ENERGY giant ScottishPower has mounted another defence of its steep price rises, saying it will have to spend GBP15 billion over the next nine years to help the UK government meet its "ambitious" carbon reduction targets.  The firm, which came under attack after hiking bills by as much as 19 per cent, said it would be investing heavily in a number of clean energy projects between now and 2020.  Power companies argue that the UK will need to find hundreds of billions of pounds over the next ten years to upgrade infrastructure if the UK and Scottish governments both want to meet goals of sourcing a greater proportion of energy from renewable sources.  ScottishPower claims it was forced into inflation-busting increases due to sharp spikes in wholesale gas and electricity prices, combined with investment in government environmental and social programmes.  Ignacio Gal??n, chairman of ScottishPower and its Spanish parent company Iberdrola, yesterday waded into the increasingly bitter battle between the firm and politicians, who claim it is profiting at the expense of hard-hit households. It was the first time Gal??n revealed such a long-term investment figure. He said: "It is clear that the UK needs major investments to upgrade its energy gene