University of South Florida, Ph.D.
EREF Scholar 2021
Economic and Environmental Assessment of Landfill Gas to Energy Technologies
When we throw things away, they either get recycled if segregated properly or most commonly, they get sent to a landfill. At the landfills, the organic waste, like the food scrap, undergoes a process called anaerobic digestion, and produces landfill gas (LFG). LFG consists mainly of methane and carbon dioxide, two potent greenhouse gases that can contribute to global warming. Due to this concern, most landfills are required to capture their LFG.
The methane content in LFG makes it suitable for energy production, and therefore, LFG can be upgraded into renewable natural gas, which has various end uses such as electricity generation, thermal applications, production of transportation fuel and feedstock for bio-products. End products of LFG, such as electricity and heat, are considered low-value commodities because when compared on an equivalent energy basis, the hydrocarbon transportation fuels are worth 3-4 times as much as electricity in the U.S. To be economically viable as an energy source, LFG needs to be converted into value-added products like drop-in fuels (i.e. fuel that can be used as a substitute for conventional petroleum-derived hydrocarbons, such as gasoline). The contaminants present in the LFG can have substantial economic and environmental consequences in the waste-to-energy (WTE) process.
Amaraibi’s project focuses on contaminants known as siloxanes. Siloxanes are an emerging contaminant in many consumer products that are landfilled, and they possess high enough vapor pressure such that a substantial amount is contained in the landfill gas. At high temperatures, siloxanes decompose into silica causing equipment damage that results in process downtime and reoccurring maintenance costs. The current purification techniques available are expensive, so much so that at times it costs less to repair damaged engine parts than to adopt the current gaseous siloxane scrubbing technology. To accelerate the adoption of waste-to-energy processes, a desire for more economical ways for removing siloxanes from LFG exists.
Amaraibi’s dissertation focuses on improving the cost competitiveness and the environmental impact of LFG to energy technologies by assessing the most efficient techniques for contaminant removal from LFG. It also attempts to critically assess different technologies for converting biogas to liquid fuel through process simulation, costing evaluation, life-cycle assessment and uncertainty analysis.
Amaraibi has a great passion for the environment and she is constantly seeking ways to make it safer for all to live in. She obtained her BEng in Chemical Engineering from Covenant University (September 2010 – June 2015). Then, she went on to earn her master’s degree in Global Sustainability with a concentration in “Climate Change and Sustainability” and a graduate certificate in “Sustainable Energy” at the University of South Florida, Tampa from January 2018 to August 2019. Following the completion of her MS, Amairabi continued her studies in Waste-to-Energy research as a PhD student in Chemical Engineering. She anticipates graduating in May 2024.