There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

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

Corrigendum to “Efficiently trapping asphaltene-type materials from direct coal liquefaction residue using alkylsulfate-based ionic liquids” [Fuel 112 (2013) 289–294]

In this study, the hydrodynamic characteristics for N2 and [Bmim][NO3] in a cross flow T-shaped square microchannel were investigated experimentally. A Micro-PIV system was used to capture ionic li...

Hydrodynamic Characteristics of N2-[Bmim][NO3] Two-Phase Taylor Flow in Microchannels

Electrochemical carbon dioxide reduction reaction (CO2RR) provides a promising pathway for both decreasing atmospheric CO2 concentration and producing valuable carbon-based fuels. Exploring efficient and lower cost catalysts for CO2RR is of great importance, but still remains challenging. Herein, the iodine-treated porous N-doped carbon is fabricated as an efficient metal-free catalyst for CO2 electroreduction. The catalyst exhibits nearly 100% CO Faradaic efficiency with partial CO current density of 38.2 mA cm−2 at a low overpotential in ionic liquid electrolyte. A detailed study indicates that the pyrrolic N serves as the active site for CO formation. The iodine treatment not only enhances the electrochemical active surface area and decreases the interfacial charge-transfer resistance of the catalyst, but also increases the content of pyrrolic N that is confirmed as active site. This work presents an efficient strategy to explore highly efficient metal-free electrocatalyst for CO2RR, which has great application potentials.

Boosting CO2 electroreduction by iodine-treated porous nitrogen-doped carbon

Suspended particles behavior in aqueous [Bmim]BF4 solution by novel on-line electrical sensing zone method

Ionic liquids (ILs) have been proved as novel excellent solvents in gas separation and so on. Due to its excellent heat and mass transfer performance, falling film evaporator is often used in the applications of high viscosity systems and has the potential to be the regeneration equipment for IL-based systems. However, there are few reports on the falling film evaporation of ILs system. The relevant experimental data are scarce. Moreover, the traditional models cannot predict the hydrodynamics of ILs well due to the specific properties of ILs. In this study, an experimental method for studying the ILs falling film flow was established. The falling film hydrodynamics of three ILs (BmimBF4, BmimPF6, OmimBF4), including film flow pattern and film thickness were investigated. The effects of streamwise flow distance and the physical property of ILs on the hydrodynamics were analyzed. A calculation model and a dimensionless empirical model of ILs film thickness were established based on experimental data. The average relative deviation of new dimensionless model is 2.83%, which is much lower than that of Nusselt model (13.48%). The measurement of key parameters and the establishment of models provide experiment data and basis for designing the falling film evaporator of IL-based systems.

Haifeng Dong

Papers

Corrigendum to “Efficiently trapping asphaltene-type materials from direct coal liquefaction residue using alkylsulfate-based ionic liquids” [Fuel 112 (2013) 289–294]

Hydrodynamic Characteristics of N2-[Bmim][NO3] Two-Phase Taylor Flow in Microchannels

Boosting CO2 electroreduction by iodine-treated porous nitrogen-doped carbon

Suspended particles behavior in aqueous [Bmim]BF4 solution by novel on-line electrical sensing zone method

Experimental study on hydrodynamics of ionic liquids systems in falling film evaporator