/ 5 March 2015

Pofadder SA’s new seat of solar power

More energy hits the semiarid earth in the Northern Cape than in most other places on Earth.
More energy hits the semiarid earth in the Northern Cape than in most other places on Earth.

The sun shines for 350 days a year in the Northern Cape. In summer, temperatures reach 50°C. More energy hits the semiarid earth here than in most other places on Earth. This starved the province of development, save for the narrow green band of agriculture along the Orange River. Now the province has an economy, thanks to a solar corridor that is turning the sun’s radiation into electricity.

Most of this energy comes from fields of conventional solar panels, owing to a pricing fault that put concentrated solar power (CSP) at a disadvantage. CSP is the only renewable energy source that provides base load power generation, which means it can provide variable power throughout the day and night. 

The country’s energy blueprint, the Integrated Resource Plan 2010 (IRP 2010), called for a 21 000MW renewable energy build inside a programme that would add 56 000MW more power-generating capacity to the grid by 2030. CSP was allocated 1 200MW of this.

The renewable component would be built by private companies, with Eskom promising to buy their electricity for a certain number of years. Three bidding windows have been held so far, for 3 725MW of capacity. And 200MW of this has been awarded to concentrated solar plants. Eskom is building its own 100MW plant. All of these are in a solar corridor stretching from De Aar to Upington.   

First plant
The first of these, the R7.9-billion KaXu Solar One, (KaXu means “open skies”) was launched this week outside Pofadder near the Namibian border. It is the only source of employment there besides seasonal grape picking and intermittent mining.

The 3km-wide and 1km-long 100MW plant uses a network of 326 000 mirrors. These are held in half-cylinder-shaped collectors, which focus the sun’s heat on thin tubes filled with a conductive fluid. This is then piped through 2m cylindrical silver pipes to a turbine hall, where water from the Orange River is turned into steam, which produces electricity.

What sets concentrated solar apart from all other renewable plants are the 10m-tall tanks in which the energy is stored in a salt mixture. This means it can provide an extra two and a half hours of electricity when it is dark or overcast. It can also increase its output should the grid need it, making it the first renewable that does what coal and nuclear plants can do.

Plant supervisor Sergio Olivier said: “We have the weather we need here. That means we can power 800 000 households.”

The 100MW plant being built next door will have nine hours of storage. About 200km away, outside Upington, the world’s fourth-tallest crane is building a 205m-tall solar tower surrounded by panels that direct sunlight on to the tower. This heat boils water to drive turbines.

Always on
In Spain, CSP plants run for 24 hours as a result of constantly evolving storage, with a lifespan of up to 60 years.

Although the technology is the only base load renewable, it is expensive compared with other energy sources. A 2013 analysis of the technology, by consultants Ernst & Young and Enolcon, said the South African plants would sell power to Eskom at R2.51 a kilowatt-hour. The power utility’s diesel plants – an emergency backup that runs nearly constantly with current energy constraints – cost R2.47/KWh.

As more CSP plants are built, costs will go down, the report said. By 2020, the cost could be R1.50/KWh. The United States energy department is working on CSP technology that could produce electricity at R0.55/KWh. With the technology being new, at least on a large scale, early adopters will have a chance to become industry leaders and export the technology, the analysis said. But South Africa is not building on the scale required – Saudi Arabia is planning a 25 000MW solar build, the report said. 

The South African Solar Thermal and Electricity Association said in parliamentary submissions in 2014 that the rest of the renewable build will be generated by “technologies that are intermittent by nature”.

The reason for the focus on solar panels is the incorrect pricing of energy in the 2010 energy plan, it said. It called for 9 600MW of concentrated solar to be built by 2030.  

Peak requirements
Johannesburg-based energy specialist Richard Worthington said this was because the electricity tariff never used to differentiate between peak and off-peak electricity. This meant conventional solar panels – which only work when the sun is out and so cannot supply South Africa’s peak demand – seemed a better option than the more expensive concentrated solar, which provides energy after the sun sets. Where there should be a mix of renewable energy sources – with CSP giving peaking ability – there was now a focus on wind and conventional solar, he said.

This was adjusted in 2011 by a new tariff, which makes electricity used during peak hours more expensive. Worthington said this drove a recalculation in a 2013 update to the IRP. It tripled the allocation of concentrated solar, and lowered the allocation to more conventional coal and nuclear power sources. The update has not been passed by Cabinet. When asked why it is not using the updated numbers, the energy department said on several occasions it had to work with the 2010 plan because the 2013 update is not a policy document.  

“This means we have started a billion-rand renewable build with little consideration for what type of energy is best for our current situation,” said Cape Town energy consultant Dirk de Vos. Conventional solar panels were being rolled out on a huge scale. This was creating an unbalanced grid, where instead each energy source should be valued according to all of its costs – such as its carbon emissions and the cost of paying for its construction. 

“The mistake we have made is in choosing a technology. Instead government should say it wants a certain amount of capacity and companies provide that through innovation,” he said. This would see developments of CSP working alongside other energy sources, to create a mixed grid that was not susceptible to failures. 

Solar panels should rather be built for areas off the national grid, or on houses. This model was being used in Germany, where the highest demand is during the day, he said. “Solar photovoltaic is not the best idea in a country where your peak is when it is dark. You need a mix.” 

Sipho Kings attended KaXu Solar One’s launch on a trip organised by Abengoa Solar and the Industrial Development Corporation.