1a. Objectives (from AD-416)
Develop catalytic and non-catalytic technologies that enable commercially-viable processes for on-farm scale production of stable and transportable pyrolysis oils that meet boiler fuel or refinable crude oil specifications. Sub-Objective 1: Quantify the effect of various agricultural feedstocks (varying in composition, maturation, post-harvest handling, and pre-treatment) on the pyrolysis process efficiency, kinetics, product yield (pyrolysis oil, syngas, and charcoal), and composition. Sub-Objective 2: Develop commercially preferred catalytic and non-catalytic processes for on-farm scale production of stable and transportable pyrolysis oils that meet specifications as boiler fuel or refinable crude oils. Sub-Objective 3: Develop technologies that enable commercially-viable fast pyrolysis and post-pyrolysis processes for biochar production from a variety of agricultural feedstocks.
1b. Approach (from AD-416)
A stepwise approach will be taken to address the objective by carrying out a series of experiments organized under the three sub-objectives. The first approach will involve screening of biofeedstocks using existing laboratory (desk-top) pyrolysis units to determine their potential use as second generation biomass feedstock. Under this same sub-objective, catalysts with the potential to stabilize pyrolysis liquid, when added to the biomass, will be screened. Under the second sub-objective large scale experiments will be carried out in the ARS fluidized-bed pyrolysis reactor with selected biomass and selected catalysts. Additional experiments will be designed under this sub-objective to explore non-catalytic pathways for producing stabilized pyrolysis oil. The next set of experiments, to be organized under sub-objective 3, will be designed to develop post-pyrolysis processes that will generate biochar with soil-amending, carbon sequestering properties. Modifications, incorporating changes that the experimental outcomes and analyses results will dictate, will be made to the pilot reactor system so as to make it compatible with the distributed scale systems envisioned for the on-farm approach.
3. Progress Report
We performed analytical pyrolysis of oak over two dozen catalysts supplied by our CRADA partners UOP using the bench-scale analytical pyrolysis system coupled with gas chromatography and mass spectrometry (py-GC/MS). The experiments were successfully used to screen for best catalysts/biomass combination that could be selected for potential pilot scale catalytic pyrolysis application. Catalysts were selectively narrowed down to two of the most promising in terms of deoxygenation and hydrocarbon production from pyrolytic vapors which were used in lieu of sand in a 5 kg/h fluidized bed reactor. We successfully produced partially deoxygenated pyrolysis liquids and demonstrated that the catalytically produced bio-oils contained less oxygen and more petroleum-like hydrocarbons than that produced non-catalytically over sand. We have begun to develop a method of cooling the pyrolysis vapors with equipment that is practical at the farm scale (distributed processing) so that the cooled bio-oil can be stored for a few weeks before transportation to a bio-fuel refinery. Bio-oil vapor will be cooled by direct contact with sprayed liquid droplets in a small vessel so as to achieve better temperature control than cooling on a cold solid surface. We demonstrated unique properties of bio-oil produced from mustard family seed cakes. Using feedstocks obtained from CRADA partners BMI/Arvens and collaborators at ARS – Peoria, IL we produced pyrolysis oil from oil-seed presscakes derived seeds of mustard family plants specifically pennycress (Thlaspi arvense L) and camelina (camelina sativa). Pyrolysis oil from these feedstocks proved to be more stable, pH netural and have higher energy content than those produced from woods, grasses or other cellulosic feedstocks. These pyrolysis oils are closer to boiler fuel specifications than others and may also be more amenable to upgrading to hydrocarbon fuels. Upgrading via hydrotreating: We have began exploring ex-situ catalytic upgrading as means of hydrotreating pyrolysis liquid after it has been produced i.e., post-process stabilization. For that we have established collaborations with Johnson Matthey (JM), a hydrotreating catalyst provider for supply of said catalysts. We have developed a technique capable of producing partially deoxygenated bio-oil with the use of JM catalysts using high pressure and temperature reaction conditions. Techno-economic Analysis: We successfully created an ASPEN+ model for distributed pyrolysis. This year the model was used to create a preliminary and approximate Excel cost model for a hypothetical 200 metric ton per day biomass feedstock, distributed pyrolysis plant. This was considered to be the smallest plant that would be cost-effective, at a feasible cost per ton of biomass, while being the largest plant that could still be considered “farm scale”. The model shows that the bio-oil may contain 60% of the mass of the feedstock and 70% of the energy (HHV). It was concluded that the cost of production of bio-oil may be commensurate with current petroleum prices.
1. Bio-oil and bio-char from by-products associated with ethanol production from barley. The production of fuel ethanol from winter barley grain is a new industry with the first commercial plant to begin production in 2010. However, no commercial uses have been earmarked for the co-products of barley production and fermentation including barley straw, hulls and distiller’s dried grains (DDGS). The latter is liable to contamination with mycotoxins during especially wet growing years, which could preclude its use as supplement to livestock feed. ARS researchers at Wyndmoor, PA evaluated the potential use of these byproducts as feedstocks for the production of advanced bioenergy carriers that can provide process energy needs and another source of income for barley-to-ethanol plants. We studied the production of bio-oil and bio-char using the fast pyrolysis technology and found that in each case about 70 wt% of the feedstock could be converted to bio-oil and 16-20 wt% to bio-char. The bio-oil is a renewable boiler fuel quality with energy content of half to three quarters that of No. 2 diesel and can also be upgraded to green diesel or gasoline.
2. Sustainable production of bioenergy and bio-char from the straw of high biomass soybean lines via fast pyrolysis. The US renewable fuel standards require production of 21 billion gallons of advanced bio-fuels from non-food biomass such as agricultural residues by year 2022. However, removing agricultural residues (i.e. soybean straw, corn stover) may cause soil erosion and decrease soil quality. There are two high-biomass soybean lines which can produce grains and large amounts of straw so more biomass can be sustainably removed from the field. Researchers at ARS, Wyndmoor, PA, evaluated the production of bio-energy from the straw of these two soybean lines via fast pyrolysis to produce bio-oil and a solid co-product, bio-char. The results indicate that these products can be produced in sufficient quantities that a sustainable farm system could be enhanced by the synergy between production of extra biomass in soybean cultivation, bio-fuel production, production and use of bio-char that can sequester carbon and amend the soil in addition to nitrogen fixation enabled by soil bacteria.
Boateng, A.A., Mullen, C.A., Goldberg, N.M., Hicks, K.B., Devine, T.E., Lima, I.M., Mcmurtrey Iii, J.E. 2010. Sustainable production of bioenergy and bio-char from the straw of high biomass soybean lines via fast pyrolysis. Journal of Environmental Progress and Sustainable Energy. 29(2):175-183.