Zinc supports clean energy technologies from solar to wind
Renewables play a key role in South Africa’s Just Energy Transition (JET) towards a low-carbon, sustainable and socially inclusive future. “R1.5 trillion will be invested in our economy over the next five years in new frontiers such as renewable energy, green hydrogen and electric vehicles,” President Cyril Ramaphosa highlighted in his State of the Nation Address on 9 February.
Renewable energy sources such as solar, wind and hydropower have significant potential in South Africa. Hence the Renewable Energy Independent Power Producer Procurement (REIPPP) programme has attracted substantial investment to the tune of 6 000 MW of renewable energy capacity.
“The Northern Cape has already attracted well over R100 billion in investments in renewable energy projects. These and other massive investments in renewable energy will create jobs and stimulate local economies not only in the Northern Cape, but also in the Eastern Cape, Western Cape and Mpumalanga, turning even the most arid desert into a giant energy source,” according to President Ramaphosa.
The focus on renewable energy has also placed the spotlight on the role played by zinc, especially in energy storage, highlights International Zinc Association (IZA) Africa Executive Director Simon Norton. The World Economic Forum (WEF) states that the metal plays a critical role in enabling green technologies like solar and wind.
“As the world transitions to a low-carbon economy, zinc will continue to play a key role in supporting clean energy technologies,” cites the WEF. Norton showcases the following areas where zinc plays an important role:
These rechargeable batteries use zinc as the anode and oxygen from the air as the cathode. When the battery discharges, zinc oxide forms at the anode. When it charges, the zinc oxide is converted back to zinc. Zinc-air batteries are low cost, have a high energy density and are environment friendly. Hence it is a promising technology for large-scale energy storage.
Zinc-bromine flow batteries
Another type of rechargeable battery that use zinc and bromine as the active materials. These batteries pump liquid electrolytes through a cell stack to oxidise the zinc and reduce the bromine. The process is reversed when the battery charges. Zinc-bromine flow batteries have high energy density and are relatively inexpensive.
Thin-film photovoltaic cells often contain a layer of zinc oxide that acts as a transparent electrode and assists in collecting the electrons generated.
Zinc rich coatings are applied to the steel used for wind turbine towers so as to protect them against corrosion and increase their lifespan.
“Overall, zinc plays a vital role in renewable energy. It stands to enable the development of low-cost, green energy storage technologies, in addition to its contribution in the area of solar panels and wind turbines,” concludes Norton.