The price of natural gas used to heat homes and generate electricity is plunging this year, thanks to a mild winter in the US and Europe - bringing some relief to consumers and helping drive down inflation. The fuel, which in the US is extracted mainly from shale deposits in Texas and around Pennsylvania, accounts for nearly 25% of residential energy needs, making it a big driver in last year's worst bout of inflation in four decades. Since the start of 2023, U.S. natural gas prices have fallen 40% so far this year and Europe's prices are not far behind.