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This paper describes a detailed technical and economic assessment of conditioning and transporting 13.1 MTPA CO 2 with impurities in an on-shore pipe-line over a distance of 500 km. The impurities that are included in the study represents 5 mol% residuals from air-components (N 2 and O 2 ) and 10 mol% residuals from natural gas components (N 2 and CH 4 ). The analysis includes compression from low pressure, after the captures process, to the pipeline conditions in the dense phase of 150 bar. In the technical analysis of the pipeline transport, thermo-physical properties depending of the pressure and temperature locally as the stream evolves through the pipeline are used as well as heat transferred with the surroundings. The case studies investigate different pipeline diameters from 18″ to 28″ to find the most economical pipeline diameter for each impurity level. The cost model includes the material, labour and energy costs and the result are dependent on the number of required, booster stations, the pipeline wall thickness, the energy consumption and cooling demand. The wall thicknesses are chosen for each investigated diameter based on strength design and rounded off to the next available standard wall thickness according to the API-standard. In the second part, a 24″ pipeline with 4 booster stations is selected and the feed flow rate has been adjusted to match the installed compression power. The results show that for the cost-optimal diameter the specific conditioning and transport cost increases by 13 and 22% for the two cases compared to transporting pure CO 2 . This represents an increase from 2.3 to 3.8 €/ton CO2 . The second scenario, where impure CO 2 is transported in an existing pipeline, the cost is shown to be around 20–40% more expensive than transporting pure CO 2 . The effect on energy consumption and cost from different ambient conditions are also discussed and it is shown that for the selected case the cost of transport will vary 0.01 €/ton/K with change in average temperature from 15 °C as the baseline. Impurities can also be expected to have a significant impact on the technical and economic performances of the whole CCS chain and it is therefore important to evaluate this on a case-to-case bases in order to find possible trade-offs between capture, conditioning, transport and storage and to provide recommendations. [ABSTRACT FROM AUTHOR]

This paper evaluates three acid gas removal concepts studied in the project "A Green Sea". Two solvent concepts (aMDEA/MDEA and Selexol) and a low-temperature concept are modelled and assessed, taking different raw natural gases and natural gas product requirements into consideration. The analyses and comparisons of the concepts and cases consider nine criteria in order to include both energy efficiencies and compactness. The assessment shows that acid gas removal using aMDEA/MDEA technology seems to perform well in terms of energy efficiency, volume and weight for low CO2 removal. However, for high CO2 content or strong polishing requirements, the chemical solvent technology loses its efficiency in terms of weight and volume. The assessment shows that the Selexol concept is an inefficient option in terms of energy efficiency, volume and weight, especially when large quantities of CO2 have to be removed from the gas stream. The assessment also shows that the low-temperature technology can be a compact and energy-efficient option, both in the case of strong polishing requirements and high bulk removal of CO2. However, the higher the amount of CO2 to be removed, the less energy efficient is the low-temperature technology. The case evaluation underlines the fact that the aMDEA/MDEA solvent concept exhibits the best or close to the best key performance indicators (KPIs) for all parameters for the RNG1Pipe case (raw natural gas specification 1 to pipeline quality specification) and therefore appears to be the best technology option. For this case, the two other technologies are slightly less energy efficient than the aMDEA/MDEA, but both are significantly less compact. For the RNG1 LNG (raw natural gas specification 1 to LNG quality specification) case, the aMDEA/MDEA and low-temperature concepts have similar KPIs. The chemical solvent technology, however, is slightly more energy efficient and compact and would therefore be preferred for the RNG1 LNG case. Finally, the RNG2 Pipe (raw natural gas specification 2 to pipeline quality specification) case shows that the low-temperature technology can be a compact option for acid gas removal, which is a critical factor in the case of offshore applications for both the equipment costs and the weight constraints on the platform. Despite its lower energy efficiency, it is therefore likely that the low-temperature technology will be selected in the RNG2 Pipe case. This choice is strengthened by some regulations which recommend that solvents such as MDEA and aMDEA should be phased out for offshore applications, as is seen, e.g. in Norway. In addition, if stricter regulations are also enforced for onshore applications, this might also argue in favour of the low-temperature technology or other chemical solvents that are otherwise less efficient than aMDEA/MDEA.Finally, the potential of hybrid concepts is discussed and suggested for future works, in order to combine the advantages of the different technologies, such as the energy-efficient performances of the aMDEA/MDEA concept and the compactness of the low-temperature concept. Three acid gas removal concepts are studied and compared using multi-criteria analyses. Three cases taking different raw natural gases and natural gas product requirements are considered. The assessment illustrates each technology trends, as well as comparison over cases. The aMDEA/MDEA technology seems to perform well for low CO2 removal. The low-temperature technology can be an efficient option for high bulk removal and polishing. [ABSTRACT FROM AUTHOR]

Abstract: The timing and selection of CO2 sources will affect the cost of achieving projected CCS based emission reductions. Performed process simulations and cost estimations clearly point out the impact of CO2 concentration and steam supply when capturing CO2 from an atmospheric gas stream with MEA-based chemical absorption. An incremental increase in CO2 concentration reduces both operating and investment costs, mainly due to lower energy consumption and reduced equipment capacity. Reduced investment costs dominate the sharp decline in net present value of costs when increasing CO2 concentration from 2.5% to 10%, while a more moderate cost decline is present when going from 10% to 20% CO2. The impact of steam cost is evident for all studied CO2 concentrations. The cost sensitivity illustrate how important it is to understand the dynamics of cost components when selecting sources appropriate for CCS or struggle to improve performance of capture processes. This work contribute to highlight the relative importance of CO2 concentration and steam supply, realizing that final selection of CO2 source for CCS will involve addition decision variables. [Copyright &y& Elsevier]

In the literature, different energy carriers are proposed in future long-distance hydrogen value chains. Hydrogen can be stored and transported in different forms, e.g. as compressed dense-phase hydrogen, liquefied hydrogen and in chemically bound forms as different chemical hydrides. Recently, different high-level value chain studies have made extrapolative investigations and compared such options with respect to energy efficiency and cost. Three recent journal papers overlap as the liquid hydrogen option has been considered in all three studies. The studies are not fully aligned in terms of underlying assumptions and battery limits. A comparison reveals partly vast differences in results for chain energy efficiency for long-distance liquid hydrogen transport, which are attributable to distinct differences in the set of assumptions. Our comparison pinpoints the boiloff ratio, i.e. evaporation losses due to heat ingress, in liquid hydrogen storage tanks as the main cause of the differences, and this assumption is further discussed. A review of spherical tank size and attributed boiloff ratios is presented, for existing tanks of different vintage as well as for recently proposed designs. Furthermore, the prospect for further extension of tanks size and reduction of boiloff ratio is discussed, with a complementary discussion about the use of economic assumptions in extrapolative and predictive studies. Finally, we discuss the impact of battery limits in hydrogen value chain studies and pinpoint knowledge needs and the need for a detailed bottom-up approach as a prerequisite for improving the understanding for pros and cons of the different hydrogen energy carriers. • Liquid hydrogen (LH 2) is a prospective hydrogen energy carrier among other options. • A review of recent value chain studies reveals highly differing estimates for overall energy efficiency, which are attributable to differences in underlying assumptions. • Assumptions pertaining boiloff ratio in LH 2 storage tanks are discussed on the background of proven technology as well as expectations for capacity and performance extrapolations. • Differences in techno-economic assumptions and battery limits are discussed. The presumptive main assumptions in different studies and their potential impacts on overall results are reviewed, compared and discussed. [ABSTRACT FROM AUTHOR]

International shipping is crucial for freight transport, but it relies primarily on fossil fuels, contributing 3% of global greenhouse gas emissions. This calls for urgent action to decarbonize the shipping industry. While renewable-based e-fuels are a strong candidate for decarbonization of this sector in the long run, deploying these to the required scale will take significant time, considering technical modifications onboard the vessels, as well as the changes in fuel production and infrastructure for distribution. Carbon capture from ships is another route to emission reduction that can be implemented faster due to the relatively high maturity of the technology. Tankers, dry bulk carriers, and container vessels contribute a majority of global shipping emissions and are therefore prime candidates for carbon capture and storage. Solvent-based post-combustion capture is chosen for this study as it is mature and suitable for marine applications, though technical, economic, environmental, and practical challenges remain. This paper assesses the technical feasibility of the capture system for ships; both retrofit and newbuild vessels. While achieving zero-emissions presents a significant challenge, it is feasible to attain 70%–90% CO 2 reduction through carbon capture in the near term. This reduction is crucial for transforming the industry into a more sustainable and environmentally friendly state. The limitation of space onboard is identified as a key factor in determining the viability, and the 70%–100% increase in energy consumption between existing ships and newbuild will be a substantial operational challenge. However, the high fuel consumption of the capture system could be economically acceptable if the price of alternative fuels remains high. [ABSTRACT FROM AUTHOR]

Abstract: A carbon chain analysis is applied to assess a complex energy conversion system with CO2 capture and storage (CCS). A coal integrated gasification combined cycle, with CCS, which co-produces electricity and liquid fuels (IGCC–LF–CCS) is taken as a case study. A process simulation method is used to estimate the technological data, and balance the heat and electricity for the whole system. Carbon and energy flows are calculated to evaluate the mass conversion efficiency and the energy efficiency. The results show that in the case in which one third of the coal is allotted to synthesize liquid fuels, globally 60% carbon is captured for storage, 19% transferred to liquid fuels, 19% emitted to the atmosphere, while the remaining carbon is discharged as waste. For the energy flow, 28.1% of total higher heating value of coal is converted into the liquid fuels. The net electricity efficiency is 20.7% accounting for the power demands by air separation, CO2 capture and compression. Three scenarios with different ratio of resource to produce electricity and liquid fuels with or without CCS have been studied. This work will provide useful information for the coal utilization with CCS in a carbon-constrained world. [Copyright &y& Elsevier]