At long last work has started on the third stage of Hwange Thermal Power Station, an expansion planned in the later 1980s for construction in the 1990s or early 2000s to complement the similarly planned extension to Kariba South Hydroelectric Station.
The two were planned by a long line of foreign consultants and Zimbabwean engineers as the best and cheapest solution to the objective of ensuring that there was enough energy generated to allow Zimbabwe’s economy to continue growing and that there would be enough generation capacity to cope with the peaks during the working day and the working year.
The requirement for the double programme was to fit physical facts. Kariba South was the optimum solution to increase power output, since the main civil works – the dam wall and the lake – were already in place but local experts, correctly as it turned out, were dubious that temporary rises in Zambezi River flows in the 1970s were anything more than a statistical blip. This would mean that the Kariba extension would not add significantly to amount of energy generated in a year in Zimbabwe, as there was no extra water to drop through the turbines, but was the obvious solution to allow Zesa to meet peak demand, which can be more than twice the base load on the system. Peak power can be expensive and Kariba South extension was the cheapest solution to meet that demand.
So to back the bigger Kariba South, there also had to be an energy generation augmentation, and the obvious candidate was extending Hwange thermal power, and at the same time sorting out a cooling deficiency arising from bad planning in Rhodesian days so that the power station would be able to work all units at full output.
The wasted decades, as President Mnangagwa rightly called much of the 2000s and 2010s, saw all these plans shelved and instead Zimbabwe, with its economy first contracting and then growing very slowly, relying on imports to meet the shortfalls. Unfortunately SADC was moving from a generation surplus to a generation deficiency so this was not a long-term policy. While our neighbours started building new stations we did not.
Eventually pressures built up for Kariba South extension, which President Mnangagwa commissioned within months of assuming office, but Hwange extensions had been kept on the back burner until the President, in April this year, managed to convince President Xi Jinping of China that he was both knowledgeable over what Zimbabwe needed and was serious about assuming the financial burden. So the logjam was broken and work now starts.
As the President continuously explains, all the Government plans for pushing economic growth up to the levels required to make our country a relatively comfortable place to live by 2030 are doomed unless the new mines, the new factories, the new irrigation systems and the new homes can be supplied with electricity. And be supplied whenever the users desire in any 24 hours.
Once the accelerated work on Hwange Thermal is complete, this station will take over the major share of supplying Zesa’s base load, basically what the country needs in low demand times. For weird reasons created by bad economics Zesa has been using its hydro station for base load and its thermal for peak output, the exact opposite of what every other utility does and a system guaranteed to increase wear and tear on the thermal station. These sort of coal stations are at their most efficient when their boilers are burning 24 hours a day, seven days a week.
The expanded Kariba South then moves into the operating mode that most utilities desperately want from hydro stations, coping with all the ups and downs of power demand during the day and being able to cope with the peak demand in the morning and evening. This might well see Kariba South making a very modest contribution to the grid at say 2am, perhaps just 200MW. But at 5pm when factories are still buzzing but a lot of homes are switching on stoves, it soars to close to its 1050MW rating, huge swings in output are easy with a hydro station.
Meanwhile of course the responsive Government is now listening to its economists and engineers and working out when each new station needs to come on line and making sure construction starts in time to meet that deadline.
This is not difficult; it is how utilities are supposed to operate. One interesting example is China, which at one stage during its drive to becoming the world’s largest manufacturing economy was commissioning a new very large thermal station every fortnight, while building the world’s largest hydro scheme at the same time.
There is a financing blip in progress right now, because we left the extensions too long and wound down maintenance at Hwange Thermal. An expanding utility can normally keep a constant capital charge in its rates by mixing cheap energy from older fully-depreciated and paid-for stations with the higher priced stuff coming from the new station. Zesa will battle slightly to meet that model as new Hwange power comes onto the grid but it will be saving on some very expensive peak-power imports so should be able to manage.
Then its next stations will form an ever smaller percentage of existing capacity as they come on stream and so the economics start favouring the consumer for a change. We are now on the right track.