A new approach by Scottish and Chinese scientists to trapping carbon dioxide (CO₂) in rocks deep underground could unlock the potentially huge storage capacity of China’s Pearl River Mouth Basin, which would massively reduce CO₂ emissions and improve air quality in one of the country’s most industrialised regions.
A team from the University of Edinburgh, one of SCCS’s founding partners, has been studying geology below the river mouth basin, which has potential for storing CO₂ but a limited ability to provide a long-term sealing mechanism. The geoscientists’ findings, from studies of three depleted oil fields in the Huizhou area, could provide decades of secure CO₂ storage offshore for full-chain carbon capture, utilisation and storage (CCUS) projects in the region – including the Haifeng CCUS project at a coal-fired power plant.
Their research, which has been funded by the Scottish Funding Council, EPSRC and NERC, suggests that a concept known as dispersion trapping could support long-term CO₂ storage by dispersing the injected CO₂ as microscopic droplets throughout the deeply buried geology. This would effectively unlock massive volumes of pore space in storage sites, which lack a single-seal cap rock (the European and North American approach to containing CO₂).
The team’s findings have been published in the International Journal of Greenhouse Gas Control.
China is one of the world’s largest emitters of CO2 due to a dependence on coal for energy. Carbon capture and storage (CCS) could play a crucial role in reducing its greenhouse gas emissions and helping to meet its commitment to the UNFCCC Paris Agreement.
Dr Niklas Heinemann, from the University of Edinburgh’s School of GeoSciences, said:
Large-scale CO₂storage sites within reasonable distance of major CO₂ emission clusters are key to enabling CCS delivery in China. The Pearl River Mouth Basin reservoirs have excellent storage potential but we need to ensure that they provide long-term containment of CO₂. Our findings will boost storage security and provide access to the vast pore space of the river basin area.
Prof Stuart Haszeldine, from the University of Edinburgh, and SCCS Director, said:
We’ve suggested an alternative method of developing this resource into secure stores using dispersion trapping. It’s a bit like having a damp sponge of CO₂ spread throughout the rock. None of the CO₂ can escape, even though there is no single seal. All the pore space can be used if injection is planned differently to disperse CO2 widely at many levels within the geology. This is like creating direct entrances into several floors of a residential tower block, rather than just using one floor. The work is applicable to many reservoirs in China, and globally, and can upgrade storage resources, which are currently unavailable.
China is the world’s largest emitter of CO₂. Although the country has shelved plans for around 150 new coal-fired power plants, it still has more than 900 GW of operating coal-fired power plant and around 90 GW under construction. Carbon capture and storage (CCS) aims to store CO₂ captured and transported from point sources (such as industrial facilities or power plants) in depleted oil and gas fields or deep aquifers, preventing it from reaching the atmosphere and enabling countries to meet emission reduction targets. More details about existing or planned CCS projects worldwide can be found on the SCCS Global CCS Map.
SCCS is one of the partners in the UK-China (Guangdong) CCUS Centre, a collaboration of Scottish and Chinese research institutes and industry.