Researchers at ETHZ and the University of Zürich showed that water can be maintained in a liquid state at temperatures as low as -120 °C by mixing it with phytantriol in a simple thermal process that produces a mesophase. Later, upon an innovative initiative launched by Sirin Orbital Systems AG of Zurich for space applications (water storage system for lunar life support and exploration), a team of researchers at IEFE, IMPE, and ETHZ, showed that up to 79 % wt. of the water in the mesophase can be extracted again by distillation. The remainder presumably forms an azeotope. Phytantriol is a commercially available non-toxic aliphatic alcohol that is widely used in the cosmetics industry.

The fact that the mesophase remains in a liquid-like state, and that repeated mixing and water extraction are possible, can be exploited to design water storage systems for cold regions that do not require active heating of external installations like pipes, tanks, etc. This makes them energetically very efficient and enables easy transport through standard hydraulic networks. Challenges that are usually associated with water storage and supply in cold regions can then be removed or minimized. This includes pipe damage due to freezing, installing pipes in permafrost, or use of (chlorinated) indoor tanks with associated health risks.

If coupled with building-based wastewater recycling units, the technology can be used to design centralized closed-loop water storage and supply systems with (nearly) net zero water consumption for settlements and research stations in cold regions. Small units can potentially be designed portable. This minimizes the need for overland water haulage to storage sites.

A key design objective is to minimize energy consumption. Significant reductions can be achieved by replacing distillation with a more energy efficient extraction process. Candidates include pervaporation and nanofiltration. The latter is expected to be energetically more efficient. Both have been used before to separate other alcohols from water. Their potential to separate water and phytantriol will be evaluated in this project by a team of researchers at IEFE and IMPE. Challenges include the selection of adequate membranes and operating parameters. Performance measures include process efficiency, purity of the extracted water, process speed, system size, and system scalability. We expect to reach TRL4 at the end of this project. A techno-economic assessment will complete the assessments.

The technology holds the potential to revolutionize water supply systems for research stations, and improve water safety, increase water availability, and minimize water waste for settlements in polar regions, who regularly suffer from poor freshwater quality, limited freshwater availability, or indeed run out of water regularly.

The work is financed by the Swiss Polar Institute. This support is gratefully acknowledged. Sirin Orbital Systems continues its involvement in an advisory role.