The power of the River Taff as it flows through Cardiff could be harnessed to generate electricity under a £1.5m proposal.
Cardiff council has submitted a planning application to install twin screw hydropower turbines at the Radyr Weir beauty spot.
The authority says the 400KW system will generate enough energy to power three of the city’s leisure centres – and save 700 tonnes of CO2 – per year.
If the plans are approved, the electricity would be sold to the national grid to cover the seven-figure cost and eventually generate extra income for the authority.
If successful, Councillor Mark Stephens, executive member for finance, said hydropower plants could be installed at other spots along the Taff, such as Llandaff Weir and Blackweir.
But the proposal must first get the approval of Environment Agency Wales (EAW), which is investigating the impact on the river, its fish and the potential for an increased risk of flooding.
The council has applied to the EAW for an abstraction licence to divert water from the watercourse. The scheme can only go ahead if the licence is granted.
“We know there is a lot of pressure on electricity prices so it’s very attractive for local authorities to look at how they can get new sources of income,” Coun Stephens said.
“This is a sustainable and long-term supply of cheap electricity.
“It’s not without its technical issues and we are discussing these with the Environment Agency, but we are making progress and we would like to be onsite this summer.”
The council wants to build the system on bankside land to the east of Radyr Weir – a popular picnic spot with families.
The scheme also includes plans for a replacement fish pass, new powerhouse building and re-routing of the existing Taff Trail cycle and footpath.
Coun Stephens said the “payback” period of the initial cost was still unknown and dependent on electricity prices.
He also confirmed the authority was in talks with potential development partners who could cover part or all of the costs.
Radyr’s Conservative councillor Rod McKerlich said the scheme was a “wonderful idea” and should be used as an educational attraction for schoolchildren.