He added the investment was needed in order to "bridge the energy gap" which could form over the next years from the closure of older coal and nuclear power stations.
Mr Duff stated: "Without major investment in UK energy infrastructure over the coming years, the UK faces shortages in the approach to 2015."
He spoke as RWE npower secured grid connections for its new nuclear energy station at Wylfa, located on the Isle of Anglesey.
The firm, one of the largest energy suppliers in the UK, recently launched a new scheme to promote energy-efficiency to small businesses over the festive period.
It claims that companies could be wasting up to £7 million a day due to poor energy efficiency.
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