Carbon dioxide removal, capture and storage

Global assessments of the climate change mitigation potential of biochar diverge, and many rely on a dated analysis, but there is strong evidence for gigaton-scale contribution, concludes a synthesis of 19 studies of biochar mitigation potential.

Given the escalating climate crisis, the task of integrating novel carbon dioxide removals into the European Union’s climate policy is urgent and long overdue. This Comment argues that there is a window of opportunity for responding now, and puts forward a solution.

Carbon Dioxide Removal (CDR) is a key element of any mitigation strategy aiming to achieve the long-term temperature goal of the Paris Agreement, as well as national net-zero and net-negative greenhouse gas emissions targets. For robust CDR policy, the credibility of certification schemes is essential.

Mineral doping of biomass prior to pyrolysis enhances carbon dioxide removal associated with biochar application to soils due to increased stable carbon yield, while also improving biochar fertiliser value through added nutrients and enhanced phosphorus availability.

Enhanced rock weathering alters ecosystem functions, particularly carbon dioxide and nitrous oxide emissions, by changing microbial carbon and nitrogen cycling genes, according to a two-year wollastonite addition manipulation experiment in a trophic rubber plantation in China.

In water nanofilm-mediated carbonation, interfacial transport occurs through anomalous quasi-2-dimensional diffusion involving intermittent diffusive hopping in the desorbed state, according to combined analysis with X-ray diffraction and advanced molecular simulation.

By 2100, bioenergy with carbon capture and storage, direct air capture, and enhanced weathering can contribute to removing 500 megatons of carbon dioxide emissions per year in Canada and are key to commitment under burden-sharing principles, according to an integrated assessment model analysis.

Calcite has a higher carbon dioxide uptake efficiency and lower cost than dunite, and it is a preferable material for enhanced benthic weathering as a carbon dioxide removal method, according to an analysis that combines laboratory incubation, benthocosm experiment, and numerical box model.

In the US, the delay in novel carbon dioxide removal until mid-century and focus on other mitigation actions reduces 2050 residual emissions to 17 percent of 2020 levels but at a high economic cost, according to an analysis that uses a market equilibrium model with a scenario approach.

In Canada, the performance of liquid-solvent direct air capture plants degrades in cold climates, while in warm climates, the performance is boosted but requires increased use of water, according to an analysis that uses an open-source model that combines chemical processes and cost data.

Carbon dioxide can be removed from the atmosphere at an uptake rate of 3.2 megatonnes of carbon dioxide per year by continually adding calcite to mud-bearing sediments in the Baltic Sea, according to an empirical model analysis.

Carbon dioxide removal via afforestation and reforestation could be scaled up globally to account for ten percent of net greenhouse gas emission reductions required between 2020 and 2030, according to an analysis of land-based carbon removal deployed in the IPCC-assessed scenarios.

Large-scale deployment of direct air carbon capture and storage (DACS) is required to offset CO2 emissions. Here, Moritz Gutsch and Jens Leker present a cost model and life cycle assessment for several combinations of off-grid DACSs, powered by photovoltaic energy and heat pumps combined with battery storage. They find a cost optimal energy system layout for implementation in Nevada USA.

Carbon dioxide removal technologies scale-up is within range of previous technological diffusion, according to analysis combining growth rates and historical adoption technology data.

Cultivating 1 million km² of the most productive exclusive economic zones, which are in the equatorial Pacific, could produce 1 Gt of seaweed carbon per year; however, beyond these productive waters carbon harvest efficiency drops dramatically, according to global dynamic seaweed growth simulations.

The German public prefers carbon dioxide removal strategies with low environmental side effects and implementation at home rather than abroad, despite insufficient potential domestically, according to a multifactor vignette experiment carried out in late 2020.

New study concludes that environmental tradeoffs of direct air capture and sequestration technologies are linked to the energy system in which they will operate, and their deployment should not equate to a relaxation of decarbonization or resource use efficiency targets.

⁸⁷Sr/⁸⁶Sr pattern of residual salts from a 100 m basalt section reveal a vertically connected pore water system unaffected by massive lava flow interiors, supporting continental margin basalt sequences as viable reservoirs for permanent CO₂ storage.

Injection of acidic chelating agents into fractured peridotite increased permeability by 21-fold within 20 minutes, significantly enhancing CO₂ mineralization potential in a designed two-stage system, enabling both in-situ and ex-situ carbonation.

Oyster farming can enhance organic carbon storage in sediments by increasing sediment organic carbon concentration up to 2.6 times, according to an analysis of 50 years of farming data from a typical oyster farm in Sanggou Bay, China.

Three key challenges to reducing uncertainty in geoenergy development—lack of large-scale time-lapse monitoring, the absence of microbial tracer selection, and the oversight of front propagation velocity—can be addressed using DNA-sequencing of microbes in subsurface fluids.

The difference between the seasonal temperature and optimal growing temperature for vegetation plays a crucial role in the timing of the start of the growing season, according to a climate dataset analysis between 1982 and 2015 coupled with remote sensing.

High-income countries that produce hydrocarbons have an advantage in implementing and benefiting from carbon dioxide geological storage, which creates disparities in global decarbonization pathways, according to an analysis of long-term climate strategies.

Application of [5%] biochar to soil could sequester around 10 billion tons of carbon in China’s soils, according to laboratory sorption experiments with pristine soil and four different biochar applications.

In China, under the high cement quality scenario, the increase of environmental taxes is projected to reduce carbon dioxide emissions and fuel consumption in the cement industry by 2060, according to an analysis that uses an integrated assessment model with the flow of energy and materials.

Discourse on carbon dioxide removal on social media has become positive over time, except for bioenergy with carbon capture and storage, with 31 percent of tweets from infrequent users, which make up 78 percent of all users, according to an analysis of Twitter (now X) data from 2010 to 2022.

Regardless of Denmark’s carbon dioxide emission reduction goal, knowledge and familiarity influence public support and willingness to pay for carbon capture and storage, according to an online survey and econometric model analysis.

Seismic monitoring of geologic carbon storage can be enhanced with the use of a rock physics model which incorporates the impact of CO2 saturation on seismic waves and replicates laboratory shear-wave observations

Drs Papathanasiou & Pini, and colleagues present a model-based approach for efficient design of sorbent-based post-combustion carbon capture. They quantify operability-cost trade-offs and identify suitable candidate designs that satisfy CO₂ purity and recovery constraints.

Molecular dynamics calculations suggest the leaching of Ca ions from Ca-olivine has a substantially lower energy barrier than the equivalent process for Mg ions from Mg-olivine, indicating the former has greater capacity for carbon dioxide mineralization.

Combining hydrogen production derived from mixed plastic waste with carbon capture and storage technologies is technically and economically feasible at current market conditions, according to a techno-economic analysis and life cycle assessment.

Use of CO2 mineralisation in the cement industry could be profitable and cut CO2-equivalent emissions by up to a third, if the process is eligible for carbon trading and its products are used in construction, suggests integrated techno-economic modelling.

Magnesium hydroxide is a sustainable material for CO₂ sequestration, according to an acid digestion and electrolysis method using olivine-rich silicate rocks in a fully recoverable system.

Ethylene glycol, widely utilized with over 40 million tons produced annually, is typically made with high CO₂ emissions. Here, the authors report an electrochemical method to produce ethylene glycol from biomass glycerol, offering a more sustainable, low-emission alternative.

The unconventional hexagonal phase CuCo PBA with open structure, large pore size, and high specific surface area is synthesized, and it delivers much better small molecular gas adsorption performance than the traditional cubic counterpart.

Water management is crucial for enhancing economic viability and minimizing the environmental impact of direct air capture (DAC) technologies, but the high energy intensity necessitates heat recovery techniques. This Perspective discusses several front-end and back-end strategies for coupling water management with heat integration in DAC processes.

Europe’s ambition for emissions reductions is to be welcomed — but look at the detail, and significant hazards emerge.

Metal–organic frameworks (MOFs) are porous materials that may find application in numerous energy settings, such as carbon capture and hydrogen-storage technologies. Here, the authors review predictive computational design and discovery of MOFs for separation and storage of energy-relevant gases.

Various methods of carbon dioxide removal (CDR) are being pursued in response to the climate crisis, but they are mostly not proven at scale. Climate experts are divided over whether CDR is a necessary requirement or a dangerous distraction from limiting emissions. In this Viewpoint, six experts offer their views on the CDR debate.

Electrochemical carbon capture is a promising way to electrify CO₂ emissions mitigation, but capacities are often low due to poor solubility of the redox-active organic molecules at the heart of the process. Here the authors report a high-capacity and high-stability electrochemical CO₂ capture system based on a phenazine derivative they have developed.

Coal–biomass co-firing power plants with retrofitted carbon capture and storage are seen as a promising decarbonization solution for coal-dominant energy systems. Framework with spatially explicit biomass sources, plants and geological storage sites demonstrate its effectiveness in China.

Drastically reduce emissions first, or carbon dioxide removal will be next to useless.

Carbon dioxide removal will be essential to reaching ambitious climate goals by offsetting hard-to-abate emissions and drawing down legacy CO₂. A diverse portfolio of CO₂ removal strategies, rather than any single approach, could achieve gigatonne-scale removals while limiting risks to the water–energy–land system.

Residual emissions, as a noticeable component of net-zero plans, should be analysed transparently and with specificity. By examining the national long-term strategies, the authors find that currently residual emissions are not clearly defined and are unlikely to be balanced by land-based carbon removal.

Afforestation on drylands can help mitigate climate change through carbon sequestration, but the water and energy implications can hinder implementation. A study now investigates the environmental and economic potential of afforestation enabled by desalination plants powered by renewable electricity.

Electrochemical approaches to carbon capture have the advantages of operation under ambient conditions and modular design, but improved sorbent molecules are still needed. Here the authors present a library of redox-tunable Lewis bases, shedding light on molecular design guidelines to tune sorbent properties.

Meeting climate targets will require considerable carbon dioxide removal in addition to emission cuts. To achieve this sustainably, a range of methods are needed to avoid adverse effects and match co-benefits with local needs.

Enhancing rock weathering across UK croplands could deliver substantial atmospheric carbon dioxide removal alongside agricultural co-benefits, according to coupled climate–carbon–nitrogen cycle model simulations.

Direct air capture (DAC) of CO₂ has garnered interest as a negative emissions technology to help achieve climate targets, but indirect emissions and other environmental impacts must be better understood. Here, Deutz and Bardow perform a life-cycle assessment of DAC plants operated by Climeworks, based on industrial data.

Carbon dioxide removal technologies may be needed to meet climate targets. In this study, national surveys and deliberative workshops in the United States and the United Kingdom show that carbon dioxide removal is perceived as too slow to address the immediate climate crisis while not addressing the root causes of climate change.