Estimation of the production cost of fast pyrolysis bio-oil

A number of papers and reports covering the techno-economic analysis of bio-oil production has been published. These have had different scopes, use different feedstocks and reflected national cost structures. This paper reviews and compares their cost estimates and the experimental results that underpin them. A comprehensive cost and performance model was produced based on consensus data from the previous studies or stated scenarios where data is not available that reflected UK costs. The model takes account sales of bio-char that is a co-product of pyrolysis and the electricity consumption of the pyrolysis plant and biomass pre-processing plants. It was concluded that it should be able to produce bio-oil in the UK from energy crops for a similar cost as distillate fuel oil. It was also found that there was little difference in the processing cost for woodchips and baled miscanthus. © 2011 Elsevier Ltd.

The potential use of bio-ultracarbofluids in a standard diesel engine

The replacement of diesel fuel by ultra-carbofluids was perceived to offer the potential to decrease the emissions of environmental pollutants such as carbon dioxide, carbon monoxide, hydrocarbons (HC's) and smoke. Such ultracarbofluids consist of a suspension of coal in fuel oil and water generally in the ratio of 5: 3: 2 plus a small amount of stabilising additive. The literature relating to the economies of coal and fuel oil production, and the production and properties of charcoal and vegetable oils has been critically reviewed. The potential use of charcoal and vegetable oils as replacements for coal and fuel oil are discussed. An experimental investigation was undertaken using novel bio-ultracarbofluid formulations. These differed from an ultracarbofluid by having bio-renewable charcoal and vegetable oil in place of coal and fuel oil. Tests were made with a Lister-Petter 600cc 2-cylinder, 4-stroke diesel engine fitted with a Heenan-Froude DPX 1 water brake dynamometer to measure brake power output, and Mexa-321E and Mexa-211E analysers to measure exhaust pollutants. Measurements were made of engine brake power output, carbon dioxide, carbon monoxide, hydrocarbons and smoke emissions over the speed range 1000 to 3000 rpm at 200 rpm intervals. The results were compared with those obtained with a standard diesel reference fuel. All the bio-ultracarbofluid formulations produced lower brake power outputs (i.e. 5.6% to 20.7% less brake power) but substantially improved exhaust emissions of CO2, CO, HC's and smoke. The major factor in the formulation was found to be the type and amount of charcoal; charcoal with a high volatile content (27.2%) and present at 30% by mass yielded the best results, i.e. only slightly lower brake power output and significantly lower exhaust pollutants.

Wear of high aluminium zinc-based alloys in plain bearing applications

Two zinc-based alloys of high aluminium content, Super Cosmal alloy containing 60% Al, 6% Si, 1% Cu, 0.3% Mn and HAZCA alloy containing 60% Al, 8% Si, 2% Cu, 0.06% Mg were produced by sand casting. Foundry characteristics in particular, fluidity, mode of solidification and feeding ability were examined. Metallographic analysis of structures was carried out using optical and scanning electron microscopy and their mechanical properties were determined using standard techniques. Dry wear characteristics were determined using a pin-on-disc test, and boundary-lubricated wear was studied using full bearing tests. Results from casting experiments were evaluated and compared with the behaviour of a standard ZA-27 alloy and those from tribological tests with both ZA-27 alloy and a leaded tin-bronze (SAE660) under the same testing conditions. The presence of silicon was beneficial, reducing the temperature range of solidification, improving feeding efficiency and reducing gravity segregation of phases. Use of chills and melt degassing was found necessary to achieve soundness and enhanced mechanical properties. Dry wear tests were performed against a steel counterface for sliding speeds of 0.25, 0.5, 1.0 and 2 m/s and for a range of loads up to 15 kgf. The high aluminium alloys showed wear rates as low as those of ZA-27 at speeds of 0.25 and 0.5 m/s for the whole range of applied loads. ZA-27 performed better at higher speeds. The build up of a surface film on the wearing surface of the test pins was found to be responsible for the mild type of wear of the zinc based alloys. The constitution of the surface film was determined as a complex mixture of aluminium, zinc and iron oxides and metallic elements derived from both sliding materials. For full bearing tests, bushes were machined from sand cast bars and were tested against a steel shaft in the presence of a light spindle oil as the lubricant. Results showed that all zinc based alloys run-in more rapidly than bronze, and that wear in Super Cosmal and HAZCA alloys after prolonged running were similar to those in ZA-27 bearings and significantly smaller than those of the bronze.

The effect of lignin and inorganic species in biomass on pyrolysis oil yields, quality and stability

This paper investigates four reference fuels and three low lignin Lolium Festuca grasses which were subjected to pyrolysis to produce pyrolysis oils. The oils were analysed to determine their quality and stability, enabling the identification of feedstock traits which affect oil stability. Two washed feedstocks were also subjected to pyrolysis to investigate whether washing can enhance pyrolysis oil quality. It was found that the mineral matter had the dominate effect on pyrolysis in compared to lignin content, in terms of pyrolysis yields for organics, char and gases. However the higher molecular weight compounds present in the pyrolysis oil are due to the lignin derived compounds as determined by results of GPC and liquid-GC/MS. The light organic fraction also increased in yield, but reduced in water content as metals increased at the expense of the lignin content. It was found that the fresh oil and aged oil had different compound intensities/concentrations, which is due to a large number of reactions occurring when the oil is aged day by day. These findings agree with previous reports which suggest that a large amount of re-polymerisation occurs as levoglucosan yields increase during the aging progress, while hydroxyacetaldehyde decrease. In summary the paper reports a window for producing a more stable pyrolysis oil by the use of energy crops, and also show that washing of biomass can improve oil quality and stability for high ash feedstocks, but less so for the energy crops.

Thermochemical characterisation of various biomass feedstock and bio-oil generated by fast pyrolysis

The projected decline in fossil fuel availability, environmental concerns, and security of supply attract increased interest in renewable energy derived from biomass. Fast pyrolysis is a possible thermochemical conversion route for the production of bio-oil, with promising advantages. The purpose of the experiments reported in this thesis was to extend our understanding of the fast pyrolysis process for straw, perennial grasses and hardwoods, and the implications of selective pyrolysis, crop harvest and storage on the thermal decomposition products. To this end, characterisation and laboratory-scale fast pyrolysis were conducted on the available feedstocks, and their products were compared. The variation in light and medium volatile decomposition products was investigated at different pyrolysis temperatures and heating rates, and a comparison of fast and slow pyrolysis products was conducted. Feedstocks from different harvests, storage durations and locations were characterised and compared in terms of their fuel and chemical properties. A range of analytical (e.g. Py-GC-MS and TGA) and processing equipment (0.3 kg/h and 1.0 kg/h fast pyrolysis reactors and 0.15 kg slow pyrolysis reactor) was used. Findings show that the high bio-oil and char heating value, and low water content of willow short rotation coppice (SRC) make this crop attractive for fast pyrolysis processing compared to the other investigated feedstocks in this project. From the analytical sequential investigation of willow SRC, it was found that the volatile product distribution can be tailored to achieve a better final product, by a variation of the heating rate and temperature. Time of harvest was most influential on the fuel properties of miscanthus; overall the late harvest produced the best fuel properties (high HHV, low moisture content, high volatile content, low ash content), and storage of the feedstock reduced the moisture and acid content.

Combustion of fuel blends containing digestate pyrolysis oil in a multi-cylinder compression ignition engine

Digestate from the anaerobic digestion conversion process is widely used as a farm land fertiliser. This study proposes an alternative use as a source of energy. Dried digestate was pyrolysed and the resulting oil was blended with waste cooking oil and butanol (10, 20 and 30 vol.%). The physical and chemical properties of the pyrolysis oil blends were measured and compared with pure fossil diesel and waste cooking oil. The blends were tested in a multi-cylinder indirect injection compression ignition engine.Engine combustion, exhaust gas emissions and performance parameters were measured and compared with pure fossil diesel operation. The ASTM copper corrosion values for 20% and 30% pyrolysis blends were 2c, compared to 1b for fossil diesel. The kinematic viscosities of the blends at 40 C were 5–7 times higher than that of fossil diesel. Digested pyrolysis oil blends produced lower in-cylinder peak pressures than fossil diesel and waste cooking oil operation. The maximum heat release rates of the blends were approximately 8% higher than with fossil diesel. The ignition delay periods of the blends were higher; pyrolysis oil blends started to combust late and once combustion started burnt quicker than fossil diesel. The total burning duration of the 20% and 30% blends were decreased by 12% and 3% compared to fossil diesel. At full engine load, the brake thermal efficiencies of the blends were decreased by about 3–7% when compared to fossil diesel. The pyrolysis blends gave lower smoke levels; at full engine load, smoke level of the 20% blend was 44% lower than fossil diesel. In comparison to fossil diesel and at full load, the brake specific fuel consumption (wt.) of the 30% and 20% blends were approximately 32% and 15% higher. At full engine load, the CO emission of the 20% and 30% blends were decreased by 39% and 66% with respect to the fossil diesel. Blends CO2 emissions were similar to that of fossil diesel; at full engine load, 30% blend produced approximately 5% higher CO2 emission than fossil diesel. The study concludes that on the basis of short term engine experiment up to 30% blend of pyrolysis oil from digestate of arable crops can be used in a compression ignition engine.

Expanding the biomass resource:sustainable oil production via fast pyrolysis of low input high diversity biomass and the potential integration of thermochemical and biological conversion routes

Waste biomass is generated during the conservation management of semi-natural habitats, and represents an unused resource and potential bioenergy feedstock that does not compete with food production. Thermogravimetric analysis was used to characterise a representative range of biomass generated during conservation management in Wales. Of the biomass types assessed, those dominated by rush (Juncus effuses) and bracken (Pteridium aquilinum) exhibited the highest and lowest volatile compositions respectively and were selected for bench scale conversion via fast pyrolysis. Each biomass type was ensiled and a sub-sample of silage was washed and pressed. Demineralization of conservation biomass through washing and pressing was associated with higher oil yields following fast pyrolysis. The oil yields were within the published range established for the dedicated energy crops miscanthus and willow. In order to examine the potential a multiple output energy system was developed with gross power production estimates following valorisation of the press fluid, char and oil. If used in multi fuel industrial burners the char and oil alone would displace 3.9 × 105 tonnes per year of No. 2 light oil using Welsh biomass from conservation management. Bioenergy and product development using these feedstocks could simultaneously support biodiversity management and displace fossil fuels, thereby reducing GHG emissions. Gross power generation predictions show good potential.

Experimental investigation of the fuel properties of glidfuel, palm oil mill effluent biodiesel and blends

Biofuels derived from industry waste have potential to substitute fossil fuels (Diesel and Gasoline) in internal combustion (IC) engines. Use of waste streams as fuels would help to reduce considerably life-cycle greenhouse gas emissions and minimise waste processing costs. In this study an investigation into the fuel properties of two waste derived biofuels were carried out, they are: (i) Glidfuel (GF) biofuel - a waste stream from paper industry, and (ii) Palm Oil Mill Effluent (POME) biodiesel - biodiesel produced from palm oil industry effluent through various treatment and transesterification process. GF and POME was mixed together at various proportions and separately with fossil diesel (FD) to assess the miscibility and various physical and chemical properties of the blends. Fuel properties such as kinematic viscosity, higher heating value, water content, acid number, density, flash point temperature, CHNO content, sulphur content, ash content, oxidation stability, cetane number and copper corrosion ratings of all the fuels were measured. The properties of GF, POME and various blends were compared with the corresponding properties of the standard FD. Significance of the fuel properties and their expected effects on combustion and exhaust emission characteristics of the IC engine were discussed. Results showed that most properties of both GF and POME biodiesel were comparable to FD. Both GF and POME were miscible with each other, and also separately with the FD. Flash point temperatures of GF and POME biodiesel were 40.7°C and 158.7°C respectively. The flash point temperature of GF was about 36% lower than corresponding FD. The water content in GF and FD were 0.74 (% wt) and 0.01 (% wt) respectively. Acidity values and corrosion ratings of both GF and POME biodiesel were low compared to corresponding value for FD. The study concluded that optimum GF-POME biofuel blends can substitute fossil diesel use in IC engines.

Fast pyrolysis oil fuel blend for marine vessels

The main driver for the investigation of fast pyrolysis oil marine fuel blends is EU directive 2012/33/EU which aims to cut the sulphur content of marine fuel and thereby reduce air pollution caused by marine vessels. The aim of this study was to investigate the miscibility of 3- and 4- component blends containing pyrolysis oil, 1-butanol, biodiesel (RME) and/or marine gas oil (MGO). The ideal blend would be a stable homogenous product with a minimum amount of butanol, whilst maximising the amount of pyrolysis oil. A successful blend would have properties suitable for use in marine engines. In order to successfully utilise a marine fuel blend in commercial vessels it should meet minimum specification requirements such as a flash point ≥60°C. Blends of pyrolysis oil, RME, MGO and 1-butanol were evaluated and characterised. The mixed blends were inspected after 48 hours for homogeneity and the results plotted on a tri-plot phase diagram. Homogenous samples were tested for water content, pH, acid number, viscosity and flash point as these give indicate a blend’s suitability for engine testing. The work forms part of the ReShip Project which is funded by Norwegian industry partners and the Research Council of Norway (The ENERGIX programme).

The development and optimisation of a fast pyrolysis process for bio-oil production

A two-tier study is presented in this thesis. The first involves the commissioning of an extant but at the time, unproven bubbling fluidised bed fast pyrolysis unit. The unit was designed for an intended nominal throughput of 300 g/h of biomass. The unit came complete with solids separation, pyrolysis vapour quenching and oil collection systems. Modifications were carried out on various sections of the system including the reactor heating, quenching and liquid collection systems. The modifications allowed for fast pyrolysis experiments to be carried out at the appropriate temperatures. Bio-oil was generated using conventional biomass feedstocks including Willow, beechwood, Pine and Miscanthus. Results from this phase of the research showed however, that although the rig was capable of processing biomass to bio-oil, it was characterised by low mass balance closures and recurrent operational problems. The problems included blockages, poor reactor hydrodynamics and reduced organic liquid yields. The less than optimal performance of individual sections, particularly the feed and reactor systems of the rig, culminated in a poor overall performance of the system. The second phase of this research involved the redesign of two key components of the unit. An alternative feeding system was commissioned for the unit. The feed system included an off the shelf gravimetric system for accurate metering and efficient delivery of biomass. Similarly, a new bubbling fluidised bed reactor with an intended nominal throughput of 500g/h of biomass was designed and constructed. The design leveraged on experience from the initial commissioning phase with proven kinetic and hydrodynamic studies. These units were commissioned as part of the optimisation phase of the study. Also as part of this study, two varieties each, of previously unreported feedstocks namely Jatropha curcas and Moringa olifiera oil seed press cakes were characterised to determine their suitability as feedstocks for liquid fuel production via fast pyrolysis. Consequently, the feedstocks were used for the production of pyrolysis liquids. The quality of the pyrolysis liquids from the feedstocks were then investigated via a number of analytical techniques. The oils from the press cakes showed high levels of stability and reduced pH values. The improvements to the design of the fast pyrolysis unit led to higher mass balance closures and increased organic liquid yields. The maximum liquid yield obtained from the press cakes was from African Jatropha press cake at 66 wt% on a dry basis.

Upgrading fast pyrolysis liquids:blends of biodiesel and pyrolysis oil

Fast pyrolysis liquid or bio-oil has been used in engines with limited success. It requires a pilot fuel and/or an additive for successful combustion and there are problems with materials and liquid properties. It is immiscible with all conventional hydrocarbon fuels. Biodiesel, a product of esterification of vegetable oil with an alcohol, is widely used as a renewable liquid fuel as an additive to diesel at up to 20%. There are however limits to its use in conventional engines due to poor low temperature performance and variability in quality from a variety of vegetable oil qualities and variety of esterification processes. Within the European Project Bioliquids-CHP - a joint project between the European Commission and Russia - a study was undertaken to develop small scale CHP units based on engines and microturbines fuelled with bioliquids from fast pyrolysis and methyl esters of vegetable oil. Blends of bio-oil and biodiesel were evaluated and tested to overcome some of the disadvantages of using either fuel by itself. An alcohol was used as the co-solvent in the form of ethanol, 1-butanol or 2-propanol. Visual inspection of the blend homogeneity after 48 h was used as an indicator of the product stability and the results were plotted in a three phase chart for each alcohol used. An accelerated stability test was performed on selected samples in order to predict its long term stability. We concluded that the type and quantity of alcohol is critical for the blend formation and stability. Using 1-butanol gave the widest selection of stable blends, followed by blends with 2-propanol and finally ethanol, thus 1-butanol blends accepted the largest proportion of bio-oil in the mixture. © 2013 Elsevier Ltd. All rights reserved.

Improvement of bio-oil stability in wood pyrolysis process

Pyrolysis is one of several thermochemical technologies that convert solid biomass into more useful and valuable bio-fuels. Pyrolysis is thermal degradation in the complete or partial absence of oxygen. Under carefully controlled conditions, solid biomass can be converted to a liquid known as bie-oil in 75% yield on dry feed. Bio-oil can be used as a fuel but has the drawback of having a high level of oxygen due to the presence of a complex mixture of molecular fragments of cellulose, hemicellulose and lignin polymers. Also, bio-oil has a number of problems in use including high initial viscosity, instability resulting in increased viscosity or phase separation and high solids content. Much effort has been spent on upgrading bio-oil into a more usable liquid fuel, either by modifying the liquid or by major chemical and catalytic conversion to hydrocarbons. The overall primary objective was to improve oil stability by exploring different ways. The first was to detennine the effect of feed moisture content on bio-oil stability. The second method was to try to improve bio-oil stability by partially oxygenated pyrolysis. The third one was to improve stability by co-pyrolysis with methanol. The project was carried out on an existing laboratory pyrolysis reactor system, which works well with this project without redesign or modification too much. During the finishing stages of this project, it was found that the temperature of the condenser in the product collection system had a marked impact on pyrolysis liquid stability. This was discussed in this work and further recommendation given. The quantity of water coming from the feedstock and the pyrolysis reaction is important to liquid stability. In the present work the feedstock moisture content was varied and pyrolysis experiments were carried out over a range of temperatures. The quality of the bio-oil produced was measured as water content, initial viscosity and stability. The result showed that moderate (7.3-12.8 % moisture) feedstock moisture led to more stable bio-oil. One of drawbacks of bio-oil was its instability due to containing unstable oxygenated chemicals. Catalytic hydrotreatment of the oil and zeolite cracking of pyrolysis vapour were discllssed by many researchers, the processes were intended to eliminate oxygen in the bio-oil. In this work an alternative way oxygenated pyrolysis was introduced in order to reduce oil instability, which was intended to oxidise unstable oxygenated chemicals in the bio-oil. The results showed that liquid stability was improved by oxygen addition during the pyrolysis of beech wood at an optimum air factor of about 0.09-0.15. Methanol as a postproduction additive to bio-oil has been studied by many researchers and the most effective result came from adding methanol to oil just after production. Co-pyrolysis of spruce wood with methanol was undertaken in the present work and it was found that methanol improved liquid stability as a co-pyrolysis solvent but was no more effective than when used as a postproduction additive.

Catalytic pyrolysis of agricultural residues for bio-oil production

Agricultural residues from Thailand, namely stalk and rhizome of cassava plants, were employed as raw materials for bio-oil production via fast pyrolysis technology. There were two main objectives of this project. The first one was to determine the optimum pyrolysis temperature for maximising the organics yield and to investigate the properties of the bio-oils produced. To achieve this objective, pyrolysis experiments were conducted using a bench-scale (150 g/h) reactor system, followed by bio-oil analysis. It was found that the reactor bed temperature that could give the highest organics yield for both materials was 490±15ºC. At all temperatures studied, the rhizome gave about 2-4% higher organics yields than the stalk. The bio-oil derived from the rhizome had lower oxygen content, higher calorific value and better stability, thus indicating better quality than that produced from the stalk. The second objective was to improve the bio-oil properties in terms of heating value, viscosity and storage stability by the incorporation of catalyst into the pyrolysis process. Catalytic pyrolysis was initially performed in a micro-scale reactor to screen a large number of catalysts. Subsequently, seven catalysts were selected for experiments with larger-scale (150 g/h) pyrolysis unit. The catalysts were zeolite and related materials (ZSM-5, Al-MCM-41 and Al-MSU-F), commercial catalysts (Criterion-534 and MI-575), copper chromite and ash. Additionally, the combination of two catalysts in series was investigated. These were Criterion-534/ZSM-5 and Al-MSU-F/ZSM-5. The results showed that all catalysts could improve the bio-oils properties as they enhanced cracking and deoxygenation reactions and in some cases such as ZSM-5, Criterion-534 and Criterion-534/ZSM-5, valuable chemicals like hydrocarbons and light phenols were produced. The highest concentration of these compounds was obtained with Criterion-534/ZSM-5.

Technoeconomic modelling of coal conversion processes for liquid fuel production

Since the oil crisis of 1973 considerable interest has been shown in the production of liquid fuels from alternative sources. In particular processes utilizing coal as the feedstock have received considerable interest. These processes can be divided into direct and indirect liquefaction and pyrolysis. This thesis describes the modelling of indirect coal liquefaction processes for the purpose of performing technical and economic assessment of the production of liquid fuels from coal and lignite, using a variety of gasification and synthesis gas liquefaction technologies. The technologies were modeled on a 'step model' basis where a step is defined as a combination of individual unit operations which together perform a significant function on the process streams, such as a methanol synthesis step or a gasification and physical gas cleaning step. Sample results of the modelling, covering a wide range of gasifiers, liquid synthesis processes and products are presented in this thesis. Due to the large number of combinations of gasifier, liquid synthesis processes, products and economic sensitivity cases, a complete set of results is impractical to present in a single publication. The main results show that methanol is the cheapest fuel to produce from coal followed by fuel alcohol, diesel from the Shell Middle Distillate Synthesis process,gasoline from Mobil Methanol to Gasoline (MTG) process, diesel from the Mobil Methanol Olefins Gasoline Diesel (MOGD) process and finally gasoline from the same process. Some variation in production costs of all the products was shown depending on type of gasifier chosen and feedstock.

An investigation of the emerging system of host government participation in the international oil industry with particular reference to Libyan participation arrangements

This study has been conceived with the primary objective of identifying and evaluating the financial aspects of the transformation in country/company relations of the international oil industry from the traditional concessionary system to the system of governmental participation in the ownership and operation of oil concessions. The emphasis of the inquiry was placed on assembling a case study of the oil exploitation arrangements of Libya. Through a comprehensive review of the literature, the sociopolitical factors surrounding the international oil business were identified and examined in an attempt to see their influence on contractual arrangements and particularly to gauge the impact of any induced contractual changes on the revenue benefit accruing to the host country from its oil operations. Some comparative analyses were made in the study to examine the viability of the Libyan participation deals both as an investment proposal and as a system of conducting oil activities in the country. The analysis was carried out in the light of specific hypotheses to assess the relative impact of the participation scheme in comparison with the alternative concessionary model on the net revenue resulting to the government from oil operations and the relative effect on the level of research and development within the industry. A discounted cash flow analysis was conducted to measure inputs and outputs of the comparative models and judge their revenue benefits. Then an empirical analysis was carried out to detect any significant behavioural changes in the exploration and development effort associated with the different oil exploitation systems. Results of the investigation of revenues support the argument that the mere introduction of the participation system has not resulted in a significant revenue benefit to the host government. Though there has been a significant increase in government revenue, associated with the period following the emergence of the participation agreements, this increase was mainly due to socio-economic factors other than the participation scheme. At the same time the empirical results have shown an association of the participation scheme with a decline of the oil industry's research and development efforts.