Carbon dioxide removal, capture and storage

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.

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.

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.

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.