The use of ethanol produced from lignocellulosic biomass for transportation fuel offers solutions in reducing environmental emission and the use of non-renewable fuels. However, lignocellulosic ethanol production is still hampered by economic and technical obstacles. For instance, the inhibitory effect of toxic compounds produced during biomass pretreatment was reported to inhibit the fermenting microorganisms, hence there was a decrease in ethanol yield and productivity. Thus, there is a need to improve the bioconversion of lignocellulosic biomass to ethanol in order to promote its commercialization. The research reported here investigated the use of poultry litter biochar to improve the ethanol production from steam-exploded poplar and corn stover. The effect of poultry litter biochar was first studied on Saccharomyces cerevisiae ATCC 204508/S288C growth, and second on the enzyme hydrolysis and fermentation of two steam-exploded biomasses: (poplar and corn stover). The third part of the study investigated optimal process parameters (biochar loading, biomass loading, and enzyme loading) on the reducing sugars production, and ethanol yield from steam-exploded corn stover. In this study, it has been shown that poultry litter biochar improved the S. cerevisiae growth and ethanol productivity; therefore poultry litter biochar could potentially be used to improve the ethanol production from steam-exploded lignocellulosic biomass.

Direct carbon fuel cell (DCFC) is a high temperature fuel cell (around 700 "C) that produces electrical energy from the direct conversion of the chemical energy of carbon. DCFC has a higher achievable efficiency of 80% compared to other fuel cells and the corresponding CO2 emission is very low compared to conventional coal-burning power plants. Moreover, a DCFC can use diversified fuel resources even waste material, which is advantageous compared to other types of fuel cells which are limited to specific fuels. DCFCs are still under development due to a number of fundamental and technological challenges such as the efficiency of carbon fuels and the effect of impurities on the performance and lifetime of the DCFC. These are key factors for the development and commercialization of these devices. In this study, three biochars obtained from the pyrolysis of poultry litters (PL) collected from Tunisian and US farmers, were characterized to see whether they can be potential anode fuels for DCFC or not. PL biochars have low fixed carbon contents (19-35 wt%) and high ash contents (32.5-63 wt%). These ashes contain around 40 wt% catalytic oxides for carbon oxidation reaction, however, these oxides have very low electrical conductivities, which resulted in the very low (negligible) electrical conductivity of the PL biochars (7.7x10-9-70.56x10-9 S/cm) at room temperature. Moreover, the high ash contents resulted in low surface areas (3.34-4.2 m"/g). These findings disqualified PL biochar from being a potential anode fuel for DCFCs. Chemical demineralization in the sequence HF/HCl followed by carbonization at 950" C of the PL biochars will result in higher fixed carbon content, higher surface area, and higher electrical conductivities. Moreover, the treated PL biochars would contain a potential catalyst (Calcium in the form of CaF2) for carbon oxidation. All these criteria would qualify the treated PL biochars to be potential fuels for DCFC. / Master of Science