Amanda Lea-Langton

Catalytic hydrothermal gasification of algae for hydrogen production: Composition of reaction products and potential for nutrient recycling

Chlorella vulgaris, Spirulina platensis and Saccharina latissima were processed under supercritical water gasification conditions at 500 °C, 36 MPa in an Inconel batch reactor for 30 min in the presence/absence of NaOH and/or Ni-Al(2)O(3). Hydrogen gas yields were more than two times higher in the presence of NaOH than in its absence and tar yields were reduced by up to 71%. Saccharina, a carbohydrate-rich macro-alga, gave the highest hydrogen gas yields of 15.1 mol/kg. The tars from all three algae contained aromatic compounds, including phenols, alkyl benzenes and polycyclic aromatic hydrocarbons as well as heterocyclic nitrogen compounds. Tars from Chlorella and Spirulina contained high yields of pyridines, pyrroles, indoles and pyrimidines. Up to 97% TOC removal were achieved in the process waters from the gasification of the algae. Analyses for specific nutrients in the process waters indicated that the process waters from Saccharina could potentially be used for microalgae cultivation.

Effect of Multifunctional Fuel Additive Package on Fuel Injector Deposit, Combustion and Emissions using Pure Rape Seed Oil for a DI Diesel

This work investigates the effect of a multifunctional diesel fuel additive package used with RapeSeed Oil (RSO) as a fuel in a DI heavy duty diesel engine. The effects on fuel injectors’ cleanliness were assessed. The aim was to maintain combustion performance and preventing the deterioration of exhaust emissions associated with injector deposit build up. Two scenarios were investigated: the effect of deposit clean-up by a high dose of the additive package; and the effect of deposit prevention using a moderate dose of the additive package. Engine combustion performance and emissions were compared for each case against use of RSO without any additive. The engine used was a 6 cylinder, turbocharged, intercooled Perkins Phaser Engine, fitted with an oxidation catalyst and meeting the Euro II emissions limits. The tests were conducted under steady state conditions of 23kW and 47kW power output at an engine speed of 1500 rpm. The in-cylinder pressure, gaseous and particulate exhaust emissions were measured. The injectors were inspected using SEM (Scanning Electronic Microscopy). The results show that the use of the multifunctional fuel additive package reduces the ignition delay (ID), increases the premixed combustion duration (PCD) and improves the combustion stability. The multifunctional fuel additive package also reduced the deposit build up on the fuel injectors and prevented the deterioration of engine-out particulate, CO and hydrocarbon emissions

Stability and Activity of Doped Transition Metal Zeolites in the Hydrothermal Processing

This study investigates the stability and activity of HZSM-5 doped with metals such as molybdenum, nickel, copper and iron in under hydrothermal conditions used for the direct liquefaction of microalgae. Catalysts have been prepared by ion exchange techniques, and MoZSM-5 was also prepared by wet incipient impregnation for comparison. Hydrothermal liquefaction is considered as a potential route to convert microalgae into a sustainable fuel. One of the drawbacks of this process is that the bio-crude produced contains significant levels of nitrogen and oxygen compounds which have an impact on the physical and chemical propriety of the fuel. Heterogeneous catalysts have been shown to improve the quality of the bio-crude by reducing nitrogen and oxygen contents. Zeolites, such as HZSM-5, are strong candidates due to their low cost compared to noble metal catalysts but their stability and activity under hydrothermal conditions is not well understood. The stability of the catalysts has been determined under hydrothermal conditions at 350 °C. Catalysts have been characterised before and after treatment using XRD, BET physisorption and STEM microscopy. Metal leaching was determined by analysis of the water phase following hydrothermal treatment. The inserted cation following ion-exchange can influence the physical properties of HZSM-5 for example molybdenum improves the crystallinity of the zeolite. In general, metal doped zeolites were relatively stable under subcritical water. Activity of the catalysts for processing lipids, protein and microalgae has been assessed. Four feedstocks were selected: sunflower oil, soya proteins, Chlorella and P. ellipsoidea. The catalysts exhibited greater activity towards converting lipids for example MoZSM-5 enhanced the formation of aromatic compounds. NiZSM-5 and CuZSM-5 were observed to be more efficient for deoxygenation.

Combustion of Solid Biomass: Classification of Fuels

The combustion of solid biomass and the classification of these fuels are considered. Firstly the different methods of combustion appliances and plants are outlined from a fundamental point of view. The forms and types of solid biomass fuels, their chemical composition and the way they are classified are then described. Characterisation by chemical analysis and instrumental methods are outlined.

Integrating microalgae into the Brazilian program for biodiesel production and use

Brazil‘s programme for production and use of biodiesel is a novel program, aimed at improving the sustainability of biodiesel by promoting social inclusion, whilst simultaneously increasing food security, diversifying feedstocks and producing a lower carbon fuel. The aims of the program have been evaluated by conducting a qualitative analysis of the system. The existing system is then compared with the introduction of microalgae as a feedstock. This research shows that revisions to the program are needed in order to address economic, social and environmental sustainability. Particular attention must be given to more thorough environmental criteria for land use and agricultural techniques. Family farmers need stronger support in order for biodiesel to become a sustainable product for them to grow. Microalgae could be included into a biodiesel program, provided sufficient incentives are given, and this could improve the overall sustainability of biodiesel production and use.

Biomass Combustion: Carbon Capture and Storage

This chapter deals with the capture and storage of carbon dioxide produced by the combustion of biomass. Since biomass combustion is potentially carbon neutral, this technique could provide a method of reducing the carbon dioxide concentration in the atmosphere. The general features of this future technology of ‘bioenergy carbon capture and storage’, known as BECCS, are outlined. These cover biomass combustion with air or oxygen, gasification and chemical looping. Carbon capture and storage processes are briefly discussed.

Pollutant Formation and Health Effects

This chapter deals with pollutant formation and the consequential health effects. The major features of pollutants arising from biomass combustion are discussed. These include smoke, Unburned Hydrocarbons (UBH), volatiles, Polycyclic Aromatic Hydrocarbons (PAH), Nitrogen Oxides (NOx), other nitrogenous pollutants, sulphur, chlorine compounds and dioxins. Trace metals and particularly the interaction of K–Cl–S chemistry and aerosol emissions are discussed.

Introduction to Biomass Combustion

The role of biomass in the world energy scene is first considered and compared with other energy sources. Estimates of the resources available are provided and discussed. The IEA world estimates of the growth in the use of biomass are also presented. Issues resulting to Greenhouse Gas emissions and sustainability are considered.

The Combustion of Solid Biomass

The combustion of solid biomass is covered in this chapter. This covers the general mechanism of combustion, moisture evaporation, devolatilisation, the combustion of the volatiles gases and tars and finally char combustion. Details are given about the kinetics of these reactions, the devolatilisation products which if unburned give CO and organic products and char combustion which if incompletely burned result in fine char particles in the combustion products.

Emissions from Different Types of Combustors and Their Control

Emissions from different types of combustors and their control methods are outlined. These include emissions from fixed and travelling bed combustors and emissions from large industrial combustion plants. Emissions from wild Fires are also considered.