In this opinion piece, the author makes the case for hybrid electricity/desalination plants to produce fresh water and transform unused semiarid land into productive agricultural zones
By Tom Blees
A recent article in Engineering News argued that wind and solar could provide the bulk of South Africa’s power at the least cost. Dr Tobias Bischof-Niemz argued that building 22 GW of wind and solar capacity and 8 GW of “backup” (in the form of coal and/or gas) was the sensible solution to supplying a reliable 8 GW of electrical power to South Africa. Apparently his argument is that the amount of money saved on fuel will outweigh the cost of such extreme overbuilding.
Having seen actual results of such folly based on computer modelling and other types of simulations, one can be forgiven for being skeptical of such claims. But even if there’s a grain of truth to it, what was missing from consideration is the option of building 8 GW of nuclear power capacity. Since nuclear fuel costs are trivial and will reliably remain so in the future (unlike volatile coal and especially gas prices), whatever fuel savings might be gained by the massive costs of building 22 GW of wind and solar are of no consequence if nuclear is used.
Currently there are plans to build nearly 10 GW of nuclear generating capacity in South Africa. Alarmists cry that this will cost R1-trillion, a number pulled out of thin air by antinuclear campaigners. In fact, the cost (based on nuclear builds happening in Korea, China, and elsewhere) should be less than half that. And with several countries vying for that business, South Africa is in a good position to get a good deal.
All the offers presented to South Africa have been to build light-water reactors (LWR), the kind of reactor used almost exclusively around the world today. But if one talks to nuclear scientists, most of them will tell you that LWRs will be phased out in the near future in favour of reactor designs that operate at or near atmospheric pressure – the two most likely being sodium-cooled fast reactors (SFR) or molten salt reactors (MSR). Both of these will be able to be mass produced and deployed quickly, for they avoid the expensive pressure vessels and other pressurised components inherent in LWR design. The atmospheric pressure operation also imparts a considerable safety factor that alone would be a compelling reason to choose an LWR alternative.
But there is another characteristic of SFRs or MSRs that can be invaluable to a country like South Africa that has much semi-arid land currently lying unused for lack of water. Both those types of reactors operate at considerably higher temperatures than LWRs, which run at about 350 °C. SFR’s operating temperature is about 550 °C, while MSRs are designed for about 700 °C. That makes them inherently more efficient at producing electricity. However, there is another advantage that those high temperatures confer – that heat can be used to desalinate seawater.
Back in 1973, the then USSR built a fast reactor, the BN-350, in what is now Kazakhstan. It was a hybrid power plant that produced electricity but also desalinated water to provide fresh water for domestic and agricultural use. To date, this is the only such hybrid nuclear power plant ever deployed, though the USSR built a larger (600 MWe) fast reactor without the desalination component (the BN-600), and that extremely reliable reactor has been operating for over 35 years. Recently a slightly larger version, the BN-800, went on line in Russia, with a 1 200 MW version planned for the near future. China, in partnership with Russia, will also be building two BN-800s. With advances in desalination technology since the BN-350 over 40 years ago, similar hybrid power/water plants using the larger BN designs are certainly an attractive prospect.
Russia’s Rosatom has offered to build a very good LWR reactor, the VVER, in South Africa. It has been said that they talked with South African policymakers about fast reactors but that there was no evident interest. Clearly the potential of fast reactors has not been recognised, but there is still plenty of time to correct that oversight.
When considering electricity generating capacity, one must plan to provide enough to meet peak demand, those times when everyone’s coming home from work and turning on air conditioners or heaters, stoves, ovens, televisions, lights, etc. But peak demand is generally 2 to 3 times average demand, depending on the industrial profile of the area served. So if peak demand is 10 GW, that means that half that capacity (or more) would go unused. If you’re powering the country with gas or coal, that means you can save money on fuel. But if you’re using nuclear power, you are far better off to keep the plants running at full power 24/7 and finding alternative uses for all that extra heat. The paltry added fuel cost is a moot point.
Herein lies a potential bonanza for South Africa. If those ten new nuclear power plants were built as hybrid electricity/desalination plants, the amount of fresh water produced from seawater would provide such vast quantities of water that what is now unused semiarid land could be turned into a garden, creating an agricultural industry worth hundreds of billions of rand a year. This has been demonstrated in the semiarid Central Valley of California (with snowmelt rather than desalination), which now produces over half the fruits, vegetables and nuts consumed in the US on land that was previously unusable. A burgeoning agriculture industry resulting from such a project in South Africa would also create countless jobs for unskilled workers, creating a path for currently unemployed South Africans to lift themselves out of poverty.
The advantages of such a path are so transformative as to be considered a national imperative. Rather than throwing vast amounts of money away building 22 GW of wind and solar facilities, choose instead to build the 10 GW of nuclear capacity with the clear stipulation that the power plants will be hybrid plants. The money saved can be put to much better use building the agricultural infrastructure that will raise the standard of living of the entire country.
– Blees is an advanced energy systems consultant from Florida, in the US. He is the author of Prescription for the Planet - The Painless Remedy for Our Energy & Environmental Crises. Blees is the president of the Science Council for Global Initiatives (SCGI), an international NGO that includes climatologists, scientists and engineers involved in cutting-edge energy systems