Techno-economic analysis of micro-algae bio-jet fuel production processes

Ewurum, Chioma Eberechukwu (2019) Techno-economic analysis of micro-algae bio-jet fuel production processes. PhD thesis, University of Nottingham.

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The production of bio-fuel from autotrophic micro-algae are being extensively studied and documented. However very few focuses specifically on the production of bio-jet fuel, with even fewer that assesses both the environmental and economic state of micro-algal bio-jet fuel production through modelling efforts.

In this research study, an integrated energy, techno-economic and life-cycle assessment deterministic model was successfully developed for the production of micro-algal bio-jet fuel. The developed model acts as a simple tool which can be used to assess the economic and environmental (Net energy ratio, greenhouse emission and water footprint) state of micro-algal bio-jet fuel production in Malaysia as well as for the identification of the key input parameters which influence these state. Prior to model construction, an initial economic investigation was carried out and compared some of the technologies/methods required for bio-jet fuel production. A base case process pathway was established based on this investigation, and formed the foundation of the process model.

The integrated model simulates the major steps involved in bio-jet fuel production, which are; micro-algal cultivation, harvesting and dewatering, cell disruption and lipid extraction, lipid purification and upgrading to bio-jet fuel and an additional anaerobic digestion of residual biomass.

Through the mass and energy balances and relevant equations, the material and net energy ratio (NER) are estimated with the aid of performance equations, Aspen plus, Matlab and reported data in literature. The economics of bio-jet fuel production process is evaluated by estimation of the capital and operating cost and discounted cash flow. Additionally, greenhouse (GHG) emissions and water resource consumption associated with the production of bio-jet fuel are assessed.

Process model results indicates the minimum fuel-selling price (MFSP) of algal derived jet fuel would be $5.89/L, which is 14 times more than the market price of fossil derived jet fuel at $0.43/L.

The NER of bio-jet fuel production was however positive, >1, more energy produced than used in the production process and CO2 is abated at a rate of -7.49tonnesCO2/L of bio-jet fuel produced. Results indicated that an additional membrane filtration process prior to centrifugation greatly reduces harvesting and dewatering energy consumption by 93%. Water usage is also estimated at 2702 tonnes/L of bio-jet fuel produced.

Sensitivity analysis results indicated that lipid recovery efficiency is one of the most influential parameter and significantly influences the NER, GHG, MFSP and water usage for micro-algal bio-jet fuel production. Case scenario studies in addition to the sensitivity analysis showed algal lipid content and algal productivity significantly influences the MFSP.

It was concluded that algal bio-jet fuel production plant would benefit from co-location with wastewater treatment plant and flue-gas producing sites in Kota Kinabalu, Malaysia. This includes exploitation of micro-algal species with high lipid fraction and productivity and cost effective technologies and combinations. The lowest possible MFSP achievable was $1.31/L based on an optimistic case scenario encompassing all the benefits aforementioned but still not sufficient in achieving an economically viable production process.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Mohammad, Khalid
Feroz, Kabir
Keywords: bio jet fuel
Subjects: T Technology > TP Chemical technology
Faculties/Schools: University of Nottingham, Malaysia > Faculty of Science and Engineering — Engineering > Department of Chemical and Environmental Engineering
Item ID: 55826
Depositing User: EWURUM, Chioma
Date Deposited: 27 Feb 2019 04:40
Last Modified: 06 May 2020 12:01

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