A second sun?

“What on earth is that?” I asked while driving towards Upington on our way to the Augrabies Falls last September. My wife and copilot to who the question was directed could not understand what we were seeing either!

Somewhere in the horizon, well above the city’s buildings, there was a very bright source of white light. From a very long distance, it looked like the reflection of the sun on one of the new glass-covered sky scrappers that are found in places such as Dubai or Singapore. But in Upington? It could not be.


The first sighting of the light.

Getting closer it became clear that the light was coming from a rather tall structure as it really dominated the landscape as a second (white) sun! As we drove past Upington towards the falls, the light remained to our starboard for about 40 km until we no longer saw it.

While we drove we discussed the “phenomenon”. The first theory involved visitors from another galaxy. We have watched District 9[1] and we knew that this had taken place in South Africa but in another city. Additionally, UFOs are not normally stationary for long and they tend to move at amazing speed doing weird things in the sky. So, unless it was an extraterrestrial contraption that had unlikely just crash-landed, the object should be terrestrial.

At some point we drove closer and we were able to see more details. It was a humongous tower that, from its top, emitted a very strong white light like a gigantic white LED. We realized that it was something to do with electricity generation from sunlight and a quick WhatsApp (with pictures) consultation with our offspring in Europe confirmed that theory.


A view of the tower and surrounding structures.

The tower came back to life during our return to Upington, after enjoying the visit to the Augrabies falls. Now ready to find more information, we paid attention to all roads going in its direction and eventually found one with a large signpost that said “Solar One”. We confirmed our suspicions that this was a large energy project.

That night, while in Upington, I was able to Google it and, what I read was rather remarkable.

The full name of the contraption is Khi Solar One (KSO) and it is a solar thermal power plant capable of producing 50 megawatts of electricity. It is the first solar tower plant in Africa and the first to achieve 24 hours of operation with solar energy only. Not that there are many in the world anyway! In fact, there are about twelve towers (1 in South Africa, 1 in Turkey 3 in USA, 3 in Spain, 1 in India, 1 in Germany and 2 in China).[2]

The KSO solar field is made of more than four thousand heliostats[3], totaling up to 576,800 m2 of mirror surface placed on an area of 140 hectares. In this case, the mirrors focus the sun rays on a boiler located on top of the cement tower. The latter is over 200m high! The KSO uses a superheated steam cycle that is able to reach a maximum operating temperature of 530°C and the energy can be concentrated as much as 1,500 times that of the energy coming in from the sun!

The steam generated is then converted into mechanical energy in a turbine, which powers a generator to produce electricity. The plant is able to accumulate steam to provide up to two hours of thermal storage at the plant. Apparently, power towers must be large to be economical. This clearly explains its size!

The project was developed by Abengoa from Spain and financed by the Industrial Development Corporation and community group, Khi Community Trust. According to Abengoa, the 50 MW, steam-driven solar thermal plant which recently began commercial operation in early February 2016, supplies enough clean energy to power around 45,000 South African households.[4]

Of note is that Abengoa has been going through tough financial times recently and KSO is one of its assets that it may need to sell if a planned company restructure does not work.


[1] https://en.wikipedia.org/wiki/District_9

[2] From Wikipedia (no date). List of solar thermal power stations. Accessed on 19 October 2016. https://en.wikipedia.org/wiki/List_of_solar_thermal_power_stations

[3] A mirror that follows the sun in order to reflect sunlight toward a target.

[4] Energyblog (2016). Khi Solar One near Upington achieves a technological milestone. Written by Abengoa on 19 October 2016 and accessed on the same date. http://energy.org.za/news/khi-solar-one-near-upington-achieves-a-technological-milestone


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