One of the big challenges we face with climate change is the need to reduce emissions at a time when energy consumption may increase. Many countries in the global South will seek a combination of increased grid access, improved grid reliability and increased grid capacity to meet growing demand. Demand in Africa is estimated to grow by about 5% per year for some time. Dealing with the increase while reducing emissions will be a challenge.
As it stands, African countries are primarily powered by a combination of large hydropower plants (several smaller countries already have near-zero emission grids) and fossil fuels. Most plans to limit future carbon emissions include expanding hydropower, with plans to add about 100 gigawatts of new generating capacity over the next few decades. But the rapidly declining costs of wind and solar power have raised questions about whether these plans still make sense.
In many cases, the answer is no, according to new research. Rather, only about half of hydropower projects are economically viable, suggesting that many African countries would be better off with other renewables. By 2050, it is estimated that half of Africa’s electricity will come from wind and solar.
bad economics
As with most predictions of this kind, the new work builds on a large collection of other models. These relate to projected energy demand and track hydropower resources and planned hydropower projects on the continent. The future was expressed in a number of scenarios, including those with normal carbon emissions and those that maintain emissions commensurate with 2°C warming.
Given the fact that climate change could alter future rainfall in Africa, projections were performed based on two different levels of production from the dam. One is based on normal production and the other is based on a ‘dry scenario’ with very little rainfall.
The model then tracked the growth of the African grid to meet demand through 2050 by comparing the cost of each hydropower plant to alternative power plants.
The results show that even under the most favorable conditions, one-third of planned hydropower facilities are uneconomical when construction is scheduled to begin. In less favorable circumstances, about 40% of planned facilities could be economical.
All of this assumes everything is fine. As researchers recognize, large projects such as hydropower facilities are more prone to delays and cost overruns, putting them at a greater disadvantage than wind and solar projects. Half of the projects that make sense to build will be completed within the next 10 years (meaning many of them have already started). Most of the rest are in one of the few large river basins, such as the Nile, Congo, Zambezi and Niger rivers.
a completely different africa
As always, though, things are a little more complicated than simple economics suggests. For example, building capacity based purely on expected power generation puts some regions at risk of power shortages during prolonged dry seasons. Hydro power generation is also suitable for combination with renewable energy because it can be easily increased or decreased even when wind and solar power generation is stopped due to weather conditions. Therefore, there may be circumstances where it makes sense to complete a project, even if it costs more than the alternatives.
There are also some geographical issues. Zambia, for example, has several potential dam sites in the Zambezi basin, but also has good relations with the Democratic Republic of the Congo, which is building a large dam on the Congo River. Therefore, some potential projects only make sense if demand increases faster than expected.
All of this suggests that the share of hydropower in Africa’s electricity will peak in the early 2030s and decline from there. “Our results show that hydropower will lose its dominant role in Africa’s renewable power mix by 2050, declining to about 10% of the continent’s electricity production,” the authors say. concludes. However, it is not replaced by a single source of information. Instead, solar power will account for 30-40 percent of the electricity generated, and wind power will account for another 10 percent or so.
Again, this is purely for economic reasons. Despite hydropower being generally very cheap, the researchers write, “the window in which hydropower can still compete economically with solar power is rapidly closing.”
But even without a significant contribution from hydropower, the scenario suggests that the continent’s dependence on fossil fuels could decline dramatically. It is estimated that about 70% of electricity in sub-Saharan Africa currently comes from fossil fuels, about a third of which comes from polluting coal and diesel. Under a more optimistic scenario, Africa could derive more than 60% of her electricity from renewables by 2050, despite rapid growth in demand.
But to do that, we need to follow through on our promise to limit climate change to 2°C. Falling costs of wind and solar are expected to make meeting these promises an easy choice.
Science, 2023. DOIs: 10.1126/science.adf5848 (About DOIs).
