The number of cities reporting they are predominantly powered by clean energy has more than doubled since 2015, as momentum builds for cities around the world to switch from fossil fuels to renewable sources.

Data published by the not-for-profit environmental impact researcher CDP found that 101 of the more than 570 cities on its books sourced at least 70 per cent of their electricity from renewable sources in 2017, compared to 42 in 2015.

The Guardian reports Nicolette Bartlett, CDP’s director of climate change, attributed the increase to both more cities reporting to CDP as well as a global shift towards renewable energy.

The data was a “comprehensive picture of what cities are doing with regards to renewable energy,” she told The Guardian.

Kyra Appleby, CDP’s director of cities, held up as evidence of a changing tide the fact that large urban centres as disparate as Auckland, Nairobi, Oslo and Brasília were successfully moving away from fossil fuels.

“Reassuringly, our data shows much commitment and ambition,” she said in a statement.

“Cities not only want to shift to renewably energy, but, most importantly, they can.”

Much of the drive for climate action at city level in the past year has been spurred on by the global covenant of more than 7400 mayors that formed in the wake of United States President Donald Trump’s decision to withdraw from the United Nations sponsored Paris Agreement on climate changed.

Burlington, Vermont, was the only US city reporting to CDP that sourced all of its power from renewable sources after having fully transitioned in 2015. Research from the Sierra Club states there are five such cities in the US in total.

Burlington is now exploring how to become zero-carbon.

Mayor Miro Weinberger said to CDP that its shift to a diverse mix of biomass, hydro, wind and solar power had boosted the local economy, and encouraged other cities to follow suit.

Across the US 58 towns and cities, including Atlanta and San Diego, have set a target of 100 per cent renewable energy.

In Britain, 14 more cities and towns had signed up to the UK100 local government network’s target of 100 per cent clean energy by 2050, bringing the total to 84.

Among the recent local authority recruits were Liverpool City Region, Barking and Dagenham, Bristol, Bury, Peterborough, Redcar and Cleveland.

However, the CDP data showed 43 cities worldwide were already entirely powered by clean energy, with the vast majority (30) in Latin America, where more cities reported to CDP and hydropower is more widespread.

In the six months to July, Latin American cities reported having instigated US$183m of renewable energy projects, less than Europe with US$1.7bn or Africa with US$236m.

Europe topped the list for projects open for investment, but laid claim to just 20 per cent of the 101 cities to be predominantly powered by clean energy.

The Icelandic capital Reyjkavik, sourcing all electricity from hydropower and geothermal, was among them.

It is now working to make all cars and public transport fossil-free by 2040.

In a report released in January, the International Renewable Energy Agency found that the cost of power generation from renewable energy will reach parity with fossil fuels in two years.

“By 2020, all the renewable power generation technologies that are now in commercial use are expected to fall within the fossil fuel-fired cost range, with most at the lower end or undercutting fossil fuels,” that report said.