Q: What's the carbon impact of your Facebook account? A: Three bananas

Facebook's 900 million users each emitted 3,228 grams of carbon by using the social networking site last year, resulting in the same environmental impact as drinking two glasses of wine, according to new figures.

The social networking giant yesterday published its carbon footprint for 2011, the first time it had revealed the carbon impact of its operations and a move that was hailed by Greenpeace as a major step towards greater transparency. 

The figures showed Facebook's operations, including travel and data centres, were last year powered by 27 per cent coal, 23 per cent "clean and renewable" energy, 17 per cent natural gas, and 13 per cent nuclear. Another 20 per cent was purchased on the open spot market so could not be catagorised.

The company also announced that it aimed to power 25 per cent of its business with renewables by 2015.  Facebook's greenhouse gas emissions totalled 285,000 metric tonnes of CO2 equivilant overall, equating to 269 grams per month per user.

In a statement on its website, Facebook said the average user's carbon impact per year was equal to the emissions from eating three bananas, or drinking a couple of glasses of wine.