by: Cameron Mackay of Engineering News
Published in Engineering News

Using microgrids offers an ideal platform for renewable-energy sources, such as wind energy, to be used more extensively, says turnkey energy project solutions provider SEM Solutions national sales manager Tiaan Hendriks.

Renewable-energy sources, such as wind and solar photovoltaic (PV) energy, cannot be solely relied on for constant energy supply, as such an exclusive reliance on renewable-energy sources can result in intermittent energy supply, he adds.

Intermittent energy is electrical energy that is not continuously available. This occurs as renewable-energy-generating sources vary in the rate at which they produce power, based on the weather.

Further, considering annual, cyclical weather and demand patterns, it is possible that energy produced will not always match energy demand; even with correctly designed systems.

However, Hendriks points out that microgrids provide two mitigation methods for intermittent energy supply.

The first method involves using energy storage systems. He states that the size of the microgrid influences the storage requirements and, as energy storage systems are inherently expensive, smaller systems required for microgrids become more feasible.

The second method involves increasing the geographical area of energy generation, which Hendriks states creates a decentralised energy generation system.

“Microgrids provide the platform for using renewable-energy sources. By equipping every microgrid with renewable generation and having many microgrids connected through a transmission network, generation capacity is decentralised.”

Hendriks states that wind energy, in particular, can play a vital role in a microgrid system, as it can contribute to increased generation capacity and provide a higher level of redundancy for the energy system.

Redundancy in engineering is the duplication of critical components or functions of a system to increase the reliability of the system. This duplication often manifests in the form of a backup system.

In the case of power generation, connecting more than one power supply to an energy system would increase redundancy to ensure continuity of power supply. This continuity occurs as the probability of a failure in the energy system occurring and affecting two separate power supplies simultaneously, is low.

Hendriks also highlights the advances in wind energy technology and the increasing impact wind energy is having on the local energy sector.

He points out that wind energy has the largest generation footprint in utility-scale projects through the Renewable Energy Independent Power Producer Procurement Programme.

According to the Integrated Resource Plan (IRP) 2019, the installed capacity of wind energy in 2018 was 1 980 MW, compared with 1 474 MW of solar PV.

“Taking all forms of renewable energy into account, wind energy is the third-largest form of renewable energy used in the local energy mix.

“However, the expectation is that it will be the most used renewable source by 2030, if the IRP 2019 is followed.”

Further, fluctuations occur in both energy supply and demand, as the flexibility of a power system depends on how it responds to these fluctuations.

Hendriks adds that the benefits of wind energy can help add flexibility to a microgrid, which is vital for any power system.

Smart Grid
Smart microgrids, which use ‘big data management’ and artificial intelligence can add further flexibility to microgrid energy storage systems, says Hendriks.

These technologies can be used to identify and track trends in generation and consumption.

A smart grid also allows for a higher capacity of renewables to be used in the energy system. It is overlaid with advanced communication systems and controls among various generation sources, loads and end-users.

These communication and control capabilities help operators of the microgrid system, working in conjunction with all parties connected to the system, to ensure a reliable power supply at all times.

Hendriks explains that these available technologies are allowing renewable-energy sources to become viable options to achieve grid parity, which occurs when renewable-energy sources produce power at a cost and performance level that is on par, or better, than that of conventional power sources.

Hendriks adds that sources such as wind and solar PV energy are already cheaper than all fossil fuel-based generation technologies. Therefore, grid parity will depend on dispatchable sources, such as gas and other energy storage technologies, which will provide backup generation when wind and solar energy supply drops.

“The question is no longer if renewable-energy sources are cost effective as an alternative to fossil fuels – the question is how these sources will be used to ensure quality of supply and mitigating the impact of climate change,” he concludes.