Integrating a full carbon capture scheme onto a 450 MWe NGCC electric power generation hub for offshore operations: Presenting the Sevan GTW concept

Sevan Marine and Siemens have developed a floating power plant – entitled Sevan GTW (gas-to-wire) – based on Sevan’s cylindrical platform and Siemens’ SCC-800 combined cycle, and SINTEF has adapted a post-combustion CO₂ capture process for on board integration including compression and preconditioning of the CO₂. Main emphasis has been placed on developing an optimised conceptual design within the structural constraints, and assessing how efficient the capture unit may be operated in consideration of the dynamic behaviour induced by the sea on the absorber and desorber columns via the floating carrier. The rational behind this technology selection is the urgency in making appropriate steps for a quick start for remote power generation at sea with the inclusion of CCS to serve offshore oil and gas operations. This calls for modular power blocks made up by high efficient combined power cycles with post-combustion exhaust gas cleaning. From this point of view a system with four absorption columns and one desorber unit has been determined based on structured packing material. The capture process has been integrated with the power cycle in due consideration of the sea forces. It is shown that a permanent tilt becomes more important than periodic movements provided the harmonic periods are kept within a certain level (<20 s). Operational conditions and constraints vis-à-vis movements and trimming of the floater have been addressed and discussed with reference to available literature. This also includes the liquid hold-up and gas–liquid interfacial area in the absorption columns linked with tilting. Optimisation reveals that a reboiler duty of 3.77 GJ/ton CO₂ would result in the lowest capture cost. With a energy penalty of 9%-points the Sevan GTW concept presents itself as a realistic concept deemed to be within reach today.     

Seasonal hydrogen storage in a depleted oil and gas field

Hydrogen storage is essential in hydrogen value chains and subsurface storage may be the most suitable large-scale option. This paper reports numerical simulations of seasonal hydrogen storage in the Norne hydrocarbon field, offshore Norway. Three different storage schemes are examined by injecting pure hydrogen into the gas-, oil-, and water zones. Implementation of four annual withdrawal-injection cycles followed by one prolonged withdrawal period show that the thin gas zone is a preferred target with a final hydrogen recovery factor of 87%. The hydrogen distribution in the subsurface follow the geological structures and is restricted by fluid saturation and displacement efficiencies. Case studies show that the pre-injection of formation gas as a cushion gas efficiently increases the ultimate hydrogen recovery, but at the cost of hydrogen purity. The injection of 30% hydrogen-formation gas mixture results in a varying hydrogen fraction in the withdrawn gas. An alternative well placement down the dipping structure shows lower storage efficiency.     

Patterning of soft polydimethylsiloxane elastomers using plasma etching

Soft polydimethylsiloxane (PDMS) elastomers spin coated on silicon wafers are patterned using plasma etching. The elastomers are formed by mixing vinyl‐terminated PDMS (prepolymer) and crosslinker containing hydride sites. The elastomers are made softer by adding either excess prepolymer, excess crosslinker, or swelling agent. The different elastomers were etched using reactive ion etching, an old and well established processing technology in the microelectronic and MEMS industry. The etch rate and profiles of the etched surfaces were dependent on the process pressure. The dependence was different for the different elastomers. It was found that at low pressure, the etch rate was dependent on the shear modulus. At high pressures, the etch rate was dependent on the chemical composition of the elastomer. The results for the swollen elastomers were different from those for the nonswollen elastomers. The etch rate was lower and the profiles of the etched cavities were different. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Methods based on discrete optimization for finding road network rehabilitation strategies

We study a dynamic optimization problem arising in the (long-term) planning of road rehabilitation activities. In this area one seeks a pavement resurfacing plan for a road network under budget constraints. Our main approach is to model this as an integer programming problem with underlying dynamic programming structure. We investigate properties of this model and propose a solution method based on Lagrangian relaxation where one gets subproblems that are shortest path problems. Some computational experiences based on realistic data are reported.     

Quantification of Fatty Acids and their Regioisomeric Distribution in Triacylglycerols from Porcine and Bovine Sources Using 13C NMR Spectroscopy

The uptake of specific fatty acids in humans is dependent on their position on the glycerol backbone. There is a great interest in methods that can access this information fast and accurately. By way of high-resolution NMR, we have analyzed TAG extracted from pig and beef tissues and obtained quantitative data for the composition and regioisomeric distribution of all major unsaturated fatty acids usually found in these source materials, using a combination of manual integration and deconvolution of ¹³C NMR spectra. In addition, we have developed a method for determining composition and regioisomeric distribution of the two main saturated fatty acids found in pork (16:0, 18:0). The results are discussed in relation to species-specific genetic characteristics of fatty acid and TAG biosynthesis. The developed method could support decisions related to breeding for desired fatty acid profiles, and stimulate further methodology developments using high field NMR.     

Techno-economic comparison of three technologies for pre-combustion CO2 capture from a lignite-fired IGCC

This paper compares the techno-economic performances of three technologies for CO₂ capture from a lignite-based IGCC power plant located in the Czech Republic: (1) Physical absorption with a Rectisol-based process; (2) Polymeric CO₂-selective membrane-based capture; (3) Low-temperature capture. The evaluations show that the IGCC plant with CO₂ capture leads to costs of electricity between 91 and 120 €·MWh⁻¹, depending on the capture technology employed, compared to 65 €·MWh⁻¹ for the power plant without capture. This results in CO₂ avoidance costs ranging from 42 to 84 €·t_CO2,avoided⁻¹ , mainly linked to the losses in net power output. From both energy and cost points of view, the low-temperature and Rectisol based CO₂ capture processes are the most efficient capture technologies. Furthermore, partial CO₂ capture appears as a good mean to ensure early implementation due to the limited increase in CO₂ avoidance cost when considering partial capture. To go beyond the two specific CO₂-selective membranes considered, a cost/membrane property map for CO₂-selective membranes was developed. This map emphasise the need to develop high performance membrane to compete with solvent technology. Finally, the cost of the whole CCS chain was estimated at 54 €·t_CO2,avoided⁻¹ once pipeline transport and storage are taken into consideration.     

A multi-start local search heuristic for ship scheduling—a computational study

We present a multi-start local search heuristic for a typical ship scheduling problem. A large number of initial solutions are generated by an insertion heuristic with random elements. The best initial solutions are improved by a local search heuristic that is split into a quick and an extended version. The quick local search is used to improve a given number of the best initial solutions. The extended local search heuristic is then used to further improve some of the best solutions found. The multi-start local search heuristic is compared with an optimization-based solution approach with respect to computation time and solution quality. The computational study shows that the multi-start local search method consistently returns optimal or near-optimal solutions to real-life instances of the ship scheduling problem within a reasonable amount of computation time.     

Looking for Skinner and finding Freud.

Sigmund Freud and B. F. Skinner are often seen as psychology's polar opposites. It seems this view is fallacious. Indeed, Freud and Skinner had many things in common, including basic assumptions shaped by positivism and determinism. More important, Skinner took a clear interest in psychoanalysis and wanted to be analyzed but was turned down. His views were influenced by Freud in many areas, such as dream symbolism, metaphor use, and defense mechanisms. Skinner drew direct parallels to Freud in his analyses of conscious versus unconscious control of behavior and of selection by consequences. He agreed with Freud regarding aspects of methodology and analyses of civilization. In his writings on human behavior, Skinner cited Freud more than any other author, and there is much clear evidence of Freud's impact on Skinner's thinking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)