CO2 Pilot Injection in Trüllikon / CITru

CITru (CO₂ Pilot Injection in Trüllikon) is an ETH Zurich-led pilot- and demonstration-scale CCS project testing CO₂ injection into a deep saline aquifer through a disused Nagra exploration borehole in Trüllikon, Canton Zurich. The site was selected because it is one of few Swiss boreholes reaching past 1,000 m, penetrating storage-suitable formations beneath an Opalinus Clay seal, and still in good mechanical condition. The storage concept is conventional: liquefied CO₂ injected into a permeable layer spreads a few hundred meters, dissolves into non-potable deep saline water, and mineralizes over the long term, after which the well is plugged and monitored with no further injection permitted. An exploration phase ran from fall 2024 through end of 2025, covering deep seismic surveys, plume simulations, risk assessment, and logistics/budget/concession work, with seismic monitoring and induced-seismicity modeling as the central research thrust given Switzerland's post-Basel sensitivity. Funding partners include Canton Zurich, ERZ, VBSA, Energie 360°, Neustark, Swisscom, and the ETH Foundatio. 44.01 joined as an advisory project partner on 24 June 2026, contributing injection, subsurface, and storage-operations input to gain an onshore continental-Europe foothold rather than bringing its basalt-mineralization technology to this saline-aquifer setting.