The billboard, which will stand on 7th Avenue, 42nd Street, is expected to be operational in December of this year. It will be powered by 45 solar panels and 4 wind turbines, and Ricoh Company Ltd. expect the change to reduce carbon emissions in the area by 18 tons each year.

The sign's predecessors can be found in San Francisco - the first of its type in the U.S - plus two in Canada, and two in South Africa.

In 2006, Johannesburg was home to the first solar powered billboard, developed by Nedbank. It supplies power to a nearby school, and displayed the phrase 'This Isn't a Billboard. It's a Power Plant'.

A second followed a year later, when Nedbank erected a new billboard in Cape Town in December 2007. It currently provides power for a local youth centre.

It was in January of this year that Pacific Gas and Electric Company installed the billboard in San Francisco. It can be found at 1000 Brannon Street, and generates a maximum of 3.4KW of power, through 20 solar panels. It was developed as part of the company's 'We Can Do This' campaign, which centres on the company's commitment to the environment.

Unlike its American and South African counterparts, the two Canadian solar powered boards are not connected to the public power grids. But they represent the same cause.

One, developed by the finance company Vancity, commissioned the sign as a symbol of their commitment to tan active environmental policy. The company claims to want to develop a carbon neutral policy, and used the billboard as a promotion of that fact.

With billboards like these springing up in some of the world's major cities, it marks a new partnership between cosmopolitan tradition and sustainability initiatives; where before sustainable energy was perhaps viewed as a rural luxury, it is now being pioneered as having a legitimate place in the city.

Now that companies such as Ricoh Company Ltd., Vancity and Nedbank are 'going green', corporations are becoming more and more aware of their environmental responsibilities.

Whilst solar powered billboards are more symbolic than practical - powering only limited areas - they can be tied to the theme of a growing environmental consciousness. With major companies investing in such installations in major cities, it shows that corporations are looking to develop an environmentally ethical image.

Indeed, many companies are bucking the trend. Waitrose - owned by the John Lewis Partnership - trialled a rapeseed oil fuel for their lorries in 2007, and most of the major supermarket chains are now encouraging the precedence of reusable bags.

It is hard to tell whether these commitments are out of genuine environmental concern or out of concern for pubic image and profits, but it marks a step, nonetheless; the more the general public demands an environmentally motivated business sector, the more the business sector will feel the pressure to concede to these demands.

With a rise in political concern for the environment, perhaps also coming out of public demand, businesses could feel the strain of legislature, too.