A new solar plant in the arid, sun-blasted Karoo will not only deliver useful energy to the grid, but function as a model of technological derring-do. Oh, and no sheep will be inconvenienced…
As power sources go, the Sun is pretty reliable. Now in comfortable middle age, it has a good 5 billion years to go before it consumes all its hydrogen fuel, kicking off a process that will end in its eventual decline into a cold, dark and rather sad dwarf. In the meantime, it delivers a formidable 173 000 terawatts (trillions of watts) of solar energy to Earth – a number vastly greater than the capacity of all our power plants combined.
This suggests that the Northern Cape’s new Kalkbult solar photovoltaic (PV) plant is a smart idea. Already up and running, and delivering the goods three months ahead of schedule, the plant takes the accolade for being the first private utility-scale renewable energy project to feed electricity to the national grid.
Located some 100 km north of De Aar, the 75 MW plant is expected to generate a virtually maintenance-free, non-polluting 135 million kilowatt hours-plus per year, or roughly the annual electricity consumption of 33 000 households, over the course of its projected 20-year lifespan. Constructed and fully commissioned in just 10 months by Norwegian-based company Scatec Solar and its local partners, Kalkbult solar PV plant is just the thin edge of the proverbial wedge. Forty-six other renewable energy projects, comprising wind, solar and mini-hydro plants, are scheduled to come on stream across the country in the near future. All of them have been awarded 20-year contracts to generate electricity under the Government’s Renewable Energy Independent Power Producer Procurement Programme (would you believe the acronym REIPPPP?). To date, their collective total investment amounts to an estimated R74 billion – an impressively large sum that could grow even bigger. Following the government’s recent acceptance of 17 new bids, investment in renewable energy projects may climb over the R100 billion mark.
It’s exciting stuff. What we’re seeing here is the emergence of an entirely new local industry, not to mention the first tentative steps towards reducing our nation’s near-total dependence on coal for power generation. Measured against the discharges of a typical coal-fired power station, the Kalkbult solar PV plant is projected to reduce annual greenhouse gas emissions by 115 000 tons.
Basking in the sun
To say Kalkbult solar PV plant is off the beaten track is hardly an understatement. Getting there for the plant’s inauguration ceremony involved a two-hour bus ride from Kimberley through historic Anglo-Boer War country, the last 60 km of the journey on dirt roads. Stepping out of the air-conditioned bus, the first thing that hit me was the oppressively dry heat. Then I began to squint – which shouldn’t have come as a surprise, considering that the De Aar area receives some 2 100 kWh/m² of sunshine annually, one of the highest solar irradiation levels in the world.
Intent on taking advantage of this natural bounty, the Department of Energy, along with various independent power producers, set out to identify suitable solar plant sites across the region. The area they earmarked, dubbed the “Northern Cape Solar Corridor”, follows the track of the Sun from De Aar to Upington in the west. Within this zone, various locations were found to be ideal for utility-scale solar power generation, including areas around Upington, Groblershoop and Prieska, not to mention the Kalkbult site north of De Aar.
Why this isolated 10 000-hectare sheep farm in the middle of the arid, sun-blasted Karoo was chosen over neighbouring farms as a viable location for a solar photovoltaic facility comes down to simple practicalities. As luck would have it, a 132 kV Eskom line, installed years earlier to power the trains hauling iron and manganese ore to the coast, runs along one of the farm’s boundaries, so hooking up to the national grid was a cinch. Two other pluses were the farm’s north-facing topography (which made the installation of the massive 105 ha solar array less complicated) and the fact that the ground’s gentle slope facilitated natural water run-off.
One couple who clearly enjoyed the inauguration ceremony were Kurt and Enid Krog, Kalkbult’s fourth-generation owners. Says Kurt: “When Scatec first contacted us in late 2010, asking to lease 105 hectares of our land for the plant, we thought it was a joke. Then, in November last year, they began with all the civil work such as roads and fencing. Ten months later, they were done.
“We didn’t really believe it would happen until we actually saw the first panels going up. My wife’s grandfather was an engineer… he’s the one who built up the farm, and this was his kind of stuff. I’m very sad he never got to see this; he would have enjoyed it immensely.”
Although the solar facility may be minuscule when measured against the vastness of a working Karoo sheep farm, to city slickers such as myself, those 105 hectares represent a very sizeable chunk of land. And looking out over that vast sea of blue, tightly configured solar panels is quite an experience.
Krog points to the sparsely clumped vegetation that struggles to survive in the rocky soil beneath the framework of the ever-expanding array: “The ground is so marginal that I can graze only 60 sheep in an area of this size. We’re not losing anything here, so for us it’s a win-win situation. Leasing the land will provide us with a good income for the next 20 years. Plus, I still get to let my sheep into the area periodically to graze under the modules; otherwise, the bushes will grow too high and cast shadows on the panels.”
Getting the job done
For Scatec Solar, completing the Kalkbult plant in 10 months – a full three months ahead of schedule – was no mean feat. Just getting the 312 000 Chinese-manufactured solar panels to the site from Port Elizabeth was a major operation that required 5 000 truckloads. Then there was the 156 km of substructure that needed to be manufactured and assembled to support the panels – all of it high-precision work. In addition, they needed about 1 800 km of cabling to connect all the panels, inverters and transformers to the new high-voltage substation.
In many respects, setting up a utility-scale solar plant from scratch is a much easier task than constructing more traditional power generation options using coal or hydro. Kari Fremme, Scatec Solar’s project director, explains: “As a general rule of thumb, for every one month of execution we need about two months’ planning time. This is the big advantage of solar; it can start feeding electricity into the grid relatively quickly. If you take hydro, for example, it can take as long as seven years to get a plant up and running.”
What makes this possible is solar’s relatively simple plug-and-play nature. As in any small domestic installation, the main components include the panels, inverters and cabling. Fremme elaborates: “Many people say solar is like LEGO, but make no mistake, on this scale we’re talking very precise LEGO. At Kalkbult, all 312 000 modules had to be precisely angled at about 30 degrees in relation to the Sun to achieve optimum results. When you consider that they’re all mounted on a substructure 156 km long over contoured ground, and that we work within tolerances of 3 mm for each panel, this requires extremely exact engineering.”
Because the Kalkbult plant covers such a large area, a decentralised inverter design was Scatec Solar’s only option. Electricity generated by each of the 204 W amorphous and microcrystalline panels is first fed into the 84 inverter hubs dotted liberally around the site, where it’s collectively stepped up to 22 kV. Each hub then feeds its electricity into the site’s substation, where it’s boosted to a more usable 132 kV before being fed directly into the grid. To manage this mammoth operation, a total of 1 500 sensors transmit real-time data to the plant’s control room, which is monitored both on site and remotely via the Web.
Says Raymond Carlsen, Scatec Solar’s CEO: “Our teams worked day and night to make this happen. Suppliers made a huge effort to deliver their services and equipment, and the local people who worked on the project were quick to learn – despite the fact that many lacked previous experience of this kind of work. This just goes to show how swiftly utility-scale solar energy plants can be built and put into operation.”
As required by government from all independent power producers, Scatec Solar is committed to ploughing part of the revenue derived from Kalkbult into local social and economic development projects located within a 50 km radius of the plant.
The company is also developing two other solar projects, both scheduled to go live during 2014 – a 40 MW plant near Hanover and a 75 MW plant near Burgersdorp in the Eastern Cape. Both plants are to have their panels mounted on single axes, enabling them to track the Sun and generate about 20 per cent more electricity than their fixed-panel Kalkbult cousin.
* 312 000 solar panels
* 105 hectares
* 1 800 km of cabling
* The 75 MW plant is expected to generate 135 million kilowatt hours-plus per year, or roughly the annual electricity consumption of 33 000 households
* The De Aar area receives some 2 100 kWh/m² of sunshine annually, one of the highest solar irradiation levels in the world
For more information, visit www.scatecsolar.co.za