Biological Systems Engineering, Department of


Date of this Version

Spring 5-2013

Document Type



Wu, H. (2013). Biomass gasification: an alternative solution to animal waste management. PhD dissertation, University of Nebraska-Lincoln.


A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska. In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Engineering (Department: Biological Systems Engineering), Under the Supervision of Professor Milford A. Hanna. Lincoln, Nebraska: May, 2013.

Copyright (c) 2013 Hanjing Wu


The overall goal of this research was to evaluate gasification of animal waste as an alternative manure management strategy, from the standpoints of syngas production and biochar application.

To meet the overall objective, the thermogravimetric characteristics of dairy manure, as a thermochemical conversion feedstock, were studied firstly. Then, gasification technology was applied to dairy manure and feedlot manure using a fluidized-bed laboratory-scale gasifier. In addition, biochar derived from the feedlot manure was examined for its effects on nutrient leaching as a soil amendment. Finally, a life cycle assessment was conducted to evaluate greenhouse gas emissions of two feedlot manure management systems (land application and gasification).

Results showed thermochemical reactions were determined mainly by temperature, and heating rate influenced the start and the end of the conversions. Also, influences of gasification parameters (temperature, equivalence ratio and steam to biomass ratio) on syngas composition and energy efficiency were carefully discussed. Lower heating values of the syngas from dairy manure and feedlot manure gasification were in the range of 2.0 to 4.7 MJ m-3, and 3.0 to 5.2 MJ m-3, respectively. Further, feedlot manure-derived biochar showed the ability to retain water and NH4+-N as the soil amendment. From the life cycle assessment, the net greenhouse gas emissions in land application scenario and gasification scenarios were 119 and -643 kg CO2-eq for one tonne of dry feedlot manure, respectively, indicating that gasification of feedlot manure is a potential technique to mitigate global warming effects.

Advisor: Milford A. Hanna