Microvawe pyrolysis of biomass: control of process parameters for high pyrolysis oil yields and enhanced oil quality

The oil yield and quality of pyrolysis oil from microwave heating of biomass was established by studying the behaviour of Larch in microwave processing. This is the first study in biomass pyrolysis to use a microwave processing technique and methodology that is fundamentally scalable, from which the basis of design for a continuous processing system can be derived to maximise oil yield and quality. It is shown systematically that sample size is a vital parameter that has been overlooked by previous work in this field. When sample size is controlled the liquid product yield is comparable to conventional pyrolysis, and can be achieved at an energy input of around 600 kWh/t. The quality of the liquid product is significantly improved compared to conventional pyrolysis processes, which results from the very rapid heating and quenching that can be achieved with microwave processing. The yields of Levoglucosan and phenolic compounds were found to be an order of magnitude higher in microwave pyrolysis when compared with conventional fast pyrolysis. Geometry is a key consideration for the development of a process at scale, and the opportunities and challenges for scale-up are discussed within this paper

Potential applications of nanotechnology in thermochemical conversion of microalgal biomass

The rapid decrease in fossil reserves has significantly increased the demand of renewable and sustainable energy fuel resources. Fluctuating fuel prices and significant greenhouse gas (GHG) emission levels have been key impediments associated with the production and utilization of nonrenewable fossil fuels. This has resulted in escalating interests to develop new and improve inexpensive carbon neutral energy technologies to meet future demands. Various process options to produce a variety of biofuels including biodiesel, bioethanol, biohydrogen, bio-oil, and biogas have been explored as an alternative to fossil fuels. The renewable, biodegradable, and nontoxic nature of biofuels make them appealing as alternative fuels. Biofuels can be produced from various renewable resources. Among these renewable resources, algae appear to be promising in delivering sustainable energy options. Algae have a high carbon dioxide (CO2) capturing efficiency, rapid growth rate, high biomass productivity, and the ability to grow in non-potable water. For algal biomass, the two main conversion pathways used to produce biofuel include biochemical and thermochemical conversions. Algal biofuel production is, however, challenged with process scalability for high conversion rates and high energy demands for biomass harvesting. This affects the viable achievement of industrial-scale bioprocess conversion under optimum economy. Although algal biofuels have the potential to provide a sustainable fuel for future, active research aimed at improving upstream and downstream technologies is critical. New technologies and improved systems focused on photobioreactor design, cultivation optimization, culture dewatering, and biofuel production are required to minimize the drawbacks associated with existing methods. Nanotechnology has the potential to address some of the upstream and downstream challenges associated with the development of algal biofuels. It can be applied to improve system design, cultivation, dewatering, biomass characterization, and biofuel conversion. This chapter discusses thermochemical conversion of microalgal biomass with recent advances in the application of nanotechnology to enhance the development of biofuels from algae. Nanotechnology has proven to improve the performance of existing technologies used in thermochemical treatment and conversion of biomass. The different bioprocess aspects, such as reactor design and operation, analytical techniques, and experimental validation of kinetic studies, to provide insights into the application of nanotechnology for enhanced algal biofuel production are addressed

Kinetics of the thermal decomposition of biomass

This paper is concerned with the kinetics of the thermal decomposition of a woody biomass, willow. It addresses two questions. First, what method of data analysis is appropriate for extracting reliable kinetic data from thermogravimetric analysis (TGA) experiments? Second, what kinetics are most suitable for high heating rate situations such as those present in pulverized fuel power stations? It contains kinetic analysis of willow TGA data using a variety of approaches. A review of previously published work on biomass and its polymeric components helps ascertain the variation in kinetics, reasons for differences, and extrapolation to flame temperatures. The data falls into two main categories: (1) very high E and A values (>100 and up to 270 kJ/mol, and up to 1017 s-1) derived when model biomass components are studied, for example, cellulose; or the data is interpreted as the sum of a number of individual first-order reactions, for example, FG-BioMass; (2) intermediate and low E andA values (50-100 kJ/mol and103 K/s) high E kinetics predict conversion well, and this can be rationalized since primary cracking reactions will dominate under these conditions. However, at heating rates of 105 K/s and temperatures of 1500 C(i.e., flame conditions), a compensation on the rates is seen and the choice of rate parameters is less critical. Two sets of kinetic data, E=178.7 kJ/ mol,A=2.21013 s-1 andE=48.7 kJ/mol,A=6.84103 s-1, both predict conversions in keeping with the available experimental data