EXTRAQT provides buildings with sustainable heating and cooling based on aquathermy

Posted on 6 Oct 2022

Within current climate issues, the fight for CO2 reduction and in the context of the energy crisis, a renewable energy mix for heating and cooling is becoming crucial. Indeed, worldwide 50% of total energy consumption is for heating and cooling, of which only 14% is currently renewable energy.

. In Flanders, that share of renewable energy is even lower, reaching only 8.9%. We asked co-founder Jan Denayer, how EXTRAQT can help boost society towards sustainable heating and cooling.

Briefly introduce EXTRAQT?

"Together with Sebastian Baes and under the guidance of Stijn De Jonge, lecturer at KU Leuven, GROEP T campus, we investigatedthe natural regeneration of heat in rivers as part of our master thesis. Together, we founded EXTRAQT in July 2021. We are a Leuven based engineering company with the ambition to boost our society towards sustainable heating and cooling. Our start-up focuses on aquathermy, a sustainable heating and cooling technology that uses heat pumps that use surface water, from rivers, lakes and canals for example, to heat and/or cool buildings."

Can you explain the technique of aquathermy a little more concretely?

"The technology behind aquathermy is not new. It is similar to the technology of an air-water heat pump. But the source, from which we extract the heat, differs. With an air-to-water heat pump, it is the outside air. With aquathermy, on the other hand, a heat pump is used to extract heat or cold from a river, lake or canal.

The water is pumped up and sent to the heat pump. Heat is then extracted from the water by a refrigerant in the heat pump. After thermodynamic compression, using electricity, the refrigerant in the heat pump is hot enough to release heat to the building. The same principle, but in reverse, can be applied for cooling, using the same heat pump.

Moreover, this technique is highly complementary to better-known heat pump technologies based on air or ground heat. For example, aquathermy achieves higher efficiency than airsource heat pumps during cold periods and the cost price is lower than that of groundsource heat."

Is aquathermy already widely used?

"No. The use of rivers, lakes, canals as aquathermal sources is modestly applied in countries such as the Netherlands, Scandinavia, and the UK, where a large-scale rollout and integration within the energy transition is visible. But we also strongly believe in the potential of aquathermal in Belgium. Here too, for instance, almost every town is located near a river. 42% of all heat demand in Flanders is within 1 km from a waterway, but Belgium also has numerous lakes and ponds. So surface water is almost everywhere."

What services do you offer?

"EXTRAQT develops energetic models ('digital twins') of rivers and lakes to estimate the potential of these sustainable heat and cold sources, after which, based on our preliminary studies, we also design the technical concept for the aquathermal plant. Thus, we go through the entire process for an aquathermal project: from feasibility studies and permit applications to the technical design of the plant and component selection."

Which buildings lend themselves to being heated/cooled based on aquathermy?

"Currently in Flanders, we are carrying out many projects on private property with stagnant water under own management, castles for example that are being renovated. But in addition, we also notice that more and more large public projects are looking at aquathermy.

In the future, we want to focus mainly on this b-to-b market: office buildings, waterfront businesses, feeding urban heat networks, residential projects in riverside city centers...

For example, we are currently involved in renewing and making the heating sustainable of the residential complex 'De Dijlemolens' in Leuven along the Dijle river. The old mill building was renovated in 1985 and transformed into a residential complex with 35 flats and a dozen commercial spaces. Due to its location on the Dijle, the building is ideally suited for aquathermy.

Together with the city of Leuven, EXTRAQT is assisting the Association of Co-owners (VME) with the renovation of the heating system with the reduction of CO2 emissions in focus . The basic heat demand will be provided by a heat pump connected to the Dijle river. For peak demand, the gas boiler will be used. The installation is a model project for aquathermy in residences and is supported by the Flemish Government's Environment Department."

What challenges do you see in Belgium?

"In Belgium, there is only limited regulation of aquathermy for the time being. There are only rules for cooling water in the industrial sector, but these can be interpreted in different ways. This is why we are working closely with all water managers to come up with an unambiguous and thermally sound regulatory framework for this technology.

At EXTRAQT, for instance, we develop very comprehensive thermal modelling of water bodies. We calculate what their capacity is, how much heat or cold you can extract from them without the water freezing or changing too sharply in temperature. So, we can determine the optimal amount of heat available without violating the ecology of the water body."

Do you focus mainly on the Belgian market?

"No, definitely not. We are looking for new projects worldwide. For example, we are currently running a large project in the United States, connecting office buildings to a lake, and we are involved in a project on the potential of hydropower and aquathermy in Colombia through the G-STIC Climate Action Programme. We also have a number of projects underway in the Netherlands, where meaningful regulations for aquathermy are also still being tinkered with."

More info: https://www.extraqt.be

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