Internet portal aims to offset all carbon emissions by.

Yahoo is preparing to make the company go carbon neutral by the end of the year.

Carbon neutral programs attempt to reach net carbon emissions through a combination of conservation, using renewable energy and investing in programmes such as re-forrestation programs.

Although Yahoo doesn't operate factories or has operations that traditionally are considered major pollutors, the internet portal's data centres consume vasts amounts of energy. In a posting on a company blog, co-founder David Filo claimed that the savings compare pulling 25,000 cars off the road for one year, or one month of power for San Francisco, a city of 740,000 people.

Carbon neutrality isn't without its critics however. The practice doesn't promote conversation and renewable energy but instead allows companies to purchase the right to pollute.

Filo acknowledged the criticisms of the system, and said that in addition to the carbon-neutral program, Yahoo will look for ways to cut the company's energy intake.

"We'll continue to be vigilant about cutting [our impact on the envirnomnent], looking for creative ways to power our facilities, encourage even more employees to seek alternative commutes, and generally inspire Yahoos around the world to think differently about their energy use."

Yahoo is part of a growing list of Tech companies to adopt a carbon-neutral program. CRM vendor Salesforce.com launched its own carbon free program earlier this year, and has committed to planting trees to offset the carbon production of its PCs and servers.

Chipmaker Via Technologies currently offers consumers a carbon-neutral CPU.