On the way to a climate-neutral Bonn, "avoidance before compensation" always applies when it comes to greenhouse gas emissions. In future, energy will be used efficiently and emissions will be reduced. Nevertheless, greenhouse gases will still be produced within the city limits that cannot be completely avoided, for example in transportation or industry. In order for the city to actually be climate-neutral in 2035, the proportion of these unavoidable CO2 emissions must be offset or compensated for. Offsetting greenhouse gases involves binding climate-damaging CO2 from the atmosphere and storing it permanently. This results in so-called "negative emissions" for the greenhouse gas balance.

The unavoidable emissions can be offset either by natural or technical CO2 sequestration. Seven percent of Bonn's urban area is agricultural land and 30 percent is forest and wooded areas. The city administration is conducting a potential study on natural compensation and the long-term storage of CO2 in the soil.

The technical compensation of unavoidable emissions is known internationally as carbon capture and storage (CCS). When carbon dioxide is captured and stored, the gas is separated, liquefied and stored using industrial processes. However, this technology is very costly and, according to the IPCC report - the assessment report of the Intergovernmental Panel on Climate Change - will only be able to account for a very small proportion of the global reduction in greenhouse gases by 2030. Avoiding greenhouse gases as opposed to technical compensation is therefore always a priority for Bonn.