“The city of the future will heat and cool with CO2”

A thermal network using CO2 as a fluid in the pipelines is being tested in the basements of the Energypolis campus in Sion. A world premiere. Designers on the $4 million project have a year to demonstrate that the technology works.

Presented at a press conference on Tuesday, the demonstrator was developed and deployed in early June in three buildings on the Energypolis campus of HES-SO Valais-Wallis by project leaders – the university and EPFL in collaboration with the start-up. up Exergo and the local companies Zero-C and Oiken. Currently, networks of this type use water as a heat transfer fluid, but CO2 is much more interesting and economical, say the latter.

They use the change in temperature of the water in the circuit to transmit power to the other facilities. CO2 networks work differently: when CO2 is condensed into a gas and becomes liquid, it releases heat. This can be used by heat pumps. On the other hand, when liquid CO2 evaporates, it requires heat and releases cold.

Accelerating the energy transition

“With a kilo of CO2 that evaporates and condenses, I will have ten times more energy than with a water network that cools or heats three degrees”, explains Jessen Page, project manager at HES-SO.

More compact, the tubes that transport CO2 are also not afraid of freezing and are much smaller. Its implementation in urban centers would therefore be easier, faster and less expensive, guarantees the professor. Which accelerates the energy transition.

Thanks to its advantages, this underground pipe network does not need to be buried deeply. Pipes can, for example, be easily integrated into prefabricated sidewalks and connect all buildings in a city as well as industrial areas, says François Maréchal, a professor at EPFL based in the Valais capital. “The city of the future will be heated and cooled with CO2”, he summarizes.

The development of this test network, which has a capacity of approximately 500 thermal kW, is spread over three years. Two years were used to design it to full size. “The third is dedicated to testing it, measuring its energy efficiency and establishing whether it is the same, better or worse than a network where water is used”, explains Jessen Page.

National and international interests

This testing phase is also a way to gain the manufacturers’ confidence in terms of efficiency and safety and convince them to adopt this patented technology, underlines Alberto Mian, director of ExerGo, the only company to be able to commercialize it. The urgency of the energy transition is felt in all countries, Alberto Mian indicates that many contacts have been made. Dubai, for example, has already shown interest.

The development of the demonstrator is financially supported by the canton and the Confederation, as well as local industrial partners. “This beautiful project is in line with the federal energy strategy”, underlined Philippe Müller, head of the CleanTech section of the Federal Office of Energy (SFOE).

The latter particularly welcomes the fact that “all partners – both research and industry – are involved in its implementation”. That bodes well for the future, says OFEN.

Furthermore, if the project is conclusive, Oiken, the electricity distributor in Valais, has already indicated that it could recover it and deploy it in a substation in the district of Sion, initially, then on a larger scale, in addition to the district heating network. .

An operational network in no time

As for the skills to install this kind of technology, Jessen Page doesn’t care. According to him, it would be possible to have an operational network in two/three years and in three decades to connect everyone.

For seven years, the professor has been explaining the CO2 network to more than 300 students. “By 2025-2030, hundreds of trained people will know where to install them and how to operate them.” He adds: without them, we will never be ready to deliver on the 2050 energy strategy.

This article was automatically published. source: ats

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