Rik Siebers, director REDstack 'The COL was a welcome and valuable addition'

Rik Siebers, director REDstack 'The COL was a welcome and valuable addition'

REDstack extracts electricity from water and at the same time has a technology that produces drinking water from seawater. The Sneek-based company was ready for a substantial scale-up. Until corona put talks with investors on-hold. Thanks in part to the COL, REDstack still managed to stay on course.

Somewhere halfway along the Afsluitdijk, near Breezanddijk, there has been a striking building, shrouded in different shades of blue, since 2014. Not an architectural masterpiece, more like an industrial hall. It is a pilot plant where tests are being conducted by REDstack on generating energy from water. From the difference in salt concentration between salt and fresh water, to be precise. Blue Energy is called this form of completely CO2-free and sustainable energy. There is a good chance that it will soon supply about 10% of the world's energy demand. Because the test results are definitely favorable. What's more, the company has already developed the technology to the point where it can be scaled up to a large Blue Energy power plant.


Realizing such a power plant and actually bringing the technology to the market requires considerable investment. In the early 2020s, everything pointed to the fact that the necessary funding would be forthcoming. Investors were enthusiastic and, above all, quite concrete; everything was in the starting blocks. Until corona struck and talks were put on-hold for a while. 'That of course had a huge impact on our plans,' says Rik Siebers, director of REDstack. 'Delays in ongoing projects we can deal with, but new projects suddenly fell by the wayside because of the corona crisis. It has been quite tense to get them moving again to some extent, in order to ensure the continuity of the company. Nevertheless, thanks in part to COL, we managed to raise our profile even higher in the market. Besides the money from our shareholder and the NOW-1 and NOW-2, the bridging loan was a welcome and valuable addition for us.

Best imaginable location

REDstack originated in 2005 as a spin-off of water technology institute Wetsus. In the first years, experiments were conducted on a very small scale, on a laboratory scale, on how electricity could be generated with Reverse Electrodialysis, or RED for short. A promising development, it soon turned out. 'But it wasn't until 2012 that things really got serious,' Rik explains. 'That's when we secured funding to build the pilot installation on the Afsluitdijk. The best conceivable location in the Netherlands to test RED technology in practice. On one side of the dike is the salty Wadden Sea and on the other the fresh water of the IJsselmeer. And when these fresh and salt water streams come into contact, energy is released. After two years of construction, the pilot power plant was officially opened by King Willem-Alexander at the end of 2014.'

Membrane stack

But this RED technology, how does it work concretely? 'With this technology, we make use of a characteristic of nature that aims to nullify differences in concentration,' Rik begins his explanation. 'For example, if you open your door on a cold day, the heat goes outside. The temperature difference is then equalized. When you bring salt and fresh water together, the same principle applies. Salt water contains positively and negatively suffered particles. In fresh water, these particles are also present, but at lower concentrations. When the particles can move between two streams of water, they move from the high to the low concentrations, that is, from salt water to fresh water. To influence this natural process, we conduct the salt Wadden Sea water and the fresh water from the IJsselmeer along a stack of very thin membranes, called membranes. This creates a voltage difference that is converted into energy. Such a membrane stack is called a RED stack, from which we took the name of the company.'


In addition to generating energy from water, REDstack also focuses on ElectroDialysis (ED), a technology used to produce fresh water, including drinking water, from salt or brackish water. By applying a voltage difference, again in a stack, salt water is separated into a freshwater stream and a brine stream. In this way, desalination is created. In other words, using ED stacks, you can turn seawater or brackish water into drinking water. 'Again, the results in the laboratory were so successful that we commissioned an ED pilot plant on the Afsluitdijk in early January 2020,' Rik says. 'In the meantime, we have also reached the point where we can scale up with this water treatment technology.'


So REDstack has been ready to storm two markets for some time. But yes, corona. Of course, Rik somewhat saw it coming in those early months of 2020. Hence measures were taken early on. 'Where possible, we started cutting back and did not hire any new staff for a while,' he explains. 'In addition, our designers and engineers suddenly had to work from home. While in our profession interaction during design processes is so important. All in all, this logically affected our plans. In order to stay on track, I applied for and received NOW-1 and NOW-2. However, realizing our plans for 2020 and 2021 required more than just support from the NOW. After another search for opportunities, the COL finally came into the picture.'

Pure Water Group

Together with NOM, REDstack worked hard to meet all the conditions for the bridging loan. An intensive process that demanded the utmost care. 'NOM is rightly critical; after all, the money has to be repaid over time,' Rik emphasizes. 'That confidence turned out to be present with NOM, because shortly after the application the COL was honored. We used the loan in particular to accelerate the ED market. Slowly this is starting to pay off. For example, we have been working closely with Pure Water Group, a renowned manufacturer of water treatment equipment, for some time now. Pure Water Group builds the systems into which we can build our ED stacks, so that we can actively work that market together. The financial opportunities we now have, thanks to the COL, have given that cooperation a big boost. I am also very positive about marketing the RED technology. It can really give a boost to the energy transition. Blue Energy is always available, not dependent on weather conditions, as with sun and wind, and its production is CO2 neutral. Wherever fresh and salt water meet, you can generate energy.'

Check out the website of Redstack Learn more about the COL View NOM's funding options
The impact of investors on your business

In this white paper you will learn:

  • What you have to deal with when you start working with investors
  • Differences and similarities between bank funding, subordinated loan and equity capital
  • In what ways NOM as an investor can help you

    Please note that this whitepaper is only available in Dutch at the moment. We are in the process of translating this whitepaper.
Read white paper