Hydrothermal liquefaction of Malaysia's algal biomass for high-quality bio-oil production

Currently, fossil materials form the majority of our energy and chemical source. Many global concerns force us to rethink about our current dependence on the fossil energy. Limiting the use of these energy sources is a key priority for most countries that pledge to reduce greenhouse gas emissions. The application of biomass, as substitute fossil resources for producing biofuels, plastics and chemicals, is a widely accepted strategy for sustainable development. Aquatic plants including algae possess competitive advantages as biomass resources compared to the terrestrial plants in this current global situation. Bio-oil production from algal biomass is technically and economically viable, cost competitive, requires no capacious lands and minimal water use and reduces atmospheric carbon dioxide. The aim of this paper is to review the potential of converting algal biomass, as an aquatic plant, into high-quality crude bio-oil through applicable processes in Malaysia. In particular, bio-based materials and fuels from algal biomass are considered as one of the reliable alternatives for clean energy. Currently, pyrolysis and hydrothermal liquefaction (HTL) are two foremost processes for bio-oil production from biomass. HTL can directly convert high-moisture algal biomass into bio-oil, whereas pyrolysis requires feedstock drying to reduce the energy consumption during the process. Microwave-assisted HTL, which can be conducted in aqueous environment, is suitable for aquatic plants and wet biomass such as algae.