I was in the first DOCS cohort and am very fond of the project, which is why I’m still involved. I think it’s indispensable if we have any hope of achieving the climate goals for 2030 and 2050. CO₂ storage is a necessary part of the energy transition.
CO₂ cannot simply be stored; first you have to process and compress it so it gets converted from a gaseous state to a supercritical and liquid state. Then you can transport that supercritical fluid to salt reservoirs under the sea. Identifying the full range of possible risks is a crucial step. After all, if CO₂ leaks from the reservoir it kills the soil life, so having a solid and safe top layer is essential.
The top layer of clay is ideally 50 metres thick or more, but much depends on the quality of the covering layer. This clay layer has to extend deep into the subsoil to ensure that the CO₂ plume remains encased as it moves. When exploring suitable locations, you first map out the locations of heavily polluting industry. Then you investigate possible undersea areas and examine the condition of the sea floor. It’s almost like travelling back in time. You can see the different layers from 150 million years ago: river deposits, deep-sea deposits, organic matter. The continents as we know them today were completely different then.
In our view, the Vlieland Sandstone Formation is well-suited to storing CO₂. It’s a kilometre or more under the seabed, which means we’re going back 140 to 120 million years in time. It’s made of sandstone that was once deposited in a coastal environment. Sandstone is suitable because it’s porous—it has coarse grains with spaces in between where CO₂ could be injected.
