Study of natural-occurring 100,000 year-old CO2 reservoirs shows no significant corroding of 'cap rock', suggesting the greenhouse gas hasn't leaked back out - one of the main concerns with greenhouse gas reduction proposal of carbon capture and storage.
New research shows that natural accumulations of carbon dioxide (CO2) that have been trapped underground for around 100,000 years have not significantly corroded the rocks above, suggesting that storing CO2 in reservoirs deep underground is much safer and more predictable over long periods of time than previously thought.
These findings, published today in the journal Nature Communications, demonstrate the viability of a process called carbon capture and storage (CCS) as a solution to reducing carbon emissions from coal and gas-fired power stations, say researchers.
CCS involves capturing the carbon dioxide produced at power stations, compressing it, and pumping it into reservoirs in the rock more than a kilometre underground.
The CO2 must remain buried for at least 10,000 years to avoid the impacts on climate. One concern is that the dilute acid, formed when the stored CO2 dissolves in water present in the reservoir rocks, might corrode the rocks above and let the CO2 escape upwards.
By studying a natural reservoir in Utah, USA, where CO2 released from deeper formations has been trapped for around 100,000 years, a Cambridge-led research team has now shown that CO2 can be securely stored underground for far longer than the 10,000 years needed to avoid climatic impacts.
Their new study shows that the critical component in geological carbon storage, the relatively impermeable layer of "cap rock" that retains the CO2, can resist corrosion from CO2-saturated water for at least 100,000 years.
"Carbon capture and storage is seen as essential technology if the UK is to meet its climate change targets," says lead author Professor Mike Bickle, Director of the Cambridge Centre for Carbon Capture and Storage at the University of Cambridge.
"A major obstacle to the implementation of CCS is the uncertainty over the long-term fate of the CO2 which impacts regulation, insurance, and who assumes the responsibility for maintaining CO2 storage sites. Our study demonstrates that geological carbon storage can be safe and predictable over many hundreds of thousands of years."
The key component in the safety of geological storage of CO2 is an impermeable cap rock over the porous reservoir in which the CO2 is stored. Although the CO2 will be injected as a dense fluid, it is still less dense than the brines originally filling the pores in the reservoir sandstones, and will rise until trapped by the relatively impermeable cap rocks.
"Some earlier studies, using computer simulations and laboratory experiments, have suggested that these cap rocks might be progressively corroded by the CO2-charged brines, formed as CO2 dissolves, creating weaker and more permeable layers of rock several metres thick and jeopardising the secure retention of the CO2," explains Bickle.
"However, these studies were either carried out in the laboratory over short timescales or based on theoretical models. Predicting the behaviour of CO2 stored underground is best achieved by studying natural CO2 accumulations that have been retained for periods comparable to those needed for effective storage."
To better understand these effects, this study, funded by the UK Natural Environment Research Council and the UK Department of Energy and Climate Change, examined a natural reservoir where large natural pockets of CO2 have been trapped in sedimentary rocks for hundreds of thousands of years. Sponsored by Shell, the team drilled deep down below the surface into one of these natural CO2 reservoirs to recover samples of the rock layers and the fluids confined in the rock pores.
The team studied the corrosion of the minerals comprising the rock by the acidic carbonated water, and how this has affected the ability of the cap rock to act as an effective trap over geological periods of time. Their analysis studied the mineralogy and geochemistry of cap rock and included bombarding samples of the rock with neutrons at a facility in Germany to better understand any changes that may have occurred in the pore structure and permeability of the cap rock.
They found that the CO2 had very little impact on corrosion of the minerals in the cap rock, with corrosion limited to a layer only 7cm thick. This is considerably less than the amount of corrosion predicted in some earlier studies, which suggested that this layer might be many metres thick.
The researchers also used computer simulations, calibrated with data collected from the rock samples, to show that this layer took at least 100,000 years to form, an age consistent with how long the site is known to have contained CO2.
The research demonstrates that the natural resistance of the cap rock minerals to the acidic carbonated waters makes burying CO2 underground a far more predictable and secure process than previously estimated.
"With careful evaluation, burying carbon dioxide underground will prove very much safer than emitting CO2 directly to the atmosphere," says Bickle.
The Cambridge research into the CO2 reservoirs in Utah was funded by the Natural Environment Research Council (CRIUS consortium of Cambridge, Manchester and Leeds universities and the British Geological Survey) and the Department of Energy and Climate Change.
The project involved an international consortium of researchers led by Cambridge, together with Aarchen University (Germany), Utrecht University (Netherlands), Utah State University (USA), the Julich Centre for Neutron Science, (Garching, Germany), Oak Ridge National Laboratory (USA), the British Geological Survey, and Shell Global Solutions International (Netherlands).
Jennifer Hayward | EurekAlert!
From volcano's slope, NASA instrument looks sky high and to the future
27.04.2017 | NASA/Goddard Space Flight Center
Penn researchers quantify the changes that lightning inspires in rock
27.04.2017 | University of Pennsylvania
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
27.04.2017 | Life Sciences
27.04.2017 | Physics and Astronomy
27.04.2017 | Earth Sciences