 60MW, and Blyth Offshore, which provides 4MW). Wind turbines do take up a great deal of space - more than, say, a coal-fired power station would - and they are disliked by some. But the landscape on which they're built can still be used by farmers to, for example, graze cattle, and should the turbines ever be taken down, there will be no lasting damage to the land. Britain aims to generate 10 per cent of its electricity from renewable energy sources by 2010, and 20 per cent by 2015. However, the British Wind and Energy Association (BWEA) claims that the UK is in danger of missing the 2010 target unless the development of new wind farms is speeded up. Around 2,000 more wind turbines are needed if the deadline is to be met.
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WATER
Tidal energy remains relatively unexplored as an energy source, although for an island such as Britain it is arguably the most suitable of all. The BWEA is a strong supporter of the possibility of developing marine energy and estimates that - because the UK has such strong tidal streams and high tidal ranges - tidal energy could ultimately provide up to 20 per cent of the 350,000,000,000 kilowatt hours (kWh) of electrical power that the UK consumers every year. Since 2003, a prototype tidal stream project called Seaflow has been working on a full scale off the north Devon coast, and there are plans under consideration to generate up to 5 per cent of the UK's total electricity from the Severn Barrage - but while the technology is available, there are no wave power machines in the UK that go beyond prototypes. This is chiefly because the sea is a harsh environment and this makes tidal power an expensive business. More conventional hydroelectric power -taken from flowing rivers - is more achievable and already produces around 0.8 per cent of the UK's electricity; and if all the potential hydroelectric power in the UK were tapped, this could be bumped up to around 3 per cent. The two biggest schemes are at Loch Shira in Argyllshire and at Loch Garbhaig in Ross-shire.
ATOMIC ENERGY
Uncertainties over the proposed takeover of British Energy by the French state-owned firm, EDF, have left plans for a "new generation" of nuclear power stations in the UK in disarray. The Government is committed to what Gordon Brown recently called "more ambitious for our plans for nuclear in the future", but it remains to be seen what will happen to EDF's plans to build four nuclear plants in the UK, starting in 2017. (These would be the first new reactors built in the UK since 1994; all but one of the existing ones had been scheduled for closure by 2023.) British Energy currently provides around 20 per cent of the UK's power, but opinion remains divided as to how prudent it is to increase this percentage. Champions of nuclear energy say it would reduce carbon emissions and dependency on declining reserves of fossil fuels; Greenpeace argues that even 10 new nuclear power stations would cut carbon emissions by only 4 per cent or so by 2025. And the intractable problem of waste remains: high-level radioactive waste remains dangerous for thousands of years - and how do you ensure that no plutonium falls into the wrong hands.
