A massive shortfall in funding for African infrastructure projects is costing the continent up to three per cent of Gross Domestic Product (GDP) a year, a senior African Development Bank official said. 'The gap right now is something like $45 billion a year and that gap is dragging down economic growth in Africa by as much as 3 percent of GDP,' Mthuli Ncube, chief economist for the lender, said at a launch event for its annual economic outlook. 'The most critical area is energy - power. Any power outages are bound to cause massive problems for growth.'