The answer to South Africa’s energy crisis may lie in the sea.
A small team of civil engineering students and academics at the University of KwaZulu-Natal (UKZN) are close to deploying a prototype hydrokite on the east coast that has the potential to harness and generate power from ocean currents.
Similar technology, in which tides are used to generate power, has been deployed by Swedish company Minesto to deliver electricity to the Faroe Islands' power grid.
The UKZN research team says their prototype can unlock as yet untapped renewable energy resources in South Africa. They expect deployment within three to five years.
This comes as Eskom this week announced it was looking at alternative energy sources to help boost constrained capacity.
The embattled power entity revealed at the Transmission Development Plan Public Forum last year that about 53GW of new additional general capacity from renewable resources would be required to safeguard energy security in the next decade.
Eskom did not respond to questions by the Sunday Times.
The UKZN project is overseen by Prof Derek Stretch and Dr Justin Pringle, who are working with PhD student Danel Capelo ahead of the kite’s deployment.
This pokes a hole in the argument that renewable energy is not consistent, like sunshine or wind. In comparison, the Agulhas current flows all year round, and consistently.
— Dr Justin Pringle, UKZN civil engineering
A study by student Tasha Smith into hydrokites using the Agulhas current to generate electricity as part of her master of science engineering degree, is helping Capelo hone the practicalities of the complicated project.
“Tasha has looked at the concept in theory and Danel is looking at the practical implementation. Danel’s goal is to design the kite, optimise its aerodynamics and deploy it,” said Pringle.
Smith said in her paper that ocean currents can be used to produce energy using turbines.
“Ocean currents are more consistent than wind with a much higher power-producing potential due to the larger density of water. The hydrokite is a lightweight and aerodynamic design consisting of a turbine mounted on a rigid wing which is tethered to the seabed.
“It can be fully submerged and controlled to fly in a ‘figure of eight’ shape making use of cross-currents and increasing energy producing potential.”
Smith said the Agulhas current on the east coast experiences high velocities.
Cape Morgan, in the Eastern Cape, has been identified as the location with the highest power-producing potential, where the prototype will be tested.
Smith said that as water moves through the turbine mounted on the kite, electrical power is generated which is then transmitted through a cable within the tether and transmitted to shore via submarine cables on the seabed.
From there substations can send power to the grid.
Capelo, who has been working on the prototype for more than seven months, said: “We’re still exploring this, but some estimates show that the kites, if installed in arrays, have the potential to power between 10,000 and 15,000 homes.
“With our tiny prototype we are expecting about 44kW per metre squared.
“A bigger kite has the potential to give off about 100kW, which obviously won’t feed the national grid.
“The solution to that would be to implement an array of these kites, maybe 100 to 200, operating in the region and on a kite farm, further up on the Agulhas current and then feeding back into the power grid.”
Pringle said they are working on maximising the power output of the device while keeping it simple.
44kW - the power the hydro kite prototype can produce
100kW - the power the final product can produce
— IN NUMBERS:
“The current moves consistently, except for a couple days because of an oceanographic event called the Natal Pulse, which causes the Agulhas current to stop for a few days.
“That’s when the advantage of an array of kites will come into place, because they can actually mitigate that.
“The kites that don’t feel the current will switch off and the kites upstream that feel the current can carry on producing power.
“We have to use our brains as engineers and scientists to design a kite to be as simple as possible. Fishermen can help maintain them while they are out.
“The idea is to optimise the shape to allow guys with no formal education to fix these and earn an income.”
Pringle says if the kites can be fitted the entire distance of the Agulhas current “in theory you can produce power for the greater part of the eastern coastline”.
Capelo is also investigating the effects on marine life as part of his research.
Pringle said the Eastern Cape is a marine protected area and would have to tread carefully when it came to deploying the device.
The project has been partly funded by the Technical Innovation Agency of South Africa and the team is hoping for more.
“UKZN has an incubation arm Inqubate, where they take the research and turn it into an application.
“They have helped us with funding. We have put in a proposal again to fund a deployment of an array of these kites.” said Pringle.
“This pokes a hole in the argument that renewable energy is not consistent, like sunshine or wind. In comparison, the Agulhas current flows all year round, and consistently.”
Pringle said the team will work with Inqubate to develop intellectual property and produce the product as well as a spin-off company.
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