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

Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

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.

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

The inherent structure tunability, good affinity with CO2, and nonvolatility of ionic liquids (ILs) drive their exploration and exploitation in CO2 separation field, and has attracted remarkable interest from both industries and academia. The aim of this Review is to give a detailed overview on the recent advances on IL-based materials, including pure ILs, IL-based solvents, and IL-based membranes for CO2 capture and separation from the viewpoint of molecule to engineering. The effects of anions, cations and functional groups on CO2 solubility and selectivity of ILs, as well as the studies on degradability of ILs are reviewed, and the recent developments on functionalized ILs, IL-based solvents, and IL-based membranes are also discussed. CO2 separation mechanism with IL-based solvents and IL-based membranes are explained by combining molecular simulation and experimental characterization. Taking into consideration of the applications and industrialization, the recent achievements and developments on the t...

Ionic-Liquid-Based CO2 Capture Systems: Structure, Interaction and Process

To mitigate the growing pressure on resource depletion and environment degradation, the development of green processes for the production of renewable energy is highly required. As a class of novel and promising media, ionic liquids (ILs) have shown infusive potential applications in energy production. Aiming to offer a critical overview regarding the new challenges and opportunities of ILs for developing green processes of renewable energy, this article emphasises the role of ILs as catalysts, solvents, or electrolytes in three broadly interesting energy production processes from renewable resources, such as CO2 conversion to fuels and fuel additives, biomass pretreatment and conversion to biofuels, as well as solar energy and energy storage. It is expected that this article will stimulate a generation of new ideas and new technologies in IL-based renewable energy production.

Ionic liquid-based green processes for energy production

A screening method is proposed for the molecular design of ionic liquids (ILs) to capture carbon dioxide (CO2), which can reduce efficiently the necessary experimental efforts. The COSMO-RS method is implemented to predict the Henry's law constants of CO2 in 408 ILs with various combinations of cations and anions. It is found by the screening that the ILs with the anion tris(pentafluoroethyl)trifluorophosphate ([FEP]) show improved capability to capture CO2, compared with other ILs reported in literature. Then, three [FEP]-based ILs are chosen to perform the solubility measurements by the intelligent gravimetric analyzer (IGA 003, Hiden Analytical), with cations of 1-hexyl-3-methylimidazolium ([hmim]), 1-butyl-1-methylpyrrolidinium ([bmpyrr]), and S-ethyl-N,N,N′,N′-tetramethylthiouronium ([ETT]) at 283.2, 298.2, and 323.2 K, up to the pressure of 1.8 MPa. The experimental data show that the solubility of CO2 in [hmim][FEP] is about 15% higher than that in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf2N]), which is in fair agreement with the screening results, indicating the method proposed in this work is reliable. © 2008 American Institute of Chemical Engineers AIChE J, 2008

Xiaochun Zhang

Papers

Carbon capture with ionic liquids: overview and progress

Ionic-Liquid-Based CO2 Capture Systems: Structure, Interaction and Process

Ionic liquid-based green processes for energy production

Screening of ionic liquids to capture CO2 by COSMO-RS and experiments

Efficient and reversible capture of SO2 by pyridinium-based ionic liquids