Energy Digital: Last year saw record growth in global renewable energy and energy efficiency investment, according to new figures published by the UN’s environment programme (Unep) last week. Spending on clean energy projects rose to almost 94bn worldwide in 2007, up 60 percent on 2006, according to the “Global trends in sustainable energy investment” report. Sustainable energy accounted for 23 percent of total new power generation added worldwide last year, with 31GW of …