Liquid water for polar regions with Swiss innovation
It may sound paradoxical, but water supply is a problem in polar regions, the worlds of ice and snow. Due to the low temperatures, residents of polar stations and Arctic communities must maintain a cost- and energy-intensive infrastructure to keep water flowing. Two research teams at the Zurich University of Applied Sciences are now developing a method to solve this problem in the future.
The proposed architectural concept is actually very simple: Water is mixed with a commercially available lipid (Phytantriol), which lowers the freezing point to as low as -120°C. The mixture forms a mesophase, which behaves like a liquid. The mesophase can be pumped, stored and transported in hydraulic networks even in very cold regions without the need to heat tanks or pipes. Water can be extracted from the mesophase by simple distillation. The lipid is then moved to a storage tank for further use, while the water vapor is liquefied by cooling and used directly in the building. After use, the water can be cleaned in a recycling unit and recombined with the stored Phytantriol to form a closed-loop water storage and supply system. This principle was developed and investigated by two research teams from the Zurich University of Applied Sciences in close collaboration with Prof. Dr. Raffaele Mezzenga and Dr. Yang Yao from the Laboratory of Food and Soft Materials at ETHZ, and the Zürich-based company Sirin Orbital Systems AG specialized in innovative space technologies. The results were published in the Journal of Aerospace Engineering.
Core elements of the proposal were conceptualized and tested for feasibility by Dr. Marius Banica from the Institute of Energy Systems and Fluid-Engineering IEFE and Jan Inauen from the Institute of Materials and Process Engineering IMPE. “We were originally asked by Sirin Orbital Systems AG to develop a mesophase-based concept for the water supply of a manned lunar station for a European Space Agency (ESA) space project,” Dr. Banica explains to PolarJournal. “Water should be stored and transported there using as little energy as possible and at low cost, which is made difficult by the low temperatures”, adds Jan Inauen.
Both institutes are part of the Zurich University of Applied Sciences in Switzerland, where around 14,000 students and around 3,600 employees offer teaching, research and development as well as services in collaboration with industry. The IEFE, headed by Prof. Dr. Frank Tillenkamp, for example, works on the development of systems to generate, store, and transport renewable energies, and on designing energy-efficient systems. Methods from electrical and mechanical engineering are used to achieve this. A separate research team is dedicated to refrigeration technology. The approximately 50 employees of the IMPE, which is headed by Dr. Rene Radis, work on materials and process technologies. They conduct research in the fields of high-performance materials, modern processing and joining technologies, innovative surface technologies and sustainable process engineering.
The ZHAW researchers based their method on two earlier papers published by Prof. Dr. Mezzenga and his team at ETHZ, and researchers at the University of Zurich. In their work, they first discovered that water can be maintained in the liquid state down to extremely low temperatures if mixed with a suitably designed lipid, due to soft nanoconfinement effects and later extended the concept of mixing water with Phytantriol, a commonly available aliphatic alcohol, to maintain the liquid state at temperatures far below the freezing point. For example, Mezzenga group showed how this cryogenic nanoconfined water can be used to run enzymatic reactions below the freezing point, something it cannot be achieved in simple bulk water.
This is the scientific basis upon which Dr. Banica and Jan Inauen developed further application scenarios for this technology and, in the process, discovered that the water can be easily removed from the mesophase by distillation. The water vapor produced in the process is liquefied by cooling it in a simple tube, while the gelatinous Phytantriol can be completely recovered. “Phytantriol is perfect for this because the substance is non-toxic, non-volatile, non-corrosive and, above all, has low flammability,” says Jan Inauen. “It is also very easy and inexpensive to obtain and only needs to be transported to the plant once. We believe that it can then be used as often as required.”
Key components of the architecture were tested on a small scale and with relatively little effort on the premises of the two institutes. The two research teams were also able to estimate the potential energy requirements. For example, the life support system for a 10-person crew on a lunar station would require less than 41 kW to circulate the mixture between the external tanks and the facilities. Further improvements to the architecture, for example by using heat exchangers and utilizing residual heat for heating purposes, could further reduce this energy requirement. “Our method is not very energy-intensive,” says Dr. Banica. “Solar and/or wind power would suffice to operate it.” Compared to the energy required to heat water pipes that come from tanks and water sources, the total energy input of around 50 kW is therefore negligible and gives the method a high degree of sustainability.
Sustainability is also ensured by post-use water purification in water treatment plants and its subsequent reuse. “Theoretically, it is even possible to produce drinking water in the recycling unit,” adds Dr. Banica. “But many people would probably have to overcome potential aversions, since the purified water would come from showers or other places.”
To test the project on a larger scale, the two teams now want to develop a larger system that can also be tested in the field. The SLF research laboratory on the Jungfraujoch in Switzerland will be used for this purpose. “The alpine area is ideal for carrying out an initial test run,” the two are convinced. If this is successful, the next step would be towards the Arctic or Antarctic, where research stations or Arctic communities could benefit directly from a technology that was originally intended for use beyond Earth but could now help solve a very earthly problem.
Dr Michael Wenger, PolarJournal
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