Hydropower, historically a “forgotten” clean energy giant, is making a comeback.
While hydropower is by far the largest renewable in the world and domestically, accounting for about a third of U.S. renewable power generation and 6.3% of total U.S. electricity generation, the H2O renewable rarely makes headlines. Perhaps this is because unlike its solar and wind counterparts, hydro has remained relatively steady in energy output over the last several decades.
All the while, solar and wind jumped off between 2000 and 2010, skyrocketing since, hydropower’s reliable renewable résumé started in the 19th century, propelled to the mainstream in 1965, and has dependably supplied power from water channels since.
Moreover, the newer pumped storage hydropower (PSH) contributes to 93% of grid storage in the country. According to a market report by the Department of Energy, PSH is growing nearly as fast as all other storage technologies combined.
However, hydropower, one of our oldest sources of clean energy, has always had environmental concerns, especially due to dams. As our biodiversity crisis worsens, and an emphasis is placed on ensuring renewables themselves are sustainable, hydropower is getting a makeover.
With a recent $28 million funding contribution from the U.S. Department of Energy, the current administration is making sure they are a part of the hydro-resurrection.
This $28 million is a part of a larger $25 billion fund for novel cleantech that’s not yet commercially-viable, but may be vital to the U.S. clean energy revolution.
Many projections, including that of the International Energy Agency (IEA) and the International Renewable Energy Agency (IRENA), prophesize a near-doubling of hydroelectric power to reach our 1.5°C climate target.
However, doubling the existing hydropower infrastructure would result in damming about half of the existing free-flowing global rivers.
At present, only a third of the world’s 246 longest rivers are free-flowing. Keeping a river free is crucial to animal habitats.
The World Wildlife Foundation describes free-flowing rivers as the freshwater equivalent of wilderness areas. As more rivers are poorly dammed, changes in river flow and connectivity can result in habitat disruption for birds, fish, and other wildlife, augmenting the biodiversity crisis.
In addition to wildlife disruption, if built in the wrong places, hydropower dams carry a number of other social and environmental concerns. As explained by MIT Climate, poorly planned hydropower can also cause more problems for the climate than it prevents. Aside from reducing river flows, it can raise the water temperature, degrade water quality, and cause sediment to build up.
Traditional hydropower needs dams, tunnels, pipelines, canals, and other necessary infrastructure for installation and operation. While hydropower has a relatively low cost compared to other energy sources (renewable and fossil-fuel based), the cost could come in other environmental and social forms.
Still, it’s an immediate source of grid power, essential to storing renewable energy, and a flexible and reliable backup power source for electricity outages or disruptions.
Aside from the habitat and biodiversity concerns, the decades-long drought in the western U.S. is resurrecting long-held worries over the feasibility of building new hydropower plants. As Bloomberg puts it, “The world’s biggest source of clean energy Is evaporating fast.” From Germany to China to California, climate-fueled heatwaves and droughts are shrinking the giant rivers hydropower plants rely on.
Thus, more than half of the administration's new hydropower funding is targeting sustainable hydro efforts, whether it be innovation in PSH tech, sustainable hydropower-related research and development, and retrofitting existing dams for hydropower.
According to the new DOE report, utilizing existing ditches, pipelines, and canals could bolster local hydroelectricity supplies.
A report released this month by the Oak Ridge National Laboratory agrees. The benefits of powering up unproductive dams are axiomatic: they include minimal new construction and leverage existing water conveyances, which minimizes many of the detriments associated with traditional dams.
What’s less obvious is how much these retrofitted dams and infrastructure can power in the future.
By mapping the power generation potential of national dam retrofits, the authors posit that these small-scale projects could generate as much as 1.4 gigawatts. This builds onto the 588 megawatts generated by the 36 dams retrofitted between 2000 and 2021.
That doesn’t sound like a lot, but individual developments can make a big difference in local communities.
“Something that is less than 1 megawatt — in a rural system, it can be used to offset existing energy from a non-renewable source,” study author Shih-Chieh Kao told E&E News. Kao is the group leader of the water resource science and engineering group at Oak Ridge. “We believe it is the low-hanging fruit for generating hydropower.”
If snatched and deployed quickly, this “low-hanging fruit” carries little overhead. Unlike new dams or turbines that invade natural waterways, these conduit projects have little environmental impact. Plus, they don’t have to jump through the hoops of the federal permitting process, desperately in need of reform.
According to E&E, these conduit hydro projects can be placed on constructed water conveyances, nestled in anything from an irrigation canal to pipes in municipal water and wastewater stations. The small generators can even be housed in the pipes that carry cooling water in and out of fossil fuel power stations.
According to the Oak Ridge study, this model can nearly triple existing generation, with the largest potential in the agricultural sector, as well as industrial sites such as cooling pipes from thermal power plants.
Locationally, the most potential is clustered in the Northeast and Southeast, and some on the West coast. Despite the region’s droughts, there’s sizable potential in Colorado and California due to the mountainous terrains. According to Kao, these slopes create the ideal conditions for pressure. The Golden State and Centennial state harbor 243 megawatts and 204 megawatts of potential alone.
For conventional generators, such as a coal plant, a megawatt of capacity will produce electricity that equates to about the same amount of electricity consumed by 400 to 900 homes in a year. Thus, with small-scale hydro systems in existing natural infrastructure and old plants, projections on the short-end estimate they can power at least 81,600 to 97,200 homes in Colorado and California respectively.
Conduit hydropower does not use additional water, meaning there is less drought concern than if states in the West were to build new hydro plants. Instead, conduit modernizes old systems to make them more integrated.
Some startups are already on the cusp of retrofitting hydropower. As of 2020, out of the 90,000 dams in the U.S., only about 2.5% generate hydropower. But that could change.
Dutch startup BladeRunner Energy is aiming to provide small-scale hydropower, with an emphasis on energy equality, sustainable power generation, and accountability for environmental impact.
Reportedly, Bladerunner’s technology harnesses energy from the natural flow of water without needing to build a dam. This is achieved by employing a proprietary rotor inspired by the natural movement of water. The small size, the company says, results in an “energy when you need it” system.
The Boston-based company, Rye Development is retrofitting dams for the same efficiency and environmental impact, targeting dams in Pennsylvania to support fish migration and the recreation of river systems. So is Emrgy, which is planning on setting up these low-impact small-scale hydropower installations along the canals that bring water to the agricultural regions of the Mountain and Pacific West.
Specifically, their mimicry comes in the form of doppelganger structures that act as natural features like log jams, beaver dams, and rock arches. In addition to developing new projects, Natal retrofits older plants and non-powered dams with these mime structures to promote river restoration.
Their current project, Restoration Hydro, aims to revitalize degraded watersheds – like those disconnected from floodplains – by removing existing dams, and coupling them with those nature-based structures and fish-safe turbines. According to the company, in 20 years' time, the process will be able to elevate the water table, which studies suggest can help alleviate the effects of drought on crop yields.
A conceptual case study performed with Natal and researchers across the industry – including those in Oak Ridge – shows that the conceptual dam removal project could reconnect 137 miles of upstream habitat for migratory fish like eel, shad, striped bass, and river herring while improving sediment transport.
In addition to biodiversity gains, there are also strong efficiency benefits. A 2012 national study by the DOE found that developing the 100 largest opportunities on non-powered dams in the U.S. could add 8 gigawatts of hydropower capacity. A similar trend is seen around the world. When the average age for a hydropower dam in the states is 70 years, the researchers suggest there will be a consistent demand for modernization.
Like the ditches, canals, and pipelines the DOE identified for hydro retrofits, in 2019, a research team from the Australian National University took the idea globally. The team identified 530,000 locations across the globe with the ideal topographic conditions to support pumped storage hydrogen or PSH battery systems.
Similar to the generators described in the DOE report, in a PSH system, the upper reservoir functions as a storage battery, and, when power is needed, it can release water back downhill to generate electricity.
According to the team at Australian National, less than 1% of identified sites are needed to provide sufficient storage to support renewable-dominated grids across the globe. These projects can be built in existing reservoirs and abandoned mining pits.
Houston-based Quidnet Energy is taking this approach underground.
By taking the reservoir underground, Quidnet’s hydro storage pumps funnel water down into the Earth to fill up cracks in-between rocks that previously held fossil fuels. This long-duration approach stores the energy in the compression of the rocks, allowing it to perform like a natural spring.
The Texas company is currently working on pilot projects in Ohio, New York, and Alberta, Canada, and recently announced a 15-year commercial agreement in its home state.
Hydropower is undergoing a resurgence. Whether it be retrofitting existing hydroplants and dams, taking the operation underground, in mines, and in abandoned ditches and canals, or foregoing the dam structure altogether, sustainable hydropower is the only way to scale the all-essential renewable.