January 2013

The University of Twente’s Green Energy Initiative wants to give researchers the opportunity to show what they’re working at. This is the fourth of a series of interviews, in which Marion Steenbergen picks out one of the personal stories within UT’s energy research themes.

Researcher:

David Vermaas, PhD student in the Membrane Technology Group (MST, faculty TNW) of Prof. Dr. Ir. Kitty Nijmeijer.

David’s research is a collaboration between the University of Twente and Wetsus, centre for sustainable water technology, located in Leeuwarden (NL).

Place:

Building Meander, room ME 117

Date:

Tuesday 4 December 2012

“I studied Hydrology and Water Quality at Wageningen University with the emphasis on Civil Engineering; I also spent some time at Delft University of Technology. But I got attracted to sustainable energy, combined with water. As a student, I organised an excursion about obtaining sustainable energy from water for my student association and I got more and more interested. Then, I saw this project’s vacancy, I applied and here I am! That’s three years ago. Most of the time, I’m in Leeuwarden, at Wetsus. Researchers on sustainable water technology are clustered there, to make it easier to exchange information and to use each other’s materials.”

In October this year, David got the Marcel Mulder Award of € 5000 (Marcel Mulder was founder of Wetsus and UT professor, see Award for David Vermaas)

I asked him why?

“In that year, I had three publications and a patent. Wetsus stimulates researchers to get patents, as it is sponsored by about 80 companies, that are interested in innovative patents to make money with! Five to seven of those companies sponsor my particular theme. I’m saving the award money, as I would very much like - on the long term - to start a lab for my own, to do experiments…”

2. What are you doing? Where does your research fit in the overall UT research?
“By mixing salt (sea) water with fresh (river) water, energy is generated. That’s because of one of the basic laws of thermodynamics: every system strives for optimal mixing. So, bringing salt and fresh water real close to each other, you get osmosis: the salts will attract the fresh water. Putting a membrane between two columns, a ‘filter’ that is selective for water, the fresh water will be attracted to the salt water, causing a higher level. Energy can be generated by this difference in level.

The other way round, you could put a membrane between that only allows the positive ions from the salt water to get to the fresh water and then that side of the membrane gets a little more + than the other side. This difference in voltage can generate energy. These membranes transport positive charge to one side, and negative charge to the other side. By putting the membranes alternately (positive – negative – positive…) and the columns too (salt water – fresh water – salt water…) the voltage gets higher and higher. With 100 membranes next to each other, you’ll get a 100 times higher voltage. If the flows of salt and fresh water continue, like where a river flows into the sea, this process continues as well.”

David brought two membranes to show me. One is totally smooth, but the other has tiny ridges. By using this one, water can flow through these tiny little canals with less electrical resistance. These have very much improved the results of the process. (By using water pressure, the membranes are staying at the right position.)

High Tech: we’re dealing here with ‘Blue Energy’, actually RED: Reverse Electro Dialysis (as ‘Blue Energy’ normally stands for water power.) RED does not need any feedstock being transported; just a plant at places where river water and sea water meet anyhow. It’s obvious that this technique very well fits in UT’s Route14+ Energy programme.

“We’re working on the Human Touch part of the story by visiting primary schools and get children interested in engineering, showing them the process.”

3. How will society benefit, on the long term?
“This is a relatively new field of research, so there is still a lot to do. There is a pilot plant to be built on the Afsluitdijk. It has been approved and financed. Most important issue is how to avoid that the membranes get polluted, not only by mud, but also by organic acids. We try several environmental friendly approaches to avoid this fouling. We want to keep the process on-going and we want to avoid using chemicals, as we aim to keep it as sustainable as possible. We want to keep on going for at least ten years.
In this process, every cubic meter fresh and salt water contains the same amount of energy as that this same cubic meter would fall down a 150 meters. At the Afsluitdijk, every second, 500 cubic meters flows through. That’s a lot! So we will need a huge amount of membranes. And therefore, we want these membranes to be cheap and of good quality; they’ll have to last a considerable time. Fujifilm aims to produce these membranes in the Netherlands. They use the capacity they used for the old films. The challenge is to make them both cheaper and pollution proof.”

4. With whom do you work together? (other chairs, companies?)
“My background is hydraulics, so I am focussing on how water flows alongside the membranes. My colleague here (Enver Güler, also PhD in MST - red.) is focussing on the chemical composition. We’re working tightly together. In Wageningen, there are two PhD’s working on something similar, using another technology. Furthermore, there is a researcher in Norway, someone in Toledo, U.S.A. And some companies’ R&D departments.
Besides, I visit congresses, but then I notice that there are very few people working on this subject. Anyway, it’s still important to expose my work, to stimulate others to join!
Lots of cities, worldwide, are situated at delta areas, where salt and fresh water meet, so there is a great potential! For example at the Mississippi, in China, and in South Korea.”

5. Will your research be continued after you’ve finished your PhD thesis?
“The companies that are investing will continue anyhow. The pilot project at the Afsluitdijk will last for four years. For this project, it will only generate max. 50 kW (would be enough for 50 households), but if it works, it will be upscaled to 200 MW (a real plant!)
The easiest way to store the energy, is not to use the water. The water in the IJsselmeer can be stored during one month. In winter, there is not much sun, then you can use the energy flow by actually ‘opening the tap’! In this way, it is easy to regulate.”