Publication: Thermochemical conversion of algal biomass via microwave-assisted hydrothermal liquefaction for bio-oil production
Date
2025-03-05
Authors
Nor Insyirah Syahira Abdul Latif
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Abstract
Currently, fossil materials make up the majority of our energy and chemical source. Many global concerns are forcing people to rethink our current dependence on fossil energy. Limiting the use of these energy sources is a key priority for most countries as a result of pledges to reduce greenhouse gas emissions. The application of biomass, used to substitute fossil resources to produce biofuels, plastics and chemicals, is a widely accepted strategy towards sustainable development. Aquatic plants, including algae are seen to have competitive advantages as biomass resources compared to terrestrial plants in this current global situation. Production of bio-oil from algal biomass are technically and economically viable and cost competitive, require no capacious lands, require minimal water use, and reduce atmospheric CO2. In particular, bio-based materials and fuels from algal biomass are considered as one of the reliable alternatives for clean energy. At the present time, there are two foremost processes for bio-oil production from biomass: pyrolysis and hydrothermal liquefaction. Hydrothermal liquefaction can directly convert high moisture algal biomass into bio oil while pyrolysis requires drying of feedstock to reduce the consumption of energy
during the process. As yet, there is still lack of study using microwave technology for the production of crude bio-oil from algae for sustainable biopolymer products. Hence, microwave-assisted hydrothermal liquefaction which can be conducted in aqueous environment, makes it suitable for aquatic plants and wet biomass such as algae. The overall aim of this project is to evaluate the direct conversion of algal biomass to crude bio-oil using hydrothermal liquefaction, performed by microwave which is specifically designed for wet biomass. To highlight the potential of algal biomass as an aquatic plant in Malaysia to be converted into high quality of crude bio-oil, this research includes a forecasting study of algal biomass resource potential specifically in Malaysia, and also mainly focus on optimisation study to obtain the optimum parameters to produce bio-oil with high content of phenol through this microwave assisted hydrothermal liquefaction process. In this work, a study was initially conducted to foresee the potential of algal biomass in Malaysia, where the predicted and target amount of conventional plastic need to be replaced with bio-based material was determined, in order to reduce the CO2 emission using carbon emission pinch analysis (CEPA). This forecasting study resulting an estimation of around 50% to 75% of CO2 emission can be reduced in 2050 by mainly utilising approximately 3885 km2 (388,500 ha) of Sabah coastal area for macroalgae cultivation and it is suggested that algal biomass can be utilised and potentially implemented in large scale cultivation, in meeting the target of plastic production and CO2 utilisation in 2050. Besides, the potentiality of Caulerpa lentillifera, Gracilaria coronopifolia and Chaetomorpha linum, as biomass feedstock were initially investigated in this study and it was concluded that seaweed is more suitable for bio-based products synthesis, i.e. bioplastic and bio-lubricants, instead of biofuel due to its relatively low calorific value (~12 MJ/kg). Since seaweed has high moisture content (~80%), hydrothermal liquefaction is mostly recommended, and its efficiency can be further enhanced through microwave technology. Hence, seaweed has high potential to be used as biomass feedstock, particularly Chaetomorpha linum. The hydrothermal liquefaction process was then carried out, and the parameters optimisation have been done using RSM, to determine the optimum operation parameters of this microwave-assisted hydrothermal liquefaction, for the production of bio-oil with high phenol content. The results show the high phenol content of bio-oil at 221.22 mg GAE/g can be obtained
Description
2024