Solar cells generate electricity from sunlight without producing' pollution, but some environmentalists have been concerned about the potential negative impact of this photovoltaic technology. This is because the manufacture of solar cells involves toxic metals such as lead, mercury and cadmium and produces carbon dioxide, which contributes to global warming. However, the first comprehensive study of the pollutants produced during the manufacture of solar cells gives them a reassuringly clean bill of health. Researchers at Brookhaven National Laboratory in New York report that photovoltaic cells produce far fewer air pollutants than conventional fossil fuel technologies when manufacturing is fully accounted for. The study will appear next month in the journal Environmental Science & Technology, Vasilis Fthenakis and colleagues gathered data from 13 solar cell " manufacturers in Europe and the US over three years. The cells included four major commercial types: multicrystalline silicon, monocrystalline silicon, ribbon silicon and thin-film cadmium telluride The study concluded that generating electricity from solar cells reduced air pollutants by about 90 per cent compared with using electricity generated in conventional power stations

The report by K.Van Oost et al., "The impact of agricultural soil erosion on the global carbon cycle" (26 October 2007, p. 626) raises two serious concerns. First, the eroded soil is severely depleted of its soil organic matter (SOM) pool, which is preferentially removed by surface runoff because it has low density and is concentrated in the surface layer. Second, the process of soil erosion by water entails three distinct stages : (i) detachment, (ii) transport/redistribution, and (iii) deposition. (Letters)

One million tons of atmospheric carbon dioxide are dissolved into the oceans every hour, a process that helps maintain the Earth's delicate carbon balance. But CO2 also makes seawater more acidic, and too much of it can wreak havoc on a marine species.

If two scientists at Los Alamos National Laboratory are correct, people will still be driving gasoline-powered cars 50 years from now, churning out heat-trapping carbon dioxide into the atmosphere

Porsche, whose cars are seen as an emblem of wealth and success in London's financial district, is planning a legal challenge to prevent its customers from paying an increased congestion charge in the UK capital. The German company intends to seek a judicial review aimed at quashing the plan by Ken Livingstone, London's mayor, to impose a

If two scientists at Los Alamos National Laboratory are correct, people will still be driving gasoline-powered cars 50 years from now, churning out heat-trapping carbon dioxide into the atmosphere

The best way to cut down on the greenhouse gases produced by power generation is to reduce America's appetite for electricity. Renewable energy sources like wind power and biomass have a helpful role to play. Yet, dependable base sources will remain necessary, and coal-fired plants will probably be part of the mix for a long time. Minimizing the impact of such plants is vital. That is why it is so discouraging that the Bush administration pulled the plug on a project for using coal to produce power without carbon dioxide emissions. For five years, the Department of Energy, coal and power companies, and several countries, including China, have been partners in developing a plant in Mattoon, Illinois, that would convert coal to gas, allowing its carbon dioxide to be captured and stored underground. The Department of Energy said it withdrew its 75 percent support from FutureGen last month because its cost had almost doubled, from $1 billion to $1.8 billion. Some have suggested the real motive might have been lingering opposition to the choice of Mattoon by administration officials from Texas, which lost out in the selection process. Congress should call on the Government Accountability Office to investigate how the department made its decision to pull out. Five years of work have come to a dead end, and the country and the world are not much closer to knowing if coal can be part of the climate change solution and not just the climate change problem.

If two scientists at Los Alamos National Laboratory are correct, people will still be driving gasoline-powered cars 50 years from now, churning out heat-trapping carbon dioxide into the atmosphere

For better or worse, free-market environmentalism is gaining credence in the country. And the latest singing hosannas to the idea is one of India's largest conglomerates, the Tata group. It is putting into place a plan to measure its carbon footprint, reduce greenhouse gas (GHG) emissions and figure out how much can the group possibly earn from carbon credits. Spearheading this initiative at the group is Tata Sons' director JJ Irani. Under him, a 10-member committee comprising top executives from various Tata group companies has been set up. Says Irani,

Germany said it would issue 451.9 million tonne say ear of carbon-dioxide pollution certificates from 2008 to 2 012, 0.3%fewer than allowed by the European Commission. Germany cut its planned emission cap because new power plants will need fewer free C02 permits than previously expected, the DEHST emissions trading unit of the environment ministry said on its website. Germany earlier set aside 11 million tonnes of C02 a year for new power plants and factories, yet permits foronly9.79milliontonnesareneeded. German utilities and energy-intensive industries want installation-level allocations of permits as they prepare for the second phase of the EU's climate control programmed. Some 1,625power plants and factories, new and in operation, will get388.86 million tones of free permitseveryyearthrough2012 according to the plan.

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