By Wallace Mawire
Zimbabwe’s Ministry of Energy and Power Development is set to embark on a wind energy resource assessment in the country in a bid to promote the uptake of windmills for water pumping and for electricity generation, said Dr. Sosten Ziuku, Director for Energy Conservation and Renewable Energy in the Ministry.
In Zimbabwe, wind energy has largely been used for water pumping mainly on commercial farms. He said the use of the technology has since declined probably due to the use of other methods, frequent breakdown of windmills and the closure of companies that work in windmill design.
The majority of commercial farms have since started using utility electricity, diesel generators and solar for water pumping.
“However, the cost of generating electricity using renewable energy technologies has been decreasing worldwide. More importantly, the capital cost of wind technologies has decreased significantly. It is against this background that the Ministry of Energy and Power Development wishes to promote the uptake of windmills for water pumping and for electricity generation. Wind energy, is a free renewable energy resource unlike other fuels such as diesel or coal,” Ziuku said.
For a number of years, it was believed that Zimbabwe did not have wind speeds sufficient for power generation. However, with the advancement in wind turbine technology, it is now possible to harness the resource at lower wind speeds for power generation. Previously, wind turbines had cut-in speeds as high as 12 meters per second but nowadays it is as low as 3 meters per second. The cut-in wind speed is the speed at which the turbine starts to rotate and generate power or pump water, according to Ziuku.
He added that when Zimbabwe joined the International Renewable Energy Agency (IRENA), the Government got a lot of assistance in as far as renewable energy resources assessment is concerned. In 2014/15, IRENA through its Africa Clean Energy Corridor Programme identified solar photovoltaic (PV), concentrating solar power (CSP) and wind energy zones covering countries in the Power-Pools of Eastern and Southern Africa. The zones or areas suitable for wind power generation were identified by considering access to roads, terrain, proximity to load centres, and land use (protected areas and other productive purposes) to derive a levelised cost of electricity. In Zimbabwe, the areas or zones with high potential for wind power include the middle-veld from the south to the north-east. These results were arrived at by processing satellite data.
The wind zones in Zimbabwe were theoretically mapped using satellite data.
“Consequently, there is therefore a need to confirm the results of the satellite study through experimental data. This can only be done by going to the zones and sites identified by IRENA and physically record wind speeds and perform other related measurements,” Dr Ziuku added.
Ziuku said the Meteorological Services Department has been measuring and recording wind speed data at heights of 10m above the ground but this height is not very helpful since wind turbines are usually mounted on hub heights of up to 80 meters above the ground.
In the project to be implemented, wind speed measurements will be done using wind masts of up to 100 meters high. The Ministry of Energy also expects to start with three sites working with experts and consultants from outside the Ministry.
Ziuku said the activities are being done in order to create an accurate database of the wind resource available in Zimbabwe through measurement and analysis and a wind power map of the country will be produced.
“This will help the country plan for renewable energy projects. The data and information generated will be used in designing large scale wind power projects, off-grid and mini-grid electrification projects, water pumping and climate change research, amongst other energy needs,” Ziuku said.