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Highlights • Economic feasibility of portable systems to utilize forest residues was investigated. • Forest residues were processed into raw and torrefied briquettes and biochar. • Minimum selling price (MSP) of biochar was estimated to $1044/ODMT. • MSP of raw and torrefied-briquettes were $162 and $274/ODMT respectively. • MSPs could be reduced by at least 50% with improved portable systems. Abstract Wildfires are getting extreme and more frequent because of increased fuel loads in the forest and extended dry conditions. Prevention of wildfire by fuel treatment methods will generate forest residues in large volumes, which in addition to available logging residues, can be used to produce biofuels and bioproducts. In this study, the techno-economic assessment of three portable systems to produce woodchips briquettes (WCB), torrefied-woodchips briquettes (TWCB) and biochar from forest residues were evaluated using pilot-scale experimental data. A discounted cash flow rate of return method was used to estimate minimum selling prices (MSPs) for each product, to conduct sensitivity analyses, and to identify potential cost-reduction strategies. Using a before-finance-and-tax 16.5% nominal required return on investment, and a mean transport distance of 200 km, the estimated delivered MSPs per oven-dry metric ton (ODMT) of WCB, TWCB, and biochar were $162, $274, and $1044 respectively. The capital investment (16–30%), labor cost (23–28%), and feedstock cost (10–13%) without stumpage cost were the major factors influencing the MSP of solid biofuels and biochar. However, the MSPs of WCB, TWCB, and biochar could be reduced to $65, $145, and $470/ODMT respectively with technologically improved portable systems. In addition, the MSPs of solid biofuels and biochar could be further reduced by renewable energy and carbon credits, if the greenhouse gas (GHG) reduction potentials are quantified and remunerated. In conclusion, portable systems could be economically feasible to use forest residues and make useful products at current market prices while simultaneously reducing potential wildfires and GHG emissions. [ABSTRACT FROM AUTHOR]

Highlights • Uncertainty in market prices drives financial outcomes. • Monte Carlo simulation allows uncertainty to be quantified. • Biochar-only production offers a potentially profitable venture. • Biofuel-biochar coproduction requires RINs to achieve financial success. Abstract A comparative techno-economic analysis of two different thermochemical biomass conversion pathways was conducted to examine the effects of fuel price and other variables on project financial performance. Monte Carlo simulation was used to quantify the effects of uncertainty and volatility of ten critical variables: biofuel, biochar and feedstock prices, discount rate, capital investment, labor cost, loan terms, feedstock drying, and biofuel and biochar conversion rates. Market prices for biofuel and biochar have the largest impact on net present value (NPV) of any variable considered, due in part to the high levels of uncertainty associated with future prices of both. Across the ranges of input values for these variables in simulation analysis, hearth-based pyrolysis biochar production had the highest likelihood of profitability with a mean NPV of $41.5 million and only 20% of outcomes resulting in a net loss, while 68% of outcomes for auger-based biochar-biofuel coproduction represented a financial loss, including a mean NPV of -$24.2 million. However, when additional revenue from Renewable Identification Numbers (RINs) credits generated by biofuel production is considered, financial outcomes of biochar-biofuel coproduction improve to 50% likelihood of experiencing a net loss. Findings of the very strong impact of market prices on financial outcomes, relative to other important technical and economic variables, can inform effective targeting of future renewable energy policy, as well as the design of future techno-economic analyses, which do not currently focus on the effect of market prices on profitability. [ABSTRACT FROM AUTHOR]

This paper presents the results regarding the parametric optimization and characterizations on codensification of Eucommia ulmoides Oliver stem using biochar and bio-oil as additives. The results reveal that the relative importance of different parameters contributing to the pellet physical stability follows the order of: particle size > bio-oil content > biochar content > pressure > bio-oil type, and smaller particles size (0.1–0.3 mm) is critical for the formation of durable pellets. The biochar functioned as the fuel promoter and improved the higher heating value and energy density, however, caused poor physical stability by secondary size reduction during densification. The apple tree branch pyrolysis oil acted as an effective binder, improved the surface morphology and enabled strong interlocking of the particles, therefore, enhanced the physical stability. Above all, codensification of Eucommia ulmoides Oliver stem with biochar and bio oil generated pellets with excellent physical stability and moisture resistance. The pellets also showed better fuel characteristics than the Eucommia ulmoides Oliver stem pellets, and the cost is significantly lower than the char pellets. With comprehensiveness, these results can guide the future industrial implementation of codensification technology for the production of clean, sustainable, and efficient fuel with low cost. [ABSTRACT FROM AUTHOR]

Biochar derived from orchid tree leaves is utilised as the fuel of a direct carbon solid oxide fuel cell (DC-SOFC), with yttrium stabilized zirconia (YSZ) as electrolyte and cermet of silver and gadolinium doped ceria (Ag-GDC) as the material of both cathode and anode, operating without any liquid medium or feeding gas. The performance of the DC-SOFC operated on the leaf char is higher than that operated on the best reported carbon fuel for DC-SOFCs, Fe-loaded activated carbon. XRD, Raman spectroscopy, SEM and EDX are applied to characterize the leaf char. It turns out that the leaf char is with porous structure and there is much Ca along with some K and Mg uniformly distributing in the leaf char. The effects of the naturally existing alkaline earth metal and alkaline metal and their distribution on the performance of the DC-SOFCs operated on the leaf char are analyzed in detail. [ABSTRACT FROM AUTHOR]

Bio-char, produced from biomass pyrolysis, can be pelletized to improve its undesirable characteristics, such as low bulk and energy densities, poor transportation and storage properties, and troublesome to co-fire with coal. In this study, rice husk char was compressed into pellets with four kinds of binders (lignin, starch, calcium hydroxide and sodium hydroxide). The compressive process, mechanical strength, basic fuel properties, and combustion characteristics were investigated to elucidate the effect of binders on the properties of bio-char pellets. Results showed that starch pellets had good hydrophobicity, but low volume density and poor mechanical strength. The softening and morphological transition of lignin during compression may account for the high elastic modulus and good bonding of lignin pellets. The low saturated moisture content of Ca(OH) 2 pellets is mainly ascribed to its hydration. NaOH pellets showed the highest compressive strength among all pellets, and also exhibited the highest moisture uptake that may worsen the handling and storage treatment of bio-char. Compared with raw bio-char, bio-char pellets had a lower ignition temperature, wider temperature interval, and higher oxidation activity according to the thermogravimetric analysis. The lignin and Ca(OH) 2 pellets showed lower compression energy consumption and moisture uptake, enhanced mechanical strength and promoted combustion performance, which demonstrated more desirable properties for utilization as biofuels. [ABSTRACT FROM AUTHOR]

Highlights: [•] The performance of HTC and LTP was compared to produce solid fuel from waste biomass. [•] Fuel qualities of the biochars produced from HTC and LTP were investigated. [•] Ash problem related metal contents in two biochars were analyzed. [•] Combustion characteristics of two biochars were determined. [•] Hydrothermally prepared biochar is suitable for use as a solid fuel. [ABSTRACT FROM AUTHOR]

Highlights: [•] Solids decomposition and hydrochar production modelled by first order kinetics. [•] Arrhenius rate constant characterisation of sewage sludge carbonisation. [•] The activation energy of synthetic faeces was higher than that of sewage sludge. [•] Reaction temperature had more effect on solids decomposition than reaction time. [•] Feedstock moisture content affected hydrochar yield and extent of carbonisation. [Copyright &y& Elsevier]

Bioenergy can be produced from a wide range of feedstocks and can be utilised for production of renewable electricity, thermal energy, chemicals or transportation fuels. Anaerobic digestion technology (AD) for biogas production has an important role in achieving circular economy goals, as it may not only recover the energy contained in the biomass but also contribute to nutrient recovery and reduction of greenhouse gas emissions. The expansion of biogas production promotes the need for assessment of the technical potential of biomass, which is available for biogas production and is not in the competition with other purposes. This research work presents a Geographical Information System (GIS) based approach for the assessment of the spatial distribution of the biogas production potential by taking into consideration seasonal variation of biomass production, in order to assess the influence of biomass seasonality. The method developed in this research work is based on a combination of statistical and spatial explicit methods. The presented approach was tested in a case study of Croatia and the final results are representing the seasonal and spatial distribution of biogas potential at the spatial level of 1 km × 1 km. The results show that there is a strong need to include the influence of seasonality in assessment of biogas potential for lignocellulosic agricultural residues. The benefits are demonstrated in two examples that resulted in 12% and 40% lower storage facility capacity by using the proposed approach, compared to currently used approaches. [ABSTRACT FROM AUTHOR]