Research finds number of 'biomass' plants has trebled in four years.
The number of power stations that are fuelled by burning plants and trees has more than trebled in four years to produce enough electricity for 7.4 million households, new figures show.
This means 'biomass' is now the second biggest source of renewable energy - behind wind power but ahead of solar and tidal energy.
An analysis by the JPIMedia Data Unit found that 43 per cent of UK local authorities have at least one biomass generator following an increase from 135 burners in 2014 to 429 in 2018.
Biomass plants are much cleaner than coal and gas-fired power stations but dirtier than other forms of renewable energy because they produce greenhouse gases.
This has made it the subject of intense debate among politicians and campaigners. The industry says wood is sourced from renewable forests, with new trees being planted which store carbon and help to offset the emissions produced.
But with the environment proving a key battleground in the election, campaigners are calling for the practice to come under more scrutiny.
"It is very concerning that in the global push to reduce emissions, more is not being said about the climate impacts of harvesting and burning wood," said Katja Garson, of the Fern forest protection charity.
Campaigners are urging the government to rethink the £1.3bn in annual subsidies that the biomass industry gets.
Almuth Ernsting, of the pressure group Biofuelwatch, said the government should instead redirect subsidies to "genuinely low-carbon renewable energy" - such as wind or tidal power. For the climate, electricity from forest biomass is no better than electricity from coal," she said.
Reaction from government and industryBenedict McAleenan, senior advisor to the Renewable Energy Association, said equating coal and biomass "misunderstands the way forestry works, ignores the important role of regulations and forgets the fact that trees are being regrown all the time."
A spokesman for the Energy Department said: "Sustainable bioenergy is further boosting our energy security and keeping costs down for consumers as we work towards our legally-binding net zero emissions goal by 2050."
