Ethiopia hosts the A.U. summit on Friday, during which the presidents of Egypt, Sudan, and Ethiopia are expected to discuss the Grand Ethiopian Renaissance Dam under construction. The mega-dam, while notable for being the largest in Africa and Ethiopia’s first self-funded one, is typical of what hydropower has looked like for decades. On the one hand it will provide an enormous amount of electricity (with an expected capacity of 6GW, although that may be exaggerated), but on the other hand the environmental impact will be commensurate with the dam’s size – it will flood almost 650 square miles of forest upriver, displacing 20,000 people.
But hydropower, which has the major advantage of being almost carbon-free renewable energy, doesn’t have to be stuck in this tradeoff. There are viable alternatives to building new mega-dams and wreaking large-scale environmental havoc as a result.
The first option is to take advantage of existing but unused infrastructure. Only 3% of dams in the U.S. are fitted to generate electricity. The rest – numbering over 80,000 — are non-powered dams (NPDs), used for a variety of services including water supply and inland navigation. But because they have already incurred many of the economic and environmental costs, a Department of Energy (DoE) report from 2012 found that adding power “can often be achieved at lower cost, with less risk, and in a shorter timeframe than development requiring new dam construction.” Thus they are tremendous opportunities to boost hydropower with little additional costs.
For reference, the U.S. currently has 101GW of hydropower capacity, generating 7% of the nation’s electricity (more than wind and solar combined). The DoE report concluded that adding power to NPDs has the potential to add up to 12GW of new renewable capacity. A majority of this potential is concentrated in just 100 NPDs, which could contribute approximately 8GW of clean, reliable hydropower; just the top 10 facilities (which are all navigation locks on major rivers and their tributaries) could add up to 3GW of new hydropower. Other countries have similar situations.
The same rationale also applies to upgrading and relicensing existing hydropower dams – at least those which meet environmental standards. (That said, not all dams should be maintained indefinitely; some aging under-used ones that harm water quality or fish migration should be removed, like four on the Klamath river between Oregon and California.)
Another approach uses small-scale hydropower. Rather than dam an entire river (with the resulting flooding, sediment buildup, and harm to aquatic life), these “run-of-the-river” plants use the existing flow of water to power turbines that generate electricity. One particularly effective model uses pipes to divert some water from natural waterfalls, which then passes through turbines along the shore and then back into the river. While it would take many of these to equal a single mega-dam, they are more efficient and have much less of an environmental impact. That includes life-cycle CO2 emissions – for comparison, electricity generated from coal produces 1.4-3.6 lbs/kwh, from natural gas 0.6-2 lbs/kwh, from large-scale hydro 0.06 lbs/kwh (or in tropical locations sometimes over 0.5 lbs/kwh), and from run-of-the-river plants only 0.01-0.03 lbs/kwh.
Small-scale hydropower also has the benefit of being able to supply nearby communities (priced through remote net-metering, a nascent but growing practice) without having to travel long distances through transmission lines. This makes run-of-the-river plants even more attractive for developing countries which lack an extensive national grid but want to provide rural electricity.
And lastly, hydropower can be generated without any rivers or dams at all. The firm Lucid Energy has developed turbines that generate electricity from water flowing through pipes — thus requiring no dams to be built, and delivering long-term savings to municipalities and businesses. The turbines capture energy that would otherwise have been wasted, and pilot installations have shown that there is no disruption to water supply. They don’t depend on the weather, and crucially, they have zero environmental impacts.
Last year Lucid Energy financed the $1.5 million cost of setting up turbines in a main municipal water pipe in Portland, Oregon, which generates enough electricity to power over 100 homes. In a model that can be replicated elsewhere, the firm is now sharing the revenue from the electricity sold to local utility PGE with the city’s water bureau. Other businesses like factories and agricultural enterprises that use huge amounts of water and electricity will find this a natural fit, since they already have the pipes in place. All that’s required is replacing sections of pipe with ones from Lucid Energy that contain turbines, and connecting the external electricity cables to the grid.
This technology could be a game-changer for generating carbon-free renewable electricity all over the world. In fact, since installing its Portland project, Lucid Energy has heard from interested water suppliers all over the world, including in China, Brazil, Canada, and Korea.
Still, we won’t be seeing the end of new mega-dams anytime soon. But from Chile to India and beyond, there is growing awareness and opposition to them, especially when there are better alternatives available. So hopefully the Grand Ethiopian Renaissance Dam will be among the last of its kind. Indeed, in early January Ethiopia’s Ministry of Water, Irrigation, and Electricity announced that about 5,000 sites have already been identified for the development of small and micro-hydropower generation. But the Ministry still intends to construct many new dams (albeit smaller ones) — 105 over the next five years. Hydropower has a rightful place in the world’s renewable energy mix, but new dams aren’t always the best solution.