In a significant finding, the global environment group Greenpeace has applauded Apple, Facebook and Google for committing to power their data centres with 100 percent renewable energy.
It, however, criticised Amazon and Twitter for their data centres in coal areas and failing to reveal energy use.
"The rise of social media is being powered by dirty forms of energy such as coal," a Greenpeace report said Wednesday.
Amazon Web Services lagged "far behind its major competitors, with zero reporting of its energy or environmental footprint to any source or stakeholder", the report added.
Apple, in particular, had cleaned up its energy profile, it noted.
The company was awarded 'A' ranks in energy transparency, deployment and advocacy, and commitment.
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According to Greenpeace, some internet companies "have refused to pay even lip service to sustainability and are simply buying dirty energy straight from the grid".
"Electricity use by data centres is one of the fastest-growing sources of greenhouse gas emissions globally, as more people come online. Internet data traffic is expected to triple between 2012 and 2017," Greenpeace commented in a press release.
Twitter also received lower grades for failing to disclose its electricity use despite going public last year.
The report looked at 19 companies that operate more than 300 data centres combined.
Apple's Clean Energy Index was 100 percent while Facebook and Google were rated by Greenpeace at 49 percent and 48 percent, respectively.