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Techno-economic models for three plants in Queensland, Australia using thermochemical conversion of 10 tonnes per hour of sugarcane bagasse to liquid crude biofuels were developed. Thermochemical conversion was chosen to maximise yield from second-generation feedstock. The process models highlighted the differences in mass and energy flows of each process. Factory models were generated reflecting current methods in heat and material recovery. Liquefaction generated the highest amount of product per kg feed, followed by pyrolysis and gasification. Key parameters affecting plant economics were also highlighted. Based on net present values, the profitability was ranked as follows: pyrolysis > liquefaction > gasification. The plants were all sensitive to product price, thermochemical conversion ratio and refining conversion ratio, thereby affecting profitability the most. Conversion ratios sharply affect the minimum selling price of products, but attenuated by high product volumes. Varying tax rates and capital costs do not affect the minimum selling price as much as conversion ratios, therefore, incentives around improving conversion rates and increasing product volume are recommended.

This study presents an overview of the context and global impacts of recent International Maritime Organization (IMO) regulations on the marine fuel oil refining industry, future marine fuel mix and ship emissions. IMO limited marine fuel sulphur content in both Sulphur Emission Control Areas (SECAs) and Nitrogen Oxide Emission Control Areas (NECAs) to 0.1% (wt. %) by 2015, and to 0.5% globally by 2020. It is anticipated that the newly implemented IMO regulations will help to mitigate negative impact of ship emissions on public health and environment. IMO regulations require significant changes to refineries to increase the production of low sulphur fuels through a shift to distillates, use of novel deep desulphurization techniques, or fuel blending. Changes to the refinery processes can bring forth increases in greenhouse gas emissions and high capital investments. Alternative fuels will need to meet the required reduction of air pollutants and greenhouse gas emissions in coastal areas. Alternative marine fuels consisting of liquefied nature gas (LNG) and biofuel may be suitable fuels to meet both targets. These two fuels are predicted to account for 50% of shipping energy demand by 2050, while the remainder will still be supplied by conventional heavy fuel oil (HFO)/marine gas oil (MGO). Switching to low sulphur fuels as a results of the new IMO regulations has led to measureable reductions in ship emissions generally. This fuel switching also resulted in changes in engine emission characteristics, especially on particulate matter chemical composition.

A novel approach for modelling hydrothermal liquefaction (HTL) biocrude is presented, using a combination of fractional distillation data of biocrude and multi-objective optimisation to simulate the biocrude various properties using the non-dominated sorting genetic algorithm (NSGA-II). The complex composition of biocrude has made it challenging to analyse and simulate in process models. Most HTL simulation studies use a simple basis for biocrude using limited GC-MS data, which may not be reliably accurate. Applying multi-objective optimisation reduced the density and TBP curve error by ten times compared to single-objective optimisation. In addition,the results were further improved by combining distillation experimental data into multi-objective optimisation, in contrast with previous studies which used only the biocrude data. Separating complicated HTL biocrude into five fractions and analysing the obtained results increased the number of candidate databank compounds from 72 to 216, which led to a noticeable improvement in the accuracy of the model.

A plant converting sugarcane bagasse to liquid fuels through thermal liquefaction in an Australian setting was modelled in ASPEN Plus. Ethanol was investigated as a liquefaction solvent due to its effect of higher yields and higher biocrude heating value compared to water (i.e. hydrothermal liquefaction). The plant produced 0.67 kg biocrude per kg dry feed, which was further processed to 0.46 kg liquid fuels per kg of dry feed for a total of 25.8 million L/y of biofuel product. Ethanol losses incurred the highest share in operating costs, although there are opportunities for cost reduction around lower solvent to biomass ratio. Over the plant life and with a corporate tax rate of 30%, it was determined that the minimum selling price for the fuel products is US$ 0.99/L, which was comparable to other liquefaction studies using water as solvent. It was demonstrated that continuous operation mode was economically more advantageous than semi-batch production. Product price, hydrodeoxygenation conversion efficiency and plant capacity were determined to be the factors to which NPV is most sensitive, while biocrude yield and hydrodeoxygenation conversion efficiency were the key factors in decreasing the minimum selling price of the product to a level that can be competitive.

Various biocrudes were characterised by their distillation curves using simulated distillation. Biocrude and petroleum crude blends were generated and analysed to assess their compatibility for processing in conventional petroleum refineries. Distillation curves of biocrudes varied widely but were comparable to petroleum crude oil in shape and distillation range. Blending biocrude with petroleum crudes in the laboratory presented some challenges in miscibility; however, blending at higher than ambient temperatures, which more closely represents industrial practice, improved miscibility as shown in the FTIR spectra of blends, and close matching of the warmer blends to models. The distillation curve of the biocrude-petroleum crude blends followed the modelled blends in ASPEN Plus. Petroleum analysis and modelling methods were also demonstrated as reliable tools to analyse biocrudes and their blends with petroleum crude. The study verifies ASPEN’s utility in modelling biocrude distillation for processing in refinery distillation columns either as a blend or separately.

Thermal liquefaction of five potential feedstocks namely, banana bunch stems (BBS), pineapple tops (PT), Forage sorghum (FS), bagasse (Ba) and Arundo donax (AD) were examined from an energy perspective at a large laboratory scale. Comparison of oil yield and higher heating value (HHV) of feedstock and bio-crude at this scale enabled analysis of the energy efficiency of the liquefaction of feedstock with varying structural compositions under different reaction conditions. Arundo donax was used to investigate degradation behaviour for bio-crude production at temperatures between 250–350 °C and biomass/solvent ratios of 1/10 to 1/25 (wt/wt). Maximum bio-crude yield of 67.3% was observed for AD at 350 °C and biomass/solvent ratio of 1/15. Liquefaction with recycled solvent in the first run improved energy recovery and the heating value of the bio-crude in comparison with fresh solvent. On the basis of the energy conversion, the feedstocks ranked as follows: BBS (105%) > FS (77%) > Ba (57%) > PT (55%) > AD (40%). GCMS results showed that the chemical composition changed in distribution and relative abundance of the oxygenated compounds, varying significantly depending on the type of biomass. Analysis of energy input and output of varying conditions and feedstock showed energy requirements and the HHV varied with the feedstock.

Generating green-based liquid fuels using hydrothermal liquefaction is a promising method for fossil fuel replacement. This study investigates the impact of recycling the aqueous phase in hydrothermal liquefaction processing on fuel yield, quality and energy efficiency using algae as the feedstock. Recycling the aqueous phase in algal hydrothermal liquefaction increased biocrude production yield by 18.9% at 350 °C, although a 12.2% increase in the biocrude nitrogen content was observed. In the second recycling, the nitrogen content increased to 17.6%, which is not environmentally favourable for direct usage in diesel engines due to the possible increase in Nitrogen Oxides (NOx) emissions. Recycling the aqueous phase in Spirulina Platensis feedstock liquefaction led to a 19–30% increase in yields for different recycling numbers, which was influenced by increasing the temperature and by applying catalysts. The heterogeneous catalyst showed a considerable increase (17.8%) in yield, a decrease (9.5%) in nitrogen content, and an improved energy consumption recovery by 30.8% after single recycling. However, a slight increase (2.7%) in nitrogen content was observed after recycling twice. It is vital to reduce the amount of energy used in the hydrothermal liquefaction process to be comparable with conventional fuels. Recycling the aqueous phase reduced the energy usage considerably. Applying the homogeneous catalyst and recycling the aqueous phase twice had the highest energy efficiency (36.8%) and production yield (51.4%) for the hydrothermal liquefaction process. The generated aqueous phase in single and double recycling experiments had up to 77% and 166% more phosphate, which may be of interest for agricultural applications.

Supercritical water gasification (SCWG) as a pathway for biofuel production, presents an attractive option for processing assorted biomass feedstock due to its ability to process wet feedstock with higher hydrogen yield. However, SCWG requires significant thermal energy input to reach its high operating temperatures leading to overall process inefficiency. Although previous studies have found microalgae-based SCWG process to be uneconomic, investigations on the choice of energy integration and process-energy configuration options to make the process economically viable has not been considered. As such, this work focused on the economic viability of integrating energy alternatives such as solar thermal options (solar tower and parabolic trough collector), natural gas (NG), and electricity in a microalgae-based SCWG fuel plant. The syngas fuel plant of 19,000 t/y was modelled in Aspen Plus using nine different energy configurations of solar and conventional energy. The economic results of the energy integrations delivered minimum fuel selling prices (MFSPs) of 52–73 AUD/GJ. The most economic options for supplying energy to the plant were shown to be NG alone or using solar parabolic trough combined with supplementary NG to further boost the feedstock temperature in the SCWG reactor. The annual variable operational cost was found to contribute 77% towards MFSP and was highly dependent on the price of microalgae and hydrogen. At higher capital cost, MFSP was affected by the discount rate and the cost of energy which are susceptible to the cost of solar energy infrastructure or price of conventional energy. Sensitivity and switch value analysis showed that natural gas and parabolic trough-natural gas energy integrations could deliver lower MFSP at considerable reductions in annual operational cost and the solar energy components of the annual capital cost. The choice of energy option and process-energy configuration was demonstrated to play a significant role in making SCWG process economical. While solar tower technology may not be viable for high temperature process plant energy utilization, combining solar parabolic trough with natural gas was determined to be a more promising outcome for lower energy cost. Higher prices of conventional energy, carbon tax credit and government policies could make the SCWG technology with algae feedstock economically viable and 100% renewable in the future.

The livestock sector is a fundamental part of the modern global economy and provides food, clothing, furnishings, and various other products. So as to ensure its resilience to changes in consumer expectations, cost of production, and environmental sustainability, the sector must shift to a circular economy model. Current strategies to recover value from wastes and low-value co-products from livestock industries yield limited value; hence, new technologies are required to upgrade wastes and co-products, and generate high-value products that can feed into the livestock value chain. Anaerobic digestion can convert high organic-content waste to biogas for energy and a stable nutrient-rich digestate that can be used as fertiliser. Microbial technologies can transform wastes to produce nutritionally advanced feeds. New materials from waste can also be produced for livestock industry-specific applications. While aiming to add commercial value, the successful implementation of these technologies will also address the environmental and productivity issues that are increasingly valued by producers and consumers.

The objective of this study was to examine the hydrothermal liquefaction of sugarcane bagasse using ethanol and black liquor (BL) in a pilot scale. Combinations of co-solvents (ethanol/ water, ethanol/BL) were studied at various concentrations and reaction conditions. The maximum oil yield of 61% was achieved with a reaction temperature of 300 °C for 30 min and using pure BL as a solvent, while the highest higher heating value (HHV) was obtained from a 50:50 ethanol-BL mixture. The oils contained alcohols, esters, phenolic compounds, aromatics, and heterocyclics. The O/C and H/C ratios of the oil were comparable with traditional biodiesel and commercial diesel. Although this study showed there are some improvements to be made to improve the chemical composition, the approach has potential for large-scale production of a substitute for fossil-fuel-based diesel.

Hydrothermal liquefaction (HTL) presents a viable route for converting a vast range of materials into liquid fuel, without the need for pre-drying. Currently, HTL studies produce bio-crude with properties that fall short of diesel or biodiesel standards. Upgrading bio-crude improves the physical and chemical properties to produce a fuel corresponding to diesel or biodiesel. Properties such as viscosity, density, heating value, oxygen, nitrogen and sulphur content, and chemical composition can be modified towards meeting fuel standards using strategies such as solvent extraction, distillation, hydrodeoxygenation and catalytic cracking. This article presents a review of the upgrading technologies available, and how they might be used to make HTL bio-crude into a transportation fuel that meets current fuel property standards.

Hydrothermal liquefaction (HTL) is an efficient thermochemical method for biomass conversion into biocrude which could be operated with a wide range of feedstock resources. However, HTL biocrude characteristics including viscosity, density, heating value, composition and stability are not comparable with conventional products. The current focus for upgrading mainly relates to catalytic and hydrogenation processes; however, physical processes are cheaper and more reliable. Fractional distillation has potential as a cost-efficient physical technique for biocrude upgrading or even co-processing with crude oil in a refinery. This review summarises and discusses changes in physical and chemical properties of biocrude using fractional distillation. Distillation reduces the oxygen content of biocrude for heavy fractions more than 53% on average. It also decreases the sulphur and nitrogen content of biocrude up to 5–44%. The potential role of distillation in preparing fuel suitable for diesel engines is investigated. The challenges and technical limitations in HTL biocrude application in industry are also discussed alongside with possible solutions and future research potential which addresses these challenges.

This paper described and analyzed the population distribution of Bukidnon. A fractal analysis was used by computing the fractal dimensions of the population distribution of the province. Data are based on the population of 20 municipalities and two (2) cities in 16 years, from 1995 to 2010. The results showed that there is a slight decrease of fractal dimensions which implies that there is an approximately equal population in the municipalities over a period. Various conditions account for the decrease of variability in the population distribution. It may be attributed to their economic situations and cultural practices.Keywords: Fractal analysis, population distribution, Bukidnon, municipalities, cities