CES: ocean battery, proposes solution to renewable energy dilemma

A wind turbine standing still on a calm day or spinning fast when demand is already covered poses a problem for renewables and is one that researchers believe can be solved under the sea.

The idea is that offshore wind farms could use seawater to store energy until needed, helping humanity move away from fossil fuels.

“We have come up with a solution we call the Ocean Stack,” Frits Bliek, CEO of the German company Ocean Grazer, demonstrating the system at the CES technology fair in Las Vegas.

Amid increasing pressure to abandon the use of energy sources that cause climate change, such as coal, it is essential to accumulate green energy, experts say, since nature does not always allow to take advantage of the force of the wind or the light of the sun at the time when electricity is most in demand.

Bliek’s “Ocean Stack” is based on huge flexible bladders on the seabed, which the wind farm fills with seawater.

When there is a demand for energy, the pressure of the ocean squeezes the water through a system on the seabed, which includes turbines, and the result is electricity.

A key consideration with energy is its cost, and storage systems that involve certain types of batteries are not only very expensive but also carry the risk of leakage or contamination of the marine environment.

Pressure-based systems are already used in hydroelectric dams that pump water into reservoirs behind the reservoir when power demand drops, effectively storing it to return through the complex’s turbines.

This technology, dubbed “pumped hydropower” in Italy and Switzerland in the 1890s, can be found today in dams around the world.

Ocean Grazer is not the only company working on the underwater version of this type of storage solution.

Get rid of fossil fuels

FLASC, a company born out of the University of Malta, has a system that uses clean electricity to pump water into a chamber that contains air at low pressure and that can turn a hydraulic turbine to generate power.

Another initiative called StEnSea (Energy Stored Under the Sea) uses hollow concrete spheres under pressure from the deep ocean, and was tested in a German lake in 2016.

Ocean Grazer’s Bliek explained that underwater systems take advantage of the free pressure that exists under the ocean, creating a system with an 80% efficiency in energy storage.

The manager sees storage systems as key in renewable energies, which have skyrocketed as the price to produce such energy has dropped and has made it an increasingly important part of the combined energy supply in the world.

Renewable energies are the fastest growing in the United States. From 2010 to 2020 they increased 42%, according to the Center for Climate and Energy Solutions, a nonprofit organization.

However, the deployment of systems such as the ocean stack at the scale necessary to function as part of a power grid is still years away.

Bliek says his company aims to have an offshore system by 2025, although in 2023 it will build one onshore in the north of the Netherlands.

Various aspects of pressure energy storage are not new, but combining them with clean energy sources represents enormous potential.

“Now that solar and wind energy become part of the grid – basically this allows us to get rid of fossil fuels – in this context this is very exciting,” says Claudio Cañizares, professor of renewable engineering at the University of Waterloo , in Canada.