“Hydro is the new gold and over the next 50 years the prerogative of hydro asset owners will be to invoice, invoice, invoice”.
I said this last week when I was invited to give a keynote address at the 50th anniversary of Hidroelectrica de Cahora Bassa (HCB). The topic was “The role of hydro in regional energy security, resilience & decarbonisation in the Sadc region”.
HCB has a nameplate capacity of 2,075MW and has been supplying SA a portion of this for decades. HCB’s role in ensuring SA’s security of supply has been immeasurable. It has often been the buffer between stage 6 and stage 8 load-shedding, providing affordable hydro that is both flexible and clean.
SA now has more than 6GW of solar production, which continues to widen the gap between Eskom’s contracted and residual demand, leading to an ever increasing “duck curve”. This curve calls for greater flexibility in generation sources, especially for the evening peak.
Climate change has had a detrimental effect on hydroelectric plants, which has affected utility revenue and energy availability. Over the past two years the region has experienced the worst drought on record, affecting millions of people in Southern Africa through food, water and energy insecurity. According to the Zambezi River Authority, Lake Kariba is now less than 19% full, from about 13% this time last year.
Over the past year, HCB has been providing SA with 800MW on average because of low reservoir levels, in addition to planned maintenance. Hydro plants typically run baseload due to technical limitations. However, a case needs to be made to change how hydroelectric assets are run.
With low dam levels, reduced rainfall and a growing need for ancillary services, hydro assets may find themselves capitalising on the evening peak by providing peaking plant capabilities, at a low-capacity factor, less operations and maintenance spend but increased revenue. They can do this by gaming the system and supplying the evening peak at a premium.
Hydro can also be an energy bank and only provide energy when needed in a constrained system, again taking advantage of dynamic market pricing.
Changing rainfall patterns have affected water availability for hydroelectric power generation, necessitating adaptive strategies. Hydro can provide the peaking capacity, dispatched ramping, energy, storage, frequency and voltage stability a dynamic grid requires.
This solution is not unique to HCB but to all hydroelectric assets, whether pumped storage or run of river. In a region with increasing variable renewable energy, both grid-tied and behind the meter, hydro plays an important role in compensating for intermittent renewables. The hydroelectric assets don’t have to be huge and can be geographically spread for greater efficiency.
When Spain suffered its blackout a few weeks ago it was hydro, gas and nuclear from its neighbours that enabled a “black start”. This should also serve as a call to the region that diversifying the energy mix is vital, but so are interconnectors. We can no longer afford isolated policymaking when grid failures would have a cascading effect on the region.
SA has coal assets, nuclear, vast solar production and wind along its expansive coastline, while Mozambique has hydro and gas, Zambia and Zimbabwe have hydro, coal and solar, and Botswana and Namibia have vast solar potential, with the latter also boasting enormous offshore gas discoveries. We are a region that is energy rich yet electricity poor.
Our biggest downfall is our limited regional energy planning and lack of collective and visionary negotiation. Until we start thinking like a region and not as isolated grids, we’ll keep powering the future with yesterday’s mistakes.
• Mashele, an energy economist, is a member of the board of the National Transmission Company of SA.
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