Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, more recently, its ability to facilitate the net removal of CO2 from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO2 capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.

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Carbon capture and storage (CCS): the way forward

In recent years, Carbon Capture and Storage (Sequestration) (CCS) has been proposed as a potential method to allow the continued use of fossil-fuelled power stations whilst preventing emissions of CO2 from reaching the atmosphere. Gas, coal (and biomass)-fired power stations can respond to changes in demand more readily than many other sources of electricity production, hence the importance of retaining them as an option in the energy mix. Here, we review the leading CO2 capture technologies, available in the short and long term, and their technological maturity, before discussing CO2 transport and storage. Current pilot plants and demonstrations are highlighted, as is the importance of optimising the CCS system as a whole. Other topics briefly discussed include the viability of both the capture of CO2 from the air and CO2 reutilisation as climate change mitigation strategies. Finally, we discuss the economic and legal aspects of CCS.

Carbon capture and storage update

Structure and nanostructure in ionic liquids.

Ionic liquids offer a unique suite of properties that make them important candidates for a number of energy related applications. Cation–anion combinations that exhibit low volatility coupled with high electrochemical and thermal stability, as well as ionic conductivity, create the possibility of designing ideal electrolytes for batteries, super-capacitors, actuators, dye sensitised solar cells and thermo-electrochemical cells. In the field of water splitting to produce hydrogen they have been used to synthesize some of the best performing water oxidation catalysts and some members of the protic ionic liquid family co-catalyse an unusual, very high energy efficiency water oxidation process. As fuel cell electrolytes, the high proton conductivity of some of the protic ionic liquid family offers the potential of fuel cells operating in the optimum temperature region above 100 °C. Beyond electrochemical applications, the low vapour pressure of these liquids, along with their ability to offer tuneable functionality, also makes them ideal as CO2 absorbents for post-combustion CO2 capture. Similarly, the tuneable phase properties of the many members of this large family of salts are also allowing the creation of phase-change thermal energy storage materials having melting points tuned to the application. This perspective article provides an overview of these developing energy related applications of ionic liquids and offers some thoughts on the emerging challenges and opportunities.

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Energy applications of ionic liquids

Starting with coal, followed by petroleum oil and natural gas, the utilization of fossil fuels has allowed the fast and unprecedented development of human society. However, the burning of these resources in ever increasing pace is accompanied by large amounts of anthropogenic CO2 emissions, which are outpacing the natural carbon cycle, causing adverse global environmental changes, the full extent of which is still unclear. Even through fossil fuels are still abundant, they are nevertheless limited and will, in time, be depleted. Chemical recycling of CO2 to renewable fuels and materials, primarily methanol, offers a powerful alternative to tackle both issues, that is, global climate change and fossil fuel depletion. The energy needed for the reduction of CO2 can come from any renewable energy source such as solar and wind. Methanol, the simplest C1 liquid product that can be easily obtained from any carbon source, including biomass and CO2, has been proposed as a key component of such an anthropogenic carbon cycle in the framework of a “Methanol Economy”. Methanol itself is an excellent fuel for internal combustion engines, fuel cells, stoves, etc. It's dehydration product, dimethyl ether, is a diesel fuel and liquefied petroleum gas (LPG) substitute. Furthermore, methanol can be transformed to ethylene, propylene and most of the petrochemical products currently obtained from fossil fuels. The conversion of CO2 to methanol is discussed in detail in this review.

Recycling of carbon dioxide to methanol and derived products – closing the loop

As an emerging carbon dioxide (CO2) capture technology, separating CO2 from industrial gases with ionic liquids is increasingly attracting remarkable interests. In this paper, the research progress on CO2 capture with ionic liquids is reviewed with particular attention on the viewpoint of potential industrial applications. We investigate and compare the CO2 capture capacities of pure ionic liquids, including conventional and task-specific ionic liquids, and ionic liquid-based mixtures. The mechanisms of chemisorption and physisorption are explained with experimental characteristics and molecular simulation, which show more and more important roles for screening suitable ionic liquids from tremendous candidates. Considering the scaling up of novel units for ionic liquid-based fluids, the studies on the transport properties and hydrodynamics of ionic liquid fluids are presented. The process design and assessment of ionic liquid processes are discussed, including the research progress on thermodynamic properties and prediction models. Besides giving an overview of research for each issue above, we also provide discussions for future work to try to identify the gap between the current work and the demand by real industrial applications. Finally, we present some perspectives of ionic liquid-based novel technologies, and the challenges which will be faced while developing industrially available technologies.

Carbon capture with ionic liquids: overview and progress

Toxicity of ionic liquids: Database and prediction via quantitative structure–activity relationship method

Ying HuangBeijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems,Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences,Beijing 100190, P.R. ChinaCollege of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences,Beijing 100049, P.R. ChinaHaifeng Dong, Xiangping Zhang, Chunshan Li, and Suojiang ZhangBeijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems,Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences,Beijing 100190, P.R. ChinaDOI 10.1002/aic.13910Published online in Wiley Online Library (wileyonlinelibrary.com).A new fragment contribution-corresponding states (FC—CS) method based on the group contribution method and thecorresponding states principle is developed to predict critical properties of ionic liquids (ILs). There are 46 fragmentsspecially classified for ILs considering the ionic features of ILs, and the corresponding fragment increments aredetermined using the experimental density data. The accuracy of the developed method is verified indirectly viapredicting density and surface tension of ILs. The results show that the FC—CS method is reasonable with an averageabsolute relative deviation less than 4%. With the calculated critical properties, corresponding states heat capacity(CSHC) and corresponding states thermal conductivity (CSTC) correlations are proposed to predict heat capacity andthermal conductivity of ILs, respectively. The predicted results agreed well with the experimental data. The proposedFC—CS method and the two corresponding states correlationsare important for design, simulation, and analysis of newionic liquid processes.

A new fragment contribution‐corresponding states method for physicochemical properties prediction of ionic liquids

Engineers often demand generalized models without sophisticated and long-time computations. To date, such models are still lacking for the density prediction of ionic liquid (IL) mixtures. In this paper, corresponding states principle combining with new mixing rules is employed to develop two new generalized models for density prediction of IL mixtures, including an extended Riedel (ER) model and an artificial neural network (ANN) model. A total of 1985 data points of binary and ternary mixtures of IL with molecular solvents, such as water, alcohols, ketones, ethers, hydrocarbons, esters, and acetonitrile, are used to verify the models. Average absolute relative deviations of the ER model and the ANN model are 0.92% and 0.37%, respectively, which indicates both the developed models can achieve a universal and accurate density prediction of IL mixtures. Moreover, the ER model does not contain any fitted parameters and thus provides a real predictive method.

Density Prediction of Mixtures of Ionic Liquids and Molecular Solvents Using Two New Generalized Models

The invention belongs to the technical field of gas separation and purification, and relates to a high-selectivity decarbonization absorbent adopting a physical method. According to the absorbent, an ionic liquid and a polyethylene glycol dimethyl ether compound solvent are taken as absorbents, wherein the ionic liquid not only has higher carbon dioxide absorbing capacity, but also can remarkably improve the selectivity for separating methane and carbon dioxide, and polyethylene glycol dimethyl ether can further improve the carbon dioxide absorbing capacity and simultaneously increases the carbon dioxide mass transfer rate; the compound solvent is contacted with treated gas, and the purpose of gas purification is achieved; and the concentration of the ionic liquid in the compound absorbent is 10%-90% at the weight percent. According to the technical scheme, the absorbent has high selectivity in separation of methane and carbon dioxide, and the mass transfer rate and the absorbing capacity are high; and the absorbent can be widely used for separating and purifying carbon dioxide in process gases such as natural gas, shale gas, coal bed gas, biogas and the like.

Ying Huang

Papers

Carbon capture with ionic liquids: overview and progress

Toxicity of ionic liquids: Database and prediction via quantitative structure–activity relationship method

A new fragment contribution‐corresponding states method for physicochemical properties prediction of ionic liquids

Density Prediction of Mixtures of Ionic Liquids and Molecular Solvents Using Two New Generalized Models

High-selectivity decarbonization absorbent adopting physical method