This is a great innovation — the streets of Europe could soon be lit by "solar trees". These self-contained streetlights could save cities energy and money too. Unlike regular streetlights, they do not require costly underground wiring to install, and they are immune to blackouts. Designed by Ross Lovegrove, the lights have 10 solar panels arrayed at the top of tree-like branches, which charge built-in batteries. The batteries then power LEDs for illumination. Compared to conventional streetlights, they emit much less light pollution, because LEDs generate a very directed light. The trees also incorporate light detectors! So the lights automatically turn on sunset and off at sunrise.

The solar trees went on display for four weeks in October on a busy street — the Ringstrasse — in Vienna, Austria. They were able to provide enough light during the night-time even when the sun did not show for as much as four days in a row. The director of the program, Christina Werner said. "Someday soon solar trees could well be the main form of street lighting in Europe."

Putting solar powered LED light systems on trees would cut down on the carbon emissions and also slash the bills of local authorities, she said.

Street lighting consumed 10 percent of all the electricity used in Europe in 2006 or 2,000 billion KWh, and resulted in carbon emissions of 2,900 million ton.

The use of more energy-efficient lighting in the Austrian city of Graz, with a population of almost 300,000 saved the city 524,000 KWh of electricity and 67,200 euros [US $96,800] in 2005.

Via: RenewableEnergyAccess