The City of Johannesburg reports that it will issue a tender in the coming months for the installation of hydroelectric turbines in its bulk water reticulation system, which could initially generate 3 MW of power for the city.

Executive mayor Parks Tau, who first mooted the scheme in his State of the City address in May, used the recent Association of Municipal Electricity Utilities conference to reaffirm the city’s intention to harness energy from its water network through the installation of in-pipe turbines.

“We anticipate that early in the new year we would be able to bring this technology to bear,” Tau reported.

City Power MD Sicelo Xulu said preliminary design work had been carried out and that the utility was optimistic about being able to introduce the first 3 MW of in-pipe power during the course of 2016.

The utility was of the view that, over time, as much as 10 MW of generation capacity could be harnessed from its bulk water network.

“We have undertaken a tour of a reference site and have met with the National Energy Regulator of South Africa to ensure that we will be in a position to apply for a licence to generate electricity through the in-pipe turbines,” Xulu added.

The system has been pioneered in the US city of Portland, in Oregon, where Portland General Electric has entered into a 20-year power purchase agreement to buy the electricity produced from turbines installed in the water pipelines.

Tau said that, while various energy alternatives were being considered to relieve the prevailing supply shortfall across the city and to reduce the risk of load-shedding, the in-pipe technology had been “deliberately” pursued, owing to its relative cost competitiveness.

“Many of the other alternative technologies have proved to be inaccessible and expensive for a developing-country city,” Tau said, while stressing that Johannesburg was also keen to tap the opportunity arising as a result of falling solar photovoltaic costs.

Xulu believes the in-pipe solution could be competitive with Eskom’s Megaflex tariff, while also having the added virtue of potentially improving pipeline pressure management.

“A lot of work has already been done and we will soon be going out on tender,” Xulu said.