Saturday, March 28, 2009
Hot air Oscars nomination: most useless invention
Nick Cook has nominated the EDF Energy ideal home show, Alex Hort, and the University of Plymouth for a Hot air Oscar for "An ingenious idea that recovers useful energy from a drain pipe". "Rain water descending a down pipe is captured and stored behind an internal 'dam'... Each rush of water turns a small, plastic turbine... providing electricity which is stored in rechargeable batteries."
The raw power of rainwater on a roof of area 40 square metres, rainfall 584 mm per year, with a drainpipe of length 6 metres, is 0.001 kWh per day. This is less than one ten-thousandth of the average British person's electricity consumption. The economic value of the power captured by this contraption is roughly 5 pence per year. The energy cost of making the system and inserting it into a drainpipe must be many times greater than the energy it would ever give back.