Our Hills Are About to Become Giant Batteries

A solution to the uphill battle to meet the world’s energy needs

Photo: Waranont (Joe)/Unsplash

The world is facing a stored energy shortage. According to the International Energy Agency, the world needs to produce 10,000 gigawatt-hours of batteries and other forms of energy storage by 2040 — that’s a 50-fold increase on today’s current output — or risk being unable to capture much of the energy produced by renewable sources. Stored energy is critical during shortages, like those caused by natural disasters.

For over a hundred years, hydroelectric dams provided much of this stored energy — energy captured at one time and stored in the grid to be used at a later point. There are hundreds of thousands of dams worldwide, with over 80,000 in the United States alone. The problem is that most are not used to produce energy, and they cause a whole host of environmental issues: They disrupt river ecosystems, cause mass displacement and flooding when they burst or break, lower oxygen levels in the water, and use a disproportionately large area of land compared to the energy they produce. Furthermore, there are very few suitable locations left to build new ones.

It’s clear that dams can no longer be the solution to our increasing energy demands. RheEnergise, a London-based startup, is proposing an alternative: a low-cost, energy-efficient, and environmentally friendly energy storage system it’s calling “High-Density Hydro.”

Based on the premise that “most potential sites have been used up, and most people consider pumped hydro a dead end,” the company has designed a solution that doesn’t need masses of land. Instead, its system can be built into hillsides.

High-Density Hydro functions similarly to hydroelectric plants, which generate energy from water as it flows from a dam through turbines. When electricity prices are low (low demand), the system uses surplus power to pump a special type of liquid uphill to storage tanks buried at the top. When prices are higher (high demand), it releases the liquid back down the hill through turbines to generate electricity and supply power to the grid. In short, the startup is looking to turn hills into giant energy batteries; a rechargeable store of energy that the power grid can tap into when it’s experiencing shortages.

Source: The Guardian/RheEnergise

The system offers several advantages to hydroelectric plants. It’s smaller than a dam or hydroelectric plant, meaning the construction costs and build time are lower. Construction is estimated to take between one and two years, compared to five to 10 years for traditional plants. It can be built beneath ground level, which frees up land for other renewable energy sources like solar and wind and allows the projects to stay entirely hidden, protecting the surrounding landscapes. It further protects the environment by working as a closed-loop system, meaning it doesn’t require an existing waterway or water source from the area it’s built into.

The secret to the company’s system is that it does not use water at all. Instead, it uses a proprietary fluid called HD R-19, which is 2.5 times as dense as water. This allows the smaller system to generate the same power as its bigger alternatives and function on hills with lower inclines than water projects, increasing potential site locations.

According to the company’s website, mapping data shows there are around 9,500 U.K. site opportunities, 80,000 in Europe, and 160,000 in Africa. Unlike pumped hydro storage and hydroelectric dams, High-Density Hydro is scalable and can meet the global demand for growth. RheEnergise believes the system can be built nearly anywhere globally, even in the 75% of the world too short of water to install traditional pumped hydro. The systems have a predicted life of over 60 years — similar to hydroelectric dams — making them highly favorable compared to other renewable energy storage technologies such as wind and solar, which have a shorter life span of 25–30 years.

RheEnergise admits that this won’t be as simple as digging up every hillside and installing a High-Density Hydro system, noting that “not every hillside location will be suitable.” Each site will need a lengthy planning and analysis process and require approval. Questions linger over the environmental impact of these systems on surrounding ecosystems, though the company says its fluid is environmentally benign, noncorrosive, inert, and safe and would “have no more impact than being an additional thin layer of clay,” if an unexpected leak occurred. And with the one- to two-year lead time per system, the company has its work cut out to install enough to help meet demand — and beat the competition. The company is not alone in developing gravity-based energy storage: Switzerland-based Energy Vault is designing a system that lifts bricks into towers and lowers the bricks back down to create new storable renewable energy. The concept was one of Fast Company’s 2019 World Changing Ideas Awards winners.

With the energy storage market expected to be worth over $640 billion by 2050, according to BloombergNEF, investment opportunities are abundant. RheEnergise company has already received £550,000 ($760,000) in grants from the U.K. government and exceeded its £100,000 funding target on CrowdCube by 740%. It hopes to have its first system operational by 2024 — beginning with smaller-scale projects at disused mines and quarries — with over 100 further systems working within the next decade.

The challenge of meeting the ever-increasing demand for energy while simultaneously minimizing the effects on the environment is an uphill battle. But with innovation and out-of-the-box thinking, there is cause for optimism.

Editor in Chief of Post-Grad Survival Guide • Columnist in Marker • Words in Forge, Debugger & more • Lets connect on LinkedIn: bit.ly/3i8wFBd

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store