How renewable energy helps keep the lights on

While the debate about South Africa’s power supply rages on, renewable energy is making strides in providing support to the national grid. According to Eskom Transmission’s load forecast data over the last two years, the country’s daily peak load sits at around 34 GW. The challenge is on to maintain grid stability and provide for the country’s energy needs.

Asante Phiri, Head of Operations and Maintenance: Southern Africa, at Enel Green Power South Africa (EGP RSA), one of South Africa’s primary independent power producers (IPPs), outlines how renewable energy works with the national grid and how it is being used to help meet the country’s current energy demand.

As of late January this year, the Renewable Energy Independent Power Producer Programme (REIPPP) has 5 901 MW of renewable energy connected to the grid. The majority of this, approximately 3 163 MW is wind power, followed by solar, at 2 212 MW and the remainder is 500 MW of concentrated solar power (CSP). These figures are expected to rise with upcoming commercial and industrial projects.

These new commercial and industrial projects are partly driven by President Ramaphosa’s recent announcement that projects under 100 MW do not require a generation licence. This paves the way for companies to take on projects of this nature without having to go through the process of applying for a generation licence.

Renewables supporting the national grid

Providing support to the national grid is not a simple operation. The fundamental difference between renewable and non-renewable energy is the manner in which electricity is generated. In a traditional thermal plant, coal is burned to create steam. Steam drives a turbine, which drives the generator.

With renewable energy, another source is used to drive the generator, for example wind. Solar panels work slightly differently, but electricity is still produced, and the electrons flow throughout the grid and become indistinguishable from each other.

Renewable energy does face one challenge that it needs to overcome in providing power. As there is no control over the sun and the wind, if the sun doesn’t shine and the wind doesn’t blow, access to those resources is lost. So, there’s a variability in terms of the power supply.

This makes it challenging for the personnel controlling the national grid, because they need a certain level of stability to maintain the integrity of the grid. However, if battery technology is integrated into the system, surplus supply can be stored and used when needed, i.e. in times of low wind or solar resource.

To control the overall dynamics of the grid, the traditional assets in the system work hand in hand with the renewable energy source, so that when the sun is shining and the wind is blowing, Eskom can lower the output of their generators to allow the renewable energy plants to generate, and when the renewable energy production is low, Eskom generators can fill in the gap.

This is a very technical process and is run by highly skilled personnel, because Eskom needs to maintain the integrity of the grid at all times. If imbalances arise in the grid, it could cascade to a point where a blackout occurs in a region or even in the country, and when this happens, it’s a difficult process to get the grid running again.

Global warming and renewable energy

Sectors that consume the most energy are generally mining, material beneficiation and materials manufacturing. Due to global warming, many countries and the companies within those countries have made a commitment to reduce their carbon footprint, and countries have signed the international treaty on climate change, namely the Paris Agreement.

Many investors these days are also keen to know the environmental and social governance (ESG) standing of the projects or companies they invest in – how these companies are tackling issues such as climate change. This is where renewable energy fits in, because it allows companies and countries to rise to the challenge of meeting the requirements of the Paris Agreement and the requirements of the investors, by allowing them to use clean and sustainable energy.

Can SA be powered solely by renewables?

With advances in technology and the resources we have in the country, it is actually envisioned that there could be quite a high contribution from renewable energy; however, Integrated Resource Plan (IRP) does make provision for other forms of technology.

If a country has good hydro resources (hydro dams), it is easier to have a fully renewable power system. And if there is storage in the system like a significant number of batteries are built into the system, then powering the country solely with renewables is theoretically possible. Battery technology is developing at a fast pace, which is exciting; however, South Africa has a way to go before it can be solely powered by renewable energy.

Can the existing renewables plants provide more power to the grid than they already are?

Many renewable plants that are connected to the system  have installed  capacity that is slightly higher than what they are contracted to produce. This is to cater for the technical capabilities that the plants need to have in order to meet the requirements for keeping the grid stable, and is referred to as grid code  compliance.

So while some IPPs have extra power at their plants, they are not currently able to supply this to Eskom due to grid code compliance. This essentially means that most IPPs are currently providing the maximum that they can technically and legally provide.

In conclusion, the supply of energy is a dynamic and technically complex process, especially in a country where the circumstances are so unique. However, with advances in technology and hopefully more and more support from renewable energy suppliers such as EGP RSA, the prospect of a national grid with higher levels of renewable energy penetration is not necessarily an ambition too far off in the future.

Asante Phiri, Head of Operations and Maintenance: Southern Africa, at Enel Green Power South Africa (EGP RSA).