Britain's electricity generation is under scrutiny as a plan to close coal-fired power plants by 2025 has created concerns about power supply shortages.
Provisional government data shows that 277.93 terrawatt hours (TWh) of electricity was generated in 2015, down 1.8 percent from 2014 and down around 19 percent from a peak in 2003.
The sharpest fall was in coal-fired electricity generation, which slumped to 71.88 TWh in 2015, down 24 percent from the previous year, as the country's domestic carbon tax made electricity from the fuel less profitable.
Several coal plant operators have also decided to close loss-making plants this year due to competition from cheap gas and renewables and the added burden of the UK carbon price floor.
Coal accounted for 25.9 percent of electricity generation in 2015, down from 33.6 percent the previous year, DECC said, while nuclear energy increased to 23 percent from 20.5 percent. Gas accounted for 31.3 percent of electricity generation, little changed from the previous year.
Electricity from nuclear and wind increased last year. There was a 10 percent increase in electricity from nuclear power to 63.89 TWh as some plants came back from outages which started in 2014, while wind power generation increased 24 percent to 33.17 TWh.
DECC said more detailed estimates on 2015 electricity generation will be available on March 31.