Emissions and combustion performance of a micro gas turbine powered with liquefied wood and its blends

The combustion of a viscous biofuel, liquefied wood (LW) produced via solvolysis of lignocellulosic biomass in acidified glycols, has been studied in a small gas turbine rig. The test rig includes a modified injection line which is compatible with acidic, viscous biofuels allowing fuel preheating and two pilot injectors, and a re-designed combustion chamber. The link between fuel properties and combustion performance of liquefied wood is investigated by burning the biofuel at different blending ratios with ethanol. Exhaust emissions have been compared to reference measurements with diesel fuel and ethanol. Combustion analysis is supported by the investigation of the engine operating parameters and the main emission species at different electrical loads. The experimental study reveals that it is possible to establish efficient operation of the micro gas turbine while utilizing liquefied wood-ethanol blends with high share of liquefied wood

Bioliquids and their use in power generation

The first EU Renewable Energy Directive (RED) served as an effective push for world-wide research efforts on biofuels and bioliquids, i.e. liquid fuels for energy purposes other than for transport, including electricity, heating, and cooling, which are produced from biomass. In December 2018 the new RED II was published in the Official Journal of the European Union. Therefore, it is now the right time to provide a comprehensive overview of achievements and practices that were developed within the current perspective. To comply with this objective, the present study focuses on a comprehensive and systematic technical evaluation of all key aspects of the different distributed energy generation pathways using bioliquids in reciprocating engines and micro gas turbines that were overseen by these EU actions. Methodologically, the study originates from the analyses of feedstock and fuel processing technologies, which decisively influence fuel properties. The study systematically and holistically highlights the utilisation of these bioliquids in terms of fuel property specific challenges, required engine adaptations, and equipment durability, culminating in analyses of engine performance and emissions. In addition, innovative proposals and future opportunities for further technical improvements in the whole production-consumption cycle are presented, thus serving as a guideline for upcoming research and development activities in the fast-growing area of bioliquids. Additionally, the paper systematically addresses opportunities for the utilisation of waste streams, emerging from the ever increasing circular use of materials and resources. With this, the present review provides the sorely needed link between past efforts, oriented towards the exploitation of bio-based resources for power generation, and the very recent zero-waste oriented society that will require a realistic exploitation plan for residuals originating from intensive material looping

Performance and emissions of liquefied wood as fuel for a small scale gas turbine

This study investigates for the first time the combustion in a micro gas turbine (MGT) of a new bioliquid, a viscous biocrude, which is a liquefied wood (LW) produced via solvolysis of lignocellulosic biomass in acidified glycols. The test rig includes a modified fuel injection line, a re-designed combustion chamber and revised fuel injection positions. The main novelties of this work are: (1) producing of liquefied wood with pure ethylene glycol as a solvent, and methanesulfonic acid as a catalyst, to obtain a bio-crude with lower viscosity and higher lignocellulosics content than previous tested formulations(2) upgrading raw liquefied wood by blending it with ethanol to further reduce the viscosity of the mixture(3) utilizing a commercially available MGT Auxiliary Power Unit (APU) of 25%kW electrical power output, with notably reduced extent of adaptations to use the newly obtained fuel mixture. Fuel properties, and their impact on combustion performance using liquefied wood, are investigated by analyzing MGT performance and emissions response at different load and blend ratios. Emissions revealed that the presence of LW in the blends significantly affects CO and NOX concentrations compared to conventional fuels. CO roughly increased from 600%ppm (pure ethanol as fuel) to 1500%ppm (at 20%kW electrical power). The experimental study reveals that it is possible to achieve efficient MGT operation while utilizing high biocrude to ethanol ratios, but a number of adaptations are necessary. The achieved maximum share of liquefied wood in the fuel blend is 47.2% at 25%kW power output. Main barriers to the use of higher share of liquefied wood in these type of systems are also summarized

Fuel rich ammonia-hydrogen injection for humidified gas turbines

The use of new fuels and operating strategies for gas turbine technologies plays a relevant component for carbon emissions reduction and the use of sustainable energy sources. Among non-carbon fuels, hydrogen-based fuels have been proposed as one of the main strategies for decarbonisation of the power sector. Ammonia is a good representative of these fuels as it is carbon-free and the second largest chemical commodity, having been produced worldwide for more than a century from various energy resources, i.e. fossil fuels, biomass or other renewable sources. However, the use of ammonia as a fuel in industrial gas turbines brings some practical challenges directly linked to the final efficiency of these systems, especially when the latter are compared to current Dry Low Nitrogen Oxides technologies. Thus, this work covers a series of analytical, numerical and experimental studies performed to determine the efficiency of using ammonia/hydrogen blends in combination with humidified methodologies to deliver competitive systems for the use of ammonia-hydrogen power generation. The study was conducted using CHEMKIN-PRO reaction networks employing novel reaction chemical kinetics, in combination with bespoke analytical codes to determine efficiencies of systems previously calibrated experimentally. Finally, experimental trials using steam injection were carried out to determine potential of these blends. The novel results demonstrate that the use of humidified ammonia-hydrogen injection provides similar efficiencies to both Dry Low Nitrogen Oxides and humidified methane-based technologies 30%, with flames that are stable and low polluting under swirling conditions, thus opening the opportunity for further progression on the topic