̽��ֱ�� of Cambridge - Mike Bickle

Carbon capture: universities and industry work together to tackle emissions

sc604 — Wed, 25 Oct 2017 07:12:18 +0000

̽��ֱ��world is not going carbon-free any time soon: that much is clear. Developed and developing countries alike rely on fossil fuels for transport, industry and power, all of which release CO₂ into the atmosphere. But as sea levels rise, ‘unprecedented’ weather events become commonplace and the polar ice caps melt, how can we balance our use of fossil fuels with the imperative to combat the catastrophic effects of climate change?

“Everything suggests that we won’t be able to stop burning carbon-based fuels, particularly in rapidly developing countries like India and China,” says Professor Mike Bickle of Cambridge’s Department of Earth Sciences. “Along with increasing use of renewable energy and improved energy efficiency, one way to cope with that is to use carbon capture and storage – and there is no technical reason why it can’t be deployed right now.”

Carbon capture and storage (CCS) is a promising and practical solution to drastically reducing carbon emissions, but it has had a stilted development pathway to date. In 2015, the UK government cancelled a £1 billion competition for CCS technology six months before it was due to be awarded, citing high costs. Just one year later, a high-level advisory group appointed by ministers recommended that establishing a CCS industry in the UK now could save the government and consumers billions per year from the cost of meeting climate change targets.

CCS is the only way of mitigating the 20% of CO₂ emissions from industrial processes – such as cement manufacturing and steel making, for which there is no obvious alternative – to help meet the world’s commitments to limit warming to below 2^oC. It works by trapping the CO₂ emitted from burning fossil fuels, which is then cooled, liquefied and pumped deep underground into geological formations, saline aquifers or disused oil and gas fields. Results from lab-based tests, and from working CCS sites such as Sleipner in the North Sea, suggest that carbon can be safely stored underground in this way for 10,000 years or more.

“ ̽��ֱ��big companies understand the science of climate change, and they understand that we’ve got to invest in technologies like CCS now, before it’s too late,” says Dr Jerome Neufeld of Cambridge’s Department of Applied Mathematics and Theoretical Physics, and Department of Earth Sciences. “But it’s a tricky business running an industry where nobody is charging for carbon.”

“Everyone always wants the cheapest option, so without some form of carbon tax, it’s going to be difficult to get CCS off the ground at the scale that’s needed,” says Bickle. “But if you look at the cost of electricity produced from gas or coal with CCS added, it’s very similar to the cost of electricity from solar or wind. So if governments put a proper carbon charge in place, renewables and CCS would compete with each other on a relatively even playing field, and companies would have the economic incentive to invest in CCS.”

Bickle and Neufeld are following discussions about CCS closely because, along with collaborators from Stanford and Melbourne Universities, they have recently started a new CCS project with the support of BHP, one of the world’s largest mining and materials companies.

̽��ֱ��three-year project will develop and improve methods for the long-term storage of CO₂, and will test them at Otway in southern Australia, one of the largest CCS test sites in the world. Using a mix of theoretical modelling and small-, medium- and large-scale experiments, the researchers hope to significantly increase the types of sites where CCS is possible, including in China and developing economies.

In most current CCS schemes, CO₂ is stored in porous underground rock formations with a thick layer of non-porous rock, such as shale, on top. ̽��ֱ��top layer provides extra insurance that the relatively light CO₂ will not escape.

̽��ֱ��new research, which will support future large-scale CO₂ storage, will consider whether CO₂ could be effectively trapped without the top seal of impermeable rock, meaning that CCS could be deployed in a wider range of environments. Their research findings will be made publicly available to accelerate the broader deployment of CCS.

“We are seeing a growing acknowledgement from industry, governments and society that to meet emissions reductions targets we are going to need to accelerate the use of this technology – we simply can’t do it quickly enough without CCS across both power generation and industry,” says BHP Vice President of Sustainability and Climate Change, Dr Fiona Wild. “We know CCS technology works and is proven. Our focus at BHP is on how we can help make sure the world has access to the information required to make it work at scale in a cost effective and timely way.”

During the project, Stanford researchers will measure the rate at which porous rock can trap CO₂ using small-scale experiments on rock samples at reservoir conditions, while the Cambridge researchers will be using larger analogue models, in the order of metres or tens of metres. ̽��ֱ��Melbourne-based researchers will use large-scale numerical simulations of complex geological settings.

“One of the things this collaboration will really open up is the ability to deploy CCS almost anywhere,” says Neufeld, who is also affiliated with Cambridge’s Department of Earth Sciences and the BP Institute. “We know that CO₂ can be safely trapped in porous rock with a seal of shale on top, but the early results from Otway have shown that even without the impenetrable seal, CO₂ can be trapped just as effectively.”

When CO₂ is pumped into underground saline aquifers, it is in a ‘super-critical’ phase: not quite a liquid and not quite a gas. ̽��ֱ��super-critical CO₂ is less dense than the salt water, and so has a tendency to run uphill, but it’s been found that surface tension between the salt water and the rock is quite effective at pinning the CO₂ in place so that it can’t escape. This phenomenon, known as capillary trapping, is also observed when water is held in a sponge.

“ ̽��ֱ��results from Otway show that if you inject CO₂ into a heterogeneous reservoir, it will mix with the salt water and capillary trapping will pin it there quite effectively, so it opens up a much broader range of potential carbon storage sites,” says Bickle.

“However, we need to start deploying CCS now, and the biggest challenges we face are economics and policy. If these prevent us from doing anything until it’s too late, and we’re at a stage when we’d have to start capturing carbon directly from the atmosphere, it will be far more expensive. By not starting CCS now, we’re building false economies.”

An international collaboration between universities and industry will further develop carbon capture and storage technology – one of the best hopes for drastically reducing carbon emissions – so that it can be deployed in a wider range of sites around the world.

We need to start deploying CCS now, and the biggest challenges we face are economics and policy. If we’re at a stage when we’d have to start capturing carbon directly from the atmosphere, it will be far more expensive.

Mike Bickle

Jerome Neufeld

Modelling CCS

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Carbon dioxide can be stored underground for ten times the length needed to avoid climatic impact

jeh98 — Thu, 28 Jul 2016 09:20:26 +0000

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.

̽��ֱ��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 principle investigator Professor Mike Bickle, Director of the Cambridge Centre for Carbon Capture and Storage at the ̽��ֱ�� 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.”

̽��ֱ��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 lead author Dr Niko Kampman.

“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.

̽��ֱ��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.

̽��ֱ��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.

̽��ֱ��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.

̽��ֱ��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.

̽��ֱ��project involved an international consortium of researchers led by Cambridge, together with Aarchen ̽��ֱ�� (Germany), Utrecht ̽��ֱ�� (Netherlands), Utah State ̽��ֱ�� (USA), the Julich Centre for Neutron Science, (Garching, Germany), Oak Ridge National Laboratory (USA), the British Geological Survey, and Shell Global Solutions International (Netherlands).

Reference:

N. Kampman, et al. "Observational evidence confirms modelling of the long-term integrity of CO2-reservoir caprocks" Nature Communications 28 July 2016.

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.

With careful evaluation, burying carbon dioxide underground will prove very much safer than emitting CO2 directly to the atmosphere

Mike Bickle

Dr Niko Kampman

Image shows a cold water geyser driven by carbon dioxide erupting from an unplugged oil exploration well drilled in 1936 into a natural CO2 reservoir in Utah.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Taking the long view on climate change

bjb42 — Sat, 01 Sep 2007 15:53:42 +0000

̽��ֱ��Earth’s climate has always changed and no doubt always will. However, this alone does not tell us very much about the climate system: we need to be able to say exactly how and why climate can change. Today this requirement has been brought to the fore by the prospect of human-induced global climate change resulting largely from greenhouse gas emissions that arise from our massive and growing appetite for fossil fuels. Thousands of scientists are now striving to predict how a sharp rise in greenhouse gas concentrations will affect the entire climate system, including the ecosystems and societies that it supports. But how can we be sure about our theories of climate change, let alone our theories of ecosystem or market response? Just how important are greenhouse gases in controlling global climate? And what are the timescales and thresholds of climate adjustment? These are just some of the urgent questions that have been raised by the prospect of anthropogenic climate change.

To help answer such questions we can look to the past, at how the Earth’s climate evolved prior to the relative stability that human society has so far enjoyed. Researchers in the Department of Earth Sciences are taking up this challenge, using marine sediments as their lens into the past, and as a guide to the future.

Palaeoclimatology

̽��ֱ��study of past climate change – palaeoclimatology – aims to reconstruct what has happened in the past, in the oceans, on the land, in the atmosphere and in ecosystems, and to infer how the global climate system works ‘as a whole’. In the last 20 years of palaeoclimate research, three major questions have emerged that are particularly relevant to modern climate change. First, how did changes in solar radiation (insolation) and atmospheric carbon dioxide (CO2) conspire to trigger massive global climate upheavals such as the glacial–interglacial (‘ice-age’) climate cycles? Second, what regulates atmospheric CO2 concentrations under changing climatic conditions, and what roles can we ascribe to marine biological productivity or ocean circulation changes in particular? And third, how abruptly can regional climate change and with what repercussions for the rest of the world?

All of these questions are interconnected of course, although each bears on a different aspect of the climate system’s ability to pace and amplify climate perturbations through sensitive ‘feedback’ processes.

Past climate by proxy

A central aspect of palaeoclimate reconstructions is the ‘proxy’ character of our observations. Because scientists cannot measure past ocean temperatures directly, they must measure the impacts of past temperature changes instead, usually based on temperature-sensitive organisms or temperature-sensitive chemical constituents in their shells or skeletons.

As a palaeoceanographer, Dr Luke Skinner specifically makes use of marine sediments as a window into the past. Among the many advantages of using marine sediments are that they can be obtained from nearly two thirds of the Earth’s surface, they generally provide unbroken and often very high-resolution records of past conditions, and they contain a diversity of constituents that can be analysed, from tiny fossil shells to grains of sand dropped by passing icebergs.

To reconstruct past climate change, Dr Skinner collects and studies the fossil calcite shells of foraminifera – single-celled blobs of protoplasm – that have accumulated on the sea floor. Using the shells of these tiny creatures, Dr Skinner has been able to generate detailed records of temperature change, both at the sea surface and in the ocean interior. In combination with ice-rafted debris and oxygen- and carbon-isotope records, these reconstructions have helped to demonstrate that the North Atlantic region experienced very intense and abrupt climate swings in the past, involving massive glacier surges as well as drastic changes in the deep ocean circulation system and the Gulf Stream. It has also been possible to show that these same changes in the Atlantic Ocean’s circulation were accompanied by a ‘see-saw’ in temperatures across the hemispheres, with heat pooling in the South to the extent that it was not efficiently delivered to the North. Based on records such as these it is now clear that global change can be heterogeneous and can occur too suddenly to be presaged by obvious warnings.

Perspectives on the future

Although it is clear that no previous climate period can really serve as a blueprint for the future, important lessons can still be learned from the study of the past. One important example is the use of palaeoclimate data to guide the improvement of our climate simulation models. Because numerical and statistical models provide our only means for predicting future climate, it is imperative that they be as general as possible. Studies like those described here are helping to achieve this, by revealing the feedbacks, thresholds and characteristic timescales for climate adjustment, across a wide range of climatic contexts.

In the future, global CO2 levels will only be stabilised if we either drastically cut our emissions or identify, trigger or create a process that ‘mops up’ exactly as much CO2 as millions of consumers are able to produce each day (the basis of carbon capture). ̽��ֱ��history of climate change tells us that we are going to need as many one-way fluxes out of the atmosphere as we can muster if are going to compete with the ‘leak’ we have created in the Earth’s largest standing carbon reservoir, the solid Earth. We have much to learn about the climate system, both for our own sake and for the sake of knowledge itself.

For more information, please contact the author Dr Luke Skinner (luke00@esc.cam.ac.uk) at the Department of Earth Sciences.

Cambridge Earth Scientists are contributing to our understanding of the climate system by studying the history of climate change recorded in sediments deposited on the sea floor.

Studies like those described here are helping to achieve this, by revealing the feedbacks, thresholds and characteristic timescales for climate adjustment, across a wide range of climatic contexts.

Irargerich from Flickr

Melting is your destiny

Carbon capture

Whenever fossil fuel (coal, oil or gas) is burnt, carbon is released as CO2 into the atmosphere, where it traps the Sun's heat. Can we counteract this build-up by capturing and storing CO2? Any solution would require storage of many millions of tonnes reliably and possibly for up to 10,000 years. Compressing and injecting CO2 into deep geological formations could provide the answer. ̽��ֱ��presence of oil, gas and natural CO2 trapped in reservoirs underground for millions of years demonstrates that storage of CO2 is feasible. At the Sleipner Oil Field in the Norwegian sector of the North Sea, CO2 is already being separated from natural gas and re-injected at about 1 km depth below the sea surface. ̽��ֱ��CO2 rises through the sandy earth before spreading out below a series of thin mudstones beneath the thick overlying mudstone. A collaborative research project between Professor Mike Bickle in the Department of Earth Sciences and Professor Herbert Huppert in the Institute of Theoretical Geophysics has been modelling the spread of these accumulations to work out how much CO2 is trapped and to understand the flow of CO2 in the reservoir. A particular challenge is to predict the behaviour of the stored CO2 over time to determine the safety of long-term CO2 storage in this way. ̽��ֱ��benefits are clear, as Professor Bickle explains: 'CO2 storage is a feasible, politically achievable and relatively inexpensive way for dealing with the problem of increasing atmospheric CO2 levels. For more information, please contact Professor Mike Bickle (mb72@esc.cam.ac.uk) at the Department of Earth Sciences.

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