Rift Valley Energy Energy Mwenga wind farm
Image credit: Rift Valley Energy (RVE)

Rift Valley Energy (RVE) has successfully been running the 4MW Mwenga hydro power station for close to a decade, powering the needs of rural communities in the Mufindi District, in the Southern Highlands of Tanzania.

However, due to the seasonality of the rainfall in this region, seasonal generational shortfalls have appeared. During the dry season, which runs from June until November, the generation capacity of the hydropower plant normally drops to about 1MW, which is well below the peak demand of the 34 villages within the associated rural network. This challenge has proven something of a blessing in disguise as the plant is located where the wind blows hardest in the dry season. As such, the development of a wind project was a natural hybrid solution to ensure that RVE will always have sufficient generation capacity on hand throughout the year to meet the rapidly growing needs of its customers.

“The wind project can be expanded into the future as and when the rural network demand grows, and has the obvious advantage over a solar solution in that the wind blows steadily at night, when our customers most require the additional power,” says Michael Gratwicke, Managing Director of Rift Valley Energy.

Knowing that this was the first wind project in Tanzania, RVE acquired extensive support from a wide range of stakeholders to bring the 2.4MW Mwenga wind project into realisation.

The timeline for the project involved two years of wind measurements, followed by 18 months of project execution. The commercial financing to successfully implement the project was raised from both the Trade and Development Bank(TDB) and the Renewable Energy Performance Platform (REPP, which is managed by Camco Clean Energy).

The project cost around $5,000,000 to implement, which was financed by RVE equity of $1,365,000 (27%), a long-term loan from TDB of $2,345,000 (47%), and a REPP long-term loan of$1,200,000 (24%).

Careful preparation for a project of this magnitude was fundamental to ensuring that the construction kicked off without a glitch. Gratwicke expands on the necessary steps that RVE had to take for efficient proceedings: “We carefully investigated what constraints we were likely to encounter in transporting the turbines within Tanzania ahead o f selecting the appropriate turbine size, and then placing the supply contract.

Unfortunately, there was a rule change with regard to road transportation after the placing o f the supply contract. This resulted in extremely high abnormal load surcharges being levied on the heaviest components(being the three bottom tower sections), and led to a significant budget overrun, and a significantly more complex road transportation permission process.”

He adds: “Had we known about the new rules ahead of placing the contract, we would have had the bottom to wer sections fabricated differently and avoided the revised abnormal load thresholds and therefore saved significant costs, time and effort.

Travel restrictions associated with the COVID-19 pandemic also meant that we had to undertake the majority of the installation and commissioning work without the usual complement of site supervision personnel from the turbine supplier.” Resolute to bring the project online, RVE relied extensively on online support instead. As a result, the Mwenga wind project has been operational since July 2020.

Highlighting some of the key results from this project, Gratwicke says: “We now have an accessible in-country demonstration of wind technology, which has already attracted wide interest from both government and private sector stakeholders. We have additionally achieved the planned balanced generation capacity across our operations this dry season. An unexpected but equally important result is that we have also been able to deploy additional reactive power support from the wind turbines, that has improved voltage control at the very ends of our network, and contributed to increased grid stability.”

The benefits of the project include the additional generation capacity that is no w meeting the rapidly growing needs o f the communities surrounding the wider project area, of which the SME sector is the lar gest and fastest-growing off taker type. The availability of unconstrained industrial-quality power has already enabled more than 500 SMEs to start-up in the area, with many more expected to follow.

The additional generation capacity has also enabled further network expansions to be considered, and we now expect to add a further 2,500 rural connections in the mid-term. The bonus factor about this project is its scalability. Gratwicke points out: “The electricity appetite o f our rural customers is expected to expand significantly as economic and semi-industrial development occurs across this rapidly developing area, and the project has been designed from the outset to be scaled up as and when additional generation capacity becomes necessary.”

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