South Africa is at a crucial moment in its energy transition: it is trying to decarbonise its economy (move away from coal) and ensure that everyone has access to reliable and affordable energy. Renewable energy storage is very important to this transition. Solar and wind energy are not always available. To keep the national grid stable, renewable energy needs to be stored somewhere and provided reliably.

The country has already made great strides in integrating renewable energy into its electricity grid through the Renewable Energy Independent Power Producer Procurement Program, which has attracted 110 private independent energy projects since 2010, investing R277.2 billion (US$14.6 billion) in renewable energy.

But South Africa’s path to a sustainable energy future is complicated by problems with energy storage technology.

As an electrical engineer and researcher, I am interested in energy transitions and the various barriers to renewable energy deployment in sub-Saharan Africa. My current research focuses on the role of energy storage in the energy transition in South Africa.

I reviewed all the existing literature on energy storage technologies, policies and market trends in South Africa to determine the overall state of renewable energy storage. I also wanted to find out how renewable energy storage can feed more renewable energy into the national grid and make the grid more reliable.

There are different types of energy storage. Lithium-ion batteries, for example, can store energy in different amounts, from small (phone size) to large (city size), depending on the size and intended use.

Pumped storage hydroelectric power plants are another way to store energy. This involves pumping water from a lower dam to an upper dam during off-peak times and then releasing it when needed to generate electricity. This is similar to a battery but uses water and gravity.

Thermal energy storage, which heats or cools materials so that the energy can be used later, is another possibility. The potential of green hydrogen as an energy storage medium is currently being discussed.

My research has shown that pumped hydro storage has historically been an important part of South Africa’s plans to expand its electricity generation capacity, but interest in this form of renewable energy storage has waned, largely due to industry concerns that there may not be enough water to support these facilities in the future.

Today, large-scale renewable energy battery systems are seen as the best future option for storing electricity from renewable energy sources, and South Africa’s state-owned electricity utility Eskom has started building battery storage facilities.

Dependent on carbon

Several factors complicate South Africa’s transition to a low-carbon energy system.

First, there is a historical dependence on coal due to its abundance and the economic importance of mining. This dependence creates resistance to change, both politically and economically.

Second, there is a lack of investment in the expansion of the national electricity grid. It needs to be modernised to accommodate renewable energy. Eskom has a huge debt burden. Since a large part of its revenue is used to service the debt, Eskom has limited funds available for infrastructure improvements.

Another problem is short-term or inconsistent government policy commitments. These can create uncertainty about the future of clean energy investments and make it difficult for companies to plan for the long term.

However, planning is necessary. Renewable energy sources such as wind and solar are intermittent and their output fluctuates depending on weather conditions and the time of day. To solve this problem, countries such as the UK, Germany and the US have set up grid-scale storage systems: large systems that store electricity for later use. This helps to balance supply and demand in the electricity grid.

Grid-scale storage includes batteries and other technologies such as compressed air storage. South Africa, which faces similar challenges with renewable energy variability, could benefit from the adoption of these proven energy storage technologies.

Incentives, skills, regulation

Energy storage technologies, especially batteries, reduce greenhouse gas emissions. In fact, they can drive decarbonization.

But the high costs pose a problem. Government and private sector must work together to create financial incentives and support research and development in the field of energy storage.

In addition, it is important to build a skilled local workforce with expertise in energy storage technologies.

Battery storage may technically be able to provide an essential service to the grid, but unless regulations or policies explicitly state that storage can provide these services, utilities and market operators may be unwilling to invest in renewable energy storage systems. Regulations are needed to explicitly recognize that renewable energy storage batteries are an important part of energy markets and provide essential services to the grid.

By providing clear guidelines on technical requirements, market participation and remuneration mechanisms, battery storage can contribute to a more resilient, efficient and sustainable energy system.

Policy, partnerships, public and planning

First, the government should take clear and supportive policies that incentivise investment in energy storage technologies. Tax breaks, subsidies and grants for research and development are common measures around the world that work well.

Second, fostering partnerships between universities, research institutions and the private sector can drive innovation and reduce costs. Joint efforts can find tailored solutions to South Africa’s unique energy needs.

Third, it is critical that the public knows and understands the benefits of energy storage. Education campaigns and community engagement initiatives can increase public support for clean energy technologies, making it easier to gain widespread acceptance of clean energy.

Finally, integrating energy storage into national energy planning is crucial. This means ensuring that storage solutions are an integral part of the country’s energy production and use, especially in large-scale future projects.

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