SCOTS could be forced to subsidise fossil fuel bills south of the Border even if the country reaches its goal   set by alex Salmond   of being entirely reliant on green energy sources by 2020, environmentalists have warned.  Friends of the Earth said in a report that UK consumers can expect electricity bill rises of around ?300 a year by 2020 as a result of a continued reliance on fossil fuels to provide energy.  a spokesman said even with the Scottish Government s ambitious green energy targets, the rises will still hit  Scottish households.  It came as Prime Minister David Cameron and Energy