Passive air conditioning
Nanolope is developing a panel-shaped thermal energy storage system that can be mounted on walls or ceilings
The specialised material used in the thermal energy storage system developed by Nanolope regulates temperature as it melts and solidifies, it is designed to noticeably reduce heating costs.
The International Space Station (ISS) is exposed to severe temperature fluctuations. On the side facing the sun, its outer shell can heat up to 120 degrees Celsius, while temperatures on the shaded side plunge to minus 160. To be sure, the conditions in a flat in Berlin do not tend to be as extreme. However, quite a few degrees lie between a sunny afternoon, which will heat up some buildings rather uncomfortably, and the cooler hours of the night.
This is where the start-up’s panels come into play. Just under three centimetres thick, they contain what is known as a phase-change material (PCM), which remains solid below room temperature and turns liquid when temperatures rise above it. “When the material melts, it absorbs a large amount of heat from its surroundings, keeping the room at a comfortable temperature,” says Felix Marske, founder and CEO of Nanolope. “In turn, PCM releases heat when it solidifies—helping to save on heating costs.”
The idea itself is more than 30 years old, says Marske, who holds a doctorate in chemistry. “There has been a great deal of research and development, but the real breakthrough never came.” Research resulted in panels with a maximum of ten percent PCM—too little to offset material and installation costs and to deliver meaningful energy savings. Fascinated by the potential, however, Marske developed a first room-temperature PCM prototype during his master’s at Leipzig University. “The material had the consistency of margarine,” he says with a laugh. “Nobody would ever put that in their flat or office.”
He pressed on—researching, discarding ideas, refining approaches, building a team—and finally developed panels with market potential. Numerous public funding bodies and investors saw it, too. The result is a bio-based composite material made up of silicates arranged like a sponge. The tiny cavities are filled with an organic PCM based on a fatty acid ester mixture, which accounts for around 85 per cent of the material by mass.
“There is no risk of the panel melting at high temperatures,” says Marske reassuringly. Within the material’s microscopic, sponge-like structure, the PCM is retained by strong capillary forces. “All we are seeing is that the material becomes slightly more transparent as it melts within the sponge structure.” However, this is only visible during manufacturing because , in the end, a coating is applied to give the panel an aesthetically pleasing surface. Like acoustic panels, the look is to be understated and unobtrusive.
The PCM itself is produced from plant-based raw materials by a supplier. The silicate component is currently based on conventional sand but is set to be replaced by rice husk ash in future, making the product fully bio-based. “Green Chemistry” and sustainability are core principles at Nanolope. Based at an Adlershof-based start-up centre, the seven-member team is already working on a successor product that will be made largely from waste materials and be flame-retardant.
But first, panel number one will have to prove itself in practice. In the coming summer, three flats in Berlin Schöneberg will be equipped with the panels—all of them on the top floor and exposed to varying levels of sunlight.
Company founder Marske already has many more ideas in mind. For example, adding the PCM in pellet form to hot water storage to make it more efficient. If successful, this would allow today’s bulky tanks to be made significantly smaller—saving ample space. To that end, he is already working with a company in southern Germany. He also sees potential applications in the cooling of food and batteries.
It seems likely that the 130 square metres of office and laboratory space Nanolope currently occupies may soon become too small.
Ralf Nestler for Adlershof Journal