Manchester Evening News: ROOF-mounted wind turbines in typical areas of Manchester generate barely enough electricity to boil a kettle once a week. A study found that in almost all circumstances, the turbines would cause more damage to the environment to build and install than they would ever pay back in ‘green’ power. The research by charity the BRE Trust will be an embarrassment to political supporters of so-called ‘micro-turbines’. Conservative leader David Cameron had one fitted to the roof …