Project description

CO2inloop aims to further develop the concept of CO2 networks for heating and cooling. CO2 networks can be used for supplying low-emission energy services to consumers in dense urban regions. In regions where district heating and cooling is already used extensively, the CO2 network may provide options for further development as it provides options for use of smaller, uninsulated pipes resulting significantly lower investment and transition to renewable heating solutions by electrification using heat pumps.

Previous studies of such CO2 grids are apparently only based on constant pressure levels. The high enthalpy of evaporation of CO2 at around 50 bar takes effect for the heat transfer between the networks and the consumer. This means that the temperature in the lines is between 10 and 16°C. The CO2inloop project aims to increase the flexibility of such CO2 grids through the variation of the pressure level. The adjustment of the pressure level in the CO2 networks influences the CO2 mass in the circuit. CO2 storage systems can compensate the variable CO2 mass in the system, resulting in increasing flexibility potential and further sector coupling solutions, like integrating Solid Oxid Fuel Cells (SOFC), that can process natural gas, or even biogas directly with a high electrical efficiency of up to 60%.

The project will cover investigation of the CO2 solution compared to conventional district energy systems from economic and environmental perspectives, including the system extensions and new control algorithms described above.

The CO2 network should also be examined with an innovative simulation software based on the so-called soft sensor technology. This technology is currently being used for the simulation of water-based heating networks and is also to be used for the first time in CO2inloop for CO2 networks. A thermo-hydraulic real-time simulation of the entire CO2 network should enable realistic monitoring with safety-enhancing effects.


Project partner

  • Prozess Optimal CAP GmbH
  • Reiterer & Scherling GmbH
  • Aros Teknik Aps
  • Technical University of Denmark
  • Aalborg Forsyning