Ethiopia is in the midst of a major nation-building project, constructing the Grand Ethiopian Renaissance Dam (GERD). Upon completion, GERD will become the largest hydropower plant in Africa, providing much needed electricity for the country’s growing population.
The project dams the Blue Nile, a river which later flows into neighbouring Sudan, where it merges with the White Nile and then flows on to Egypt. Like all rivers that flow across political boundaries, concerns have been raised about the equitable management of the water resources to the benefit of those upstream and down. Too much water dammed upstream in GERD could have negative effects on Egyptian agriculture reliant on river flows, for example. Efforts are ongoing to find a peaceful solution that suits all parties. Recently, suggestions have been made to supplement the dam’s power output with solar and wind to minimise disruption to the river’s users.
A Delicate Balance
Of course, there’s nothing physically stopping the Ethiopian dam from simply holding as much water as is desired and using it as it sees fit. However, farmers downstream don’t tend to appreciate their precious water supply suddenly drying up to keep the lights on across the border. Both Egypt and Sudan also dam some of the river flow for their own hydroelectric dams too. Thus, it’s in their interests that the river continues to flow and flow well. Talks between the countries involved have repeatedly stalled, with no easy solution in sight.
A recent paper published in Nature by researchers from Vrije Universiteit Brussel and KU Leuven, proposes a plan that involves leveraging a combination of resources to maximise the benefit to all parties. The typical operation of a hydropower plant calls for filling up the dam from the river flow in the rainier season, and emptying it in the drier season. Flows are managed to allow production of electricity year-round. Obviously, the more water that is kept in the dam, the more electricity can be generated by letting it flow out later. GERD is big enough that it could dam the river’s entire annual flow if so desired. The action of damming the river alters the natural flow, with the river’s water level depending on how much water is allowed to flow out of the dam rather than following normal rain patterns. In drier years, most of the water could be kept in the dam, heavily reducing flow to countries downstream.
The GERD project intends to generate a great deal of electricity, of course, and thus dam a large amount of the river’s annual flow. However, in Ethiopia, it bears noting that there is a great deal of sunshine and wind, particularly in seasons opposite to those in which Blue Nile flow is the greatest. Thus, solar and wind generation resources could be used in concert with GERD. In the hotter, drier, windier season, solar and wind would provide a lot of electricity, reducing the amount of water required to be dammed for hydropower — water which would then flow on to agricultural users downstream who need it most at this time. Conversely, when the wetter months come through, water is in abundance. With plenty to go around, hydropower production can be stepped up at this time to offset the lower production of wind and solar assets. With more generation from GERD’s hydropower in the rainy season, this keeps the river level high at the expected time as per the natural seasonal variations. This is ideal as existing users — whether agricultural or other hydroelectric dams — have built their operations around this flow regime. Maintaining seasonality is often key to a river’s ecological health, too.
Building On Multiple Approaches
It’s a great example of how multiple sources of renewable energy can be combined to cover off each other’s blind spots. It also offers a tidy solution to the issue of keeping the Blue Nile flowing with regularity for down stream users, potentially making the political issue easier to solve. However, there is no free lunch. The plan requires significant investment in solar and wind assets, totalling around 3 GW of generation capacity in the dry season. It’s not outside the realms of possibility, however — Ethopian plans for many megawatts of renewable energy are already on the table.
There are other possible benefits too. With such a large dam upstream, additional water capture in wetter years could be used to supplement outflows in drier years, smoothing out natural annual variations. This could be of particularly benefit to stabilising agricultural yields that would otherwise be at the mercy of the natural available water supply.
Whether the proposal will be enough to see the three parties come to an agreement is yet to be seen. However, it serves as a great template to work from for hydropower projects looking to make the most out of the power available while minimising negative impacts on river communities. With just a few years left before GERD is fully operational, time is of the essence if the project is to continue smoothly.
I like it – essentially treating the dam as a grid battery has a lot of benefits.
that said, I wonder how much arable land and other benefits would accrue from having essentially a constant flow year round – does planting season matter much at that latitude? How much shoreline would be recovered if the water level stayed the same all year? Stability is generally preferable to variation, tons of nitty gritty factors to consider though
The flow of the Nile system is highly seasonal and the farming in the area has adapted to that fact. The alternative to a dam regulated flow is not a constant Mississippi river like flow, but a seasonal variation between flooded plains and a minor stream running through arid plains.
sure – but is that optimal, or just adaptation to the environment? Disruptions to existing systems aren’t free of course, but if the nile *became* like the mississippi there’s a host of benefits (as well as downsides ofc)
The river banks are fertilized by the floods. When they built the Aswan dams, Egypt could convert fields from seasonal flood irrigation to controlled irrigation, which allows two crops per year, but the loss of sediments from the flooding removed the equivalent of 6,000 tons of potash, 7,000 tons of phosphorus and 17,000 tons of nitrogen every year, which had to be substituted with artificial chemical fertilizers and then some, because they expanded the irrigated area many times over. This production technically consumes more energy than the dam produces, but fertilizers are made out of petroleum, not by electricity.
Didn’t the aswan dam smooth the flooding already
If it’s pretending to be a battery, better not write Duracell on it otherwise it’ll leak and cause a horrendous mess.
Possibly this will work:
https://en.wikipedia.org/wiki/Run-of-the-river_hydroelectricity
Would appear that design is far beyond the beaver they hired.
If they don’t name it Jean-Claude I will personally mount a boycott.
Floating solar panels would reduce evaporation and not use up land area.
Plenty of handy water to occasionally rinse them too, which would mostly return to the pond. The cooler air would possibly make the cells a little more efficient too.
Reducing flooding shouldn’t have any ill effects on a few thousand years of agricultural practices formerly based on said flooding….
The trick is, the flood plains are limited to areas next to the river, whereas artificial irrigation extends into the desert, multiplying the land area they’re able to cultivate.
Did you mean a total of 3 GW with solar and wind? 3 MW is too small.
Fixed!
Uhhh, I think your analysis is fatally flawed. You’re treating water dammed as being consumed. When water is being stored, power is not being generated. Power is generated when the water is released. Hence, the rainy, or storage season is when you need the alternative power source. When it’s dry and you release water for downstream consumption, that’s when the hydropower is generated.
I don’t think it works as you said in this case. There won’t be any solar power when it’s raining.
You let water running turbines while it’s rainy season because otherwise it will overfill. More water enters the pond than the one leaving it for generation.
Then once it stops raining you can let hydropower run for a bit more but once a threshold is met you cut it and by that time solar and wind already picked up.
Jeff is right. Just to clarify, there is indeed an inconsistency in the above article.
It states “In the hotter, drier, windier season, solar and wind would provide a lot of electricity, reducing the amount of water required to be dammed for hydropower — water which would then flow on to agricultural users downstream who need it most at this time”.
This is incorrect. As Jeff notes, to produce hydroelectricity, the water has to be turbined and therefore will end up downstream.
In fact, the idea of the solar-wind-hydro combination is the following.
In the dry season, solar and wind power will provide a lot of electricity, and so there’s no need to release and turbine a lot of water from the hydro dam. Of course the hydro dam won’t be shut down fully, since anyway a minimum guaranteed flow has to go to the downstream countries, but it won’t be running at full throttle. Then when the rainy season starts, e.g. when the sun and wind resources weaken, the hydro dam can be powered up, meaning many more turbines will be active at any moment, turbining much more water that will be released downstream. (That’s no problem, because it’s the season with most water incoming to the reservoir lake anyway.)
Thus, the seasonality of the river will be (to a major extent) preserved – low flow in the dry season, high flow in the wet season. This will limit the effects on downstream dam operation and agriculture. But the dam will add additional benefits. It will (i) *always* ensure a minimum outflow in the dry season, protecting downstream countries from extreme droughts, and (ii) mitigate the differences between dry and wet years, both of which can be detrimental to agriculture.
(In the interest of full disclosure – I am the lead researcher of the scientific study that proposed the solar-wind-hydro combination, see https://www.nature.com/articles/s41560-021-00799-5.)
EU should just fund it and bribe Egypt to go along with it … because currently the most likely future for the dam is getting bombed.
For sure these countries in Africa have gone to war over far less than a little water. It’s always been obvious those at site , up stream and along with those within the borders of the region, care little to nothing about resource management for those down stream and outside of the border. Syria, Lebanon, and Israel are another example of this same situation with a Dam on one of the tributaries of the Jordon River recently noted in the news. The Dead Sea is Dying, due to poor resource management in that region. That Dam there is too small to really be a highly productive Hydro plant but with water being such a scarce commodity as is in the Arid middle east and Palestine exploding as it has, the issue has recently made headlines and is causing real problems. I personally fail to see how any large scale project could be classified as positive industrial development no matter where it is undertaken beyond a short sited gain. Flooding up stream is still going to present the problem of silting up the impoundment within say 30 to 50 years which will only reduce the volume the facility will be able to contain for production of either power or stabilized resource management. Then there is the issue of instability Sudan has been noted for, along with the agriculture industry Egypt must maintain for there own survival. The next thing that comes up is the impact environmentally and ecologically concerning the live of everything living in the river, around it and what depends on water flow along the riverbed. There just isn’t truly any way people can deal with something of this magnitude without causing harm if not destruction. The 3 Rivers Dam in China, which hasn’t had any issue I’m aware of yet, but surely will someday, and when it does, it will affect millions by itself, the Sayano-Shushenskaya turbine failure, Russia largest hydro plant which killed 75, Dam failures in the U.S, Oroville, Calif. which I believe had more than 1 problem within a short time of a year or so, could be off on that and another in Missouri fairly recently, in Brazil, there was so much damage done there when record flooding took out major facilities, Colombia, Laos, India are just some of the places listed on just one internet site I just went to. Within the last 15 years millions of peoples lives have been affected by catastrophic failures of Hydro plants and one dam in Colombia wiped out 131 villages. There is no way a seasonal flood is likely to affect a river bed the way a failure of such a large scale dam construction is, ( not if but when ) it fails and it will. I used to live near a not so small but not large dam with no power plant which was flooded in Jan. 92 when an unusually heavy rain caused by a tropical storm ran through east Tx. the lake level went up nearly 40ft within in a few days and it flooded hundreds if not at least a few thousand square miles of farm land cutting off several small towns and communities around the area, it took some months to get that lake back down to a normal level from what I remember. Several other impoundments in east central Tx. were also overwhelmed from north of Dallas east and west all the way to the coast. Flooding was record level, damaging farm land for most of the year. Many years later, I was in S.D. to witness one of the worst seasons seen around there when the Missouri was overwhelmed and the biggest dam on that river was releasing over XXXs# of acre ft . of overflow a day. I saw how this river AND the Mississippi was flooded that year in northern Minnesota. The affects on the 29 dams on the upper reaches there were horrendous during the 08-09 flooding which cost this country around $6 billion. I go along whole handidly with supplementing Hydro with Solar and Wind power. It seems to me that here in the U.S. we produce around 45% or our power from Hydro and that may be a high figure, and the rest is from Nuclear and coal, less than 20% is from wind and solar but that is changing. I haven’t seen recent figures. The big problem is when a hydro plant goes down it can take years to get it back, putting a huge deficit in production. Solar takes so much space and is only a part time output at best. Industry needs to spend a lot more on research in ways to store power in ways that doesn’t affect the environment like damming up rivers and taking up productive land or turbines that cause problems, and like any other machine they will with out fail, fail. Solar systems catch on fire, turbines catch on fire and or crash to the ground. A turbine rated at 3MGW is no small investment by itself. The answer is not in constructing huge fields of turbines but putting them strategically placed to produce where they can be used efficiently instead of forcing power companies to transmit large amounts of power over long distances with associated line losses. Germany is a shining example of how to do closer to the right way than any place I have seen, and I saw it when I was there.
The article mentions “In the hotter, drier, windier season, solar and wind would provide a lot of electricity, reducing the amount of water required to be dammed for hydropower — water which would then flow on to agricultural users downstream who need it most at this time.”
This is wrong. To produce hydropower, water must be turbined, e.g. it flows downstream *whenever electricity is produced*.
The idea of the proposed solar-wind-hydro strategies is, rather, the following:
More solar and wind in the dry season means less hydropower needed, i.e. less water has to be turbined in the dry season. That means less water has to be stored *in the wet season* (as the article correctly notes, dry-season dispatch is enabled by wet-season storage). This, again, makes sense in combination with solar and wind – those resources weaken in the wet season, so you’d want to turbine lots of water in the wet season to let the dam run “at full throttle”, so to speak, and make up for the solar-wind deficit.
This operation will preserve (to a major extent, albeit not fully) the natural seasonality of the river – low flows in the dry season, high flows in the wet season, a seasonality which agriculture, ecology and dam operation downstream have adapted to.
Of course, the dam will always guarantee a minimum dry-season outflow to downstream countries (it will never fully stop running, even when there’s enormous amounts of sun & wind), and it will mitigate anomalously dry years as it will have some water stored from previous wet years to make up for the difference. So while the seasonal character of the river will be preserved, downstream countries will be better protected against extreme droughts and floods.
(FYI, I am the lead researcher of the team that proposed the solar-wind-hydro idea.)