Letters archive

Your article on vaporising garbage to turn it into fuel shows interesting perspectives on making good use of trash (25 April, p 33) . However, the smouldering remains of the World Trade Center should not be compared with high-temperature pyrolysis. The former is low-temperature combustion in ambient air while the latter occurs under controlled conditions. …

If, as Eric Chaisson asserts in "The heat to come..." (4 April, p 24) , the second law of thermodynamics makes dangerous global warming an inevitable consequence of further human population growth, then this is primarily driven by our dependence on fossil fuels. By contrast, plant life has a cooling, entropy-defying impact on the climate. …

The editorial and article about "the ghastly experience of being on a battlefield" (25 April, p 3 and p 40) being the cause of mysterious symptoms in war veterans seem to miss a crucial point: unlike the majority of first and second world war veterans, some of the veterans of Vietnam, Iraq and Afghanistan questioned …

Your recent article on the UK's potential river Severn barrage asserts that "only big projects can deliver big quantities of renewable energy" (18 April, p 32) . A big project with less environmental impact than this tidal barrage would be installing solar panels on every roof in the UK. If energy companies were allowed to …

You map railways in your article on the remotest places on Earth, saying "they are confined mainly to the richer nations of Europe, the US, Australia and Japan" (18 April, p 40) . What puzzles me is that you omit Canada, yet include Australia. A list of railways accessing remote regions should make mention of …

Bob Holmes suggests that the bacterium Syntrophus would produce pure hydrogen for us, were it not for its attendant methanogenic archaebacteria, which convert the hydrogen into methane (18 April, p 8) . In fact, Syntrophus would not grow at all in isolation – and the name reflects this. Syntrophus and the archaebacteria work by syntrophic …

In your Feedback item regarding the website of energy company EDF, you said that the dummy text "'Lorem ipsum...' looks as if it means something, but doesn't" (2 May) . Contrary to popular belief, Lorem Ipsum, which has been the printing industry's standard dummy text for hundreds of years, is not random text. It originates …

• Let's be clear: the rate at which sunlight delivers energy to the Earth's surface should be expressed in terawatts. Our "For the record" of 25 April (p 25) not only contained a nonsense of its own (suggesting that a terawatt is different from a terajoule per second), but also failed to address our original …