Solution to energy crisis or land of make believe?
Giles Turnbull (Could your lawn keep you warm? January 26) describes a system as "capable of achieving 400% efficiency" but the diagram claims it "can bring in four times more energy than is needed to run them", which would make it 500% efficient. But no matter the intended figure, it seems to be describing a perpetual motion machine. Once started, we could use a quarter (or a fifth) of the energy output as feedback to operate the pumps and all our energy problems would be solved.
Gerard Lancaster Stockport
· Heat pumps are not so new, even in Britain. The Royal Festival Hall was heated and cooled at the expense of the Thames, using heat pumps, when it opened in 1951, although the system was later replaced with a conventional one.
A friend in Berkhamstead in the late 1950s had the almost unheard-of luxury of central heating, courtesy of a heat pump, with a heat source/sink in the garden, and a walk-in cooled larder as a heat source. It seemed to work well, although he did say that milk froze if two people had baths in rapid succession.
David A Bender University College, London
· Reading your article on heat pumps made me feel I had been transported to a parallel universe where the laws of thermodynamics have been suspended.
The heat in the ground is free, but the energy needed to recover it is high-quality energy, which costs far more than a cheap heat source. You pay 8.4p per Kwh for the electricity to run the heat pump against 1.9p per Kwh for town gas or 2.5p (average over the last year) for heating oil. Even allowing for a 4:1 return on the electricity (3:1 is more realistic) and 90% efficiency of a gas boiler (95% for a modern oil boiler) the margin of heat pump over traditional systems is slim to non-existent and does not begin to cover the loss of interest on the enormous capital outlay. If the sample family expects to replace a £1,000 oil bill with a £250 electricity bill they are in for a shock!
Colin Rourke University of Warwick
Bring back Mir
≥The article on the International Space Station (A waste of space, January 26) takes me way back to when you would watch Newsround before Blue Peter while eating Postman Pat spaghetti shapes. It was called Space Station Freedom. My space-obsessed heart would swell with happiness at the smooth white curves of the computer generated graphics (then a novelty), with all the little bumps, solar panels and habitation nodules. It was pure sci-fi, a shining white village of scientific endeavour, serviced by a fleet of shuttles, and later, sleek one-stage spaceships. It made Mir look like the skanky green rustbucket it was.
Fast-forward 14 years. Newsround lied to me. The ISS is a shambles, a complete waste. With the shuttle programme in disarray and Bush's new focus on returning to the moon, it'll probably never get finished. Let's face it: Mir rocked.
Preying on the punters
Surely Kieren McCarthy's plea for help (Technobile, January 26) is rhetorical! It is received wisdom that stores such as PC World, Dixons and Comet are to be avoided for the very reasons covered. It's a mystery to me how they have survived. Guess it's a case of enough innocent consumers to keep them going.
Rod Warrington, Chester
I know we Mac-heads sound like broken records, but to find competence in a computer store, visit an Apple Store.
Jon Connell Bluntisham
True cost of internet radio
≥An Ask Jack question (January 26) reveals that if you listen to an online radio station at around 56kbps for four hours a day, you'd get through around 3GB a month. The biggest monthly usage plan I can see on Orange, for example, is £52.88 a month (Mobile Office Max 05 for personal users). To listen to that amount of radio would be in excess of £150 a month. And that's before other data usage like emails or phone calls.