Assessment of the potential for hydrogen production from renewable resources in Argentina

The potential for hydrogen production from three major renewable resources (wind energy, solar energy and biomass) in Argentina is analyzed. This potential for the annual production of wind, solar and biomass hydrogen is represented with maps showing it per unit area in each department. Thus, by using renewable resource databases available in the country, a new Geographic Information System (GIS) of renewable hydrogen is created. In this system, several geographic variables are displayed, in addition to other parameters such as the potential for renewable hydrogen production per department relative to transport fuel consumption of each province or the environmental savings that would imply the production of hydrogen required to add 20% V/V to CNG, with the aim of developing the cleaner alternative CNG + H₂ fuel. In order to take into account areas where energy development would be restricted, land use and environmental exclusions were considered.     

Lignin yield maximization of mixed biorefinery feedstocks by organosolv fractionation using Taguchi Robust Product Design

Lignin, isolated from switchgrass (Panicum virgatum) and tulip poplar (Liriodendron tulipifera) using organosolv fractionation is currently being explored for its potential use in the production of value-added chemicals and bio-based polymers. Taguchi Robust Product Design (TRPD) was applied to maximize lignin yield from the fractionation process. The following four controllable design factors were used in the TRPD: process temperature (120 °C, 140 °C and 160 °C), fractionation time (56 and 90 min), sulfuric acid concentration (0.025 M, 0.05 M and 0.1 M), and feedstock type (switchgrass/tulip poplar chip ratios of 10/90, 50/50 and 90/10). Process noise was induced in the experiment by using either the mass- or volume-based feedstock charges of switchgrass and tulip poplar chips. A maximum mean lignin yield of 78.63 wt% and signal-to-noise ratio of 37.90 was found at a 90 min runtime, a process temperature of 160 °C, a sulfuric acid concentration of 0.1 M, and a feedstock composition of 10% switchgrass and 90% tulip poplar. Process temperature was the most significant factor that influenced lignin yield. This study may provide a pathway for industrialists and researchers interested in maximizing lignin yield in the organosolv fractionation process.     

Influence of feedstock properties and pyrolysis conditions on biochar carbon stability as determined by hydrogen pyrolysis

We produced 18 thermosequences of biochar from common feedstocks at ten temperatures from 300 to 900 °C to investigate their influence on carbon stabilization in biochar. Using hydrogen pyrolysis we were able to isolate the stable polycyclic aromatic carbon (SPAC) fraction that is likely to be resistant to mineralization on centennial timescales. SPAC formation was generally <20% of total organic carbon (TOC) at temperatures <450 °C and rises to >80% of TOC at temperatures above 600–700 °C depending on feedstock type. SPAC formation was retarded in feedstocks with high ash contents, and further retarded in those feedstocks when the final hold time at maximum pyrolysis temperature was reduced from one hour to 10 min. Given that aromatization of organic material in many feedstocks is usually completed by ca. 450 °C, the data suggests that a significant pool of aromatic biochar carbon exists in a ‘semi-labile’ form that may not be persistent on centennial timescales. For most feedstocks biochar yield and SPAC content are optimized at pyrolysis temperatures of 500–700 °C.     

Harvesting eucalyptus energy plantations in Brazil with a modified New Holland forage harvester

Modified foragers represent a cost-effective option for harvesting high-density short-rotation energy plantations. However, new energy plantations grown in Brazil far exceed the stocking and the stem size characterizing plantations in the Northern hemisphere, which raises the question about the ability of modified foragers to perform effectively. A study was conducted on five eucalyptus plantations, located in different Brazilian States and spanning over a wide range of work conditions in terms of clone, age, planting density and row system (e.g. single or twin rows). Field stocking varied between 90 and 157 t ha⁻¹, and breast-height diameter between 5 and 8 cm. The tests were conducted with a New Holland 9060 forager, equipped with a 130 FB energy wood header. This machine was capable of negotiating all test fields, and reached a productivity on these sites between 39 and 65 t h⁻¹, which was comparable with the productivity values recorded in Europe and North America. The machine coped well with the high field stocking and stem size levels encountered in Brazil. Blockages accounted for a very small proportion of total harvesting time, which was similar to that recorded in studies conducted on poplar and willow in the Northern hemisphere. Productivity was directly proportional to field stocking and target chip length. Changing target chip length from 30 to 20 mm resulted in a 20–30% reduction in productivity. These figures reflect work conditions in uncoppiced first-rotation plantations, and they should be applied with some caution to following rotations.     

Waste and residue availability for advanced biofuel production in EU Member States

The EU is adopting policy measures to promote the use of advanced biofuels for transport made from sustainable sources including wastes and residues. As Member States prepare to implement these policy changes, they will need to understand if they have sufficient resource to meet an advanced biofuel target. This study assesses the availability of agricultural residues, forestry residues, and biogenic wastes that could potentially be used for advanced biofuel production in EU Member States at the present and projected to 2020 and 2030. This analysis incorporates specific information on agricultural, forestry, and waste production, management practices, and environmental risks in each Member State in order to model the amounts of residues needed to preserve soil quality and that are utilized in other industries; we exclude these quantities in order to determine the sustainable biomass potential that can be achieved without significant adverse impacts on the environment or biomass markets. We find that most EU Member States are likely to have more than enough sustainably available feedstock to meet the advanced biofuel requirement, and a majority may have more than 10 times the necessary amount. While this study does not assess economic viability of advanced biofuel production, from a resource perspective, the target appears to be achievable in most Member States. Some countries, including Austria, Cyprus, Denmark, Estonia, Ireland, Luxembourg, Malta, and Slovenia, may need to import either feedstock or advanced biofuel from neighboring countries to meet the target.     

Biochar from microwave pyrolysis of biomass: A review

Microwave based technology is an alternative heating method and has already been successfully used in biomass pyrolysis for biochar and biofuel production thanks to its fast, volumetric, selective and efficient heating. Previous review mainly focused on production and analysis of bio-oil and gas instead of biochar. The current paper provides a review of microwave-assisted pyrolysis (MWP) of biomass and its biochar characteristics, including product distribution and biochar yield, biochar properties, microwave absorbers (MWAs) and catalysts commonly used in MWP, as well as comparison of biochar derived from MWP and conventional pyrolysis (CP). MWAs not only absorb microwave energy, they also act as catalysts to interact with gas, vapor and solids in the reactor, adjusting the product distribution and quality of products. It was reported for MWP that the highest biochar yield was >60 wt% and the maximum BET surface area was about 450–800 m²/g. Technology status and economics of MWP of biomass in China were briefly introduced. The Optimization of yield and quality of biochar strongly depends on feedstock properties, reactor types, operating parameters, MWAs and catalysts added to the system.     

Ni-Ce/SiO2 nanocomposite: Characterization and catalytic activity in the cracking of tar in biomass gasifiers

The synthesis of Ni/SiO₂ and Ni-Ce/SiO₂ nanocomposites by deposition–precipitation method (DPM) has been reported. The nanocomposites were characterized by XRD, HR-SEM, HR-TEM, and BET. The XRD results confirmed the formation of Ni/SiO₂ and Ni-Ce/SiO₂ nanocomposites. The sphere-like morphology of Ni/SiO₂ and Ni-Ce/SiO₂ were confirmed by HR-SEM and HR-TEM. Surface area of the sample was determined by BET analysis. Furthermore, the prepared nanocomposites have been used as a catalyst in the cracking of tar. The tar cracking efficiencies of Ni/SiO₂ and Ni-Ce/SiO₂ nanocomposites were 93.0% and 98.5%, respectively, at a catalytic bed temperature of 800°C.     

Flash pyrolysis of palmyra palm (Borassus flabellifer) using an electrically heated fluidized bed reactor

Agriculture residues such as palmyra fruit bunch are one of the biomass categories that can be utilized for conversion to bio-oil by using pyrolysis process. Flash pyrolysis experiments have been conducted in the electrically heated fluidized bed reactor to determine the effect of pyrolysis temperature, particle size, and sweep gas flow rate on the pyrolysis product yield. In this study the maximum oil yield of 48.2% was achieved at a temperature of 500°C, particle size of 1 mm, and at a sweep gas flow rate of 2 m³/h. The results show that the effects of pyrolysis temperature and particle size on pyrolysis yields are more significant than that of sweep gas flow rate. Bio-oil was identified as a biofuel candidate and it was further upgraded for better-quality biofuel. Various physical and elemental analyses were performed for bio-oil and the same characteristics study was also carried out for biofuel.     

Probabilistic single box approach for modeling PAHs associated with combustion aerosols in a typical indoor environment

Firewood, coal, dung cake, kerosene and Liquefied Petroleum Gas (LPG) are the most commonly used fuels for cooking and heating purposes in developing countries. Combustion of such fuels leads to high concentrations of pollutants in the indoor environment. Polycyclic aromatic hydrocarbons (PAHs) are emitted during residential combustion, and have carcinogenic and genotoxic properties. In this study, data from an experimental setup for estimation of emission rate of particulate-bound PAHs generated during combustion of such fuels are used. PAHs emission rates were used in a probabilistic single box model for prediction of time average particle associated indoor B(a)P equivalent (B(a)P_eq) concentrations of PAHs resulting from typical Indian cooking. Model parameters such as fuel consumption rate, stove power and cooking time were also evaluated experimentally. Particle bound B(a)P_eq PAH emission factor was found to be highest (0.96 mg kg⁻¹) for dung cake, and lowest for LPG (0.48 mg kg⁻¹) among tested fuels. The time averaged B(a)P equivalent concentrations in indoor environment were found to be 0.82, 0.45, 0.87, 0.30, and 0.14 μg m⁻³ for firewood, coal, dung cake, kerosene and LPG respectively. Results reveal that there was higher B(a)P equivalent concentration during combustion of biomass (dung cake, fire wood) as compared to fossil fuels (coal) and non-solid fuels (kerosene, LPG). Predicted time averaged indoor air B(a)P_eq concentrations of PAHs were found to be much higher than the WHO indoor air guideline values for all tested fuels.     

Potential of poor lignite and Biomass blends in energy production

The present study investigated the potential of using poor lignites from different seams in N. and S. Greece and biomass blends in energy production. The experiments were conducted in a thermogravimetric analysis system, over the temperature range 25–850°C. The efficiency of the process was evaluated in terms of combustion rate, burnout temperature, and time, as well as ignition and combustion indices. The thermochemical reactivity of lignites from N. Greece increased when biomass materials were added, while the fuels showed more or less an additive behavior upon blending. However, for lignites from S. Greece, co-combustion with biomass fuels showed synergy between component fuels.