December 27, 2012

Carbon Capture and Storage

Intergovernmental Panel on Climate Change

Elizabeth Finkel & Belinda Smith:
China and India plan to build more than 1600 new coal-fired power plants between them by 2030, according to the online Global Coal Plant tracker.
(p 82)

[The Chinese ultra-supercritical] plants are designed to scrub air pollutants, not CO2.
But they are more efficient than standard coal plants, and reduce CO2 emissions by 30%.
(p 55)

CarbonNet was conceived in 2008 [by the Victorian state government] to connect CO2 emissions from coal-fired power stations [and] oil and gas fields to an offshore geological deposit capable of storing at least 20 billion tonnes of CO2.
When Australia repealed the carbon price the project did not advance.
(Can We Bury the Problem?, Cosmos, Feb-Mar 2016, p 54)

IPCC:
Scenarios that are likely to maintain warming at below 2°C include
  • more rapid improvements in energy efficiency and
  • a tripling to nearly a quadrupling of the share of zero- and low-carbon energy supply from renewable energy, nuclear energy and fossil energy with carbon dioxide capture and storage (CCS), or bioenergy with CCS (BECCS) by the year 2050.
(AR5 Synthesis Report — Longer Version, 1 November, 2014, p 39)

CSIRO:
Electricity, industrial emissions and transport deliver 40 to 75% of cost-effective national abatement by 2050 (assuming successful deployment of carbon capture and storage technologies) …
Modelling confirms that successful global deployment of carbon capture and storage has a crucial role in limiting the rise in global average temperature to 2°C.
(Australian National Outlook, October, 2015, p 25)

George Marshall:
There are currently eight large-scale CCS projects and eight more under construction …
[We] will need sixteen thousand more plants … to deal with current emissions [and] another thousand plants [per year] to keep up with the annual increase [in emissions.]
(Don't Even Think About It, 2014, p 179, emphasis added)

Wikipedia:
Of the 22 demonstration [clean coal] projects funded by the US Department of Energy since 2003, none are in operation as of February 2017, having been abandoned or delayed due to capital budget overruns or discontinued because of excessive operating expenses. (Coal pollution mitigation, 19 February 2017)

Costs and Potential


In most scenarios for stabilization of atmospheric greenhouse gas concentrations between 450 and 750 ppmv CO2 and in a least-cost portfolio of mitigation options, the economic potential of CCS would amount to 220-2,200 GtCO2 (60–600 GtC) cumulatively, which would mean that CCS contributes 15–55% to the cumulative mitigation effort worldwide until 2100, averaged over a range of baseline scenarios.
It is likely that the technical potential for geological storage is sufficient to cover the high end of the economic potential range, but for specific regions, this may not be true. …


For CCS to achieve such an economic potential, several hundreds to thousands of CO2 capture systems would need to be installed over the coming century, each capturing some 1–5 MtCO2 per year.

The actual implementation of CCS, as for other mitigation options, is likely to be lower than the economic potential due to factors such as
  • environmental impacts,
  • risks of leakage and
  • the lack of a clear legal framework or public acceptance. …

[The] inclusion of CCS in a mitigation portfolio is found to reduce the costs of stabilizing CO2 concentrations by 30% or more.
(p 12, emphasis added)

Three industrial-scale storage projects are [presently] in operation:
  • the Sleipner project in an offshore saline formation in Norway,
  • the Weyburn [Enhanced Oil Recovery] project in Canada, and
  • the In Salah project in a gas field in Algeria.
(p 7)


Tim Flannery


[When] compressed to liquid form, [the daily CO2 output of Australia's coal fired power plants] would take up a cubic kilometre …
[Given that] Australia accounts for less than 2% of global emissions [imagine] injecting 50 cubic kilometres of liquid CO2 into the Earth’s crust every day of the year for the next century or two.

If geosequestration were to be practised on the scale needed to offset all the emissions from coal, the world would very quickly run out of [safe and / or readily accessible] reservoirs …
(p 254)

(The Weather Makers, 2005)


Contents


What is CO2 capture and storage and how could it contribute to mitigating climate change?

What are the characteristics of CCS?

What is the current status of CCS technology?

What is the geographical relationship between the sources and storage opportunities for CO2?

What are the costs for CCS and what is the technical and economic potential?

What are the local health, safety and environment risks of CCS?

Will physical leakage of stored CO2 compromise CCS as a climate change mitigation option?

What are the legal and regulatory issues for implementing CO2 storage?

What are the implications of CCS for emission inventories and accounting?

What are the gaps in knowledge?


INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE


  • Carbon Dioxide Capture and Storage, IPCC Special Report, Summary for Policymakers approved at Eighth Session of IPCC Working Group III, 22-24 September, 2005.
    Juan Carlos Abanades, Makoto Akai, Sally Benson, Ken Caldeira, Heleen de Coninck, Peter Cook, Ogunlade Davidson, Richard Doctor, James Dooley, Paul Freund, John Gale, Wolfgang Heidug, Howard Herzog, David Keith, Marco Mazzotti, Bert Metz, Leo Meyer, Balgis Osman-Elasha, Andrew Palmer, Riitta Pipatti, Edward Rubin, Koen Smekens, Mohammad Soltanieh, Kelly and Thambimuthu.


    What is CO2 capture and storage and how could it contribute to mitigating climate change?


    Carbon dioxide (CO2) capture and storage (CCS) is a process consisting of the separation of CO2 from industrial and energy-related sources, transport to a storage location and long-term isolation from the atmosphere.
    This report considers CCS as an option in the portfolio of mitigation actions for stabilization of atmospheric greenhouse gas concentrations. …

    The Third Assessment Report (TAR) indicates that no single technology option will provide all of the emission reductions needed to achieve stabilization, but a portfolio of mitigation measures will be needed.



    What are the characteristics of CCS?


    Capture of CO2 can be applied to large point sources.
    The CO2 would then be compressed and transported for storage in geological formations, in the ocean, in mineral carbonates, or for use in industrial processes.


    Large point sources of CO2 include
    • large fossil fuel or biomass energy facilities,
    • major CO2-emitting industries, natural gas production,
    • synthetic fuel plants and
    • fossil fuel-based hydrogen production plants …

    Potential technical storage methods are:
    • geological storage (in geological formations, such as oil and gas fields, unminable coal beds and deep saline formations),
    • ocean storage (direct release into the ocean water column or onto the deep seafloor) and
    • industrial fixation of CO2 into inorganic carbonates.
    (p 3)

    The net reduction of emissions to the atmosphere through CCS depends on the fraction of CO2 captured, the increased CO2 production resulting from loss in overall efficiency of power plants or industrial processes due to the additional energy required for capture, transport and storage, any leakage from transport and the fraction of CO2 retained in storage over the long term.

    Available technology captures about 85–95% of the CO2 processed in a capture plant.
    A power plant equipped with a CCS system (with access to geological or ocean storage) would need roughly 10–40% more energy than a plant of equivalent output without CCS, of which most is for capture and compression.
    For secure storage, the net result is that a power plant with CCS could reduce CO2 emissions to the atmosphere by approximately 80–90% compared to a plant without CCS …
    (p 4)


    What is the current status of CCS technology?


    There are different types of CO2 capture systems: postcombustion, pre-combustion and oxyfuel combustion …
    The concentration of CO2 in the gas stream, the pressure of the gas stream and the fuel type (solid or gas) are important factors in selecting the capture system.

    • Post-combustion capture of CO2 in power plants is economically feasible under specific conditions. …
      Separation of CO2 in the natural gas processing industry, which uses similar technology, operates in a mature market.
    • The technology required for pre-combustion capture is widely applied in fertilizer manufacturing and in hydrogen production.
      Although the initial fuel conversion steps … are more elaborate and costly, the higher concentrations of CO2 in the gas stream and the higher pressure make the separation easier.
    • Oxyfuel combustion is in the demonstration phase and uses high purity oxygen.
      This results in high CO2 concentrations in the gas stream and, hence, in easier separation of CO2 and in increased energy requirements in the separation of oxygen from air.

    Pipelines are preferred for transporting large amounts of CO2 for distances up to around 1,000 km. …

    Pipeline transport of CO2 operates as a mature market technology (in the USA, over 2,500 km of pipelines transport more than 40 MtCO2 per year).
    (p 5)

    Shipping of CO2, analogous to shipping of liquefied petroleum gases, is economically feasible under specific conditions but is currently carried out on a small scale due to limited demand.
    CO2 can also be carried by rail and road tankers, but it is unlikely that these could be attractive options for large-scale CO2 transportation …

    Storage of CO2 in deep, onshore or offshore geological formations uses many of the same technologies that have been developed by the oil and gas industry and has been proven to be economically feasible under specific conditions for oil and gas fields and saline formations, but not yet for storage in unminable coal beds.
    (p 6)

    Ocean storage potentially could be done in two ways:
    • by injecting and dissolving CO2 into the water column (typically below 1,000 meters) via a fixed pipeline or a moving ship, or
    • by depositing it via a fixed pipeline or an offshore platform onto the sea floor at depths below 3,000 m, where CO2 is denser than water and is expected to form a “lake” that would delay dissolution of CO2 into the surrounding environment.
    Ocean storage and its ecological impacts are still in the research phase. …


    The dissolved and dispersed CO2 would become part of the global carbon cycle and eventually equilibrate with the CO2 in the atmosphere. …

    The reaction of CO2 with metal oxides, which are abundant in silicate minerals and available in small quantities in waste streams, produces stable carbonates.
    The technology is currently in the research stage, but certain applications in using waste streams are in the demonstration phase.


    The natural reaction is very slow and has to be enhanced by pre-treatment of the minerals, which at present is very energy intensive.
    (p 7)

    Industrial uses of captured CO2 as a gas or liquid or as a feedstock in chemical processes that produce valuable carbon-containing products are possible, but are not expected to contribute to significant abatement of CO2 emissions. …

    Components of CCS are in various stages of development.
    Complete CCS systems can be assembled from existing technologies that are mature or economically feasible under specific conditions, although the state of development of the overall system may be less than some of its separate components.



    What is the geographical relationship between the sources and storage opportunities for CO2?


    Large point sources of CO2 are concentrated in proximity to major industrial and urban areas.
    Many such sources are within 300 km of areas that potentially hold formations suitable for geological storage.
    Preliminary research suggests that, globally, a small proportion of large point sources is close to potential ocean storage locations.

    (p 8)

    Scenario studies indicate that the number of large point sources is projected to increase in the future, and that, by 2050, given expected technical limitations, around 20–40% of global fossil fuel CO2 emissions could be technically suitable for capture, including 30–60% of the CO2 emissions from electricity generation and 30–40% of those from industry.

    Emissions from large-scale biomass conversion facilities could also be technically suitable for capture.
    The proximity of future large point sources to potential storage sites has not been studied.

    CCS enables the control of the CO2 emissions from fossil fuel-based production of electricity or hydrogen, which in the longer term could reduce part of the dispersed CO2 emissions from transport and distributed energy supply systems.
    (p 9)


    What are the costs for CCS and what is the technical and economic potential?


    Application of CCS to electricity production, under 2002 conditions, is estimated to increase electricity generation costs by about 0.01–0.05 US dollars per kilowatt hour (US$/kWh), depending on the fuel, the specific technology, the location and the national circumstances.
    Inclusion of the benefits of EOR would reduce additional electricity production costs due to CCS by around 0.01-0.02 US$/kWh …
    Increases in market prices of fuels used for power generation would generally tend to increase the cost of CCS.
    The quantitative impact of oil price on CCS is uncertain.
    However, revenue from EOR would generally be higher with higher oil prices.
    While applying CCS to biomass-based power production at the current small scale would add substantially to the electricity costs, co-firing of biomass in a larger coal-fired power plant with CCS would be more cost-effective. …

    Retrofitting existing plants with CO2 capture is expected to lead to higher costs and significantly reduced overall efficiencies than for newly built power plants with capture.
    The cost disadvantages of retrofitting may be reduced in the case of some relatively new and highly efficient existing plants or where a plant is substantially upgraded or rebuilt. …

    In most CCS systems, the cost of capture (including compression) is the largest cost component.

    (p 10)

    Energy and economic models indicate that the CCS system’s major contribution to climate change mitigation would come from deployment in the electricity sector.
    Most modelling as assessed in this report suggests that CCS prices begin to reach approximately 25–30 US$/tCO2.

    (p 11)

    Available evidence suggests that, worldwide, it is likely that there is a technical potential of at least about 2,000 GtCO2 (545 GtC) of storage capacity in geological formations. …


    What are the local health, safety and environment risks of CCS?


    The local risks associated with CO2 pipeline transport could be similar to or lower than those posed by hydrocarbon pipelines already in operation.

    For existing CO2 pipelines, mostly in areas of low population density, accident numbers reported per kilometre pipeline are very low and are comparable to those for hydrocarbon pipelines.
    A sudden and large release of CO2 would pose immediate dangers to human life and health, if there were exposure to concentrations of CO2 greater than 7–10% by volume in air.
    Pipeline transport of CO2 through populated areas requires attention to route selection, overpressure protection, leak detection and other design factors.
    No major obstacles to pipeline design for CCS are foreseen.

    With appropriate site selection based on
    • available subsurface information,
    • a monitoring programme to detect problems,
    • a regulatory system and
    • the appropriate use of remediation methods to stop or control CO2 releases if they arise,
    the local health, safety and environment risks of geological storage would be comparable to the risks of current activities such as natural gas storage, EOR and deep underground disposal of acid gas.

    (p 12)

    Features of storage sites with a low probability of leakage include
    • highly impermeable caprocks,
    • geological stability,
    • absence of leakage paths and
    • effective trapping mechanisms. …

    There are two different to local high CO2 concentrations in the air that could harm types of leakage scenarios:

    1. abrupt leakage, through injection well failure or leakage up an abandoned well, and

    2. gradual leakage, through undetected faults, fractures or wells.

    Impacts of elevated CO2 concentrations in the shallow subsurface could include lethal effects on plants and subsoil animals and the contamination of groundwater.
    High fluxes in conjunction with stable atmospheric conditions could lead to local high CO2 concentrations in the air that could harm animals or people.
    Pressure build-up caused by CO2 injection could trigger small seismic events. …

    The effectiveness of the available risk management methods still needs to be demonstrated for use with CO2 storage.
    (p 13)

    If leakage occurs at a storage site, remediation to stop the leakage could involve standard well repair techniques or the interception and extraction of the CO2 before it would leak into a shallow groundwater aquifer.
    Given the long timeframes associated with geological storage of CO2, site monitoring may be required for very long periods.

    Adding CO2 to the ocean or forming pools of liquid CO2 on the ocean floor at industrial scales will alter the local chemical environment.
    Experiments have shown that sustained high concentrations of CO2 would cause mortality of ocean organisms.
    CO2 effects on marine organisms will have ecosystem consequences.
    The chronic effects of direct CO2 injection into the ocean on ecosystems over large ocean areas and long time scales have not yet been studied. …


    Model simulations, assuming a release from seven locations at an ocean depth of 3,000 m, where ocean storage provides 10% of the mitigation effort for stabilization at 550 ppmv CO2, resulted in acidity increases (pH decrease >0.4) over approximately 1% of the ocean volume.
    For comparison purposes: in such a stabilization case without ocean storage, a pH decrease >0.25 relative to pre-industrial levels at the entire ocean surface can be expected.
    A 0.2 to 0.4 pH decrease is significantly greater than pre-industrial variations in average ocean acidity. …

    Conversion of molecular CO2 to bicarbonates or hydrates before or during CO2 release would reduce the pH effects and enhance the retention of CO2 in the ocean, but this would also increase the costs and other environmental impacts.

    Environmental impacts of large-scale mineral carbonation would be a consequence of the required mining and disposal of resulting products that have no practical use.

    Industrial fixation of one tonne of CO2 requires between 1.6 and 3.7 tonnes of silicate rock.
    The impacts of mineral carbonation are similar to those of large-scale surface mines.
    They include
    • land-clearing,
    • decreased local air quality and
    • affected water and vegetation
    as a result of drilling, moving of earth and the grading and leaching of metals from mining residues, all of which indirectly may also result in habitat degradation.
    Most products of mineral carbonation need to be disposed of, which would require landfills and additional transport.


    Will physical leakage of stored CO2 compromise CCS as a climate change mitigation option?


    Observations from engineered and natural analogues as well as models suggest that the fraction retained in appropriately selected and managed geological reservoirs is very likely to exceed 99% over 100 years and is likely to exceed 99% over 1,000 years.

    For well-selected, designed and managed geological storage sites, the vast majority of the CO2 will gradually be immobilized by various trapping mechanisms and, in that case, could be retained for up to millions of years. …

    Release of CO2 from ocean storage would be gradual over hundreds of years.

    If continuous leakage of CO2 occurs, it could, at least in part, offset the benefits of CCS for mitigating climate change.
    Assessments of the implications of leakage for climate change mitigation depend on the framework chosen for decision-making and on the information available on the fractions retained for geological or ocean storage as presented [above.]


    [Some] studies allow future leakage to be compensated by additional reductions in emissions [while in others] compensation is not seen as an option because of political and institutional uncertainties …
    (p 14)


    What are the legal and regulatory issues for implementing CO2 storage?


    Some regulations for operations in the subsurface do exist that may be relevant or, in some cases, directly applicable to geological storage, but few countries have specifically developed legal or regulatory frameworks for long-term CO2 storage.

    Existing laws and regulations regarding inter alia mining, oil and gas operations, pollution control, waste disposal, drinking water, treatment of high-pressure gases and subsurface property rights may be relevant to geological CO2 storage.
    Long-term liability issues associated with the leakage of CO2 to the atmosphere and local environmental impacts are generally unresolved.
    Some States take on longterm responsibility in situations comparable to CO2 storage …

    No formal interpretations so far have been agreed upon with respect to whether or under what conditions CO2 injection into the geological sub-seabed or the ocean is compatible.

    There are currently several treaties … that potentially apply to the injection of CO2 into the geological sub-seabed or the ocean.


    What are the implications of CCS for emission inventories and accounting?


    The current IPCC Guidelines do not include methods specific to estimating emissions associated with CCS. …

    Specific methods may be required for the net capture and storage of CO2, physical leakage, fugitive emissions and negative emissions associated with biomass applications of CCS systems.

    The few current CCS projects all involve geological storage, and there is therefore limited experience with the monitoring, verification and reporting of actual physical leakage rates and associated uncertainties.

    CO2 might be captured in one country and stored in another with different commitments.
    Issues associated with accounting for cross-border storage are not unique to CCS.



    What are the gaps in knowledge?


    There are gaps in currently available knowledge regarding some aspects of CCS.
    Increasing knowledge and experience would reduce uncertainties and thus facilitate decision-making with respect to the deployment of CCS for climate change mitigation
    .
    (p 15)

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