Negative Emissions Technologies and Reliable Sequestration A Research Agenda (2019) / Chapter Skim
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8 Synthesis
8 Synthesis
Pages 351-402
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From page 351... ...
In contrast, because it will likely be very expensive to decrease anthropogenic emissions once they reach low levels, methods for reduced and negative emissions will probably be competitors for an extended period, even during a sustained period of net negative global emissions. Conclusion 1: Negative emissions technologies are best viewed as a component of the mitigation portfolio, rather than a way to decrease atmospheric concentrations of carbon dioxide only after anthropogenic emissions have been eliminated.
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From page 352... ...
; • ~$200/t CO2 combination of the 45Q rule and the recently announced changes in credits under California's Low Carbon Fuels Standard, which would allow fuels made with CO2 from direct air capture;4 and • the carbon price of more than $1,000/t CO2 in year 2100 estimated by several integrated assessment models (IAMs) reviewed in the latest IPCC report (IPCC, 2014b)
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From page 353... ...
These tables provide the evidence to support the committee's conclusions about the readiness of NETs: Conclusion 2: Four negative emissions technologies (NETs) are ready for largescale deployment: afforestation/reforestation, changes in forest management, uptake and storage by agricultural soils, and bioenergy with carbon capture and sequestration (BECCS)
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From page 354... ...
Impacts Coastal Blue Carbon: 0.024-0.050a 0.13b-0.80c 0.26– 4.0a 8b -65c 0 0 10d Multiple co Annual Carbon Burial benefits; competition for land and submerged habitats Terrestrial Carbon 0.25e-0.6f 2.5 e-9f 015-38g 1125-570g (3-4)
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From page 355... ...
Direct Air Capture: 0l 0l Limited by economic Limited by 0.5-5.8m 0.5-5.8m 90-600n Not assessed Solvent- and Sorbent- demand or by economic per per based Approaches practical barriers to demand or by Gt CO2 Gt CO2 pace of scale-up practical barriers to pace of scale up Carbon Mineralization: 0.001 0.02-0.20 <1 10 NA <1 10-20 Possible water Surficial Existing and air contami Tailingso nants Carbon Mineralization: Unknown Unknown Essentially unlimited Essentially Tailings: Tailings: 50-500 Possible water Surficial Mining and unlimited 0.1-1 3-30 and air contami Grindingo mm/Gt microns/ nants CO2 /area Gt CO2/ of US area of oceans continued 355
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From page 356... ...
Impacts Carbon Mineralization: NA NA NA NA NA NA <10 Possible concerns Produce Alkaline but no formal Water from Calciteo work published Carbon Mineralization: Unknown Unknown Essentially unlimited Essentially NA NA 20-5000 Possible concerns In Situ Basalt and unlimited but no formal Peridotiteo work published NOTES: The factors that impact the ranges provided for each of the attributes vary among each of the NETs. In general, the upper bounds in the rate and capacity ranges for terrestrial-based NETs represent more aggressive programs and would likely lead to adverse societal, economic, and environmental impacts.
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From page 357... ...
n Upper bound is the current demonstrated cost of direct air capture (see Chapter 5)
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From page 358... ...
contamination similar, Olivine and leak risk lower, compared Serpentinec 200-500 [serpentine] to saline aquifer storage.
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From page 359... ...
a Based on approximately 25 percent and 100 percent implementation of areas augmented with carbon sourced from outside coastal areas b Based on estimated fraction of areas augmented with carbon in the United States. c There is a wide variety of carbon mineralization applications and a limited number of published analyses and demonstrations.
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From page 360... ...
Feasible scenarios, such as the one in Figure 8.1, thus rely on 10 Gt CO2 of removal and storage approximately by midcentury and 20 Gt CO2 by the century's end. Conclusion 4: If the goals for climate and economic growth are to be achieved, negative emissions technologies will likely need to play a large role in mitigating climate change by removing ~10 Gt/y CO2 globally by midcentury and ~20 Gt/y CO2 globally by the century's end.
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From page 361... ...
. NOTES: Green represents mitigation, brown represents anthropogenic greenhouse gas emissions, and blue represents anthropogenic negative emissions.
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From page 362... ...
For example, afforestation/reforestation and BECCS are primarily limited by competing needs for the land, removal and storage in agricultural soils by the low per-hectare rate of CO2 removal, direct air capture by its current high cost, and carbon mineralization and coastal/near-shore blue carbon approaches by a lack of fundamental understanding of future uptake rates. These constraints are also reflected in Table 8.1 by the large ranges for potential CO2 removal rates, capacities, and land requirements for forestry approaches and BECCS; by the large current costs for direct air capture; and by the large ranges in cost for the two high-capacity carbon mineralization options (ex situ mining and grinding of reactive rocks and in situ capture and sequestration in basalt or peridotite)
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From page 363... ...
Fortunately, most proposed solutions for the food problem suggest the possibility to meet midcentury food demand on roughly the current agricultural land (crop plus pasture) by increasing agricultural productivity and reducing food waste (Foley et al., 2011; Thornton, 2010; Tilman et al., 2011)
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From page 364... ...
Because this problem combines limited understanding with the most severe consequences if we get it wrong, the committee believes that humanity should develop new high-capacity NETs such as low-cost direct air capture and carbon mineralization. The safe levels of afforestation/reforestation, forest management approaches, and BECCS in Table 8.1 are set to minimize the risk of unintended consequences of land-use transitions.
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From page 365... ...
Agricultural soils options generally have large positive side benefits, including increased productivity, water holding capacity, stability of yields, and nitrogen use efficiency, but sometimes cause increased N2O emissions. Afforestation/reforestation, BECCS, and potentially some direct air capture routes may have substantial water requirements.
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From page 366... ...
However, afforestation/reforestation, forest management, and agricultural soils activities in the United States are already supported by well-developed state and federal (U.S. Department of Agriculture [USDA]
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From page 367... ...
Biochar soil amendment has been proposed as a promising path for long-term carbon removal strategy (for both agricultural soils and the biomass-to-fuel and biochar BECCS pathway) ; however, questions remain about the long-term stability of biochar in soil environments.
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From page 368... ...
Research Cost Duration Performers of Addressed or Item NET Title $M/y Years Summary Research Frontier 1 Coastal Basic 6 5-10 5 projects at $2M/y for 10 years to address NSF Scientific/ research in fate of organic carbon produced and USACE Technical understanding buried in soils/sediments of coastal DOE Understanding and using ecosystems; 5 projects at $2M/y for 10 Industry Permanence coastal years to address change in area coastal ecosystems as blue carbon ecosystems in response to a NET change in major climate change or sea level rise and management drivers; 5 projects at $2M/y for 5 years to address selection of materials and coastal plants/phenotypes producing high organic carbon density materials with slow decay rates buried in coastal sediments carbon. 2 Coastal Mapping 2 20 $2M/y (tidal wetland: $1.5M; seagrass: NASA Scientific/ current and $500K)
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From page 369... ...
Governance restoration and carbon removal projects. 369 continued
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From page 370... ...
carbon, and on the response of coastal land Governance owners and managers to carbon removal and storage incentives.
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From page 371... ...
. Attempt to improve Governance impacts understanding of impacts of land diversion to afforestation/reforestation and energy crops on food prices, food security, ecosystem services, biodiversity, albedo, and hydrology.
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From page 372... ...
. 11 Forest Man- Research on 1 3 Research on greenhouse gases and USDA Other agement greenhouse social impacts of reducing traditional NSF Environmental gases and uses of biomass for fuel, which involves Constraints social impacts households and small entities using wood Energy Use of reducing biomass for heating and cooking.
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From page 373... ...
. Monitor adoption and permanence of agricultural soils on U.S.
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From page 374... ...
17 Agricultural High carbon 40-50 20 Screen and develop crop varieties and DOE Frontier Soils input crop species specifically to enhance storage in USDA phenotypes agricultural soils. The DOE/ARPA-E ROOTS NSF program is currently funded for $35M total.
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From page 375... ...
21 BECCS Biomass-to-fuel 40-103 10 Assess the carbon removal potential of all DOE Scientific/ with biochar biomass conversion to fuel pathways and USDA Technical develop negative carbon fuel pathways Industry Understanding that are cost-competitive. Cost 375 continued
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From page 376... ...
and a Technical economic public database to facilitate rapid progress. Understanding analysis, third- Cost party materials Energy Use testing and evaluation, and public materials database 24 Direct Air Scaling up 10-15 10 Scale materials synthesis to >100 kg, design DOE Scientific/ Capture and testing novel system components and equipment Technical of air capture for a pilot-scale effort, test integrated lab- Understanding materials and scale air capture system (>100 kg/d CO2)
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From page 377... ...
Energy Use 27 Direct Air National Air 10-20 10 Establish National Air Capture Test Center DOE Scientific/ Capture Capture Test to support pilot efforts, including 3rd- NIST Technical Center support party front-end engineering design and Industry Understanding of pilots economic analysis, and creation and Cost maintenance of a public database on plant Energy Use performance. 377 continued
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From page 378... ...
Cost demonstrations Energy Use 30 Carbon Min- Basic 5.5 10 5 projects at $500K-$1.5M for 10 years. USGS Scientific/ eralization research on DOE Technical mineralization NSF Understanding kinetics 31 Carbon Min- Basic research 17 10 Exploration of positive and negative USGS Frontier eralization on rock feedbacks between reaction and fluid flow, DOE mechanics, for in situ carbon mineralization, in situ NSF numerical mining, geothermal power generation, modeling, and extraction of oil and gas from tight field studies reservoirs, ensuring integrity of reservoir
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From page 379... ...
Constraints Governance 33 Carbon Min- Surficial (ex 3.5 10 Ex situ mine tailings, broadcast of reactive USGS Cost eralization situ) carbon minerals and rocks on soils, beaches, DOE Energy Use removal pilot shallow ocean.
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From page 380... ...
35 Carbon Min- Development 2 5 Database that would allow the results of USGS Scientific and eralization of a resource carbon mineralization research activities Technical database are disseminated broadly to the research Understanding for carbon community. 4 projects at $500K for 5 years.
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From page 381... ...
37 Carbon Min- Examination of 5 10 10 projects at $500k for 10 years. NSF Cost eralization the social and Other environmental Environmental impact of an Constraints expanded Practical extraction barriers to scale industry for the up purpose of CO2 removal NOTE: ARPA-E=Advanced Research Projects Agency-Energy, CCUS=Carbon Capture, Utilization and Storage, DOE=Department of Energy, EPA=Environmental Protection Agency, FIA=Forest Inventory and Analysis, FTE=Full-Time Equivalent, IAM=Integrated Assessment Model, LCA=Life Cycle Assessment, LTER=Long-Term Ecological Research, NET=Negative Emissions Technology, NIST=National Institute of Standards and Technol ogy, NRI=National Resource Inventory, NSF=National Science Foundation, ROOTS=Rhizosphere Observations Optimizing Terrestrial Sequestration, USACE=US Army Corps of Engineers, USDA=US Department of Agriculture, USFS=US Forest Service, USGS=US Geological Survey.
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From page 382... ...
Coastal blue carbon and storage could be monitored and verified with inexpensive remote methods backed up by onsite measurements of a statistical sample. However, fine-scale spatial heterogeneity in coastal wetlands will likely require finer spatial resolution than monitoring and verification of afforestation/reforestation, forest management, agricultural soils, and BECCS.
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From page 383... ...
Monitoring and verification of direct air capture would be straightforward. Monitoring and verification of sequestration in saline aquifers requires sophisticated methods such as seismic imaging, measuring pressure in and above the sequestration reservoir, and routine measurements of well integrity.
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From page 384... ...
The scientific understanding of coastal blue carbon is at a similar state of development, albeit more advanced for tidal wetlands than for seagrass meadows. The carbon removal caused by restoration and creation of tidal wetlands can be predicted with some confidence.
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From page 385... ...
Thus, the research plan calls for a large investment in direct air capture, despite its current high cost and expected future cost of not far from $100/t CO2, and mineralization as a second option with significant potential. The research plan also includes a substantial investment to increase carbon removal and to understand and perhaps soften the land constraint facing afforestation/reforestation, forest management, agricultural soils, and BECCS.
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From page 386... ...
40 BECCS Biomass-to-fuel Ongoing research Advance cellulosic ethanol. DOE Cost with CCS efforts are sufficient Energy Use 41 Carbon Min- Mine tailings and 1 10 Kiloton to megaton per year field DOE Science/ eralization industrial wastes experiments, together with extensive NSF Technical field inventories and laboratory USGS Understanding characterization of the reactivity of Cost various potential solid reactants.
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From page 387... ...
examine evolution of subsurface reaction Cost fronts, determine the nature of local Energy Use carbon mineralization reactions, and Other feedbacks affecting permeability and Environmental reactive surface area. $10M/y for 10 years.
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From page 388... ...
44 Geologic Se- Increasing the 45 10 Partner with industry to develop and test DOE Science/ questration: efficiency and innovative approaches for characterizing NSF Technical Saline Aquifer accuracy of site greenfield sites, which usually require on EPA Understanding Storage characterization the order of $100M to assess whether a DOI Cost and selection site is suitable. Industry Governance Practical Barriers
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From page 389... ...
45 Geologic Se- Improving 50 10 The proposed research program would DOE Monitoring questration: monitoring and provide for 4-6 projects at a cost of $5- NSF and Saline Aquifer lowering costs for 10M/y. The collaborative projects would EPA Verification Storage monitoring and develop and demonstrate approaches to DOI Cost verification optimize integrated monitoring programs Practical that reduce costs while increasing quality Barriers and access to real-time information about the status of stored CO2.
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From page 390... ...
The experiment would require a trapping combination of field experiments, multi scale laboratory experiments, numerical modeling, and monitoring. 47 Geologic Se- Improving 10 10 This program would support 2-3 teams DOE Science/ questration: simulation models of researchers to develop improved NSF Technical Saline Aquifer for performance simulation models for predicting the fate EPA Understanding Storage prediction and and transport of CO2 in the subsurface, DOI Permanence confirmation particularly with regards to the effects of geological heterogeneity, secondary trapping mechanisms, geochemical reactions, geomechanical responses to CO2 injection, and the coupling between them over thousands of years.
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From page 391... ...
Permanence 49 Geologic Se- Developing 50 10 Develop and demonstrate reservoir DOE Science/ questration: reservoir management practices to co-optimize NSF Technical Oil and Gas engineering CO2-EOR and CO2 sequestration to EPA Understanding Field Seques- approaches for achieve negative emissions during DOI Practical tration co-optimizing oilfield operations. Quantify the extent Industry Barriers CO2-EOR and of negative emissions that can be sequestration achieved by co-optimization.
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From page 392... ...
Provide educational EPA ment effectiveness materials for increasing awareness of the DOI with local com- need, opportunity, risks, and benefits of munities and the geological sequestration for negative general public emissions. NOTES: All projects not only should be part of any comprehensive research effort on carbon mitigation, but also would support the advancement of negative emissions methods.
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From page 393... ...
Conclusion 7: Although their potential for removing carbon is lower than other negative emissions technologies, coastal blue carbon approaches warrant continued exploration and support. The cost of the carbon removal is low or zero because investments in many coastal blue carbon projects target other benefits such as ecosystem services and coastal adaptation.
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From page 394... ...
Inexpensive direct air capture or carbon mineralization could allow for indefinite use of fossil fuels without climate impacts. The scale of the recommended research budget is consistent both with the need for NETs that can solve a substantial fraction of the climate problem and the possible magnitude of the return to the U.S.
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From page 395... ...
, $2M/y for 20 years for a data center (item 4) , and $5M/y for 10 years for social science research on cost-effective adaptive management of coastal blue carbon and on the response of coastal land owners and managers to carbon removal and storage incentives (item 6)
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From page 396... ...
Uptake and Storage by Agricultural Soils The cost of the research on carbon removal and storage by agricultural soils is intermediate relative to the research budget for other NETs. Unlike foresters, agricultural plant breeders have not focused specifically on aspects of plant productivity that would increase carbon removal and storage (i.e., above-ground biomass for trees, but deep and difficult to decompose roots for agricultural crops)
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From page 397... ...
This is much more straightforward for afforestation/reforestation, agricultural soils, coastal blue carbon, direct air capture, and even carbon mineralization. Several agencies within USDA, DOE, and EPA are active in and capable of effectively carrying out most of the proposed basic and applied research components and tasks for BECCS.
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From page 398... ...
The challenge of direct air capture development is that no commercial driver for the activity exists in the absence of a high carbon price (unlike afforestation/reforestation, agricultural soils, BECCS-to-fuels, and coastal blue carbon)
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From page 399... ...
Moreover, contracting mechanisms, such as fixed-fee or cost-plus contracts, would prove useful for developing direct air capture technology. However, no public investments should be made without first identifying a clear market incentive for carbon removal; in the absence of a market incentive for carbon removal, industry will not invest in the commercial deployment of direct air capture systems.
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From page 400... ...
Saline aquifer storage is vital to mitigate fossil power emissions and to make direct air capture and BECCS carbon negative. The proposed research plan includes $50M/y to reduce risks of induced seismicity (item 43)
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From page 401... ...
Nonetheless, existing options (coastal blue carbon, afforestation/reforestation, forest management, agricultural soils, and BECCS) cannot yet provide enough negative emissions at reasonable cost, without substantial unintended harm to the global food supply and environment.
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