Hydropower is a much under-rated source of electricity, given that 35 countries in the world get over 50% of their power from damming rivers. It is also growing extremely rapidly.

According to the International Hydropower Association (IHA), capacity grew by 26 GW in 2021, reaching 1,360 GW and producing 4,250 TWh, which is roughly one and a half times all the electricity used in the European Union. The speed at which countries have been building hydropower capacity worldwide is illustrated by the fact that global capacity has more than doubled since 2000.

One problem with this is that it is not enough. According to the doomsters of the International Energy Agency (IEA) it is far too low. In their assessment, the world needs to increase its capacity by at least 45 GW a year if it is to reach net zero carbon by 2050. A secondary issue would appear to be that 80% of the new additional capacity recently added was in China, where it less than counteracts their equally impressive new coal-fired capacity, which is set to expand by 28 GW by 2025. What is also clear is that straight run hydropower has to be matched by large amounts of additional pump-storage capacity to balance future grids dominated by wind and solar

It is also the case that large-scale hydro capacity takes a long time to build, or at least as long as large nuclear plant. Furthermore, it may require international agreements on water flow. What is also apparent is that it may be subject to significant increases or decreases as a direct effect of the climate change it is hoped to mitigate. One University of Cincinnati study put this down to the depletion of glaziers, the reduction in snow melt, the increase of precipitation of rain and increased water evaporation. Frankly, a study of the scientific literature reaches no obvious conclusion, but some of the history is not encouraging.

This is particularly true of hydropower in Africa, which given that the Congo, Ethiopia, Malawi, Mozambique, Namibia and Zambia all get 90% of their electricity by this means, is particularly concerning. While it is true that the Congo, Zambezi and the Nile may well have the room for more, what is apparent is that the river flows appear to be becoming much more variable.

To take Zambia, which shares the power with Zimbabwe, the Kariba dam had to use its spillways in February 2008 to prevent the dam being damaged by too much water. This flooded substantial areas downstream. Seven years later, the supply of power to the copper industry had to be cut due to a drought in 2015, which was followed in December 2022 with a reduction of power to Zimbabwe for the same reason. One of the obvious complexities of this fluctuation is that it takes some years of a regular and steady flow of rain to raise the level of the reservoirs after a drought. Flash flooding is not helpful.

It should be noted that out of Africa’s total population of 1,420 billion people, some 600 million have no access to electricity at all. The localised source of electricity is invariably small diesel generators in the case of hydropower disruption, in spite of the fact that Africa has at least 60% of the world’s potential solar power. Given the ever-increasing requirement for electricity in modern communications, localised renewable electricity is vital for the continent’s development. In any case just think for moment on what the addition of 600 million people, using fossil fuel energy at the rate of the US, China and Europe, would do for the planet!

That aside, the IEA did a sobering report on the likely impact of climate change on African hydropower in 2020. Their conclusions are that it is likely to decline in central and southern Africa and on the north shore and in the west. The only areas likely to see an increase in hydropower output from existing dams are on the Nile in the north. The Agency points out a number of physical things that can be done to counteract the effects of greater and more irregular precipitation. These include better flood controls, strengthening and raising electricity despatch points and more upstream hydro dams to control the flow. They also add, as if it was necessary, that these countries do not have much money.

What is particularly ironic about Africa’s reliance on hydropower for electricity is that Africa as a whole only has around 9% of global freshwater. The fact that it has some of the world’s mightiest rivers makes it particular vulnerable to rapidly increased precipitation. In March 2019 tropical cyclone Idai pretty much trashed the economies and hydropower of Mozambique, Malawi, Madagascar and Zimbabwe, killing at least 1,600 people and causing immense flooding and a cholera outbreak. If cyclones of such power are to become regular events, then Africa’s reliance on its rivers for electricity is likely to be increasingly difficult, not least because big sources of electricity require large wire connections to the areas of demand. These are, to say the least, equally vulnerable to storms.

Needless to say, Africa is not alone in such problems. Venezuela has had difficult time, suffering major blackouts in 2010, 2016 and most recently in 2019. Its major source of power is the Guri dam on the Caroni River in Orinoco. The third largest in the world, this was completed in 1986 with a capacity of 10,200 MW. Quite why, in an era before climate change was on the map, Venezuela, a major oil producer, decided to put all its electricity eggs into this basket remains unknown, but its reliance on this single source for 75% of its power has been nothing but trouble ever since.

Or rather, it worked remarkably well until the “Bolivarian Revolution” under Hugo Chavez arrived in 1999, when under nationalisation of the private sector, anybody with any technical expertise attempted to flee the country; a process that has continued ever since. The result was a chronic lack of basic maintenance, not to mention electricians. In the case of the 2019 blackouts, the initial problem was fires around very long power lines, which shorted. Every attempt to bring the turbines back on line brought further failures and explosions, some even in sub-stations miles away. The net result was blackouts in Caracas and chronic shortages of power elsewhere, starting on 7^th March and lasting most of the month, which ended with power rationing thereafter.

Indeed, the Venezuelan power collapse of 2019 was almost a caricature of what can happen to a country when its power grid goes down. Looters hit the streets in Caracas, hospitals and schools closed down, water supplies failed, lack of refrigeration destroyed food. Even the refineries, which could have supplied alternative fuel for generators, ceased to function, as did the internet. Bank card transactions failed too, leading to a chronic shortage of cash. Predictably, the government of Nicolas Maduro blamed his political rival, Juan Guaido, arrested a lot of workers and it was suggested that the US had deliberately destroyed the grid with some sort of nuclear-powered electromagnetic wave. Needless to say, power outages remain a significant problem in Venezuela to this day.

By contrast, Brazil, which has also had its drought problems and a 66% dependency on hydropower, is shifting away from it into other renewables. Its Ten-Year Plan of 2020 emphasised wind, of which the country already had 17,198 MW, with an additional 1,063 MW coming from ENEL’s Lagos dos Ventos with 230 turbines in 2021. It remains the largest in South America. Around 8% of its electricity now comes from biomass, while it is completing the third of its Angra nuclear reactors. What is particularly significant about Brazil, compared with Venezuela, is the country’s emphasis on localised solar. In late 2022, it was estimated that Brazil had 16 GW of solar capacity, but this has to be an estimate not least because it is being installed in the poorer favelas and countryside in small, penny pieces. There is still potential new hydropower capacity in the northern Amazon, but Brazil’s technical leadership seems to have realised that power generated miles away from demand may well be subjected to unpleasant surprises as the climate changes.

The international political issues relating to hydropower have to be mentioned. Turkey is one of the main sources of argument here, with over 700 hydroelectric facilities, currently providing around 17% of its power. The largest of these – the Ataturk dam – is at 2,500 MW, with additional capacity nearby, one of the largest in the world, but the country uses both the Euphrates and the Tigris, which clearly creates issues for the countries in the south. After the recent earthquakes, there was concern that the Ataturk might have been cracked by seismic activity, but this proved wrong. What did happen was flooding in Syria as a result of their own dams being damaged, but this was put down to a lack of maintenance due to the war. What does remains as a matter for concern is the potential impact of seismic movement and the fear that very large volumes of water may create it due to its weight.

Turkey continues to build dams, the latest being at Ilisu with 558 MW pf capacity on the Coruh river flowing into Georgia. It says a lot about the Turkish Government’s obsession with dams that it has built eight on the Coruh already with plans a further 17 and ten more in the catchment area. Given that the World Wildlife Fund for Nature regards the river as one of the finest areas of biodiversity remaining in the world, this is not necessarily good news. What is undoubtedly true is that big dams seriously affect fish. Most western companies have pulled out as a result.

Another controversial dam project is the Grand Ethiopian Renaissance Dam, known as GERD, which has been the discussed in the UN, following Egyptian and Sudanese objections. This 6,500 MW project on the Blue Nile, around 45 km from the Sudanese border, is now 90% complete, having taken 21 years to build for $4 billion. It will have a lake, containing 74 cubic kilometres of water, which is expected to take five years to actually fill. Experts fear that 1.4 cubic kilometres will evaporate every year. Naturally enough, the Egyptian Government is concerned that it may well affect its own Aswan dam. Attempts at a joint agreement on water flows have yet to be agreed, hence the UN talks. What is also alleged is that even when the lake is full, there is too much power capacity to be actually run. That said, 60% of Ethiopians have no access to the grid.

The need for hydropower on such a scale should remain controversial, not least because many grid systems are moving away from distance grids as electricity supplies become more localised and variable due to solar and wind power. In this regard, hydropower undoubtedly has a major role to play, not least in balancing localised grids. In this regard, requiring as it does some assessment of the likely daily shifts in output from wind and solar, governments seem mighty slow to think ahead. Such hydropower “batteries” take years to build, but without them wind power in particular is wasted.

The European Union is well aware of this. In 2022, the European Energy Technology Observatory published a report saying that EU hydropower output varied as a result of changing weather by 80 TWh a year, while averaging around 355 TWh/yr. in the past decade. This is a substantial amount and can be mitigated by more integration in the European grid itself, particularly with Norway’s substantial hydro-capacity, through subsea links to Germany and the UK. They also noted and approved the sudden recognition after 2000, that far more pump storage capacity was needed and was being built. By 2010, 2,443 MW of such capacity had been added, but this has risen by 11,562 MW in the following decade, with new capacity and the upgrading of older plant. Significantly, it was noted that that both control systems and generators had greatly increased the efficiency of such plants since the 1970s when most were built.

In this regard, the British Government has been a little slow on the uptake. In spite of the fact that the British system lost 3.6 TWh of wind power in 2020 because there was nowhere to store it, it has been rather slow in working out how the reward system for storage can be calculated. The UK has not built any long-term electricity storage for over 40 years and in spite of the fact that the energy research group Aurora says that 24 GW will be needed to move toward net zero, very little is actually being done. Drax, to take one example, has had a plan to build a second pump storage plant in the mountain at Cruchan in Scotland for 600 MW and has been hanging around waiting permission for the past two years. Although it is a manifestly good idea, it seems as if Whitehall is too busy creating more wind farms offshore than to notice their effects on the grid. Mind you, this could be because they are still looking for those elusive economic advantages of Brexit.