India needs to add the equivalent of about half the electricity generating capacity of the UK each year - or about 30 gigawatts - if it is to maintain its present rapid rate of economic growth, a new report shows. Yet the country in the past decade has managed to build an average of only 4GW of fresh capacity a year, a fraction of what the study by McKinsey & Co estimates will be required if the economy is to continue to expand at 8 per cent a year.