An internet shopping site is trying to drive up the price of carbon credits in an effort to cut pollution.

Saving the planet while you shop has become a recurrent theme with entrepreneurs looking to cash in on the current wave of green consumerism.

Shopping portal GoCarbonFree claims to be doing exactly that by buying carbon credits using its profits with the aim of raising their price and hence reducing pollution.

The scheme is based on the simple economic theory that scarcity raises prices. Using profits from the sale of consumer goods, the portal buys carbon credits under the United Nations' Clean Development Mechanism and destroys them.

The aim is to raise the price of carbon credits by taking some off the market, making them scarce and thus forcing UK businesses to buy fewer credits because they will be more expensive, and in turn to emit less carbon.

Jeremy Walters, marketing director at GoCarbonFree, admits that his company's contribution to raising the price of carbon is a drop in the ocean at this stage.

"But we hope to make a difference by building a momentum of people behind the idea," he said.

Tradable certificates, known as carbon credits, were issued in the wake of international agreements, such as Kyoto, which set quotas for greenhouse gas emissions by which countries have agreed to abide.

These credits rate greenhouse gases, such as carbon dioxide, methane and industrial pollutants like trifluoromethane (HFC-23), in equivalent carbon tonnage. A tonne of HFC-23, for example, is worth 11,700 tonnes of carbon.

Organisations can buy carbon credits from organisations like the European Emission Trading Scheme as a 'permit' to pollute up to the limit of their credits.

To pollute more than their carbon credit limit, the organisation would have to buy credits from companies that have reduced emissions to the extent that they have spare credits.

Thus a commodity market in carbon credits has been created, traded largely from the exchanges in London and Chicago, which is worth €22.5bn a year, or the equivalent of 1.6 billion tonnes of carbon.

A set number of carbon credits are issued by each country each year, so the trade in credits effectively sets the global price of carbon.