In the September 4th edition of South Africa’s Mining Weekly, in a report entitled “SA mulls cost and benefits of mega solar project,” South Africa’s Eskom power utility is about to build a 100 MW solar thermal electric generating plant, using the “power tower” design (see our post “Solar Thermal Power” which describes design options).
In the report, Eskom’s resources and strategy division renewable-energy corporate specialist Dr Louis van Heerden explained that “central-receiver technology … concentrates the sun’s energy through multiple large mirrors, using the concentrated thermal energy to produce steam to drive a conventional steam turbine for electricity generation.
The energy concentration is achieved by a field of large sun-tracking mirrors (called heliostats), which reflect the sunlight to a receiver, mounted on a central tower in the middle of the mirror field.
A heat-transfer medium (molten salt) is pumped through the receiver, absorbing the highly-concentrated radiation reflected by the heliostats. The heated fluid is then circulated through a heat exchanger, where the thermal energy is used to generate steam and power a turbine.”
South African solar doesn’t end there. Back on February 11th in “Photovoltaics are the Wild Card” we referenced a report from South Africa on breakthrough photovoltaics. In this earlier story “SA solar research eclipses rest of the world” by Willem Steenkamp, they report “In a scientific breakthrough that has stunned the world, a team of South African scientists, led by Professor Vivian Alberts, has developed a revolutionary new, highly efficient solar power technology” and “The South African solar panels consist of a thin layer of a unique metal alloy that converts light into energy.”
The photo-responsive alloy can operate on virtually all flexible surfaces. The new panels are approximately five microns thick (a human hair is 20 microns thick) while the older silicon panels are 350 microns thick. Alberts claims the cost of the South African technology is a fraction of the cost for less effective silicon solar panels.”
This claim is corroborated in today’s story in the South Africa Mining Weekly, where alongside the report about Eskom’s solar thermal project there is this: “The University of Johannesburg’s Professor Vivian Alberts, from the department of physics, has developed solar panels that may just take this technology further into the main-stream, owing to the cost reductions he has achieved.
Alberts’ invention is five micro-metres thick, combining several semiconductor materials which are as effective, if not more so, than silicon. As it uses no silicon, costs are dramatically lower. It makes use of normal window glass as a substrate, with molybdenum applied as back contact, followed by the core component, being a compound semiconductor comprising five elements – copper, indium, gallium, selenium and sulphide, replacing the silicon – with cadmium sulphide as a buffer layer, followed by an intrinsic zinc oxide layer and, finally, a conductive zinc-oxide layer. The most expensive part of the panel is the glass,” said Alberts.
The pilot plant has shown the production cost per watt to be less than one South African Rand (which is about US $0.15), verified for a 25-MW production facility, assuming a 10% efficiency and average production yield of 85%,” Alberts claimed in the Mining Weekly Report. Alberts went on to say he predicted retail costs for this locally manufactured photovoltaic panel would be one-fifth the current cost of imported panels.
These are very huge claims. So who will be first to market with volumes of inexpensive photovoltaics? A South African consortium, or Silicon Valley’s own Nanosolar, or someone else? Like electric cars, the technology of photovoltaic panels is advancing rapidly. They are both transformative technologies and they are becoming increasingly economically viable.