Potential Environmental Impacts of CO2 Leakage from the Study of Natural Analogue Sites in Europe

AbstractSites of natural CO2 leakage provide opportunities to study the potential environmental impacts of such leakage on near-surface ecosystems. As part of the FP7 RISCS (Research into Impacts and Safety in CO2 Storage) project a geochemical, botanical and microbiological study have been conducted on a natural CO2 vent in Florina, Greece and the findings are compared with the results drawn from Latera, Italy and Laacher See, Germany. Plant and microbial communities appear to have adapted to long-term CO2 exposure. Therefore the findings may not be representative of the effects of potential leakage from man made storage sites

Comparison of the impacts of elevated CO₂ soil gas concentrations on selected European terrestrial environments

Selected European studies have illustrated the impacts of elevated CO₂ concentrations in shallow soils on pasture. For the first time, general unified conclusions can be made, providing CO₂ thresholds where effects on plants and soil microbiology are observed and making recommendations on how this information can be used when planning projects for CO₂ storage. The sites include those where CO₂ is being naturally released to the atmosphere from deep geological formations; and a non-adapted site, with no previous history of CO₂ seepage, where CO₂ has been injected into the unsaturated soil horizon. Whilst soil gas concentrations will be influenced by flux rates and other factors, the results suggest that a concentration of between 10% and 15% CO₂ soil gas at 20 cm depth, which is within the root zone, is an important threshold level for observing changes in plant coverage. Site-specific plant ‘indicators’ are also observed for CO₂ concentrations at ≥35%. Microbiological changes are seen where CO₂ soil gas concentrations are between 15% and 40%. As part of site characterisation, an evaluation of the risks of leakage and their potential environmental impacts should be undertaken

New and established techniques for surface gas monitoring at onshore CO2 storage sites

New methods for the monitoring of CO2 near the ground surface at geological CO2 storage sites have been tested over areas of natural CO2 emission. Mobile open path laser measurements and ground-surface portable infrared measurements show great promise for rapid assessment of large areas. Such techniques would help to focus more detailed investigations needed to verify the extent and source of the gas being emitted. It is envisaged that they would be used in conjunction with established field and laboratory techniques and continuous monitoring methods as part of an overall monitoring strategy for a CO2 storage site

Environmental impacts of CO2 leakage: recent results from the ASGARD facility, UK

Carbon Capture and Storage is increasingly seen as a way of combating rising CO2 concentrations in the atmosphere. Although storage sites will be designed for zero leakage it is important to consider the possible environmental effects in the unlikely event that leakage does occur, for both risk and environmental impact assessments. The potential responses of ecosystems depend on CO2 concentrations, event duration, the sensitivities of different organisms and external environmental factor