Biosphere risk assessment for CO2 storage projects

The aim of this paper is to describe the methodology developed to link the quantitative outputs of the geosphere risk assessment to the semi-quantitative assessment of risk to the biosphere. It also shows how good practice stakeholder engagement principles can be incorporated into the risk assessment process to achieve transparency in project decision making. The objective of the biosphere risk assessment portion of the Weyburn-Midale Project was to develop a risk assessment methodology that can be applied to a range of CO2 storage projects. Preliminary modelling of potential biosphere impacts associated with the Weyburn-Midale Project was undertaken to enable the risk assessment methodology to be tested and to demonstrate the nature of the biosphere risk assessment outputs, and how the process and outputs can be used to facilitate stakeholder acceptance.The method to assess the biosphere risk at the Weyburn-Midale Project uses the outputs (pathways, likelihoods and CO2 mass) from geosphere risk assessment to identify the general physical and chemical effects on the fundamental biosphere components (groundwater, surface water, soil, air) and the consequential impacts on organisms, habitat, amenity and public safety. The approach applies an existing environmental impact assessment methodology to derive outputs that stakeholders can use to assess the risk and impacts to environmental assets.The outcomes of biosphere risk assessment are used to: develop risk mitigation strategies and future monitoring options; understand whether the project will likely have unacceptable impacts on safety or valued community assets; decide whether the project should proceed; and to assist engagement with regulators and the community.

► Geosphere risk assessment outputs are used to determine impacts on the biosphere.
► Projects can demonstrate the environmental and social impacts of CO2 storage.
► Clear identification, analysis and communication of complex environmental issues.
► Outcomes are used to develop risk mitigation and monitoring strategies.
► Biosphere risk assessment is a key tool to gain stakeholder acceptance.