Greenpeace has named online companies such as Facebook and Apple to be responsible to what it calls a "rapidly growing environmental footprint of the online world."

On the Earth Day, the environmental watchdog released a report on the effects of cloud computing which graded 10 technology companies based on energy use in their data centres. The study measured each company on different parameters: clean energy index, coal intensity, transparency, infrastructure siting and mitigation strategy.

According to the report, about half of the companies used coal to meet over half of their energy needs instead of renewable energy resources like wind and solar.

Apple, with 54.5%, got the worst score for its "coal intensity", Facebook was in a close second at 52.8%.

While Akamai earned the best grade, B, for transparency, Google and Twitter both earned Fs.

Greenpeace concludes that the IT industry is ignoring renewable power and is opaque in disclosing how it uses energy.

Greenpeace IT policy analyst Gary Cook said, "We expect these companies to play a pivotal role in ensuring we move to clean, safe renewable energy systems and avoid future disasters like Fukishima."

Cook added, "But the IT industry’s failure to disclose basic information on its rapidly growing energy footprint has hidden a continued reliance on 19th century dirty coal power to power its 21st century infrastructure.

We think consumers want to know that when they upload a video or change their Facebook status, that they are not contributing to toxic coal ash, global warming, or future Fukishimas."

Cook also said that Yahoo and Google have shown how to use clean energy and at the same time be energy efficient.

"Green IT should not be a choice between energy efficiency and clean electricity — companies need to give equal attention to both for green data centres," Cook said.

"As Yahoo and Google are demonstrating, forward-thinking companies can help lead us toward energy security and safety by stating a preference for renewable power and supporting strong policies that move us to a low-carbon economy."

Greenpeace has said that it is difficult to measure the impact of data centre energy usage.