The oil palm industry has been under public scrutiny during the last decades due to environmental and social issues related to its practices. Oil palm (Elaeis guineensis Jacq.) trunks (OPTs) are of special interest as they are left idle in the field after the replanting process which is performed every 25 years. This common practice results in harvesting challenges, phytosanitary risks, and a loss of bioenergy potential. Due to their high moisture content and fibrous nature, OPTs present a problem for traditional conversion processes that require a dry and homogeneous material. This study evaluates the feasibility of converting OPTs into a bio-crude oil and biochar to increase the sustainability of the oil palm sector. To date, research efforts have primarily focused on hydrothermal liquefaction (HTL) of OPT without catalysts, resulting in a limited understanding of the potential of OPTs. Thus, the main novelty of this work is the evaluation of the effects of catalyst dosage (0–5 wt%) on the bio-oil yield, reaction temperature (260–300^∘C), and residence time (15–60 min) using a half-fraction experimental design methodology. For this, OPTs extracted from two plantations in Guatemala were used. The maximum bio-oil yield (26.77 ± 3.60 wt%) was found at 260^∘C for 15 min and 5 wt% catalyst with a high heating value (HHV) of 19.29 ± 1.33 MJ kg⁻¹. Nonetheless, the bio-oils produced without a catalyst at 300^∘C and 15 min have higher HHV (27.63 ± 1.35 MJ kg⁻¹) and are similar to Diesel fuel based on their H/C and O/C ratio. These results indicate that there is a potential trade-off between the bio-crude oil mass yield and HHV when using the catalyst.

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Long transport distances and extended storage of biomass pellets especially in humid environments provide a suitable setting for enhanced degradation in the form of moisture sorption, cracking and attrition. We developed an optically transparent, low-cost and environmentally friendly coating to reduce moisture sorption and storage degradation of pellets. The developed coating is a hybrid sol–gel, based on tetraethoxysilane (TEOS) and 3-glycidoxypropyl-trimethoxysilane (GPTMS) precursors. We coated two types of untreated and one type of torrefied wood pellets and stored them in a climate chamber during 1 month simulating a ship's hold, at a constant condition of 40 °C and 85% relative humidity. After 1 month of storage, the mean water contact angle increased by a factor of two compared to the uncoated ones. The lower wettability of the sol-gel coated untreated pellets compared to the non-coated torrefied pellets might provide an alternative to torrefaction.

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Application of biochar to landfill cover soils can purportedly improve methane (CH4) oxidation rates, but understanding the combined effects of soil texture, compaction, and biochar on the activity and composition of the methanotrophs is limited. The amendment of wood biochar on two differently textured landfill cover soils at three compaction levels of the Proctor density was explored by analyzing changes in soil physical properties relevant to methane oxidation, the effects on CH4 oxidation rates, and the composition of the methanotrophic community. Loose soils with and without biochar were pre-incubated to equally elevate the CH4 oxidation rates. Hereafter, soils were compacted and re-incubated. Methane oxidation rates, gas diffusivity, water retention characteristics, and pore size distribution were analyzed on the compacted soils. The relative abundance of methanotrophic bacteria (MOB) was determined at the end of both the pre-incubation and incubation tests of the packed samples. Biochar significantly increased porosity at all compaction levels, enhancing diffusion coefficients. Also, a re-distribution in pore sizes was observed. Increased gas diffusivity from low compaction and amendment of biochar, though, did not reflect higher methane oxidation rates due to high diffusive oxygen fluxes over the limited height of the compacted soil specimens. All soils, with and without biochar, were strongly dominated by Type II methanotrophs. In the sandy soil, biochar amendment strongly increased MOB abundance, which could be attributed to a corresponding increase in the relative abundance of Methylocystis species, while no such response was observed in the clayey soil. Compaction did not change the community composition in either soil. Fir-wood biochar addition to landfill cover soils may not always enhance methanotrophic activity and hence reduce fugitive methane emissions, with the effect being soil-specific. However, especially in finer and more compacted soils, biochar amendment can maintain soil diffusivity above a critical level, preventing the collapse of methanotrophy.@en

Our work provides a thorough characterization of different biochars produced by a novel 50 kW_th Indirectly Heated Bubbling Fluidized Bed Steam Reformer. This study investigates the effect of temperature and gasification agent on the physico-chemical properties of biochars. We combined macro, micro and nano characterization techniques to provide a clear picture of the biochar characteristics, surface functionality and its “inert” nature toward potential applications. Our results demonstrate that indirect gasification is capable of producing carbon-rich biochars (> 92%) with increased porosity (89–198 cm³.g⁻¹), high heating value (28–31 MJ.kg⁻¹ a.r.) and aromaticity compared to the parent biomass. All biochars have lower O/C (0.02–0.04) and H/C atomic ratios (0.09–0.19), similar to anthracite. For the range of tested gasification conditions, air/steam gasification at an equivalence ratio of 0.20 and steam-to-biomass ratio of 1.2 provides the highest biochar yield (7.3%), while maintaining syngas composition optimal. On the other hand, air gasification produces biochars with relatively high content of inorganic elements. Indirectly heated biochars are compliant with the European Biochar Certificate regarding the carbon content, O/C ratio, H/C ratio. Our biochars may provide an improvement in agricultural yield and CO₂ adsorption, especially those produced under air/steam gasification conditions. Our novel indirect design not only constitutes a promising development in the field of biomass allothermal gasification but also can help improving gasification circularity through the production of high quality biochar.

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The use of biomass pellets as a source of renewable energy has increased in recent times. However, pellet storage during transportation can compromise their properties, due to fluctuating temperature and humid environments. Here, we show that extended storage of one month at 40 °C and 85% relative humidity causes significant biomass pellet degradation. This was evidenced by higher pellet porosity, weight gain, increased inclusion body formation and creation of an internal network of cracks. We quantify the inclusion and pore growth processes at the surface and within the pellets, which has implications for subsequent thermochemical conversion. The global bioenergy transition may depend upon biomass pellets, and this study shows that storage conditions are critical in the supply chain, so to maintain their quality. Without the development of stronger policies to avoid premature degradation of biomass pellets, they may not realize their full potential as a bioenergy source.

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Fostered by environmental and economic drivers, liquid biofuels are expanding in the global energy matrix. However, many countries with biofuel potential, such as Guatemala, have yet to develop domestic biofuels markets. During the last decade, ethanol production in Guatemala has increased significantly, yet a domestic market does not appear to be in the horizon. It is a kind of paradox: a world class sugarcane producer and ethanol exporter does not use any blend of ethanol and gasoline in vehicles. This paper presents a techno-economic analysis and review of barriers that have delayed ethanol-gasoline blends in Guatemala. The cost assessment considers data from an existing distillery in Guatemala. Results show that Guatemala could produce annually a maximum of 250 million liters of ethanol from molasses, more than the amount required to introduce E10. For the current conditions, results from the modelling indicate that the cost of ethanol has minimal impact on the price of E10, but taxes could represent one third of the cost of E10 at the retail level. Since supply conditions are favourable and technical barriers are not relevant, strong government intervention and a coherent price structure for ethanol-gasoline blends is needed to create an ethanol market in Guatemala.

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Biomass pellets provide a pivotal opportunity in promising energy transition scenarios as a renewable source of energy. A large share of the current utilization of pellets is facilitated by intensive global trade operations. Considering the long distance between the production site and the end-user locations, pellets may face fluctuating storage conditions, resulting in their physical and chemical degradation. We tested the effect of different storage conditions, from freezing temperatures (−19 °C) to high temperature (40 °C) and humidity conditions (85% relative humidity), on the physicochemical properties of untreated and torrefied biomass pellets. Moreover, the effect of sudden changes in the storage conditions on pellet properties was studied by moving the pellets from the freezing to the high temperature and relative humidity conditions and vice versa. The results show that, although storage at one controlled temperature and RH may degrade the pellets, a change in the temperature and relative humidity results in higher degradation in terms of higher moisture uptake and lower mechanical strength. @en

Biomass co-firing with coal can help to reduce greenhouse gas emissions and can act as a low-cost stepping-stone for developing biomass supply infrastructures. This paper presents a techno-economic assessment of the biomass co-firing potential in coal-fired boilers in Czech Republic, France, Germany and Poland. The current coal power plant infrastructure is characterized by means of geographic location of the coal power plants, installed boiler capacity, type of boiler technology and year of commissioning, as extracted from the Chalmers Power Plant Database. The assessment considers type of boiler technology, type of biomass, co-firing fraction, implementation costs, breakeven prices for co-firing and an alkali index to determine the risk of high-temperature corrosion. The main factors affecting the co-firing potential are the biomass price, carbon price and alkali index. Results indicate that the total co-firing potential in the four countries is around 16 TWh year⁻¹, with the largest potential from a conversion perspective in Germany, followed by Poland. Biomass co-firing with coal is estimated to be competitive at biomass prices below 13 € MWh_input⁻¹ when the carbon price is 20 € t⁻¹ CO₂. On average, 1 TWh of electricity from biomass co-firing substitutes 0.9 Mt of fossil CO₂ emissions.

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