Zimbabwe is currently experiencing up to 18 hours of load-shedding daily, the result of a variety of problems stemming from economic collapse and hyperinflation. Kariba dam provides around 57 percent of Zimbabwe's electricity, but low water levels in the dam have resulted in a decrease in production. Hwange colliery which provides almost all of Zimbabwe's coal for power generation is producing less due to deteriorating and outdated infrastructure and the country is already in debt to neighbouring countries South Africa and Mozambique for electricity imports. For more information see the IDTechEx report on Distributed Generation: Minigrid Microgrid Zero Emission 2018-2038.
Business development service provider Ngonyezi Projects executive director Tomas Persson says the company's pumped hydroelectric energy storage power plant at Osborne dam, in Zimbabwe, will contribute to the reduction of the hours of load-shedding in the country. Ngonyezi Projects has entered into a nonconsumptive water-use agreement with the Zimbabwe National Water Authority, the purpose of which is to install a combined 2 000 MWh pumped-storage hydro and a 300 MW solar photovoltaic (PV) plant.
The combination of hydro and solar will allow the solar plant to, on sunny days, provide electricity to the population, and when the weather is either bad or it is night, the pumped storage power station takes over. "Also, the fact that the solar panels are covering the dam's water surface will save some 20-million cubic water, by reducing evaporation - this saving will support the planned irrigation scheme," Persson tells Engineering News Online.
The location of the installation is Osborne dam on the Odzi river in Manicaland province, where the surrounding community is set to also benefit from an irrigation programme provided in return for the land on which the dam is built.
The installation produces electricity owing to a reversible system. In practical terms, the plant operates with two tanks (upper and lower), and the water from the upper reservoir flows down into the lower reservoir by rotating the turbines of the hydroelectric power plant. The water from the lower tank is pumped again to supply the upper tank, and so on.
The pumped hydro is generally built to provide backup support for the national power grid and is launched during peak hours when network capacity declines.
According to Ngonyezi Projects, the peak in electricity consumption is observed for eight-and-a-half hours a day in Zimbabwe. Following the completion of the pumped storage project, Zimbabwe will become the second country in Africa with pumped storage, after South Africa. However, before construction of the project can begin, all permit approvals will first need to be received, after which construction of the solar PV section is expected to be completed in less than a year, whereas the pumped storage section could take up to three years before implementation.
Zesa Holdings Ltd, the utility that is subjecting Zimbabweans to 18-hour power cuts, is now going off the grid and is inviting bids for a roof-top solar power installation at its head office in the capital, Harare, to ensure that its staff enjoy uninterrupted power.
Sources: Ngonyezi Projects, Africa Energy Portal