Yahoo has announced plans to go carbon neutral by the end of the year.

Carbon neutral programmes attempt to reach net carbon emissions through a combination of conservation, renewable energy and investing in initiatives such as reforestation.

Although Yahoo does not operate factories and is not considered a major polluter, the internet portal's data centres consume vast amounts of energy.

Yahoo co-founder David Filo claimed on a company blog that the potential savings compare to taking 25,000 cars off the road for one year, or one month of power for the 740,000 residents of San Francisco. 

Carbon neutrality is not without its critics, however. The practice does not promote conversation and renewable energy but instead allows companies to purchase the right to pollute.

Filo acknowledged the criticisms, and said that Yahoo will look for other ways to cut the company's energy intake in addition to the carbon-neutrality initiative.

"We will continue to be vigilant about cutting [our impact on the environment], 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," he said.

Yahoo is part of a growing list of tech companies adopting carbon-neutral programmes.

CRM vendor Salesforce.com launched its own carbon free initiative earlier this year, and Dell 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.