Climate change is a risk issue of global proportions. Human health and environmental impacts are anticipated from hazards associated with changes in temperature and precipitation regimes, and climate extremes. Increased natural hazards include storms and flooding, extreme heat, drought, and wildfires. Reduced food and water quality and quantity, reduced air quality, new geographic range of infectious diseases, and increased exposure to ultra-violet radiation are also predicted. In order to make a measurable contribution to reducing carbon dioxide emissions at point source fossil fuel and industrial process sites that contribute to climate change, estimates suggest that up to 3,000 dedicated large scale carbon capture and geological sequestration (CCS) projects will be necessary by 2050. Integrated projects include carbon dioxide capture; compression into a supercritical stream; transport, most often by pipeline; deep injection at wellheads; and sequestration in suitable saline aquifer geological formations, usually 800 metres or more below the earth’s surface. In implementing CCS as part of an overall climate change mitigation strategy, it is important to note that population health and environmental risks are associated with each of these value chain components of integrated projects. Based on an assessment of existing regulatory and non-regulatory guidance for risk assessment/risk management (RA/RM), an analysis of the application, assessment, and approval process for four large scale Canadian projects, and findings from a structured expert elicitation focused on hazard and risk issues in injection and storage and risk management of low probability high impact events, this research developed an Integrated Risk Management Framework (IRMF) for CCS in the Canadian context. The IRMF is a step-wise systematic process for RA/RM during the life of a project, including engagement with wide ranging government and non-government partners that would contribute to a determination of acceptable risk and risk control options. The execution of the IRMF is an intervention that could reduce local hazards and associated risks in terms of likelihood and consequence, as well as identify and document risk management that could underpin broad acceptance of CCS as a climate change mitigation technology. This would thereby also have an important part in protecting global population health and wellbeing in the long term. Indeed, diverse stakeholders could be unforgiving if hazard assessment and risk management in CCS is considered insufficient, leading to ‘pushback’ that could affect future implementation scenarios. On the other hand, RA/RM done right could favourably impact public perception of CCS, in turn instilling confidence, public acceptance, and ongoing support for the benefit of populations worldwide. This thesis is composed of an introduction to the research problem, including a population health conceptual framework for the IRMF, followed by five manuscripts, and concluding with a discussion about other barriers to CCS project development, and a risk management policy scenario for both the present time and during the 2017-2030 implementation period.

Jordens befolkning behöver kraftigt reducera koldioxidutsläppen till atmosfären för att förhindra klimatförändringar. Klimatmål har sats upp av unioner och länder där de bland annat vill förhindra en global temperaturökning över 1.5 grader. För att uppnå dessa klimatmål menar forskare och institutioner på att stora mängder koldioxid kommer att behöva avskiljas vid utsläppskällor och lagras geologiskt (eng. carbon capture storage, förkortad CCS). I Sverige har ett fåtal CCS-projekt tagit fart men CCS är fortfarande inte kommersiellt tillgängligt. Frågeställningen för det här arbetet var därför: vilka är de mest relevanta utmaningar som kommersiellt tillgänglig CCS står inför idag i Sverige?Metoderna som användes var en litteraturstudie och tre\newline intervjuer. Personerna som intervjuades var en forskare från Chalmers Tekniska högskola, en chef från företaget Stockholm Exergi och en civilingenjör från projektet Northern lights. Utmaningarna delades in i kategorierna: tekniska-, politiska-, ekonomiska- och övriga utmaningar, för att enklare identifieras och jämföras. Resultaten visade att det fanns utmaningar i samtliga kategorier. Den tekniska utmaningen låg framförallt i att bygga upp och anpassa den tillgängliga CCS-tekniken till olika tillämpningsbara industrier. Politiskt var utmaningen främst att övertyga politiker att satsa på CCS, men också att införskaffa tillräckligt stora ekonomiska styrmedel, incitament och investeringar. Detta eftersom de som existerar idag antingen saknades helt eller ansågs vara för små. De ekonomiska utmaningarna var att stimulera investerare samt att bygga upp en fungerande och hållbar ekonomisk plan för CCS. I kategorin övriga utmaningar var den främsta utmaningen att övertyga befolkningen och att sprida kunskap kring CCS och dess potential. Avgränsningar i det här arbetet var framförallt bristen på resurser och tid. Fler intervjuer och en djupare litteraturstudie hade varit önskvärd för att fördjupa studien men begränsades av tid och möjligheter för kursens omfattning. / The world population need to reduce its carbon dioxide emissions to the atmosphere in order to prevent a climate change. Climate targets have been set by unions and countries to reduce carbon dioxide emissions before the average temperature rise exceeds 1.5 degrees Celsius. To achieve these climate goals, researchers and institutions believe large amounts of carbon dioxide needs to be stored below ground (carbon capture storage, abbreviated CCS). In Sweden have a small number of projects taken off, but CCS is still not commercially available. The question for this work was therefore: what are the most relevant challenges that commercially CCS currently faces in Sweden?The methods used were a literature study and three interviews.The persons interviewed were a researcher from Chalmers Tekniska university, a manager from the company Stockholm Exergi and an engineer from the Northern Lights project. The challenges were divided into four categories: technical-, political-, economic-, and other challenges, to make it easier to identify and compare. Results showed that there were challenges in all four categories. The technical challenge was mainly to build and adapt the available CCS technology to different types of industries. Politically, the challenge was primarily to increase their interest and support towards CCS. This along with the challenge of acquiring financial instruments, incentives and investments that was currently lacking or was too small. The economic challenges were to stimulate investors from both private and political quarters and to organize and operate a functioning and sustainable financial plan. In the category other challenges, the most mentioned challenge was convincing the population and to spread knowledge about CCS and its potential. Delimitations in this work was above all the lack of resources and time. More interviews anda deeper literature study would have been desirable to deepen the study but was limited by time and opportunities for the scope of the course.

This work presents model development and model analyses of CO2 storage in deep saline aquifers. The goal has been two-fold, firstly to develop models and address the system behaviour under geological heterogeneity, second to tackle the issues related to problem scale as modelling of the CO2 storage systems can become prohibitively complex when large systems are considered. The work starts from a Monte Carlo analysis of heterogeneous 2D domains with a focus on the sensitivity of two CO2  storage performance measurements, namely, the injectivity index (Iinj) and storage efficiency coefficient (E), on parameters characterizing heterogeneity. It is found that E and Iinj are determined by two different parameter groups which both include correlation length (λ) and standard deviation (σ) of the permeability. Next, the issue of upscaling is addressed by modelling a heterogeneous system with multi-modal heterogeneity and an upscaling scheme of the constitutive relationships is proposed to enable the numerical simulation to be done using a coarser geological mesh built for a larger domain. Finally, in order to better address stochastically heterogeneous systems, a new method for model simulations and uncertainty analysis based on a Gaussian processes emulator is introduced. Instead of conventional point estimates this Bayesian approach can efficiently approximate cumulative distribution functions for the selected outputs which are CO2 breakthrough time and its total mass. After focusing on reservoir behaviour in small domains and modelling the heterogeneity effects in them, the work moves to predictive modelling of large scale CO2  storage systems. To maximize the confidence in the model predictions, a set of different modelling approaches of varying complexity is employed, including a semi-analytical model, a sharp-interface vertical equilibrium (VE) model and a TOUGH2MP / ECO2N model. Based on this approach, the CO2 storage potential of two large scale sites is modelled, namely the South Scania site, Sweden and the Dalders Monocline in the Baltic Sea basin. The methodologies developed and demonstrated in this work enable improved analyses of CO2 geological storage at both small and large scales, including better approaches to address medium heterogeneity. Finally, recommendations for future work are also discussed.