By Ron Bousso LONDON (Reuters) – Shell has injected nearly $1.5 billion into its British energy retail business this year to help it weather huge volatility in power prices that caused the collapse of several rival UK power utilities, Shell Energy said in a filing on Thursday. Britain’s power utilities have been rocked by huge fluctuations in energy prices since the end of 2021 due to a shortage in natural gas supplies, which was exacerbated after Russia sharply reduced supplies to Europe following its invasion of Ukraine in February. The volatility led to several bankruptcies in the sector, i…