Slashdot Mirror
Solar Tree Bears Fruit
Hugh Pickens writes "A prototype solar tree that recently went on display on a busy street in Vienna, Austria has passed a key test by providing light during the night-time even when the sun had been blocked by clouds for four days in a row. The branches of the solar tree were decorated with 10 solar lamps, each one powered by 36 solar cells. The tree included rechargeable batteries and electronic systems to measure the amount of light in the atmosphere and trigger the solar lamps to go on. 'Not just trees but other objects could be decorated with solar cells and so keep streets well lit at night time,' said Christina Werner from Cultural Project Management. Google uses a similar concept to light their parking lots with 3,000 solar panels that provide up to 10 percent of the Googleplex's power demand. We discussed Google's solar initiative last year."
How much non-renewable energy does it take to produce each solar tree
If that were the only energy concern, then you'd have a point. It probably does take more energy in the beginning to produce it. However, the better (and more relevant) measure is total energy consumpption over its lifespan. That is, compare the manufacturing energy + energy use from grid + maintenance (replacement bulbs, etc.) over its projected lifepan to a standard lighting system. If it turns out that the overall energy used is less than that of a standard one, you come out ahead. You could also do cost analysis, but any pilot system has a much higher cost than production systems.
You also need to factor in the public safety benefit of it working even if the electricity is out. A whole city that stays lit up during a disaster could be very beneficial.