This time our blog post comes from Clea Kolster a PhD student in both the Centre for Environmental Policy and the Centre for Process Systems Engineering. In this post she outlines her research into storage of CO₂ to help the UK meet its emissions targets.

To avoid dangerous climate change the UK, and Europe, needs to meet their targets to reduce carbon emissions within the next couple of decades. One way of doing that is for carbon dioxide capture and storage technologies (CCS) to be integrated in power plants that burn fossil fuels. This is where my research comes in. My work focusses on what can we do with the carbon dioxide (CO₂) once we have captured it.

I am a PhD student here at Imperial College London, funded by the Grantham Institute and the Natural Environment Research Council (NERC). I have always held a strong interest in climate change mitigation technologies and policies as well environmental sustainability and economics. My research allows me to combine my MEng in Chemical Engineering with these interests; bringing process modelling, petroleum engineering concepts, financial management and policy considerations to bear on the problems of CCS.

CCS has recently moved to the top of the agenda as the Intergovernmental Panel on Climate Change’s (IPCC) synthesis report urged that it should be integrated into all power plants as long as fossil fuels are still being burnt. But where do you store the CO₂ once you’ve captured it? The two favoured options are in saline aquifers and depleted oil reservoirs. This second option comes with the added benefit that CO₂ can be used for enhanced oil recovery and then stored in the resulting depleted oil reservoirs. This helps make CCS pay as captured CO₂ can be sold to oil companies.

Part of my research has focussed on these different options. I have been using computer simulations of reservoirs to understand how CO₂ can be used and then stored in deep geological formations and how much of it can be used and sequestered. I also have to take into account the growing presence of intermittent renewable energy in the energy mix, which means CO₂ will be captured and transported at different rates in time. These variations can have a massive effect on the storage efficiency of reservoirs or saline aquifers.

One aspect that makes storing CO₂ tricky is that depending on what option you choose CO₂ purity matters. It needs to be more, or less, pure according to the storage method chosen. Matching up the right capture technology with the right storage solution is necessary to ensure that it is done efficiently and economically. Again my research has led me to look in to this problem. I have developed methods for understanding how the cost of CO₂ capture technologies are affected by how pure you want your CO₂. If you have chosen a technology that can only produce a certain purity level at a high cost your choices for storage change. My work has let me establish the minimum price at which CO₂ needs to be sold in order for various technologies and storage solutions to be economically viable.

My research could be seen as an engineering problem, an economics problem or even a political one. However my research brings all these areas, and more, into consideration and might just mean that the UK meets those emissions targets.