This paper, which is part of a special issue of the International Journal of Greenhouse Gas Control, gives an overview of the latest achievements in the pre-combustion decarbonisation route for the production of electricity with CO2 capture. Pre-combustion technologies applied to two different fuels are considered, natural gas and coal, since they cover most of electricity production from fossil fuels worldwide. The work first discusses in detail the different sections in which a power plant with pre-combustion CO2 capture can be divided. For each section, the available technologies with corresponding advantages and disadvantages are presented. Next, the plant lay-outs for natural gas and coal proposed in literature, including heat & mass balances and the economic assessment, are discussed. In general, research activity in pre-combustion decarbonisation for power production focused more on coal than on natural gas-based plant since in the latter case the plant complexity and costs are not competitive with post-combustion CO2 capture, which is a technology on the verge of commercialization. Finally the paper briefly discusses pre-combustion CO2 capture in industry especially those projects where CO2 is captured and stored or used for EOR

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The Shell coal integrated gasification combined cycle (IGCC) based on the gas quench system is one of the most fuel flexible and energy efficient gasification processes because is dry feed and employs high temperature syngas coolers capable of rising high pressure steam. Indeed the efficiency of a Shell IGCC with the best available technologies is calculated to be 47-48%. However the system looses many percentage points of efficiency (up to 10) when introducing carbon capture. To overcome this penalty, two approaches have been proposed. In the first, the expensive syngas coolers are replaced by a ''partial water quench'' where the raw syngas stream is cooled and humidified via direct injection of hot water. This design is less costly, but also less efficient. The second approach retains syngas coolers but instead employs novel water-gas shift (WGS) configurations that requires substantially less steam to obtain the same degree of CO conversion to CO 2 , and thus increases the overall plant efficiency. We simulate and optimize these novel configurations, provide a detailed thermodynamic and economic analysis and investigate how these innovations alter the plant's efficiency, cost and complexity.

Biomass torrefaction was tested on pilot scale (50 kg h À1 throughput) for 3 types of wood: spruce, ash and willow at torrefaction temperatures of 250 Ce265 C. Quantitative analysis of process streams was accomplished by utilising on-and off-line analytical methods. The data obtained from the pilot tests could be very well translated into large-scale operations. A theoretical overall thermal efficiency of 88e89% was calculated for a large-scale heat-integrated torrefaction process that uses wet woody feedstock containing a mass fraction of 45% moisture. These results show that a pilot plant is most suitable not only for exploration of (new) feedstocks but also for generating experimental data that provide valuable information for the design of full-scale plants. The detailed mapping of the mass and energy balances presented in this work can be used further as input for process optimisation, evaluation of commercial viability and techno-economic analyses which can further help in up-scaling and commercialisation of the torrefaction technology.

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