Deployment Of Negative Emissions Technologies Research Articles

Investigating the socio-political acceptance of negative emission technologies: A group model building approach

Reaching climate targets can require sustainability transition strategies that include negative emissions technologies, hence, there is a current need for more social science research on these technologies. In this study, we focus on four negative emissions technologies: (1) converting algae and/or waste bioresources into power, heat, and/or hydrogen with CCS (bioCCS), (2) the removal of CO2 from water (direct ocean capture), (3) the removal of CO2 from air (direct air capture), and, lastly, (4) the removal of CH4 from air. Through group model building (GMB) workshops, we examine stakeholder perspectives on reaching negative emissions by 2040 in Norway and the barriers and thresholds for socio-political acceptance of the four technologies. Stakeholders highlighted that to reduce emissions to negative emissions by 2040 in Norway, policymakers should ensure better science-based policies, laws, incentives, and regulations. These science-based policies, laws, incentives, and regulations, referred to as ‘framework conditions’ by the stakeholders, can help industrial and political leaders to feel secure in their decision making. For socio-political acceptance, policymakers should ensure framework conditions that facilitate the availability and management of resources, mostly energy. Policymakers should take heed to the fact that despite technological differences, timeframes for implementation, physical requirements for implementation, and technological readiness levels, the main exogenous variables driving socio-political acceptance are largely similar across the four technologies, potentially facilitating the political process of implementing them simultaneously or separately. Methane removal from air, however, could lack socio-political acceptance due to being sometimes seen as a mitigation technology rather than a removal technology. Overall, these results are a good starting point for a discussion on concrete policymaking actions for the development and potential large scale technological deployment of negative emission technologies.

Spatially resolved land and grid model of carbon neutrality in China

China has committed to achieve net carbon neutrality by 2060 to combat global climate change, which will require unprecedented deployment of negative emissions technologies, renewable energies (RE), and complementary infrastructure. At terawatt-scale deployment, land use limitations interact with operational and economic features of power systems. To address this, we developed a spatially resolved resource assessment and power systems planning optimization that models a full year of power system operations, sub-provincial RE siting criteria, and transmission connections. Our modeling results show that wind and solar must be expanded to 2,000 to 3,900 GW each, with one plausible pathway leading to 300 GW/yr combined annual additions in 2046 to 2060, a three-fold increase from today. Over 80% of solar and 55% of wind is constructed within 100 km of major load centers when accounting for current policies regarding land use. Large-scale low-carbon systems must balance key trade-offs in land use, RE resource quality, grid integration, and costs. Under more restrictive RE siting policies, at least 740 GW of distributed solar would become economically feasible in regions with high demand, where utility-scale deployment is limited by competition with agricultural land. Effective planning and policy formulation are necessary to achieve China's climate goals.

Analysis of production routes for silicon carbide using air as carbon source empowering negative emissions

A rapid defossilisation of the industry sector is required to stop further greenhouse gas emissions and to curb global warming. Additionally, to avoid irreversible consequences caused by climate change, the deployment of negative emission technologies is required to reduce the carbon dioxide (CO2) concentration in Earth’s atmosphere to a sustainable level. A novel approach to store gaseous CO2 from direct air capture facilities in solid silicon carbide (SiC) is presented. A chain of established processes to produce SiC from renewable electricity and air is evaluated in terms of energy and mass balances. Furthermore, possible fields of SiC utilisation are considered. Electricity-based SiC (e-SiC) can serve the growing global market for technical ceramics and can possibly be used to tackle increasing construction sand shortages in the construction industry by partially substituting sand. Calculations of the levelised cost of carbon dioxide removal show that storing ambient CO2 in solid SiC that can be subsequently sold on the world market can eventually create profit. In 2050, a net benefit of 259 €/tCO2 or 631 €/tSiC can be realised if the SiC product is sold at the world market with additional carbon compensation. Therefore, the proposed SiC production chain might be able to challenge conventionally produced SiC, while empowering negative emissions. In 2050, the net CO2 emission potential is limited to about 290 MtCO2/a for technical ceramics, but may reach up to 13.6 GtCO2/a for construction sand. Results show that e-SiC production is economically feasible for technical ceramics but not for construction sand without further process cost decrease. Alternative processes to produce e-SiC are described and evaluated. Future research opportunities are discussed.

Nature-based solutions are critical for putting Brazil on track towards net-zero emissions by 2050.

Most of the world's nations (around 130) have committed to reaching net-zero carbon dioxide or greenhouse gas (GHG) emissions by 2050, yet robust policies rarely underpin these ambitions. To investigate whether existing and expected national policies will allow Brazil to meet its net-zero GHG emissions pledge by 2050, we applied a detailed regional integrated assessment modelling approach. This included quantifying the role of nature-based solutions, such as the protection and restoration of ecosystems, and engineered solutions, such as bioenergy with carbon capture and storage. Our results highlight ecosystem protection as the most critical cost-effective climate mitigation measure for Brazil, whereas relying heavily on costly and not-mature-yet engineered solutions will jeopardise Brazil's chances of achieving its net-zero pledge by mid-century. We show that the full implementation of Brazil's Forest Code (FC), a key policy for emission reduction in Brazil, would be enough for the country to achieve its short-term climate targets up to 2030. However, it would reduce the gap to net-zero GHG emissions by 38% by 2050. The FC, combined with zero legal deforestation and additional large-scale ecosystem restoration, would reduce this gap by 62% by mid-century, keeping Brazil on a clear path towards net-zero GHG emissions by around 2040. While some level of deployment of negative emissions technologies will be needed for Brazil to achieve and sustain its net-zero pledge, we show that the more mitigation measures from the land-use sector, the less costly engineered solutions from the energy sector will be required. Our analysis underlines the urgent need for Brazil to go beyond existing policies to help fight climate emergency, to align its short- and long-term climate targets, and to build climate resilience while curbing biodiversity loss.

Farmer perspectives on carbon markets incentivizing agricultural soil carbon sequestration

Climate change mitigation efforts to achieve net-zero emissions require not only decreasing current greenhouse gas emissions, but also the deployment of negative emissions technologies. Soil organic carbon sequestration in agricultural lands is one such negative emissions strategy, currently being incentivized predominantly through voluntary carbon offset markets. Through semi-structured interviews, we assess both conventional and organic farmer perspectives on soil carbon offset programs that have been created in the United States since 2017. The perspectives of farmers both participating and not participating in agricultural soil carbon markets were similar and consistent. Farmers in both groups expressed concerns about the convoluted, burdensome and unpredictable nature of receiving offset credits and emphasized that they were implementing practices for their own business interests and sustainability concerns, not the financial incentive of the generation of carbon credits. Based on our research, carbon offset credit payments for agricultural soil carbon sequestration are largely reaching farmers who were already implementing these beneficial practices or were already strongly interested in implementing these practices, and the payments for the offset credits are seen as a ‘gravy on top’, suggesting that these offset markets face strong challenges of ensuring true additionality essential to effective climate mitigation.

Cost and deployment consequences of advanced planning for negative emissions with direct air capture in the U.S. Eastern Interconnection

Negative emissions systems differ from net-zero systems by deploying significantly more negative emission technologies. The emerging literature on negative emission power systems assumes straight transition pathways from the present systems to final negative emissions systems. Such straight transition paths are unlikely, as deployment of negative emission technologies such as direct air capture might occur via crash course to respond to climate crises and utilities are investing towards net-zero systems instead of negative emissions systems. In this paper, to inform policymakers of the different outcomes of planning for negative emissions systems at different timelines, we quantify the value of planning for a negative emissions power system beginning now versus after achieving a net-zero emissions system in 2050. We apply a macro-scale capacity expansion planning model to the Eastern Interconnection power system to quantify the technological deployments and cost consequences of these two decarbonization pathways to reach a negative emission power system. We find advanced planning for a negative emissions system favors more deployment of storage technologies, which increases system flexibility and allows for better utilization of renewable generation to reduce investments in other technologies, including transmission lines. This change in distribution of investments across technologies leads to small annual cost saving of $6 billion, or 1%. We also find that further delay in planning for a negative emission system after reaching net-zero by 5, 10, and 15 years could significantly increase total system cost by 29%, 35%, and 41% respectively due to higher deployment of negative emission technologies. Our results indicate that, given small annual cost saving from advanced planning for a negative emission power system, economically utilities are on the right path in planning for a net-zero power system by 2050. However, planning should not be delayed further after reaching net-zero to avoid missing cumulative emission targets or significant cost consequences.

Bioenergy with carbon capture and storage (BECSS): Life cycle environmental and economic assessment of electricity generated from palm oil wastes

Rapid deployment of negative emissions technologies (NETs) will be needed to help mitigate climate change. Among various NETs, bioenergy with carbon capture and storage (BECCS) is seen as an option with multiple environmental benefits, including increasing the share of renewable energy while capturing carbon and providing an effective solution for waste management if waste biomass is utilised. This research presents the first environmental and economic sustainability assessments of BECCS utilising palm oil waste abundant in palm oil producing countries, such as Malaysia. The following five types of waste are considered: fronds, trunks, empty fruit bunches (EFBs), shells and fibres. Process simulation, techno-economic analysis and life cycle assessment (LCA) are combined to determine the life cycle impacts and costs of BECCS from cradle to grave. Two units of analysis are considered for both the impacts and costs: ‘generation of 1 MWh of electricity’ and ‘capture of 1 tonne of CO2’. The global warming potential (GWP) is net-negative for both functional units, ranging from −1270 to −1410 kg CO2 eq./MWh and −840 to −1729 kg CO2 eq./t CO2 removed, the latter depending on the credits for electricity generation. However, all other 17 impacts increase by 13–217% with the addition of CCS. The systems without CCS have net-positive GWP of 59–126 kg CO2 eq./MWh. Per MWh electricity, the system with fibres has the lowest and palm fronds the highest impacts for most of the categories considered; per tonne of CO2 removed, there is no clear feedstock preference. The levelised costs of electricity (LCOE) of BECSS plants are US$98–119/MWh, with fibres being the best and fronds the worst feedstock. Compared to the systems without CCS, the LCOE of BECCS are 3.6–4.1 times higher. The costs of BECSS per tonne of CO2 removed are US$66–74, with CCS contributing US$50–53/t CO2. Based on the current availability of palm oil wastes in Malaysia, the system could generate 7730 GWh/yr, boosting the national share of bioenergy by 7.6 times, while removing 12 Mt CO2/yr, equivalent to 10% of annual emissions from the electricity sector.

Impact of Biogenic Carbon Neutrality Assumption for Achieving a Net-Zero Emission Target: Insights from a Techno-Economic Analysis.

Global pathways limiting warming to 2 °C or below require deep carbon dioxide removal through a large-scale transformation of the land surface, an increase in forest cover, and the deployment of negative emission technologies (NETs). Government initiatives endorse bioenergy as an alternative, carbon-neutral energy source for fossil fuels. However, this carbon neutral assumption is increasingly being questioned, with several studies indicating that it may result in accounting errors and biased decision-making. To address this growing issue, we use a carbon budget model combined with an energy system model. We show that including forest sequestration in the energy system model alleviates the decarbonization effort. We discuss how a forest management strategy with a high sequestration capacity reduces the need for expensive negative emission technologies. This study indicates the necessity of establishing the most promising forest management strategy before investing in bioenergy with carbon capture and storage. Finally, we describe how a carbon neutrality assumption may lead to biased decision-making because it allows the model to use more biomass without being constrained by biogenic CO2 emissions. The risk of biased decision-making is higher for regions that have lower forest coverage, since available forest sequestration cannot sink biogenic emissions in the short term, and importing bioenergy could worsen the situation.

Optimization and decision support models for deploying negative emissions technologies

Negative emissions technologies (NETs) will be needed to reach net-zero emissions by mid-century. However, NETs can have wide-ranging effects on land and water availability, food production, and biodiversity. The deployment of NETs will also depend on regional and national circumstances, technology availability, and decarbonization strategies. Process integration (PI) can be the basis for decision support models for the selection, planning, and optimization of the large-scale implementation of NETs. This paper reviews the literature and maps the role of PI in NETs deployment. Techniques such as mathematical programming, pinch analysis (PA), process graphs (P-graphs), are powerful methods for planning NET systems under resource or footprint constraints. Other methods such as multi-criteria decision analysis (MCDA), marginal abatement cost curves, causality maps, and machine learning (ML) are also discussed. Current literature focuses mainly on bioenergy with carbon capture and storage (BECCS) and afforestation/reforestation (AR), but other NETs need to be integrated into future models for large-scale decarbonization.

DECO2—An Open-Source Energy System Decarbonisation Planning Software including Negative Emissions Technologies

The deployment of CO2 capture and storage (CCS) and negative emissions technologies (NETs) are crucial to meeting the net-zero emissions target by the year 2050, as emphasised by the Glasgow Climate Pact. Over the years, several energy planning models have been developed to address the temporal aspects of carbon management. However, limited works have incorporated CCS and NETs for bottom-up energy planning at the individual plant scale, which is considered in this work. The novel formulation is implemented in an open-source energy system software that has been developed in this work for optimal decarbonisation planning. The DECarbonation Options Optimisation (DECO2) software considers multiperiod energy planning with a superstructural model and was developed in Python with an integrated user interface in Microsoft Excel. The software application is demonstrated with two scenarios that differ in terms of the availabilities of mitigation technologies. For the more conservative Scenario 1, in which CCS is only available in later years, and other NETs are assumed not to be available, all coal plants were replaced with biomass. Meanwhile, only 38% of natural gas plants are CCS retrofitted. The remaining natural gas plants are replaced with biogas. For the more aggressive Scenario 2, which includes all mitigation technologies, once again, all coal plants undergo fuel substitution. However, close to half of the natural gas plants are CCS retrofitted. The results demonstrated the potential of fuel substitutions for low-carbon alternatives in existing coal and natural gas power plants. Additionally, once NETs are mature and are available for commercial deployment, their deployment is crucial in aiding CO2 removal in minimal investment costs scenarios. However, the results indicate that the deployment of energy-producing NETs (EP-NETs), e.g., biochar and biomass with CCS, are far more beneficial in CO2 removal versus energy-consuming NETs (EC-NETs), e.g., enhanced weathering. The newly developed open-source software demonstrates the importance of determining the optimal deployment of mitigation technologies in meeting climate change targets for each period, as well as driving the achievement of net-zero emissions by mid-century.

Emerging trends in direct air capture of CO2: a review of technology options targeting net-zero emissions.

The increasing concentration of carbon dioxide (CO2) in the atmosphere has compelled researchers and policymakers to seek urgent solutions to address the current global climate change challenges. In order to keep the global mean temperature at approximately 1.5 °C above the preindustrial era, the world needs increased deployment of negative emission technologies. Among all the negative emissions technologies reported, direct air capture (DAC) is positioned to deliver the needed CO2 removal in the atmosphere. DAC technology is independent of the emissions origin, and the capture machine can be located close to the storage or utilization sites or in a location where renewable energy is abundant or where the price of energy is low-cost. Notwithstanding these inherent qualities, DAC technology still has a few drawbacks that need to be addressed before the technology can be widely deployed. As a result, this review focuses on emerging trends in direct air capture (DAC) of CO2, the main drivers of DAC systems, and the required development for commercialization. The main findings point to undeniable facts that DAC's overall system energy requirement is high, and it is the main bottleneck in DAC commercialization.

Geochemical Negative Emissions Technologies: Part II. Roadmap

Geochemical negative emissions technologies (NETs) comprise a set of approaches to climate change mitigation that make use of alkaline minerals to remove and/or permanently store carbon dioxide (CO2) as solid carbonate minerals or dissolved ocean bicarbonate ions. This roadmap accompanies the comprehensive review of geochemical NETs by the same authors and offers guidance for the development and deployment of geochemical NETs at gigaton per year (Gt yr.−1) scale. We lay out needs and high-priority initiatives across six key elements required for the responsible and effective deployment of geochemical NETs: (i) technical readiness, (ii) social license, (iii) demand, (iv) supply chains, (v) human capital, and (vi) infrastructure. We put forward proposals for: specific initiatives to be undertaken; their approximate costs and timelines; and the roles that various actors could play in undertaking them. Our intent is to progress toward a working consensus among researchers, practitioners, and key players about initiatives that merit resourcing and action, primarily focusing on the near-term.

Environmental sustainability of negative emissions technologies: A review

Negative emissions technologies (NETs) are expected to play a significant role in mitigating climate change. However, there are also concerns that a large scale deployment of NETs may cause various environmental impacts due to the use of land, water and energy resources. A number of studies have assessed the environmental performance of various NETs; however, a comprehensive review comparing a range of different NETs is not available in the literature. To address this research gap, this paper compares life cycle assessment (LCA) studies of the following options for which the data were available in the literature: bioenergy with carbon capture and storage (BECCS), biochar incorporation into soil, afforestation and reforestation, soil carbon sequestration, building with biomass, direct air carbon capture and storage (DACCS), enhanced weathering and mineral carbonation. It is evident from this review that these technologies can have net negative life cycle GHG emissions, ranging from −603 kg CO 2 eq./t CO 2 removed for building with biomass to −1173 kg CO 2 eq./t CO 2 removed for biochar incorporation into soil. However, the estimates of GHG removal potentials vary widely among the studies for each technology as well as among the NETs owing to technological differences, methodological choices and differing assumptions. For example, the net global warming potential (GWP) of biochar varies among the reviewed studies between a net positive impact of 1710 to a net negative GWP of 3300 kg CO 2 eq./t CO 2 removed, depending upon the feedstock, pyrolysis technology and the assumptions for credits for co-products and co-benefits. Overall, biochar used as soil amendment has the lowest GWP per tonne of CO 2 removed, followed by soil carbon sequestration, while building with biomass ranks last. The review also reveals that the removal of CO 2 by these technologies could lead to a significant increase in other environmental impacts. Especially, the use of energy in non-bio NETs (DACCS, enhanced weathering and mineral carbonation) leads to relatively high fossil depletion, acidification and human toxicity. These impacts can be reduced if the energy demand of NETs is met by renewables instead of fossil fuels. The paper also identifies several methodological issues and challenges in conducting LCA of NETs and provides recommendations to address them.

Optimization of low-cost negative emissions strategies through multi-resource integration

The deployment of negative emissions technologies (NETs) is pivotal in achieving climate targets. The exigent nature of climate change stipulates that multiple NETs must actively remove emissions from the atmosphere in conjunction with other technologies that reduce the release of these emissions. The potential of these NETs has either been analyzed individually or through their co-deployment. However, these assessments have yet to analyze the potential for integration between NETs. Fundamentally, NETs utilize and produce specific material and energy resources to capture and store atmospheric emissions in biological or geological compartments. With sustainability concerns surrounding multiple resources, integrations between processes involving common resources are fervently advocated. A systematic approach is presented in this work to enable the integration of shared resources between NETs. A design optimization problem is formulated to achieve emission removal in the presence of economic and environmental constraints representing the limitations these technologies face on deployment. A case study demonstrates the use of this approach to create profitable integrated NET systems where the least land footprint obtained and most profits generated were 0.22 ha/t net CO2 removed and $315/t net CO2 removed. The outputs of this approach can aid policymakers and network stakeholders achieve negative emissions targets through integrated NET networks.

Analysis of mathematical modeling methods in the processes of underground injection, storage, and conversion of carbon dioxide

The problem of carbon dioxide utilization is of increasing concern to the public, since measures to reduce greenhouse gas emissions are no longer sufficient to prevent a global increase in temperature on the planet. Most modeling scenarios show that a significant deployment of negative emission technologies is required. Carbon dioxide is often used as an agent for enhancing hydrocarbon production in the development of oil and gas fields, which is technologically consistent with projects for its utilization and underground storage in depleted reservoirs, saline aquifers, and shale rocks. For the successful implementation of such sequestration projects, it is necessary to conduct a complex of experimental, modeling, and field studies. It is necessary to understand the characteristic physical and chemical changes that occur in a subterranean formation during sequestration processes, such as dissolution, chemical reactions, convective mixing, advective processes, and dispersion. Computer modeling of ongoing processes is seen as a very important task for the correct functioning of such projects. The article deals with topical problems of computer modeling of processes associated with underground injection and storage of carbon dioxide, and also presents the results of laboratory studies on the utilization of carbon dioxide through its catalytic conversion into useful energy resources—hydrogen and hydrocarbons. The findings of this study can help to better understand physicochemical mechanisms that can occur in subterranean formations when carbon dioxide is injected. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Geochemical Negative Emissions Technologies: Part I. Review

Over the previous two decades, a diverse array of geochemical negative emissions technologies (NETs) have been proposed, which use alkaline minerals for removing and permanently storing atmospheric carbon dioxide (CO2). Geochemical NETs include CO2 mineralization (methods which react alkaline minerals with CO2, producing solid carbonate minerals), enhanced weathering (dispersing alkaline minerals in the environment for CO2 drawdown) and ocean alkalinity enhancement (manipulation of ocean chemistry to remove CO2 from air as dissolved inorganic carbon). CO2 mineralization approaches include in situ (CO2 reacts with alkaline minerals in the Earth's subsurface), surficial (high surface area alkaline minerals found at the Earth's surface are reacted with air or CO2-bearing fluids), and ex situ (high surface area alkaline minerals are transported to sites of concentrated CO2 production). Geochemical NETS may also include an approach to direct air capture (DAC) that harnesses surficial mineralization reactions to remove CO2 from air, and produce concentrated CO2. Overall, these technologies are at an early stage of development with just a few subjected to field trials. In Part I of this work we have reviewed the current state of geochemical NETs, highlighting key features (mineral resources; processes; kinetics; storage durability; synergies with other NETs such as DAC, risks; limitations; co-benefits, environmental impacts and life-cycle assessment). The role of organisms and biological mechanisms in enhancing geochemical NETs is also explored. In Part II, a roadmap is presented to help catalyze the research, development, and deployment of geochemical NETs at the gigaton scale over the coming decades.

Carbon Accounting for Enhanced Weathering

The inevitable deployment of negative emission technologies requires carbon accounting to incentivise the investment and to foster an active CO2 certificate trading schema. Enhanced Weathering as one of the negative emission technologies is being tested in the field now, but lacks a verifiable and cost-effective carbon accounting approach. Based on results from a lab scale column experiment and field observations, it is hypothesized that the observed stable positive correlation between total alkalinity and electrical conductivity may present a way to easily predict the initial CO2 sequestration at the application site by chemical mineral weathering at low costs. Alkalinity is a measure to track weathering products. It is not difficult to measure, yet continuous and mid- to high-frequency sampling and analyses are expensive and time consuming. The observed strong correlation of alkalinity with electrical conductivity could be harnessed and enable a CO2 uptake monitoring by simple electrical conductivity measurements in soils or any point in the discharge system. For a successful implementation and calibration, data are needed, covering the most likely employment scenarios of soil, climate, hydrology, rock product, application scenario and plant abundance. Incorporated in a growing public database, this could be used as an assessment and benchmark system for future EW deployment.

Carbon Capture and Storage Potential in Ireland — Returning Carbon Whence It Came

Summary Carbon capture and storage (CCS) involves the capture of CO2 emissions produced from industrial and electricity generation sources, followed by transport to permanent underground geological storage. Hence, CCS is one mitigation option available to achieve the targets set out in the Paris Agreement. Here we discuss CCS potential with particular reference to Ireland’s emission targets, policy positions and geological storage options. In Ireland, CCS could be utilised (1) with gas-powered electricity to provide secure and reliable low-emissions electricity, (2) to reduce emissions in hard-to-abate industries such as cement manufacturing, and (3) to facilitate the future deployment of negative emissions technologies. Ireland has significant potential to store CO2 in geological formations in depleted gas fields and deep saline aquifers in its offshore sedimentary basins. Two high-graded options are the offshore Kinsale Head and Corrib gas fields. Provisional estimates for the CO2 storage capacity of these two fields are 321 Mt and 44 Mt respectively. The depleted Kinsale Head gas field alone could have sufficient storage capacity to take the equivalent of up to 40 years of CO2 emissions from the top 10 point-source emitters in Ireland. Further work is needed to fully characterise and mature the potential for CCS in Ireland.

Direct Air Capture of CO2 Using Solvents.

Large-scale deployment of negative emissions technologies (NETs) that permanently remove CO2 from the atmosphere is now considered essential for limiting the global temperature increase to less than 2°C by the end of this century. One promising NET is direct air capture (DAC), a technology that employs engineered chemical processes to remove atmospheric carbon dioxide, potentially at the scale of billions of metric tons per year. This review highlights one of the two main approaches to DAC based on aqueous solvents. The discussion focuses on different aspects of DAC with solvents, starting with the fundamental chemistry that includes the chemical species and reactions involved and the thermodynamics and kinetics of CO2 binding and release. Chemical engineering aspects are also discussed, including air-liquid contactor design, process development, and technoeconomic assessments to estimate the cost of the DAC technologies. Various solvents employed in DAC are reviewed, from aqueous alkaline solutions (NaOH, KOH) to aqueous amines, amino acids, and peptides, along with different solvent regeneration methods, from the traditional thermal swinging to the more exploratory carbonate crystallization with guanidines or electrochemical methods.

Technology, technology, technology: An integrated assessment of deep decarbonization pathways for the Canadian oil sands

As a party to the Paris Agreement, Canada has an ambitious climate target of net-zero emissions by 2050. The country also holds the world's third largest oil reserves in the Alberta oil sands. Given increasing emissions from the oil sands sector, achieving Canada's net-zero target requires significant oil sands decarbonization. If, while phasing out fossil fuels, there is still a demand for Canadian oil sands, then the decarbonization of the resource production process becomes crucial. In this study, we use an enhanced version of the Global Change Analysis Model (GCAM) with a detailed unconventional oil sector for Canada, including mining and in situ resources. We ask, what is the future of the oil sands sector in deeply decarbonized global and Canadian economies? We address this question under four mitigation scenarios with varying global net-zero GHG emissions constraints, three additional representative lower carbon extraction technologies available for the oil sands sector, as well as global direct air capture (DAC) deployment. We find that lower carbon technology deployment allows a 20%–44% increase in oil sands production by 2050 for scenarios with net-zero GHG emissions in 2100 or 2075. DAC helps maintain oil sands production in the most ambitious global decarbonization scenario (net-zero GHG by 2050), without which low international oil demand makes Canadian oil sands production uncompetitive. Canadian oil sands production thus depends highly on the availability of lower carbon extraction technologies and international oil demand, which to a certain extent relies on the availability and global deployment of negative emissions technologies.