Sand dunes by the sea

Energy storage at sea augments grid stability

​To reach the climate goals, society will have to rely more on renewable energy. However, solar and wind power, do not necessarily supply electricity exactly when needed. Now researchers at Chalmers have received EUR 420,000​ from the EU to develop offshore energy storage to stabilize the electricity production.​
Wind-, hydro- and solar power are seen by many as the main methods to produce sustainable electric power. But when it is calm or cloudy, wind and solar power cannot supply enough electricity to the grid. And if there is no prerequisite for controllable hydropower, the risk of electricity shortages increases. To satisfy the need for electricity at any moment, the surplus energy generated under favourable conditions needs to be stored for later occasions.

“With the entire society and our modern lifestyle built around electric power, it is incredibly important to have a stable electricity supply. Our project will develop techniques to stabilize the electricity grid by storing energy in seawater reservoirs. The idea is that seawater is pumped into the reservoirs when there is an excess of electricity and then release it through turbines to ‘get back’ the electricity when there is a deficit”, says Håkan Nilsson, professor in the Department of Fluid Science at the Department of Mechanics and Maritime Sciences.

New technology at sea

The technique of storing water in reservoirs already exists in mountainous areas where there are large differences in altitude. This project aims to develop corresponding technology for flat coastal areas. Since the space is limited in existing coastal regions, an alternative is to build so-called "energy islands" offshore. The offshore plants are required to handle very small altitude differences and to be able to operate with saltwater instead of freshwater.

The project has received EUR 5 million in total and is coordinated by TU Delft. In addition to the Department of Mechanics and Maritime Sciences at Chalmers, another 11 industries and universities in Europe are participating, with broad expertise to meet the goal. The competencies include civil engineering, fluid mechanics, electromechanics, machine design, economy and environment. Chalmers has received EUR 420,000 over 4 years.​

“The role we have at Chalmers is to design and optimize pump turbines for these specific conditions. We will also look at what loads and deformations these are exposed to in different operating cases and change between pumping and running as a turbine. We will also conduct a smaller validation experiment for one of the techniques”, says Håkan Nilsson.

Read more about the project: Augmenting grid stability through Low-head Pumped Hydro Energy Utilization & Storage​

Text: Anders Ryttarson Törneholm​

Published: Fri 17 Jan 2020.