Steven E. Taylor

Production of hydrocarbon fuels from biomass using catalytic pyrolysis under helium and hydrogen environments

This study is focused on hydrocarbon production through changing carrier gas and using zeolite catalysts during pyrolysis. A large reduction in high molecular weight, oxygenated compounds was noticed when the carrier gas was changed from helium to hydrogen during pyrolysis. A catalytic pyrolysis was conducted using two different methods based on how the biomass and catalysts were contacted together. For both methods, there was no significant change in the carbon yield with the change in pyrolysis environment. However, the mixing-method produced higher aromatic hydrocarbons than the bed-method. In addition, two methods were also tested using two ratios of biomass to catalyst. Nonetheless, there was no significant increase in hydrocarbon yield as the catalyst loading was increased from two to five times of biomass in the catalyst-bed method. In contrast to this, a significant increase was noticed for the catalytic-mixing method when the biomass to catalyst loading was increased from 1:4 to 1:9.

ACCURACY OF TRACKING FOREST MACHINES WITH GPS

This paper describes the results of a study that measured the accuracy of using GPS to track movement of forest machines. Two different commercially available GPS receivers (Trimble ProXR and GeoExplorer II) were used to track wheeled skidders under three different canopy conditions at two different vehicle speeds. Dynamic GPS data were compared to position data established through precision surveying techniques. Maps from data collected by both receivers showed general travel patterns of the skidders. Mean position errors in data collected by the GeoExplorer (2.75 m) were significantly greater than those of the data collected by the ProXR (1.34 m). When tested under different canopy conditions, GPS position accuracy showed a decreasing trend as the canopy changed from open to heavy. Finally, the machine speeds tested did not significantly affect the accuracy of GPS positions.

Simulation of low temperature anaerobic digestion of dairy and swine manure.

The data reported by L.M. Safley, P.W. Westerman [Bioresource Technology 47 (2) (1994) 165-171] from the laboratory digestion of dairy and swine manure at psychrophilic temperatures (i.e., 10-23 degrees C) have been used to determine the response of the latest comprehensive dynamic mathematical model of methanogenesis [D.T. Hill, S.A. Cobb, Transactions of the ASAE 39 (2) (1996) 565-573] in this low temperature range. Extensive performance data from digesters using animal waste in this temperature range have been lacking, thus allowing limited validation of the comprehensive model. The results of the comprehensive model simulations were compared with the actual data reported by Safley and Westerman (loc. cit.) and with their empirical regression models. Results indicate that the comprehensive model is as accurate as Safley and Westermans models for three of the four cases reported, but shows a great dissimilarity for the fourth case.

Effects of end products on fermentation profiles in Clostridium carboxidivorans P7 for syngas fermentation.

Clostridium carboxidivorans P7 is a strict anaerobic bacterium capable of converting syngas to biofuels. However, its fermentation profiles is poorly understood. Here, various end-products, including acetic acid, butyric acid, hexanoic acid, ethanol and butanol were supplemented to evaluate their effects on fermentation profiles in C. carboxidivorans at two temperatures. At 37°C, fatty acids addition likely led to more corresponding alcohols production. At 25°C, C2 and C4 fatty acids supplementation resulted in more corresponding higher fatty acids, while supplemented hexanoic acid increased yields of C2 and C4 fatty acids and hexanol. Supplementation of ethanol or butanol caused increased production of C2 and C4 acids at both temperatures; however, long-chain alcohols were still more likely produced at lower temperature. In conclusion, fermentation profiles of C. carboxidivorans can be changed in respond to pre-added end-products and carbon flow may be redirected to desired products by controlling culture conditions.

In situ esterification and extractive fermentation for butyl butyrate production with Clostridium tyrobutyricum

Butyl butyrate (BB) is a valuable chemical that can be used as flavor, fragrance, extractant, and so on in various industries. Meanwhile, BB can also be used as a fuel source with excellent compatibility as gasoline, aviation kerosene, and diesel components. The conventional industrial production of BB is highly energy‐consuming and generates various environmental pollutants. Recently, there have been tremendous interests in producing BB from renewable resources through biological routes. In this study, based on the fermentation using the hyper‐butyrate producing strain Clostridium tyrobutyricum ATCC 25755, efficient BB production through in situ esterification was achieved by supplementation of lipase and butanol into the fermentation. Three commercially available lipases were assessed and the one from Candida sp. (recombinant, expressed in Aspergillus niger) was identified with highest catalytic activity for BB production. Various conditions that might affect BB production in the fermentation have been further evaluated, including the extractant type, enzyme loading, agitation, pH, and butanol supplementation strategy. Under the optimized conditions (5.0 g L−1 of enzyme loading, pH at 5.5, butanol kept at 10.0 g L−1), 34.7 g L−1 BB was obtained with complete consumption of 50 g L−1 glucose as the starting substrate. To our best knowledge, the BB production achieved in this study is the highest among the ever reported from the batch fermentation process. Our results demonstrated an excellent biological platform for renewable BB production from low‐value carbon sources. Biotechnol. Bioeng. 2017;114: 1428–1437.

Reducing sugars facilitated carbonyl condensation in detoxification of carbonyl aldehyde model compounds for bioethanol fermentation

We investigated the inhibitory effects of ortho-phthalaldehyde (OPA) as a carbonyl aldehyde model compound on the fermentation and growth of Saccharomyces cerevisiae and its alkaline detoxification. OPA was a potent inhibitor on the fermentation and growth of S. cerevisiae compared to vanillin, furfural and hydroxymethyl furfural (HMF) at the same concentration level. The inhibition of OPA on the fermentation and growth of S. cerevisiae was dose dependent. Ethanol production and growth of S. cerevisiae were both completely inhibited in the presence of 1.0 mM OPA. The inhibition of the fermentation and growth of the yeast decreased with the decrease in the OPA concentration between 0.02 mM–1.0 mM. OPA at 0.02 mM showed no inhibition on both the fermentation and growth of yeast, the ethanol final yield was even increased by 4.6% compared to the control. The inhibition of OPA at a low concentration could be overcome by increasing the inoculation size of the yeast. Most interestingly, we found OPA inhibition could be detoxified under alkaline conditions (pH∼10) at 60 °C for 2 h in the presence of a reducing sugar (ketone or aldose), but not a non-reducing sugar. Mass spectral analysis of the OPA reaction products in negative ion mode revealed a high intensity mass at 313.09 m/z ([M − H]−). This molecule (314) was predicted to be the aldol reaction product of the reducing sugar and OPA under alkaline conditions. One of the CHO groups on OPA was converted into a hydroxyl group by nucleophilic addition of the enolate ion of the reducing sugar. Loss of one CHO group of OPA could be the key factor for the removal of OPA inhibition.

Gasification of Wood Chips, Agricultural Residues, and Waste in a Commercial Downdraft Gasifier

In this study, gasification of different biomass feedstocks, including pine wood chips, sawdust, peanut hulls, and poultry litter (the latter three in pelletized form), was conducted in a 25 kWe commercially available, mobile downdraft gasifier. Ultimate and proximate analyses were carried out to characterize the biomass feedstocks used for gasification. The synthesis gas obtained from different feedstocks and different operating conditions (biomass flow rate and moisture content) was analyzed using an on-site gas analyzer. Gasification of peanut hull pellets showed the highest heating value (6.1 MJ per normal cubic meter, Nm-3) of synthesis gas, whereas poultry litter gasification gave the lowest heating value (4.8 MJ Nm-3).

Co-processing of woody biomass and poultry litter for bio-oil production with high pH.

Two-thirds of Alabama is covered with forest, and Alabama also ranks as the third largest state in the U.S. for poultry production. As a result, the state has significant amounts of forest residues and poultry litter available, which can be converted into biofuels. Bio-oil derived from pine wood is acidic, whereas bio-oil obtained from poultry litter is basic. The main objective of this work was to co-process woody biomass and poultry litter so that high pH bio-oil could be produced. Three different mixtures of poultry litter (5, 10, and 15 wt%) in pine wood were used to determine the effect of poultry litter on bio-oil yield and properties at 500°C using an auger reactor. The pH of the bio-oil increased from 3.73 to 3.94 when 15 wt% of poultry litter was mixed with pine. However, the bio-oil yield decreased with the increase in poultry litter with pine wood. For example, at 5 wt% of poultry litter, the bio-oil yield was 37.3 wt%; however, at 15 wt% of poultry litter, the bio-oil yield was 34.8 wt%. This study concludes that the pH of bio-oil increased with the increase in poultry litter in the feedstock.

Production of bio-oil from underutilized forest biomass using an auger reactor.

Conversion of underutilized forest biomass to bio-oil could be a niche market for energy production. In this work, bio-oil was produced from underutilized forest biomass at selected temperatures between 425–500°C using an auger reactor. Physical properties of bio-oil, such as pH, density, heating value, ash, and water, were analyzed and compared with an ASTM standard to document the effect of pyrolysis temperature. All of the properties analyzed in this study, except for the ash content of the bio-oil, met the ASTM standard. Chemical composition of bio-oil was also analyzed, and the concentration of each species was compared at different temperatures.

Field Investigation of Stress-Laminated T-Beam and Box-Beam Timber Bridges

This paper describes the field performance of stress-laminated T-beam and Box-beam bridges as evaluated during an intensive field inspection program for selected bridges in West Virginia. Several bridges had cracks in their asphalt wearing surfaces at locations that corresponded to the location of the webs, which indicates that slip may be occurring between the webs and the flanges. The occurrence of slip would result in levels of structural safety lower than what has been assumed by the designers. Low stressing bar forces indicates that these bridge systems require more periodic maintenance than is currently being provided by local or state agencies. Overall, while the bridges are carrying vehicle traffic, there are several potentially serious issues that will affect their long-term ability to safely carry vehicle loads in a cost-effective manner.