Carbon Sequestration

The overproduction of carbon dioxide emissions is currently one of humankind's largest and most threatening problems. As outlined in the Paris 2016 climate summit, countries across the globe will try to keep global temperature rise below 1.5 degrees, and have agreed not to go above 2 degrees. From everything that our most recent measurements tell us, the 1.5 degree mark will not be attained, but we can still make the 2 degree mark if we can find ways to drastically cut down our CO2 production.

Many of the energy budgets set out by various different countries assign a substantial proportion of their CO2 reduction to carbon sequestration - a method of capturing CO2 at source (e.g. power plants and factories) and pumping it deep beneath the Earth where it can be stored in saline aquifers, either by dissoloution or trapping in the rock pores and boundaries (see image to the right, taken from [1]).

Understandably, CO2 sequestration is currently a topic of research with great momentum. One of the main questions is how to predict the long-term motion and trapping, to ensure sustainable and safe storage. In particular, the aquifers which have been identified as potential sites for carbon storage are typically composed of many layers of rocks with potentially vastly different flow properties (e.g. porosity). Working with Jerome Neufeld and Mike Bickle at the University of Cambridge, I am currently researching how these rock layers, which vary on a small scale, can affect the flow at large scale. Such an `upscaling' approach is much less computationally demanding than entire resevoir simulations, and hence will be useful in creating faster and more intuitive predictions of carbon sequestration [2].

[1] Huppert, H. and Neufeld, J.A. The Fluid Mechanics of Carbon Dioxide Sequestration, Annu. Rev. Fluid Mech. 46:255–72, (2014).

[2] Benham, G.P., Bickle, M.J., Neufeld, J.A. Upscaling multiphase flow through heterogeneous porous media, Submitted (2020). [pdf]

Water management in Cyprus

In island countries and coastal regions where a significant part of the water supplies rely on aquifers, drought and over-extraction can lead to a drop in the aquifer water table. This drop increases the risk of sea water intrusion, which can render the aquifers unusable for a long period of time. In the case of drought, the water table lowers due to a decrease in the natural underground seepage flow in the aquifer. In order to maintain the water table and mitigate the risk of sea water intrusion, many coastal aquifers are replenished by pumping water back into the aquifer. Therefore, the water table height and consequently the management of aquifers requires a balance between the natural underground seepage, the extraction of water for consumption and the artificial recharge of water.

During a workshop in Limassol, Cyprus, I worked with several other academics from different countries to create a mathematical model for the water table in a sloping coastal aquifer [3]. Based on the nearby Germasogeia aquifer (see aerial view to the right), which supplies water to the Limassol region, our model can be used to determine extraction/recharge strategies to ensure the water table does not diminish to a dangerous level (i.e. to stop sea water intrusion).

[3] Mondal, R., Benham, G.P., Mondal, S., Christodoulides, P., Neokleous, N., Kaouri, K. Modelling and optimisation of water management in sloping coastal aquifers with seepage, extraction and recharge, Journal of Hydrology, 571, 471-484, (2019). [pdf]