Even with aggressive decarbonization, cities face residual emissions from waste incineration, industrial processes, and hard-to-abate sectors that cannot be eliminated by 2030–2040 deadlines. Reaching net-zero therefore requires negative emission technologies — carbon capture at point sources, direct air capture, or carbon mineralization — that are expensive, unproven at scale, and carry the risk of becoming an excuse to delay emission reductions.
Basel-Stadt faces approximately 90,000 tonnes of residual CO2-equivalent emissions that cannot be eliminated through direct decarbonization. KVA Basel (the waste-to-energy plant) is the primary CCS candidate. VBSA has launched a CHF 90,000 pilot feasibility study due by end 2027. Deep geothermal energy remains off the table after the 2006 earthquake.