Integrated biomass thermochemical conversion for clean energy production: Process design and economic analysis

Abstract

In this study, conversion of Napier grass bagasse into biofuel was carried out through steady state process modelling and simulation using Aspen Plus software. An integrated thermochemical system consisting pyrolysis, gasification and combustion section for pyrolytic oil production and upgrading, non-condensable gas/syngas and bio-char valorisation was developed in a single flowsheet with capacity of 49 kg/h feedstock. Aspen process economic analyser was used to generate both capital and operating costs estimates, and other investment analysis following first quarter 2016 pricing basis. The simulation result showed that about 68 wt% of the feedstock could be processed into pyrolytic oil at 480 °C with corresponding liquid biofuel yield of 5.35 kg/h, which is equivalent to about 11 wt% of the initial feedstock through in-situ hydrodeoxygenation process. The result of economic evaluation of the entire process plant indicated that a total capital cost of $2.13 M and operating cost/year of $0.3 M is required for 25-year economic life of the project with net present value of $15.18 M at 8% internal rate of return. The standalone biomass refining plant is expected to produce fuel at minimum fuel selling price of $5.81/gallon ($1.45/L) gasoline equivalent, mainly driven by the capital cost. This work presents a systematic combination of process units that will be needed to produce advanced cellulosic biofuels in the near future.