How Underwater Concrete Spheres are Transforming Solar Energy Storage

Brief

Innovative underwater concrete spheres utilise ocean pressure to store solar energy, offering a sustainable solution to energy storage challenges.

Insight

The quest for sustainable and efficient energy storage solutions has led to groundbreaking innovations beneath the ocean’s surface. A pioneering approach involves the use of massive underwater concrete spheres to store solar energy, addressing the intermittent nature of renewable sources and the limitations of land-based storage systems.

These hollow concrete spheres, each approximately 9 metres in diameter and weighing around 400 tonnes, are anchored at depths ranging from 600 to 800 metres.

The concept, developed by Germany’s Fraunhofer Institute under the StEnSea (Stored Energy at Sea) project, leverages the immense pressure found at these depths to store and release energy efficiently. When surplus solar energy is available, it powers pumps that expel water from the spheres, creating a vacuum.

To retrieve the stored energy, valves are opened, allowing seawater to rush back in, driving turbines that generate electricity.

Initial tests in Lake Constance have demonstrated the viability of this method, leading to plans for a full-scale prototype off the coast of Long Beach, California, by 2026. This prototype aims to generate 0.5 megawatts of power with a storage capacity of 0.4 megawatt-hours, sufficient to supply an average household for approximately two weeks.

The potential of this technology is substantial. Estimates suggest a global storage capacity of up to 817,000 gigawatt-hours, enough to power 75 million homes across Germany, France, and the UK for a year. Moreover, the cost-effectiveness is notable, with storage costs projected at around 5.1 cents per kilowatt-hour and investment costs at $177 per kilowatt-hour of capacity.

Beyond the impressive technical specifications, the environmental benefits are significant. Unlike traditional storage solutions, these underwater spheres do not occupy valuable land space and have minimal impact on marine ecosystems. Their deployment could revolutionise the way we store solar energy, making it more reliable and accessible.

In conclusion, the answer to the question, “Can solar energy be stored underwater?” is a resounding yes. Through innovative engineering and utilisation of natural oceanic pressure, underwater concrete spheres present a promising and sustainable avenue for energy storage, aligning with global efforts to transition towards cleaner energy sources.

Highlights

These hollow concrete spheres, each approximately 9 metres in diameter and weighing around 400 tonnes, are anchored at depths ranging from 600 to 800 metres.
When surplus solar energy is available, it powers pumps that expel water from the spheres, creating a vacuum. To retrieve the stored energy, valves are opened, allowing seawater to rush back in, driving turbines that generate electricity.
he potential of this technology is substantial. Estimates suggest a global storage capacity of up to 817,000 gigawatt-hours, enough to power 75 million homes across Germany, France, and the UK for a year.
Moreover, the cost-effectiveness is notable, with storage costs projected at around 5.1 cents per kilowatt-hour and investment costs at $177 per kilowatt-hour of capacity.