Removing Carbon Dioxide from the Atmosphere

In October 2018 the Intergovernmental Panel on Climate Change (IPCC) issued a Special Report updating the occurrence of weather and climate extremes since 2014.  It compared the effects of an increase in the long-term global average temperature of 2°C (3.6°F) with that of a 1.5°C (2.7°F) increase, referenced to the pre-industrial climate, on humanity and the natural world.  Its conclusions emphasized the necessity of limiting warming to the more stringent goal of 1.5°C to avoid severe harms to our planet by later in this century.

In its models the Report used four climate scenarios.  All the scenarios admit that global emission rates, to greater or lesser extents, will not be reduced adequately, or fast enough, to limit the temperature increase without deployment of technologies to remove carbon dioxide (CO₂), a principal greenhouse gas, from the atmosphere.  CO₂ results from humanity’s burning of fossil fuels.  CO₂ removal, also called “negative emissions”, would compensate for any failure to reduce direct emission rates of greenhouse gases from their original sources.  An example of one of the scenarios is shown here:

Net emission rates per year throughout the remainder of the 21^st century (Blue line), representing the result of the following contributions.  Grey shading , annual CO₂ emission rates from burning fossil fuels; Brown shading , annual CO₂ emission rates or reductions from agriculture and forestry;  Gold shading , annual CO₂ reduction rates from bioenergy with carbon capture and storage.

Source: IPCC Special Report, Summary for Policymakers https://www.ipcc.ch/site/assets/uploads/sites/2/2018/07/SR15_SPM_High_Res.pdf

 

Large scale CO₂ removal is considered in an article by Lu and coworkers, entitled “Gasification of coal and biomass as a net carbon-negative power source for environment-friendly electricity generation in China”, released April 9, 2019 in Proceedings of theNational Academy of Sciences.

 

As an aside, the importance of scrutiny of scientific reports by anonymous peer reviewers is brought out in this article, for the authors thank “…the reviewers for valuable and constructive suggestions. We are particularly grateful to one of the reviewers for her/his painstaking efforts to critique several versions of the manuscript and for questions raised that contributed to an important improvement in the final presentation.”  Peer review remains the gold standard for assessing the worthiness of scientific reports.

 

The authors recognize the wide availability of plant waste in China.  In Combination with the widespread use of coal already in place in the country, the authors model using various mixtures of agricultural Biomass with coal in an efficient technology for generating Electricity, coupled with use of process heat to drive CO₂ Capture and Storage (CBECCS).  The model extends over the long-term lifetime of such equipment. 

 

The authors find:

• Crop waste proportions greater than 35% mixed with coal would yield net-zero emission of CO₂ evaluated over the service lifetime, moving toward significant levels of negative emissions as the crop waste proportion increases;
• The cost of generating electricity over the lifetime, including the equipment costs, is US$ 0.092/kwh (kilowatt-hour);
• As China moves toward a national policy of imposing a price on carbon in the near future, a cost of US$52/ton would render CBECCS competitive with China’s current pulverized coal power plants; and
• Conventional pollutants widely acknowledged to arise from coal-fired electricity generation and vehicle exhaust (oxides of sulfur, oxides of nitrogen, black soot and PM_2.5 aerosols (2.5-micrometer or smaller particles detrimental to human health)) are significantly reduced by CBECCS. Severe urban smog in China has been a major driver to curb use of fossil fuels because they produce high levels of these pollutants.  CBECCS would contribute significantly to improving public health in the country.

CBECCS is especially feasible in China at the scale needed because the country is endowed with a very large geological storage capacity for the CO₂ produced in the carbon capture and storage portion of the technology.  The model projects that only 0.036% of known geological formations suitable for storage would be needed each year; this capacity is widely distributed geographically across China.

The article lists barriers to implementing CBECCS technology at scale, including

• Deploying and integrating the many component advanced technologies to ensure smooth operation, and to extend it on a scale needed to make a significant contribution to reducing net emission rates;
• Implementing infrastructure to enable delivery of waste biomass to the CBECCS facilities at the scale and regularity needed; and
• Infrastructure and operating costs evaluated for CBECCS are more than double those for current coal generation. These costs can become competitive as China’s carbon pricing regime becomes operational as planned in 2020.

CO₂ Removal from the atmosphere (ambient air) in a pilot project in Canada.

The New York Times published a report on April 8, 2019 describing new technology for CO₂ removal from ambient air and preparing it for geological storage underground.  The company doing this work, Carbon Engineering, has attracted funding from oil companies Chevron and Occidental Petroleum, and the large Australian mining company BHP, as well as others.  Recently the company raised US$68 million.  The oil companies, sensitive to enterprise risk as renewable energy threatens to displace gasoline for transportation, are interested in carbon removal technologies such as being developed by Carbon Engineering as a way potentially to offset CO₂ emissions due to use of their products.  Fiona Wild, BHP’s vice president for sustainability and climate change states “This is about recognizing that climate change poses significant risk to all economic sectors.  Climate change is … a business risk that requires a business response.”  Similarly, Dieter Helm, professor of energy policy at Oxford University, says “If money is being spent on research and development to develop ways to sequester carbon, that is a good thing.”

A schematic flow diagram of Carbon Engineering’s technology is shown here:

Flow diagram for capturing the dilute CO₂ gas present in ambient air (1, left), and preparing it as pure CO₂ (upper arrow at stage 3, Calciner) for storage underground or for use in chemical processes to synthesize fuels.  The fan units include an alkaline solution that serves to absorb most of the ambient CO₂.  As shown at the right, the alkaline substance needed to absorb the CO₂ is regenerated and ultimately fed back to absorb more CO₂ in the fan units.

Source: New York Times, https://www.nytimes.com/2019/04/07/business/energy-environment/climate-change-carbon-engineering.html.

 

So far, according to the report, the pilot plant has produced the calcium carbonate pellets in stage 2.  Calcium carbonate is the mineral limestone.  If heated to a high temperature in the calciner the limestone would release pure gaseous CO₂ for collection.  

 

Discussion

 

An alarming impression of fossil fuel consumption by humanity since the beginning of the industrial revolution is shown here:

Global annual use of the three fossil fuels (gray, coal; orange, crude oil; teal, natural gas) shown from 1800 (before the industrial revolution) to 2017, in energy units of terawatt-hours.  For 2017 the energy from each fuel translates to approximately 5.4 billion metric tons/yr of coal; 30 billion barrels/yr of oil; and 122 billion cubic feet/yr of natural gas (using conversions provided at https://www.unitjuggler.com/convert-energy-from-kgSKE-to-Wh.html). Source: https://ourworldindata.org/fossil-fuels

 

These fuels, when burned, yield man-made CO₂ in comparably large amounts.  Since planetary warming is determined by the total amount of CO₂ that we have added to our atmosphere, one need only look back to this graphic and in her mind’s eye estimate the total area under the curve shown.

 

This result should impress the reader about the daunting task facing implementation of negative emission technology.  Even achieving fractional depletion of added CO₂, as suggested in the first graphic above, is a huge challenge.  A mitigating factor is that humanity has perhaps 1-2 decades to begin carbon removal at scale; in the first graphic above significant negative emissions (Gold shading) aren’t apparent until about 2040.

 

Carbon capture and storage technology at a less sophisticated level than presented here by Yu and coworkers has been known for more than a decade.  Even so, there are only a handful of such projects, operating as pilots, around the world.

 

Occidental Petroleum, and other petroleum extracting companies, already use CO₂, injecting it into operating oil wells to pressurize the crude oil and enable extracting more.  Thus CO₂ is being injected underground to produce more oil, which when refined and burned produces fresh CO₂!  Occidental believes this cycle could help make its operations carbon-neutral.

 

Carbon Engineering, and Chevron, in contrast, envision using CO2 to synthesize fuels, a process that requires the input of at least as much energy as was released when a fossil fuel was burned and yielded CO₂. Carbon Engineering plans to use renewable energy to generate hydrogen gas needed for making the synthetic fuel.  Thus a competition is implied, wherein a choice must be made between using renewable energy to serve the public directly versus using it in industrial processes to regenerate a carbon-containing fuel. 

 

As with the CBECCS process described by Lu and coworkers, the hurdle to achieve operation of the direct CO₂ removal at scale, as envisioned by Carbon Engineering, is high.  A single Carbon Engineering plant could remove 1 million tons of CO₂ per year.  This is a tiny fraction, about 0.003%, of the CO₂ produced by humanity around the world per year.

 

Both technologies described here are believed by the protagonists to become price competitive as the scale of operations increases and as use of fossil fuels falls due to market pressure if and when a meaningful price on carbon fuels is implemented.  In the meantime governmental resources and the private sector will drive the development of these technologies.

© 2019 Henry Auer

Carbon Capture and Storage Investment Is Strongly Needed

Summary.  Increased burning of fossil fuels leads to greater global warming, resulting in disasters from extreme weather events.  These carry heavy financial burdens.  An important, but unproven technology for mitigating global warming is removal and burying waste carbon dioxide using carbon capture and storage.  Worldwide research, development and demonstration, while active, is considered inadequate to lead to industrial implementation by about 2020.  Expanded support by government funding and private investment is needed to attain commercialization of this technology.  Considered as a zero-sum undertaking, current investment expenditures in capture and storage would abate future expenses of responding to extreme weather disasters.

Introduction.

Increased Use of Fossil Fuels.  Energy use around the world is projected to continue increasing in coming decades, due mostly to use by developing countries, especially China and India, as they progress toward becoming advanced industrialized nations themselves.  Most of this energy demand will still be satisfied by burning fossil fuels (coal, natural gas and petroleum) although the share provided by renewable sources is increasing.

Stronger Greenhouse Effect.  This increased burning of fossil fuels is directly responsible for the ever-increasing content of the greenhouse gas carbon dioxide (CO₂) in the earth’s atmosphere.  This has led to an increase in the long-term global average temperature, whose trend over time coincides with the trend of increasing use of fossil fuels and emission of CO₂.

Climate Models Confirm Man-Made Greenhouse Gases Are Responsible for Warming.  Climate models that include the extra CO₂ from fossil fuels over the past 50 years successfully reproduce the observed rise in global temperature.  But if the extra CO₂ is omitted, the predicted temperature falls below the observed values.  This shows, first, that the climate models correctly predict past events, and second, that past temperature increase is due to the extra CO₂ from fossil fuels.

Climate Models Predict Increased Occurrence of Extreme Weather Events.  Since the above results validate climate models, they can be used to project future climate developments.  The United Nations-sponsored Intergovernmental Panel on Climate Change (IPCC) projects increased occurrences of extreme weather events, such as heat waves and heavy rain, as more greenhouse gases accumulate in the atmosphere.  These in turn lead to harms and damages to human life, including wildfires in forests, flooding, droughts and decreased agricultural production.

The Effects of Long-Term Temperature Increases Are Worsening 

Several recent articles point up the unprecedented effects of warming of the planet.  Their occurrence is consistent with projections by climate scientists that extreme weather events will increase in number and/or severity.  These are given under Details at the end of this post.

Carbon Capture and Storage

Carbon Capture and Storage, or Carbon Capture and Sequestration (CCS), refers to technologies that remove most of the CO₂ from power plant exhaust before the gas is dispersed into the atmosphere.  The captured CO₂ is then transported to a suitable site, and injected for permanent storage underground in impermeable geological formations (see this previous post).  The storage must truly be permanent, lasting hundreds to thousands of years, in order for it contribute to reducing atmospheric greenhouse gas levels.  If implemented on an industrial scale world-wide, CCS could make a major contribution to reducing the rate of warming of the planet.

The Nations of the World Have Failed to Limit Greenhouse Gas Emissions.  The nations of the world have so far not been able to agree on a follow-on agreement to the Kyoto Protocol limiting greenhouse gas emissions, which expires at the end of 2012.  Domestically in the U. S., there is no legislated national policy for reducing emission of greenhouse gases.  The U. S. Environmental Protection Agency (EPA), however, has recently issued regulations limiting emissions from large sources.  EPA and the National Highway Traffic Safety Administration have issued rules increasing vehicle fuel efficiency.

To date, only the European Union, the United Kingdom and the American state of California have implemented economy-wide plans to reduce greenhouse gas emission by at least 80% by 2050. 

CCS Is Critical to Decarbonize Energy Production by 2050.  A nonofficial report issued by the California Science and Technology Council (CSTC) recognized that existing technologies could not accomplish California’s objective (see this post).  Rather, CSTC proposed that vehicle transportation had to shift from burning fossil fuels to electricity, and that consequently electricity generation had to be essentially completely decarbonized.  CSTC’s report relies heavily on industrial-scale CCS to attain this objective.

The European Union likewise recognizes the crucial role to be played by CCS in achieving its decarbonization goals.

Unfortunately, CCS at present is only an experimental technology, not a proven one (see this post).  The Carbon Sequestration Leadership Forum (CSLF) is an international consortium of 25 nations directed toward research, development and demonstration (RD&D), and implementation, of CCS.  According to its Technology Road Map 2011 (TRM) , there are fewer than 100 planned or operating CCS experimental projects worldwide.  These vary in size, the particular technology being studied, and the nature of the geological formation chosen for injection.  Of the 100 projects, only four are operational commercial scale installations with validated assessment systems, meaning that the scale of storage is at an industrially-feasible level, in the range of about 1 million tons of CO₂ stored per year.  Additional projects worldwide are planned or in development at pilot to industrial scales.  

There are about 40 such pilots in the U. S. and Canada.  Only seven use geological storage, and more than half are devoted to “beneficial reuse” (referring to EOR; see below).

China is currently the nation emitting the highest amount of CO₂ in the world, and its emission rate is projected to grow significantly in future decades because of its dynamic economic expansion.  Even so, the TRM identifies only four pilot scale projects in China, not all of which are directly related to capturing and storing CO₂ emissions from power generation.

In the U. S., Chemical and Engineering News (C&EN), a publication of the American Chemical Society, reported on July 16, 2012 that the U. S. Department of Energy (DOE) is supporting 8 industrial and electric utility CCS pilots for startup between 2013 and 2017.  DOE is contributing US$2.8 billion out of a total investment of US$10.0 billion for 7 of the 8 pilots.

Many CCS projects cannot be considered true tests of new storage technology, because the CO₂ is being injected into pre-existing fossil fuel depositories which clearly have not leaked their holdings for millions of years.  Furthermore, other pilots are using the CO₂ in the previously known process of Enhanced Oil Recovery (EOR), in which the gas is used to force additional crude oil out of a well that otherwise would be nearing the end of its useful life.  Since new fossil fuels are being harvested by EOR, this method cannot be considered to contribute to the net removal of CO₂ from the atmosphere, which is the intended purpose of CCS.  Nevertheless, the CSLF, in the Second Update to its Strategic Plan, has expanded its objectives to include industrial utilization of captured CO₂, including EOR but also other industrial uses as well.

Gaps in Knowledge and Technological Capabilities in CCS

The TRM identifies several unknown factors or insufficiencies in the present state of the technology that need to be addressed under RD&D objectives (see its Module 3).  These fall into the three main processes for CCS, first, new technologies for capturing CO₂; second, transportation of CO₂ from the site of its capture to the storage site; and third, technologies for identifying and developing permanent geological storage sites.  Zoback and Gorelick recently raised the strong possibility that injecting industrial volumes of CO₂ into geological formations carries a significant risk of inducing seismic events that would allow  leakage back to the surface. 

Zoback and Gorelick calculated that worldwide, CCS has to dispose of 3.5 billion tons of CO₂ produced per year.  This would require that worldwide about 3,500 industrial-scale injection facilities be operational by mid-century, which averages to about 85 facilities added per year.  RD&D on scaling up is critical for current as well as to-be-developed technologies, and to optimize economies of scale.  RD&D projects need to be operational by 2020 or earlier. 

The Need for Government Support 

The High Cost of RD&D. Each CSS pilot project is a major industrial operation requiring large investments of capital and long lead times for implementation.  The TRM identifies several governments, including the U. S., that together have committed more than US$26 billion for RD&D, which should enable between 19 and 43 RD&D projects by 2020.  It points out, however, that “the time, cost, and resources required…for multi-billion investment decisions are often heavily underestimated by the funders, be they governments or other CCS project proponents.” 

The U. S. RD&D Effort Is Diminishing In Recent Years.  The TRM notes that the American Recovery and Reinvestment Act (the “stimulus” of 2009) allowed for US$3.4 billion for CCS projects.  Unfortunately this fiscal stimulus has reached its end and is not being renewed. The DOE Fossil Energy Research and Development Program appropriation amounts are shown in the table below; the decrease from 2010 to the request for 2012 is 31%. 

Fiscal Year	Expenditure or Congressional Request, US$ millions
2009	692
2010	660
2011	672 (continuing resolution)
2012	453 (Congressional request)

Sources: TRM (http://www.cslforum.org/aboutus/index.html?cid=nav_about);

Department of Energy FY 2012 Congressional Budget Request (http://www.cfo.doe.gov/budget/12budget/Content/FY2012Highlights.pdf). 

High Costs And Other Factors Have Resulted in Cancellations of RD&D Projects.  The TRM reports that, of the projects listed in its preceding TRM dated 2009, several were canceled by 2011, and more than half underwent budget contractions.  This has led to delaying of timelines and the potential for further cancellations.  Principal reasons for these reductions included lack of government funding and “changed economics” (which this writer interprets as cost increases arising from updates and review).  Itemization of some canceled projects is given below, in Details. 

Conclusions 

Mankind’s projected increase in use of fossil fuels for energy in coming decades will lead to increased world-wide average temperatures.  This trend is expected to increase the number and severity of extreme weather events, leading to serious economic and societal harms to affected populations around the world.  These harms are accompanied by massive economic costs that ultimately are borne by the tax-paying public and by higher insurance policy premiums. 

It appears not practical at present to reduce emissions of greenhouse gases by cutting back on use of fossil fuels to the extent needed.  Rather, an important aspect of abating emissions would be the development and widespread deployment of carbon capture and storage technology added on to fossil fuel-powered energy providers. 

Yet CCS is an experimental technology not yet proven to be capable of or adequate for decarbonizing energy generation at an industrial scale.  One estimate proposes a need for about 3,500 industrial-scale CCS facilities world-wide by 2050. 

RD&D and industrial implementation of CCS requires investment in large scale experimental and pilot projects having long lead times.  Currently political environment generally is not sufficiently supportive of such efforts.  Large scale support from the governments of both developed and developing countries, in collaboration with private sector industrial investment, is needed to vindicate and validate CCS.  Yet generally at present the trend of both political and financial support is diminishing rather than growing.  

It is recommended that expanded planning be started right away for CCS development and deployment.  This requires long-term commitments at both the political level and in fiscal and financial support.  Such expenditures now would lead to economies of scale as CCS is implemented. 

Globally, the expenses borne by society in response to the harms inflicted by the worsening effects of global warming, on the one hand, and the expenses of needed investment in greenhouse gas abatement technologies, on the other, are the elements in a zero-sum energy undertaking.  The more investment undertaken now for abatement would be rewarded by minimizing the economic damages inflicted by extreme weather events in the future.  It behooves the nations of the world to make the necessary investments for the betterment of their citizens.

                             ******************************************      

Details on The Effects of Long-Term Temperature Increases 

On July 25, 2012 the New York Times reported that in only four days (July 8 to July 12) the extent of the surface of the ice sheet covering Greenland that was melting grew from 40% to 97%, a phenomenon never seen in recent times.  It is in accord with two recent ice sheet calving events, involving sections twice and four times the size of the island of Manhattan, respectively. 

In the U. S., the extreme drought in the Midwest has severely affected agricultural yields, the Times reported on July 26, 2012.  So far, this year is the hottest year on record in the U. S.  More than 50% of the country was classed as suffering moderate to extreme drought in June 2012 , the worst in nearly 60 years.  The drought reduces the corn crop, which impacts livestock and poultry production as well as production of corn ethanol.  As a result food prices in 2013 are expected to increase 4-5%, affecting the economic wellbeing of all Americans. 

Also on July 26 the Times reported that extreme heat was damaging a large number of infrastructure elements, including roads, subways and electric utilities. 

The large number and severity of forest wildfires experienced in the western U. S. in 2012 is to be expected as global temperatures rise, according to a teleconference of climate scientists convened the last week in June, 2012.  Prof. Michael Oppenheimer, a member of the IPCC, stated “the disastrous fires we’ve seen fit into a pattern of increased fire risk … it’s a vivid image of what we can expect more of as the world warms more”.  The Waldo Canyon fire in Colorado in June 2012 destroyed nearly 350 homes and burned over 17,000 acres (6,880 hec).

James Hansen, a pioneering climate scientist, has warned of the dangers of global warming for several decades.  He and two colleagues analyzed recent weather extremes by statistical probabilities.  They conclude “the distribution of seasonal mean temperature [deviations from historical averages] has shifted toward higher temperatures and the [size of these deviations] has increased. ….Extreme heat waves, such as that in Texas and Oklahoma in 2011 and Moscow [Russia] in 2010, [are attributed to] global warming, because their likelihood was negligible prior to the recent rapid global warming.”

More generally, Coumou and Rahmstorf (Nature Climate Change 2, 491-496 (2012); doi:10.1038/nclimate1452) analyzed weather extremes from 2000 to 2011 around the world.  They conclude that events such as heat waves and/or drought, and heavy precipitation, are linked to mankind’s effect on the climate. 

Details on Cancellations of RD&D Projects.   

The Guardian on June 17, 2012 reported that the chief executive of Scottish and Southern Energy warned “CCS is…at the demonstration stage….We do not know that this technology will work”.  He called for UK government support at this demonstration phase of the project. 

The same article noted that another company, Scottish Power, working with Shell, abandoned CCS technology last year because it needed at least £1.5 billion (US$2.3 billion), higher than the UK government could support. 

Similarly, the Guardian reported on June 26, 2012 that Ayrshire Power (Scotland) abandoned its planned new CCS-fitted 1852 MW power plant because it feared it could not obtain funding from the UK and the European Commission. Several other UK pilot projects have been canceled in recent years, for both financial and technical reasons. 

C&EN reports that American Electric Power terminated its projected CCS pilot, an add-on to an existing coal-fired power plant.  A company officer stated “it is difficult to show any justification for carbon capture when Congress has taken no action and has [no future action planned]….A utility would be very reluctant to build a new power plant with CCS. There is no known technology that can do it.”

© 2012 Henry Auer

Induced Earthquakes A Potential Hazard for Geological Storage of Carbon Dioxide

Summary.  The world is burning fossil fuels at an ever-increasing rate, resulting in increased release of the greenhouse gas carbon dioxide into the atmosphere.  This results in an increase in the long-term globally averaged temperature.  Consequently there is great interest in developing carbon capture and storage in geological repositories to help abate the increase in atmospheric carbon dioxide.

Zoback and Gorelick have just published a paper that a) emphasizes the vast amounts of carbon dioxide that need to be captured and stored, and b) analyzes in detail the likelihood that small-scale earthquakes may be induced at the injection sites because of the increased fluids introduced into the storage sites.  Their concern is that even small to medium scale earthquakes may destroy the integrity of the sites, leading to significant leakage of carbon dioxide back into the atmosphere.  They conclude that extensive deployment of carbon storage involves considerable risk.

Background.  Zoback and Gorelick have analyzed the long-term geological storage of carbon dioxide (CO₂) as a means of permanently removing this greenhouse gas from the atmosphere by carbon capture and storage (CCS; see the next section).  First we present some introductory information on CCS. (Background on CCS may be found in this earlier post.)

The European Union (EU) has embarked on the only multinational program in the world, based on binding enacted policies, to reduce emissions below the emissions levels of 1990 by 20% by 2020, and by 80-95% by 2050 (the EU Roadmap; see this post).  Achieving such goals requires decarbonization of most energy sources.  The EU recognizes that a major portion of this reduction should come from use of CCS for large scale fixed sources involved in generating electricity. 

To begin research and development of CCS technology, the EU has selected six demonstration projects in six member countries, using differing capture and sequestration technologies.  The EU has committed EUR1 billion (US$1.25 billion) to them.  Variously, they range in size from one at 30 MW (to be scaled up to over 300 MW) to 900 MW, with most projects expected to capture about 90% of the emitted CO₂.  Storage will be in land-based or offshore saline aquifers, and depleted land-based or offshore gas fields.

In the U. S. the state of California is implementing a plan very similar to the EU’s Roadmap.  In a non-official report detailing how California might attain these goals, the California Science and Technology Council (CSTC) relies heavily on decarbonizing energy sources to the greatest extent possible (see this earlier post).  Electricity generation is to be decarbonized, to the extent that use of fossil fuels is maintained, by use of industrial-scale CCS, even though the report recognizes that this technology remains unproven.  Decarbonization of electricity generation is especially important because CSTC envisions use of electric vehicles to decarbonize transportation.

The U. S. Department of Energy (DOE) is sponsoring research on CCS, as reported in the Carbon SequestrationProgram: Technology Program Plan of the National Energy Technology Laboratory.  Its budget request for Fiscal Year 2011 was about US$140 million, with anticipated sharing by an equal amount from Regional Carbon Sequestration Partnerships with universities and corporations.  This budget has grown from about US$10 million in 2000.  Recent support from the American Recovery and Reinvestment Act of 2009 (the fiscal “stimulus”), included in the recent growth of this funding, is essentially exhausted at this time. All aspects of the various stages in capture, release and concentration, transportation and geological storage, as well as monitoring, verification and accounting, are being investigated at laboratory and small pilot scale.

Similar programs are also supported in the DOE Fossil Energy program.  Their requested budget for Fiscal Year 2013 is about US$276 million for CCS and Power Systems, which supports projects as large as industrial scale pilot projects.

Cautionary Analysis of CCS.  Zoback and Gorelick analyzed the dangers to maintenance of reservoir integrity in geological sequestration of CO₂, in a paper published in the Proceedings of the National Academy of Sciences, June 26, 2012, vol. 109, pp. 10164-10168 .  As background, the authors note:

·        CCS will be very costly;

·        in the U. S. use of coal for generating electricity produces about 2.1 billion metric tons of CO₂ a year, or about 36% of all U. S. emissions;

·        China’s emissions are about 3 times more than this from coal-fired generation, corresponding to about 80% of its emission rate;

·        annually, on a worldwide basis, CCS has to contend with 3.5 billion tons of CO₂, which requires injecting an amount of CO₂ underground roughly equal to the volume of all the oil extracted from oil wells worldwide;

·        this amount of injected CO₂ requires that worldwide about 3,500 functional industrial-scale injection facilities be operational by mid-century, averaged to about 85 facilities added per year; and

·        geological storage must remain faultlessly leak-tight in order to compare with freedom from emissions of renewable energy sources.

The authors include the following analyses:

o       The paper itemizes several instances of earthquakes apparently triggered by underground injection of liquids.  This can arise because many geological formations are already in states of unresolved stress, so that the relatively minor perturbation arising from fluid injection releases the stress in an earthquake.  The fluid in essence makes it easier for the stressed surfaces to slide over one another, which is the hallmark of an earthquake.  Zoback and Gorelick emphasize that it is not any land-based earthquake damage to human wellbeing that concerns them, but rather that even small earthquakes, likely not to produce damage to structures, are likely to damage the geological structures holding the pressurized CO₂.  CO₂ could then readily permeate to or near the surface, permitting release into the atmosphere and defeating the intent of the storage in the first place.  They present the results of calculations that even a small earthquake of Magnitude 4 could induce slippage of several cm. along a fault of about 1-4 km (0.6-2.4 mi).

o       In stressed geological formations, it is not only the pressure of injected CO₂ that is potentially hazardous, but also the rate of injection.  More rapid pressure buildup is more likely to trigger an earthquake event; the need to dispose of large volumes of CO₂ would be an incentive for high injection rates.

o       A widely known injection site is the Utsira formation of the Sleipner gas field in the North Sea.  About 1 million tons of CO₂ has been separated from natural gas and reinjected below ground every year, for the past 15 years.  There has been no earthquake activity to date.  The authors calculate that about 3,500 such sites would have to be identified and put into service to accommodate storage needs projected for 2050 (most of which would be needed right now, in fact).  The authors conclude “Clearly this is an extraordinarily difficult, if not impossible task” if only geologically suitable sites are to be used.

o       Depleted oil and gas wells, while seemingly attractive as potential injection sites, are not numerous enough to satisfy the need, and are not necessarily located conveniently for the need.

The authors conclude “multiple lines of evidence indicate that preexisting faults found in brittle rocks almost everywhere in the earth’s crust are subject to failure, often in response to very small increases in pore pressure. In light of the risk posed to a CO₂ repository by even small- to moderate-sized earthquakes, formations suitable for large-scale injection of CO₂ must be carefully chosen.”  Because of the extremely large volumes of CO₂ needing to be disposed of, the industrial-scale CCS needed will be “extremely expensive and risky for achieving significant reductions in greenhouse gas emissions”.

Certain CCS projects have been abandoned due to risk and lack of financing.  The very factors identified by Zoback and Gorelick are echoed in these two recent news reports. 

The Guardian on June 17, 2012 reported that Ian Marchant, chief executive of Scottish and Southern Energy, while still favoring CCS development, warned the British Parliament that a CCS project his company is undertaking is “the most risky project I’ll ever invest in….CCS is…at the demonstration stage….We do not know that this technology will work”.  He called for UK government support at this demonstration phase of the project.

The same article noted that another company, Scottish Power, abandoned CCS technology last year.  Together with Shell, the company evaluated it would need at least £1.5 billion (US$2.3 billion), and the UK government could not support such a funding level.

Similarly, theGuardian reported on June 26, 2012 that Ayrshire Power (Scotland) abandoned its planned new CCS-fitted 1852 MW power plant because it feared it could not obtain funding from the UK and the European Commission.  Nevertheless, the Scottish energy minister still strongly supports CCS development since it borders North Sea offshore CO₂ storage sites.

Rebuttals of Zoback and Gorelick’s warnings.  There has been response from the CCS community rebutting the serious concerns expressed by Zoback and Gorelick.  For example, two scientists were featured in the internet-based Carbon CaptureJournal (accessed June 27, 2012).

Dr. Malcolm Wilson, Chief Executive Officer, The Petroleum Technology Research Centre (PTRC), provided a detailed accounting of the experience gained at the Weyburn-Midale Project, an oil field storage development project in Saskatchewan, Canada, which it seems is an extended oil recovery project as well.  Storage has been under way there for 11 years, with a total of 21 million tonnes (metric tons) of CO₂ stored in that time.  Detailed research and characterization of the site has been undertaken throughout this time; indeed, seismic events with Magnitudes of -1 (extremely small) have been recorded.  Dr. Wilson considers this site now to be industrial scale, as 2.8 million tonnes of new CO₂, and more than 5 million tonnes when recycled CO₂ are included, have been injected; no earthquake activity or leakage has been identified.

PTRC is also conducting research on their Aquistore Project, for storage in saline aquifers.  Noting with approval that Zoback and Gorelick cite aquifers favorably because of their very large storage capacities, Dr. Wilson notes that the Aquistore Project will be the first industrial scale storage project, since it will receive CO₂ from a coal-fired power plant.

Dr. Bruce Hill, senior staff geologist at Clean Air Task Force (CATF) rebuts the concern over lack of integrity of storage sites due to earthquake activity by emphasizing the rate of CO₂ migration toward the surface, rather than the total amounts potentially released.  Dr. Hill emphasizes that there are many layers of rock structures, extending thousands of feet, overlaying injection sites, seeming to belittle the concerns of Zoback and Gorelick.  Dr. Hill feels that the examples cited by the authors are not representative.  He points out that “approximately 1 billion tons of CO₂ have been safely injected (and stored) in the process of enhanced oil recovery in the U.S. since the late 1970s, with no reported seismic incidents. In fact, there have been no earthquakes reported anywhere from saline CO₂ injections either”.

Dr. Hill concludes that CCS technology is “viable” and should play a significant role in potentially storing the very large amounts of CO₂ that need to be recovered to reduce atmospheric CO₂ accumulation.

George Peridas responded to the paper on the Natural Resources Defense Council Blog on June 22, 2012.  Mr. Peridas believes that Zoback and Gorelick raise valid issues, including whether CCS can cause earthquakes and whether such earthquakes could lead to leakage of the injected CO₂.  But in his opinion, the conclusions reached by the authors are more extensive than warranted by the evidence, for example with respect to the second issue, leakage.  He does not agree that an earthquake event would lead to migration of CO₂ all the way to the surface.  He believes that an experiment cited by the authors, performed on granite, a brittle mineral, is not representative of capstone layers anticipated in CCS, which would be more compliant, yet impermeable, shales.  In the case of existing fossil fuel geological reservoirs, large earthquakes have been known to occur without loss of the materials.  Mr. Peridas additionally cites Sally Benson (Stanford University and Lead Coordinating Author of the Underground Geological Storage Chapter in the Intergovernmental Panel on Climate Change Special Report on CCS) as stating that naturally care must be taken in choosing CCS injection sites, but that finding such sites should be feasible.

Discussion

Our earlier post, “Carbon Capture and Storage: A Needed yet Unproven Technology”, presented background information on the various technologies that may be employed in each phase of capturing CO₂, from the burning of fossil fuels for energy, to transporting the CO₂ to a storage site, and finally the actual storage process.   Many problems remain to make CCS industrially viable for utility-scale facilities.  Resolving these problems requires investment of large sums of money, worldwide, to arrive at practical CCS by about 2020.  Currently a relatively small number of demonstration and pilot projects are under way around the world.

The use of fossil fuels is projected to grow considerably in the coming decades around the globe, primarily in developing countries which will power their rapidly expanding economies with energy derived from burning fossil fuels.  This means that the annual rate of CO₂ emissions will continue expanding, and that the total accumulated concentration of atmospheric CO₂ likewise will continue increasing.  Even in developed countries having programs to abate CO₂ emissions at various stages of maturity, a major aspect of such abatement involves shifting transportation to electric power.  Thus the total demand for electricity is projected to grow in developed countries as well; to the extent that this demand is not met by renewable sources the need for contending with abatement of CO₂ emissions likewise will grow.  For this reason emission abatement programs will rely ever more heavily on technologies such as CCS.

The paper by Zoback and Gorelick serves at least three useful functions.  First, by arithmetic analysis, it underscores the vast, unprecedented need for functional and effective injection sites projected by 2050.  Some of this information has been summarized above.

Second, its geophysical modeling emphasizes the many unknown factors remaining in choosing and developing new CO₂ injection sites.  The seals installed surrounding well bores, and the many geological factors involved in retaining the injected CO₂ out of contact with the atmosphere for hundreds or thousands of years must be essentially fail-safe.  Yet this work emphasizes that the very act of injecting pressurized fluid facilitates potential small-scale earthquakes that, according to the modeling, have the potential of opening fissures in these seals that could lead CO₂ back to the surface.

Third, it has engendered fruitful debate in the CCS community about the integrity of proposed injection sites.  Although these issues were already known among workers in the community, they have now been aired among a wider public.  This has the effect of ensuring that research and data gathering, involved in characterizing new injection sites, will be carried out diligently and effectively so that wise siting choices may be made.

The critics of Zoback and Gorelick, such as those cited above, include examples in their rebuttals of injection sites taking advantage of pre-existing wells used in the extraction of oil and gas from their geological repositories.  These have kept the fuels underground for millions of years, and so are cited as justifying CO₂ injection for the same reasons.  These are likely not representative of the thousands of new storage injection projects that will be needed to accommodate the demand.  Overall the number of pilot injection sites worldwide is small, and many are new experimental projects.  The concerns raised by Zoback and Gorelick merit careful attention going forward as CCS technology is developed further and deployed in number.

© 2012 Henry Auer