Reuters reported that Rio Tinto has invested nearly EUR 80 million in its Dunkirk aluminum plant in the past 18 months and plans to invest at least that much again over the next 5 years on energy saving and efficiency improvements.

The largest aluminum plant in the European Union with 2012 production of 286,600 tonnes, seaside Dunkirk is the biggest single point user of electricity in France, consuming 485 MW per hour or half the output of one nuclear reactor at the nearby Gravelines site.

As Rio Tinto's 25 year contract with French utility EDF expires at the end of 2016, its electricity bill which adds up to 23% of production costs could rise as much as 80% from 2017, as contract prices catch up. But Rio Tinto is investing heavily to improve efficiency.

Mr Colin McGibbon Plant director of Rio Tinto said that the firm's main challenge is to avoid this increase but he is confident about reaching a deal with EDF. We need an energy agreement that gives us sufficient visibility and value so that we can keep investing here. We think that is achievable.