Double carbon research | Hydropower destroys African river systems: how solar and wind energy can solve this problem

Hydropower has destroyed the river system in Africa:

How can solar and wind power solve this problem

In order to meet the growing power demand, more than 300 hydropower projects are planned to be built across the African continent. Some of these projects need to build large dams, which may cause serious negative impacts on the environment. Another problem caused by hydropower is that the water cycle will be affected by climate change. In the coming decades, the supply of water resources in some regions will decrease, and the stability will also decrease.

Africa Mirror is a team composed of environmental and energy system researchers. The energy system studies how to produce energy to meet the needs of all sectors of society. Environmental system modeling is used to simulate the natural environment and assess the impact of infrastructure on the natural environment.

The team analyzed the development trend of Africa's energy system from 2020 to 2050, studied the change of energy demand, land use and its impact on energy, and how climate warming will affect water supply.

The per capita electricity consumption of the African continent is still 80 per cent lower than the global average. However, considering the future population growth and the improvement of living standards, Africa's power demand will increase, which also means that new power generation infrastructure is needed.

The team found that by 2030, the power generation benefits of wind and solar energy projects in Africa will be greater than those of hydropower projects. This means that only 40% to 68% of the planned hydropower installed capacity in Africa is economically feasible.

In addition, it is also necessary to consider that reducing the impact of drought on the energy system requires substantial infrastructure construction. This means that more energy infrastructure than the average demand needs to be built to ensure resistance to extreme drought. Therefore, the entire African continent needs to increase investment in new power plants by 1.8% to 4% every year.

Considering the worst-case scenario brought about by hydropower, such as the impact of climate change and the reduction of renewable energy costs on the expansion of the power system, investment needs to be increased.

01

Hydropower is no longer the solution

At present, hydropower is the main source of renewable power in the African continent, with an installed capacity of about 40 GW and annual power generation of about 150 TWh, accounting for 15% of the total power in the continent. For example, this is enough to meet the annual power consumption of Morocco and Algeria, two countries with a total population of 82.5 million. Hydropower has always been considered as a low-cost source of electricity with a low carbon footprint. But strictly speaking, this is not the case.

Hydropower has the following problems.

Renewable energy sources such as solar energy and wind energy are becoming more and more competitive in terms of cost. These energies can reduce the dependence on hydropower, make the energy structure of countries more diversified, and reduce the impact of building more hydropower dams on the environment.

River basins in Africa support terrestrial and freshwater ecosystems and are hot spots of global biodiversity. Of the 543 major rivers in the world, 156 (29%) are located in Africa. The dam, however, cut off the flow of the river to the river.

In Africa, 26% of the rivers are fragmented, far below the global average of 43%. African rivers are important hubs connecting river habitats. It is estimated that if all planned African hydropower projects are completed, the average fragmentation rate of African rivers may rise to 42%, leading to serious loss of biodiversity.

For example, researchers found that the Renaissance Dam built in Ethiopia will lead to the displacement of 122000 people, release 7 million tons of carbon dioxide, and change the water temperature of the Blue Nile, making it unsuitable for the survival of local animals and plants.

Every time a new dam is built, water will flood the land. Soil and other substances on land (biomass) are decomposed underwater, and this process will release carbon dioxide and methane (a powerful greenhouse gas) to the atmosphere, and these emissions will continue to be released within a few years after the completion of the dam.

At least in the next few decades, hydropower will lead to an increase of nearly 25 million tons of carbon dioxide equivalent every year, seriously hindering the realization of net zero emissions, which is equivalent to the total carbon emissions of 25 million transatlantic round-trip flights.

Hydropower projects are vulnerable to climate change: as drought intensifies and water resources dry up, the availability and cost-effectiveness of hydropower will decline significantly. From the perspective of the whole energy system, the previous research of the Africa Mirror team found that the availability of hydropower, together with the decline in the cost of solar energy and wind energy, means that about 32% to 60% of the proposed hydropower projects are no longer economically competitive. Compared with all proposed hydropower projects, the overall energy system cost of new solar and wind energy renewable systems is lower.

In addition, the team's latest research shows that by deploying more renewable energy, it is possible to reduce the impact of cost competitive hydropower projects on the environment. Under the condition of almost no increase in the guaranteed electricity price (up to 1.4%), the river fragmentation and hydropower carbon emissions can be reduced by at least 50%.

02

The importance of re planning the energy system

At present, energy system planning is mostly based on engineering and economic considerations. However, if the government can comprehensively consider the existing technology, costs and the overall costs of environment and community costs (such as the damage caused to the environment and community by large dams) when planning the new energy system, it will be more cost-effective in general.

The Africa Mirror team believes that the scope of energy system planning must be expanded to take all factors into account. In fact, considering the impact on society and the environment is the key to ensuring a clean and fair energy transition.

This research result is very important because people mistakenly believe that hydropower stations are the cheapest renewable energy, and many long river basins are still planning to build hydropower stations.

In order to achieve the best results in Africa, countries need to strengthen cooperation, which is also conducive to overcoming the problem of uneven distribution of investment costs and potential energy deficits among countries.

Compiled by: Yang Siyi (Ministry of New Energy)

Checked by: Liu Xuan (Ministry of New Energy)

Editor: Yang Siyi (Ministry of New Energy)

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