Spin-off: Commercializing large scale energy storage using salt and fresh water

Published on
November 16, 2017

In 2014 former ETE Ph.D. researcher Jan Post founded AquaBattery. The spin-off company aims to commercialize energy storage using just water and salt. It is closely associated with ETE’s research on Blue Energy, where energy is generated by mixing salt and fresh water. After three years, AquaBattery and partners have been successful in generating several substantial grants, and are planning to launch a commercial unit within two years. 

When Post finished his Ph.D. on Blue Energy in 2009, funding to start a pilot plant was lacking. Therefore, he applied his knowledge to desalination research. ‘Desalination is the reverse process of Blue Energy’, Post explains. ‘Removing salt from one solution and placing it in another one costs energy. Mixing these solutions again generates energy; this process is studied in the Blue Energy project. So, you can store energy by desalination. That is the principle of AquaBattery.’ But back in 2010 research was focused on energy generation, not on storage, so the idea of AquaBattery was not further developed.

Energy storage
But with increasing generation of sustainable energy, the attention slowly shifted towards energy storage. When Post founded Aqua Battery in 2014, he had no funding whatsoever. To involve people with the right knowledge in his project he paid them in AquaBattery shares. ‘This way, I have given away more than half of the company’, Post says. ‘But I got a lot of knowledge in return!’ A year ago the young company won the Herman Wijffels innovation prize from the Rabobank in the category Circular Economy, based on their innovative set-up in a garage box. The 20.000 euro gave Post the opportunity to hire the first employee. But things had to become more seriously. Post: ‘We asked ourselves: are we going to continue winning prizes or do we aim for a working product? Hiring personnel was risky, but it was a necessary step: no guts no glory!’

Schematic overview of the principle of Aqua Battery.
Schematic overview of the principle of Aqua Battery.

Minimal viable product
The dedication of the team was rewarded in 2016 by a substantial EU grant. AquaBattery and their partners, Wetsus and Fuji Membranes, got four million euro for a four-year project to further develop their technology.  Two weeks later a second grant, a 580.000 euro project budget, followed for AquaBattery and Blue Energy firm REDstack. Post: ‘This is the start of something great!’ With these two grants, Post and partners aim to develop what they call ‘a minimal viable product’: a table-top aqua battery that works, is well designed and attractive, and can be sold for individual households. At the same time, the team is working on a large-scale pilot plant in The Green Village in Delft, a living laboratory located at the campus of Delft University. Here, innovations on sustainability are developed and tested. Post: ‘Energy from solar panels is stored in our batteries and enables residents to enjoy renewable energy 24 hours a day!

Green Village. Artistic impression of Green Village in Delft. The red circle indicates the container with the pilot plant of AquaBattery.
Green Village. Artistic impression of Green Village in Delft. The red circle indicates the container with the pilot plant of AquaBattery.

Safety and sustainability
The future for AquaBattery lies in the development of much bigger battery units that are placed underground and store energy for residential areas of about 100 to 200 households. Post has calculated that such an underground battery measures just a mere 10x10x3 meter. ‘Using bigger units has the advantage that peak use due to energy-demanding equipment, like a vacuum cleaner, is divided over the whole battery’, says Post. ‘A smaller single household unit is less able to generate such a peak power.’ The advantage of this system is its safety and sustainability: unlike in lithium batteries, there’s no fire or explosion risk, all materials are natural, while the battery has no power loss. ‘AquaBattery will revolutionize the way we store energy and will promote the growth of renewable energy technologies around the globe’, Post concludes.  

Pumping and filtering unit of the Aqua Battery pilot plant