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.

/pdf/energy-applications-of-ionic-liquids-4xj70drpc5.pdf

Energy applications of ionic liquids

Ionic liquids tailored amine aqueous solution for pre-combustion CO2 capture: Role of imidazolium-based ionic liquids

BACKGROUND
Ionic liquids have become potential absorbents to treat exhausted gases containing NH3, which threatens the living environment of human beings.

RESULTS
In this study, 10 kinds of protic and conventional ILs were synthesized and characterized and their densities, viscosities and thermal decomposition temperatures were measured. The NH3 solubility in ILs from the VLE experiments revealed that the chain length of cations had little influence on the NH3 solubility of the protic ILs because of the high NH3 capacities in protic ILs resulting from protic hydrogen atom compared to the conventional ILs. Besides, the 2-H atom on the cation influenced the NH3 solubility in both protic and conventional ILs with different trends as the pressure increased. Considering the effect of anions with the same cation [Bim]+, the order of NH3 solubility in protic ILs was [Bim][NTf2] > [Bim][SCN] > [Bim][NO3]. Dynamic absorption of NH3 in [Eim][NTf2] preliminarily revealed that the absorption was fast under ambient pressure and through 5 cycles of absorption and desorption, the NH3 absorption ability kept stable.

CONCLUSIONS
The relationship between the NH3 solubility and the structures of both protic and conventional ILs were revealed, indicating the protic ILs as an alternative material for the treatment of NH3 - containing exhausted gases.

Enhanced NH3 capture by imidazolium-based protic ionic liquids with different anions and cation substituents

The densities and viscosities of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf2]) + N-methyl-2-pyrrolidone (NMP) and [EMIM][NTf2] + ethanol mixtures were investigated over the mole fraction range from (0.1 to 0.9) and at temperatures from (293.15 to 323.15) K at intervals of 5 K. The densities can be well-represented by the quadratic equation, and the viscosities can be represented in the form of the Vogel equation. The excess molar volumes (VE) and viscosity deviations (Δη) were calculated, and the results were fitted to the Redlich–Kister equation using a multiparametric nonlinear regression method. The estimated parameters of the Redlich–Kister equation and standard deviation were also presented. The results showed that the densities and viscosities were dependent strongly on NMP or ethanol content. Comparatively, the viscosity deviation Δη was more sensitive to temperature than the excess molar volume VE.

Densities and Viscosities of the Binary Mixtures of 1-Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide with N-Methyl-2-pyrrolidone or Ethanol at T = (293.15 to 323.15) K

Haifeng Dong

Papers

Ionic liquids tailored amine aqueous solution for pre-combustion CO2 capture: Role of imidazolium-based ionic liquids

Enhanced NH3 capture by imidazolium-based protic ionic liquids with different anions and cation substituents

Densities and Viscosities of the Binary Mixtures of 1-Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide with N-Methyl-2-pyrrolidone or Ethanol at T = (293.15 to 323.15) K

Solubilities of CO2, CH4, H2, CO and N2 in choline chloride/urea

CO2 Electroreduction in Ionic Liquids: A Review