CO2 storage in coal can be predicted better

The ‘Enhanced Coalbed Methane process’ kills two birds with one stone: carbon dioxide (CO2) is stored in coal seams in the ground and at the same time methane (CH4) is obtained from the process. To optimise this process it is important to know how coal retains and stores some fluids and gasses whilst allowing others through. The network of cracks is essential for this. Mazumder developed a measuring technique using CT scans that led to an improved understanding of the patterns of cracks.

He also did experiments with waste gas and pure CO2 to determine the uptake capacity of single and multi-component gasses. In both wet and dry experiments, CO2 was strongly absorbed and CH4 was released. This methane production in a coal seam can vary over the course of time. Mazumder developed two estimating methods to gain a better understanding of this. When used together these could generate good predictions.

Problems due to swelling

The research revealed that a considerable quantity of CO2 could be removed from waste gas by allowing it to be adsorbed onto coal under high-pressure. According to Mazumder this means that the injection of waste gas into coal seams can be applied to filter out CO2 on an industrial scale and to retain it. Mazumder also carried out a preliminary study into the decrease in porosity and permeability as a consequence of coal swelling due to the injection of CO2. The decrease in the permeability can give rise to serious injection problems in the area of the well into which CO2 is injected.

The doctoral research ‘Dynamics of CO2 in Coal as a Reservoir’ was, amongst other things, part of the programme ‘Transition to sustainable use of fossil fuels’ funded by the NWO/SenterNovem Stimulation Programme Energy Research. The programme aims to develop knowledge in the natural and social sciences for the transition to a sustainable energy supply.