Church of England places of worship, along with Catholic, Baptist, Methodist, Quaker and Salvation Army congregations, have made the switch to 100% renewable electricity, and faith leaders are urging more to follow suit.
Some 15 Anglican cathedrals including Salisbury, Southwark, St Albans, Liverpool, Coventry and York Minster are among the buildings signed up to green electricity tariffs.
Church leaders warn climate change is "one of the great moral challenges of our time", and hurts the poor first and worst.
With an average annual church electricity bill of around £1,000, British churches have diverted more than £5 million from fossil fuels to clean energy providers, it is estimated.
The number of cathedrals running on 100% renewable electricity is down to the Church of England's procurement group Parish Buying turning its bulk electricity basket to 100% renewables.
Other churches have made the move through the Big Church Switch campaign run by Christian charities Christian Aid and Tearfund and the Church of England's Environment Programme.
Parishes can sign up to national church buying group 2buy2, which pools the combined buying power to negotiate the cheapest possible tariff.
Often the renewable energy tariff is cheaper than the fossil fuel-dominated one they were on before, Christian Aid said.
Bishop of Salisbury Nicholas Holtam, the Church of England's lead bishop on the environment, said: "Climate change is one of the great moral challenges of our time and so it's fantastic to see churches doing their bit to ensure they reduce their impact on the environment.
"They are also giving a boost to clean energy, which is essential to reduce harmful carbon emissions.
"Climate change is an enormous injustice and is hurting the poor first and worst.
"Switching to responsible sources of electricity may seem like a small thing on its own, but when joined together it can make a real difference."
Former archbishop of Canterbury and chairman of Christian Aid Dr Rowan Williams said the Church of England had agreed to sell its shares in fossil fuel companies not on track to meet the aims of the Paris Agreement on tackling climate change.
"Churches are part of a global network and so are often very aware of the plight of our brothers and sisters suffering from droughts, floods and extreme weather around the world," he said.
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