“This is a highly ambitious project. The technological improvements which we hope to achieve in the collaboration can become a game changer, opening new markets,” says SaltPower CEO Lars Storm Pedersen. When two bodies of water with different salinities are separated by a selectively permeable membrane, a process of water diffusion will begin. This is osmosis. The process is constantly occurring in all living cells. In recent years it has transpired that osmosis can be utilized for energy production. In a world that craves renewable and non-carbon-emitting energy, the market for osmotic power production – or “salt power” if you will – is large.
Salt producers are the first customers
SaltPower already has several commercial projects in the making or under discussion. The first plant will be operational in March 2023 at the Nouryon salt producing plant in Mariager, Denmark. “Salt producing plants are obvious candidates to become our clients, since they have high salinity water readily available. Further, we don’t need to produce electricity for the grid, since production of salt, like so many industrial processes, require energy consumption,” Lars Storm Pedersen explains. Since 300 million tons of salt are produced worldwide annually, this market holds plenty of opportunities for growth for SaltPower. “Salt production mainly in USA and Europe will be our initial market. But not so far further down the line will be hydrogen storage. These storages can be built in underground salt structures, and they also require large amounts of power to be built, and thereby could benefit directly from establishing osmotic power facilities,” the CEO comments, noting that in this context the young company will depend on market developments: “Several nations have announced or are considering programs which will make hydrogen a significant part of their energy supplies. Therefore, we expect many new hydrogen storages to be built in the coming years.”
Differentiating over a set of equations
The main role for DTU Chemical and Biochemical Engineering is development of an improved membrane able to sustain high pressure. The solutions currently marketed by SaltPower operate at a pressure of 70 bars. While this is a high pressure it is still quite a lot lower than the optimal for the purpose, notes Lars Storm Pedersen: “The higher the pressure, the more power can be produced per cubic meter of water through osmosis. However, you do reach a point where a further increment in pressure would be unfeasible since the additional costs begin to outweigh the extra power production. This is a classic engineering problem. When you compose your set of equations and differentiate, you end up with 200 bars as the optimal pressure,” Lars Storm Pedersen explains. So, why does the current solutions operate The power of osmosis Electricity produced by exploiting the difference in potential between saline and non-saline water is becoming a commercially viable green energy source. Danish startup company SaltPower, Danfoss, and DTU Chemical and Biochemical Engineering have teamed up to take the promising technology to the next level. 28 at 70 bars? This is because the underlying technology was originally developed for de-salination. In collaboration with DTU Chemical and Biochemical Engineering and Danfoss, SaltPower strives to develop the first generation of technology specifically with osmotic power production as its purpose. While the DTU researchers cooperate with SaltPower on membranes able to tolerate 200 bars, Danfoss is developing pumps able to supply this level of pressure under the challenging conditions encountered in the relevant industries. Also, Danfoss is engaged in development of novel energy recovery devices for osmotic systems.
Disruptive improvements ahead
A further role for the DTU researchers is contributing to simulations across the osmotic system. “This is not just about developing the individual technologies – pumps, membranes etc. You need to be careful with the details, and especially assure that you are not wasting energy across the system,” Lars Storm Pedersen notes. "Only if we manage to get this right, will we be able to harvest the benefits from operating the system at the optimal 200 bars. We estimate that the current power production per cubic meter of water can be increased by somewhere between 50 and 300 per cent. This will reduce the cost of produced power significantly, representing a disruptive improvement.” “Notably, we are not only concerned with the technological development. As a commercial company, we are always looking at costs. Since we are talking about a technology with a very wide market potential, it will be crucial for us to be able to offer the solutions at competitive prices.”
The “Hi-PreM” project (High Pressure Membranes) project is supported by Innovation Fund Denmark under its Grand Solutions investment program. Participants are Danfoss, DTU Chemical and Biochemical Engineering, and SaltPower. The project will run until 2024.