Energy-efficient CO₂ liquefaction for biogas and dry ice
Low electricity consumption is the central design priority of Solveno Technologies’ CO₂ recovery and liquefaction systems. For plants operating thousands of hours per year, reducing the electricity required per tonne of recovered liquid CO₂ can materially improve operating economics.
Our systems serve two applications: CO₂-rich off-gas from biogas upgrading to biomethane and CO₂ gas recovered during dry ice production. This guide explains how to assess the value of energy efficiency within these applications.
Discuss electricity consumption for your CO₂ recovery project
What is each saved kWh per tonne worth?
The financial value of lower electricity consumption depends on annual liquid CO₂ production and the electricity price:
Annual electricity cost saving = reduction in kWh/t × annual liquid CO₂ production in tonnes × electricity price in €/kWh.
For an illustrative annual production of 8,000 tonnes of liquid CO₂ and an electricity price of €0.15/kWh:
| Reduction in consumption | Saving per tonne | Annual saving |
|---|---|---|
| 10 kWh/t | €1.50/t | €12,000 |
| 20 kWh/t | €3.00/t | €24,000 |
| 30 kWh/t | €4.50/t | €36,000 |
This is a sensitivity calculation, not a statement of Solveno’s guaranteed savings. It compares equal quantities of liquid CO₂ meeting the same specification. Actual savings depend on the agreed operating conditions and equipment scope.
For biomethane producers, this lowers the electricity cost of producing saleable CO₂. For dry ice producers, it lowers the electricity cost of recovering CO₂ for reuse and replacing purchased liquid CO₂.
Compare the complete electrical duty
A figure for the refrigeration package alone cannot be compared directly with electricity consumption for a complete recovery system. Establish whether compression, drying, refrigeration, pumps, fans and external cooling equipment are included.
Use electrical consumption per tonne of usable liquid CO₂. Compressor shaft power, installed motor power and measured electrical consumption describe different quantities.
For annual performance, divide electricity consumed within the agreed boundary by conforming liquid output over the same period. Account for partial-load operation, standby and restarts.
Why biogas and dry ice require separate assessments
- Biogas upgrading: the CO₂-rich stream remains after methane separation. Residual methane, moisture and non-condensable gases influence treatment and recovery. Solveno combines compression, liquefaction and purification by distillation for this application.
- Dry ice production: gas released during production is collected, compressed and reliquefied for reuse. Collection pressure, gas quality and the production schedule determine the recovery duty.
Inlet pressure matters: gas arriving at a lower pressure requires a different compression duty. An energy figure from dry ice recovery therefore cannot automatically represent performance on biogas off-gas.
These systems are intended for the two CO₂ sources described above. Suitability is assessed from the actual gas analysis and operating conditions.
How Solveno approaches energy-efficient recovery
Solveno combines modular CO₂ recovery equipment, R744 natural-refrigerant technology and project-specific engineering. The evaluation considers compression, cooling, purification and integration together, with low electricity consumption as a central selection criterion.
Energy performance must be assessed alongside usable liquid output and product quality. A lower kWh/t figure has limited value if the comparison uses different product specifications or overlooks CO₂ losses.
For equipment capacities and configurations, see our biogas CO₂ recovery systems. Application details are available for CO₂ recovery from biogas upgrading and CO₂ recovery from dry ice production.
Assess your site's electricity costs
Start by identifying the source: biogas upgrading or dry ice production. Share the gas flow and composition, inlet pressure and temperature, annual operating hours, expected flow variations and required liquid CO₂ specification.
Add your electricity price and site cooling conditions. These inputs support an assessment of energy consumption, annual electricity costs and integration requirements.