Who needs electricity to power a giant billboard? Not Ricoh, a UK-based document management and printing company, who turned on its new 36-meter-square billboard earlier this week, unveiling the 96 solar panels and five micro wind turbines that will power the board's lighting. The billboard will be illuminated only by energy generated by wind turbines and solar panels.

You can see the sign driving into London on the M4. The "engine" behind the billboard are expected to generate 12.6kw a day to light up the red lettering from first light or first wind until about three o'clock the following morning. And to prove it's solely powered by green energy, Ricoh's billboard will be disconnected from the grid.

This isn't the first eco-friendly billboard for Ricoh, though. They already installed a solar powered billboard in Manhattan's Times Square and are planning three further "eco boards" at different headquarters around the globe.

Expect to see this trend to continue to gain monentum over the coming months and years. In fact, last year Lamar Advertising announced plans to convert 1,370 of its billboards in Florida to be powered by renewable energy and even feed power back into the grid, creating a network of miniature power plants.