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Limited overall efficiency and excessive complexity can hinder the competitiveness of biomass gasifier solid oxide fuel cell micro combined heat and power systems. To overcome these problems, hydrocarbons direct internal reforming is analysed as a strategy to increase efficiency and reduce system complexity. To the same end, two biosyngas heating-up strategies are compared: catalytic partial oxidation and afterburner off gases utilization. A comprehensive approach combining thermodynamic equilibrium calculations, experimental measurements, and system modelling was used. The gas cleaning unit should operate at 400 °C to decrease H2S and HCl below 1 ppmv. A tar amount of 120–130 g Nm−3 dry biosyngas for woodchips and 190 g Nm−3 for straw pellets was measured and 2-methoxyphenol, hydroxyacetic acid and hydroxyacetone were selected as representative compounds. With direct internal reforming the cathode air flow rate decreases from approximately 90 kg h−1 to 60 kg h−1. This leads to an increase of around 1% point in electrical efficiency and of even 5–6% points in thermal efficiency. Direct internal tar reforming seems therefore an advantageous strategy. The catalytic partial oxidation unit increases the system overall efficiency but reduces the electric efficiency from roughly 38%–30% and is therefore not advised.

An alternative way has been proposed for the PVC-containing medical wastes valorization by co-hydrothermal carbonization (HTC) with lignocellulosic biomass. The organic-Cl in PVC can be converted to the inorganic-Cl via hydrolysis, defunctionalization, recondensation, and aromatization in the HTC process. Followed by the washing process with the condensed water, the inorganic-Cl with high water-solubility could be removed from the solid products (i.e. hydrochar). Lignin as a biomass component can significantly improve the dechlorination efficiency of PVC in the HTC process. Here, the dechlorination performance of lignocellulosic components is given as the following order: lignin > cellulose > hemicellulose. In addition, lignin can adjust the particle sizes of solid products by inhibiting the agglomeration in the order of lignin > hemicellulose > cellulose. In the pilot-scale HTC process, the addition of woodchips improves the dechlorination efficiency of hospital wastes (HW). The hydrochar particles with low-chlorine content and higher heating value could be used as a clean coal-alternative fuel.

Biomass-based fuel is a potential renewable energy source despite its low energy density, high moisture content, and complex ash components due to its carbon-neutral nature. Torrefaction process, a promising biomass pretreatment method for upgrading biomass properties, is effective to generate fuel with higher calorific value and energy density. Torrefied biomass performs higher energy density and improved grindability characteristics as well as lower ratios of O/C and H/C compared to its raw source. This study presents an evaluation of the hydrogen production from steam gasification using torrefied woodchips as a feedstock in a pilot-scale bubbling fluidized bed reactor. The feedstock used is torrefied woodchips, which were treated at 250 °C in the N2 atmosphere. The experiments were conducted under isothermal and negative gauge pressure conditions in a pilot-scale bubbling fluidized bed reactor at different operating conditions such as gasification temperatures, steam-to-biomass ratio (SBR), and equivalence ratio (ER). Experimental results show that the high temperature and SBR are more favorable for hydrogen production and improve carbon conversion efficiency, while higher ER lowered content and yield of hydrogen. The optimal value of the steam-to-biomass ratio at 850 °C is 1.2 with the hydrogen content of 48.41% and the hydrogen yield of 0.039 Nm3/h.

This study analyses the impact on the GHG (greenhouse gas) emissions of the raw material supply chain, the utilisation of excess heat and CO2 storage for a bio-SNG (biomass gasification-based synthetic natural gas) system by applying a consequential life cycle assessment approach. The impact of the biomass supply chain is analysed by assessing GHG emissions of locally produced woodchips and pellets with regional or transatlantic origin. Results show that the supply area for the gasification plant can be substantially increased with only modest increases in overall GHG emissions (3-5%) by using regionally produced pellets. The transatlantic pellet chains contribute to significantly higher GHG emissions. Utilising excess heat for power generation or steam delivery for industrial use contributes to lower emissions from the system, whereas delivery of district heating can contribute to either increased or decreased emissions. The production technology of the replaced heat and the carbon intensity of the reference power production were decisive for the benefits of the heat deliveries. Finally, the storage of CO2 separated from the syngas upgrading and from the flue gases of the gasifier can nearly double the GHG emission reduction potential of the bio-SNG system. (C) 2015 Elsevier Ltd. All rights reserved.

Thermodynamic and thermoeconomic investigations of a small-scale integrated gasification solid oxide fuel cell (SOFC) and Stirling engine for combined heat and power (CHP) with a net electric capacity of 120 kW e have been performed. Woodchips are used as gasification feedstock to produce syngas, which is then utilized to feed the anode side of the SOFC stacks. A thermal efficiency of 0.424 LHV (lower heating value) for the plant is found to use 89.4 kg/h of feedstock to produce the above mentioned electricity. Thermoeconomic analysis shows that the production price of electricity is 0.1204 $/kWh. Furthermore, hot water is considered as a by-product, and the cost of hot water is found to be 0.0214 $/kWh. When compared to other renewable systems of similar scales, this result shows that if both SOFC and Stirling engine technology enter the commercialization phase, then they can deliver electricity at a cost that is competitive with the corresponding renewable systems of the same size.

This paper presents a thermo-economic analysis of an integrated biogas-fueled solid oxide fuel cell (SOFC) system for electric power generation. Basic plant layout consists of a gasification plant (GP), an SOFC and a retrofitted steam-injected gas turbine (STIG). Different system configurations and simulations are presented and investigated. A parallel analysis for simpler power plants, combining GP , SOFC , and hybrid gas turbine (GT) is carried out to obtain a reference point for thermodynamic results. Thermodynamic analysis shows energetic and exergetic efficiencies for optimized plant above 53% and 43% respectively which are significantly greater than conventional 10 MWe plants fed by biomass. Thermo-economic analysis provides an average cost of electricity for best performing layouts close to 6.4 and 9.4 c€/kWe which is competitive within the market. A sensitivity analysis of the influence of SOFC stack cost on the generation cost is also presented. In order to discuss the investment cost, an economic analysis has been carried out and main parameters such as Net Present Value (NPV), internal rate of return (IRR) and Time of Return of Investment (TIR) are calculated and discussed.

Biomass has emerged in the renewable energy area with high potential to contribute to the energy needs in both the industrialized and developing countries. The objective of this study is to evaluate and compare the economic feasibility of three different configurations of a woodchips power plant based on the circulating fluidized-bed (CFB) gasification: (1) a gas engine, (2) a gas turbine, and (3) gas & steam turbines. A comprehensive model of the power plant was developed employing the process simulator, Aspen Plus. The economic feasibility was analyzed in terms of the payback period (PBP), return on investment (ROI), and discount cash flow rate of return (DCFROR). It was proposed that the power plant has an economic benefit for plant sizes of over 150 t/d of dry woodchips in all the three cases. The gas engine was a better choice for the power plant sizes smaller than 200 t/d or 22 MW e , while the gas & steam turbines had the highest benefit at big plant sizes over 200 t/d. A sensitivity analysis was performed for the 150 t/d plant to identify key variables that have a strong impact on DCFROR. The total capital investment (TCI) and plant size had a major influence on DCFROR.