Submitted to: Journal of Environmental Management
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/7/2013
Publication Date: 7/8/2013
Citation: Hammer, N.L., Boateng, A.A., Mullen, C.A., Wheeler, C.M. 2013. ASPEN+ and economic modeling of equine waste utilization for localized hot water heating via fast pyrolysis. Journal of Environmental Management. 128:594-601. Interpretive Summary: Both climate change and dependence on global petroleum are issues facing the United States of America where investment into low-cost technologies to convert commercial and agricultural waste biomass to liquid fuels, heat, and power is a promising outlook. But these are often large, commercial scale operations that prevent them from on-site, small farm scale biomass utilization. Hence there is a market for a process that can convert biomass to fuel for direct use on site effectively and economically. Fast pyrolysis is a way to achieve this as it is done by rapidly heating the biomass in the absence of air and then quickly cooling the vapors. A case study at the Equine Rehabilitation Center at Morrisville State College in New York requires waste disposal of the horse manure and bedding by an outside vendor and also has an oil based facility heating system. Feedstock samples were pyrolyzed at the USDA/ARS and the biomass, pyrolysis oil, bio-char and gas were analyzed. The data collected was used in software called ASPEN Plus to develop a model of the pyrolysis process that provided data for economic analysis. The results indicate that the system sized for utilization of all available Equine Rehabilitation waste from 41 horses is too small to be economical at current diesel prices. However, a system for waste generated by an additional 150 horses at the expanded area including the College and its vicinity is economical and could result in $71,000 savings/year if diesel prices are above $3.27/gal and the system is in operation for at least 5 years.
Technical Abstract: ASPEN Plus based simulation models have been developed to design a pyrolysis process for the on-site production and utilization of pyrolysis oil from equine waste at the Equine Rehabilitation Center at Morrisville State College (MSC). The results indicate that utilization of all available Equine Rehabilitation waste from 41 horses requires a 6 oven dry metric ton per day (ODMTPD) dual fluidized bed combustion reduction integrated pyrolysis system (CRIPS) developed at USDA’s Agricultural Research Service (ARS) but it will require a 15 ODMTPD system for waste generated by an additional 150 horses at the expanded area including the College and its vicinity. The model is further used to advise the combustion of the produced pyrolysis oil in an existing boiler that generates hot water for space heating at the Equine Center. The ASPEN model results show the potential for both the equine facility and the College to displace diesel fuel with pyrolysis oil in their boilers with an added benefit of alleviating the costly waste disposal problem. Based on the systems mass and energy balance we predict that if ~40% of the biochar co-product and an excess recycle gas are used for combustion, then all the heat required to operate the pyrolyzer could be supplied in-situ. Results of a Techno-economic Analysis that followed shows that the 6 ODMTPD CRIPS system designed for the rehabilitation center would not be economically viable unless diesel prices increase to $5.97/gallon. However the 15 ODMTPD designed for both the Center and the College campus could result in $71,000 savings/year if diesel prices are above $3.27/gal and the system is in operation for at least 5 years.