If you have ever burned your initials into a block of wood using a magnifying glass, you understand the principles of concentrated solar power, known as CSP. In theory, using mirrors to concentrate the sun’s rays is an excellent way to harness the immense power of the sun. But it’s not quite that simple.
According to The Guardian, CSP installations are expensive and have proven difficult to make work at smaller scale. Called heliostats, the shaped mirrors in some types of CSP are usually large with a huge central base set in concrete. Using current technology, they are expensive to produce, have to be connected through costly wiring and need to be installed by highly skilled construction crews. That’s why electricity from CSP plants is more expensive than from solar panels. (Plus, solar PV is just super cheap these days.)
Paul Gauché is founding director of the Solar Thermal Research Group at Stellenbosch University in South Africa. His group is testing a new way to produce miniature CSP units that will be cheap and quick to install. “We are developing plonkable heliostats. Plonkable means that from factory to installation you can just drop them down on to the ground and they work.” If his process proves commercially viable, he may go down in history as the man who invented the word “plonkable.”
No costly cement, no highly-trained workforce, no wires — just two workers to lay out the steel frames on the ground and a streetlight-style central tower. “Every part in it is manufacturable and installable by two sets of hands — or one rugby player, as we found out,” he says with a laugh.
Helio100 is a pilot project with over 100 heliostats of 24 square feet each. In total, they generate up to 150 kilowatts of electricity — enough to power about 10 households. According to Gauché, the array is already cheaper than using diesel, the current fuel of choice during the regular power outages in South Africa. Google once attempted to build systems like this but abandoned its research after deciding it could not do it cheaply enough. What Gauché’s team has done differently is to reduce the cost of creating heliostats.
Around the world, CSP is in decline after an initial growth spurt because it currently costs about three times more than using a hybrid system of PV panels together with wind power to generate electricity, explains Prof Tobias Bischoff-Neimz, manager for energy at South Africa’s Centre for Scientific and Industrial Research. “The future for CSP rests with creating power at changing rates. Not like a base load power station that runs at full power all the time, but a system that makes the grid more flexible.” He says Gauché’s work to reduce the cost of the technology is vital if CSP is to reach its potential.
Gauché’s team uses smaller mirrors that focus the sun’s rays onto a small surface at the top of the tower. The mirrors track the sun all day and then reset for morning. They focus the sun’s rays into a beam so intense it that can melt the collector in less than five seconds if its cooling water stops flowing. The heating element is like a car’s radiator in reverse — the heat is transferred to moving water that can either create electricity or be used for other work.
The team wants its system fully functional by the end of October 2015. Gauché predicts that once they refine the technology, then economies of scale will follow. Referring to Henry Ford’s famous mass-market breakthrough, he says: “We are not yet at the Model T in CSP. The moment you start to get high volumes, industrialization, get more scientists, more of everything, then the costs will come down radically.”
Elon Musk couldn’t have said it any better.
