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Hydrogen is a promising energy carrier for future low carbon economy as fuel or chemical for various industrial applications (e.g. heat and power, petro-chemical, metallurgy etc.) as well as for transport sector. In order to decarbonise the energy sector as well as the transportation sector, the fossil fuels need to be efficiently converted to hydrogen and the resulted CO2 to be captured and then used / stored. The Carbon Capture, Utilisation and Storage (CCUS) technologies are promising options of efficiently combating climate change (by significantly reducing the greenhouse gas emissions) as well as continuing of using the fossil fuels. This paper is assessing the key updated technical and economical performances of hydrogen production based on natural gas reforming with and without carbon capture. As illustrative examples, conventional steam reforming and autothermal reforming (using both oxygen and air) of natural gas were evaluated. The CO2 capture technology was based on pre-combustion capture configuration using gas-liquid absorption. As illustrative cases, Methyl-DiEthanol-Amine (MDEA) as a chemical solvent and SelexolTM as a physical solvent were assessed for their performances. The evaluated hydrogen production concepts have a capacity of 100,000 Nm3/h (corresponding to 300 MWth based on lower heating value) with a purity higher than 99.95 % (vol.). The paper presents in details the evaluated hydrogen production concepts based on natural gas reforming, modelling and simulation aspects, model validation, mass and energy integration issues as well as proposing an integrated methodology for quantification of key economic aspects. As the results show, the conventional steam reforming has higher energy utilisation factor (about 5 net percentage points) than the autothermal reforming cases. The carbon capture rate is about 65 - 70 % for the conventional steam reforming considered as an illustrative case. The economic indicators show better performances for conventional steam reforming in comparison to autothermal reforming in term of specific capital investment cost (about 12 - 24 % lower), operational and maintenance costs (about 7 % lower), hydrogen costs (about 5 - 10 % lower). Physical absorption is more energy and cost effective than chemical absorption as pre-combustion capture method.

Biomass utilisation for energy production is very important in modern society. At EU level, by 2030, 27 % of the energy requirements are expected to be covered by renewable energy sources, biomass being one of the most important sources. Also, for the same period, the greenhouse gas emissions are expected to be reduced by at least 40 % below the 1990 level. In this context, carbon capture and storage (CCS) technologies are equally important for transition to low carbon economy. Chemical looping technique is a particular promising carbon capture option for reducing CO2 capture energy and cost penalties. This paper evaluates, from techno-economic and environmental perspective, the hydrogen and power co- generation based on biomass direct chemical looping systems with total decarbonisation of the fuel. As illustrative example, an ilmenite-based chemical looping system was assessed to generate about 500 MW net electricity with a flexible hydrogen output in the range of 0 to 100 MWth (based on hydrogen LHV). The capacity of evaluated plant concept to produce flexible hydrogen output is an important aspect for integration in modern energy conversion systems in which flexible operation scenario is of great importance due to greater integration of high time-irregular renewable energy sources (e.g. solar, wind). The carbon capture rate of evaluated concepts is almost total (>99 %). In addition, considering biomass (e.g. sawdust, agricultural wastes etc.) processing, the investigated power plant concepts have negative fossil CO2 emissions. The performances are assessed for a number of case studies (including some benchmark cases) through process flow simulations. The simulation results are used to assess the main techno-economic and environmental indicators, e.g. energy efficiency, ancillary consumption, carbon capture energy and cost penalty, specific CO2 emissions, capital and operation costs, cost of electricity, implication of hydrogen co-production on techno-economic and environmental performances etc.

The steel industry is currently a major water pollution source, releasing high quantities of chemicals. One of the pollutants is phenol, known for its toxicity even when it is present in low concentrations. Liquid-liquid extraction employing various aromatics and cycloalkanes (i.e., benzene, toluene, cyclohexane, ethylbenzene) and ketones (i.e., methyl isobutyl ketone, cyclohexanone and mesityl oxide) as solvents, is studied in the present paper. A comparison among the seven solvents is performed based on process modelling simulation tools and Life Cycle Assessment (LCA). The simulations of the seven cases under study are conducted at the same wastewater flowrate of 100 tons/h, with a phenol content of 0.2 wt.% and compared using various parameters (i.e., quantity of solvent, steam and power used, quantity of solvent present in the output phenol streams). The simulation results show that the lowest quantity of solvent is registered in the phenol removal which uses cyclohexanone as solvent (e.g., 34,212.40 kg/h), followed by the case which uses mesityl oxide for the liquid-liquid extraction (e.g., 34,759.80 kg/h) and by the case involving cyclohexanone (e.g., 37,490.60 kg/h). The lowest steam consumption is registered also in the case of cyclohexanone usage (e.g., 47.56 GJ/h) while the lowest power consumption corresponds to mesityl oxide usage (e.g., 11.20 MJ/h). The simulation results are then used to perform an environmental analysis, quantified in terms of environmental key performance indicators, embedding several solvents production methods as well as various fuels. Our life cycle assessment leads to the conclusions that the most environmentally friendly design is phenol removal using cyclohexanone as a solvent, whose provision comes from cyclohexane, which in turn is produced from benzene in conjunction with steam production from natural gas. For instance, the lowest global warming potential indicator score is about 342 kg CO2 equivalents per kg of phenol, while the same indicator for the worst solvent, i.e., toluene produced using reforming technology and steam being produced using hard coal as fuel, is almost double (e.g., 341.94 kg CO2 equivalents per kg of phenol vs. 575.30 CO2 equivalents per kg of phenol). Lower values for other impact indicators are also obtained in the phenol removal using cyclohexanone as a solvent with steam being generated form natural gas (e.g., acidification potential indicator is 0.42 kg SO2 equivalents per kg of phenol, eutrophication potential is 4.21 × 10−2 kg PO43- equivalents per kg phenol, ozone depletion potential is 1.13 × 10-9 kg R11 equivalents per kg phenol).