31 AUG 2019
If all the hydro-power dams in the United States were removed and replaced with solar panels, it would take up a fraction of the land and produce substantially more electricity, according to a new analysis.
The idea is ambitious, and for now, it’s really just a thought experiment. Today, hydropower is a significant source of renewable energy in the US, accounting for roughly six percent of the country’s total electricity output.
Removing all 2,603 hydro dams in America would leave a huge energy void behind, but it could also provide room for greener opportunities.
While it’s true that hydropower dams are a renewable source of energy, they still produce large amounts of greenhouse gases and can be environmentally destructive and costly to maintain in the long term.
In recent years, these criticisms have led to a growing dam removal movement. And although it’s theoretical, a massive investment in solar power might be able to cushion that loss.
To cover for all the hydro dams currently in use, scientists estimate we would need nearly 530,000 hectares of photovoltaics (PV). While this sounds like a lot, it’s a “surprisingly modest” amount compared to the combined size of most reservoirs, which cover nearly 4 million hectares nationwide.
In fact, the new analysis suggests that substitute solar panels could match the total energy output from hydro dams while using just 13 percent of the same land.
“I think that’s pretty astonishing and tantalising too,” John Waldman, an aquatic conservation biologist from the City University of New York, told Carbon Brief.
“I’m hoping this presents a different mindset for people who think about our energy futures.”
The potential land sitting under reservoirs right now is immense, and if only 50 percent of that surface is drained and used for solar panels, it could greatly improve energy efficiency, producing nearly three-and-a-half times the amount of energy hydropower currently generates.
Even in a more conservative hypothetical, where only a quarter of that drained land is used for solar farms, Waldman and his colleagues calculate energy production could increase 1.7 fold.
In some states, this has the potential to free up huge swathes of land for other purposes, including wildlife habitat, recreation, and agriculture. In Florida, for instance, scientists calculated a solar farm the size of New York’s Central Park (341 hectares) could replace 26,520 hectares of the state’s hydro dams.
The new analysis focused on solar power because it is easily scalable, but the authors argue the same logic can also be applied to wind power on a reservoir’s surrounding ridges and hydrokinetic turbines in a newly-flowing river.
“Also, potentially expensive and difficult-to-permit electrical lines that transmitted the hydropower already exist at these locations and could potentially be repurposed to carry electricity from alternative sources,” the authors argue.