Zimbabwe through the National Water Authority in conjunction with Ngonyezi Projects, a business development service provider, plans to construct a 2000MWh pumped hydroelectric energy storage (PHES) plant plus a 300MW solar photovoltaic (PV) plant over Osborne dam.
According to Ngonyezi Projects executive director, Tomas Persson, the plan comes following a no consumptive water-use agreement signed by the two parties (Zimbabwe National Water Authority & Ngonyezi Projects).
Implementation of the solar PV plant is expected to take less than a year after the project enablers are given a go-ahead, while that of the PHES plant could take up to three years.
The contemplated pumped hydroelectric energy storage (PHES) plant
Upon completion, the project will make Zimbabwe the second country in the entire African continent that has a PHES, after South Africa.
The PHES plant will operate by storing energy in the form of gravitational potential energy of water, which will be pumped from a lower elevation reservoir to a higher elevation reservoir using low-cost surplus off-peak electric power. During periods of high electrical demand, the stored water will be released through turbines to produce electric power.
Mr. Persson said that the produced electric power will provide backup support for the national power grid and it will ordinarily be launched during peak hours when network capacity declines.
Reasons for the combination of hydro and solar facilities
The combination of the PHES and solar power plants, Mr. Persson said, will allow the solar plant to provide electricity to the population on sunny days, when otherwise, the PHES station will take over.
“Furthermore, by installing solar panels over the surface of the dam we expect to save approximately 20-million cubic meters of water, through reduction of evaporation, in favor of the planned irrigation scheme,” explained the executive director.
The developer plans for an irrigation program in return for the land on which the dam is built to benefit the surrounding community.