Case Story Switzerland

Renewable CO2 from food waste based Biogas – a case story from Switzerland

September 2024

Food waste is a perfect feedstock for biomethane production. Every day, the Recycling Energie AG in Nesselnbach, Switzerland processes 300 tons of food waste from restaurants, hospitals and residential facilities and turns this into biogas. App. 800 m³/h of the raw biogas is then upgraded and fed as natural gas substitute into the gas grid. The annually injected biomethane equals an energy equivalent of 35 GWh/a.

The upgrading of the biogas produces an offgas, which contains mainly the renewable CO2 and a residual proportion of methane, the so called methane slip. In general such waste gas streams are – depending on valid regulation – either combusted to reduce methane emissions or they are discharged into the environment. Since March 2023 in Nesselnbach the offgas is treated further to turn the CO2 into a commercial product. The CO2 cleaning and liquefaction plant is one of only a few plants in Europe to provide biogenic CO2 in a food grade quality. CO2 is an important base product for the chemical and food industries. Large quantities of biogenic and therefore renewable and emission neutral CO2 are needed to substitute fossil CO2 which is currently the standard within the industries. Beside such applications, so called carbon capture and utilization (CCU) there might be an increasing market for carbon capture and storage (CCS) technologies, where the CO2 is stored underground.

The CO2 upgrading and liquification plant is operated by an separate company, the CO2 Energie AG. The liquefaction plant produces up to 4000 tons of food-grade liquid CO2 per year. Industrial gases company Messer Schweiz AG collects the CO2 three times a week by a tanker and sells it to manufacturers – for example producers of dry ice or carbonated drinks. CO2 Energie AG generates further income for the operation of the plant through the sale of CO2 compensation certificates, which is done via the Swiss climate protection foundation KliK. The sale of certificates is an essential aspect – the revenue from selling the CO2 alone is not sufficient to cover production costs.