Wind energy is important in driving potential demand for energy storage, says nonprofit organisation South African Wind and Energy Association (SAWEA) CEO Ntombifuthi Ntuli.

“The demand particularly pertains to . . . the hybridisation of wind energy, which allows for electricity to be generated from two or more sources with storage. This has the potential to enable wind farms to provide a dispatchable power capacity.” 

She adds that the timing is right, owing to the costs of storage falling sharply and continuing to decline as competition increases and the technology matures, while the roll-out of wind energy is still increasing.

Wind energy can be considered a game changer for energy storage in South Africa and this can be attributed to the incentives of wind variability, generation costs and operation flexibility, says Ntuli.

“The integration of energy storage represents a feasible solution to one of the key technical drawbacks of wind energy, namely that of variability.”

The variability of wind energy causes fluctuations in its speed, which, ultimately, changes the energy content of wind. Therefore, the energy output from a wind turbine will vary as the wind alters.

The solution to the issue of variability lies in wind and storage hybrid plants, and is the first catalyst for using energy storage. Such energy storage will ensure smooth energy output from wind facilities.

Energy storage will simultaneously introduce the properties to facilitate local load matching, which will enable power stations to store excess power for release during peak periods and even allow for addressing baseload requirements on the grid, explains Ntuli.

The second incentive can be attributed to generation costs, for which Ntuli says there is potential, even though the initial funds required to acquire the battery storage may be higher. Over time, the increased use, availability and sales of stored energy would increase revenue and lower the levelized cost of energy (LCOE). 

Hybrid solutions, including full dispatchable storage, are already cheaper than peaking plants. These are power plants that operate only when there is higher demand and it is technically feasible to do so. If permitted, these hybrid solutions can be used for other technical grid-related tasks.

Battery storage is a mature technology that is also rapidly declining in cost.

“According to Bloomberg New Energy Finance, the LCOE that can be achieved for battery energy storage means that new-build batteries can be competitive on cost with gas peaker plants,” says Ntuli.

She adds that the cost of battery storage is expected to become even cheaper, especially when coupled with low-cost generators, such as wind, which will, ultimately, create a cost-effective solution.

The third incentive, operation flexibility, refers to the ability of a power system to respond to changes in electricity demand and generation.

Hybrid plants will enable wind plants to meet the energy needs a day-ahead of schedules to avoid penalties while providing additional capacity for the grid operator for grid support to ensure stability.

Moreover, Ntuli notes that there is a global wave of hybrid projects that use wind and battery storage. These projects will stabilise grids, provide ancillary grid services and increase efficiencies through increased capabilities to do load matching while maintaining the cost effectiveness associated with utility-scale wind.

Meanwhile, several SAWEA members have submitted hybrid projects in response to the Department of Mineral Resources and Energy’s (DMRE’s) request for information for the Risk Mitigation Independent Power Producers Procurement Programme (RMIPPPP) in January last year. This programme aims to allow for a greater supply of renewable energy to be used.

In March, Minister of Mineral Resources and Energy Gwede Mantashe announced preferred bidders for the RMIPPPP. Out of the eight preferred bidders, two projects, Oya Energy and Umoyilangac, are hybrid facilities incorporating solar photovaltaic, wind power and battery storage, explains Ntuli.

After being announced as preferred bidders, these projects have four months to reach financial close before the power purchase agreements are signed, after which construction – expected before the end of 2021 – can start.

Ntuli highlights the economic potential of these projects, stating that the DMRE reported that the RMIPPPP would attract R45-billion to the South African economy, of which a portion will be allocated to the hybrid projects.