No abstract

Twenty-four biomass-derived compounds and mixtures, identified based on their physical properties, which could be blended into fuels to improve spark ignition engine fuel economy, were assessed for their economic, technology readiness, and environmental viability. These bio-blendstocks were modeled to be produced biochemically, thermochemically, or through hybrid processes. To carry out the assessment, 17 metrics were developed for which each bio-blendstock was determined to be favorable, neutral, or unfavorable. Cellulosic ethanol was included as a reference case. Overall economic and, to some extent, environmental viability is driven by projected yields for each of these processes. The metrics used in this analysis methodology highlight the near-term potential to achieve these targeted yield estimates when considering data quality and current technical readiness for these conversion strategies. Key knowledge gaps included the degree of purity needed for use as a bio-blendstock. Less stringent purification requirements for fuels could cut processing costs and environmental impacts. Additionally, more information is needed on the blending behavior of many of these bio-blendstocks with gasoline to support the technology readiness evaluation. Overall, the technology to produce many of these blendstocks from biomass is emerging, and as it matures, these assessments must be revisited. Importantly, considering economic, environmental, and technology readiness factors, in addition to physical properties of blendstocks that could be used to boost engine efficiency and fuel economy, in the early stages of project research and development can help spotlight those most likely to be viable in the near term.

Chemical looping with oxygen uncoupling (CLOU) is a promising CO 2 -capture ready energy technology that employs oxygen carriers with thermodynamic properties that cause oxygen to be spontaneously liberated as gaseous O 2 in the fuel reactor, where it can react directly with solid fuels. One of the promising CLOU carrier materials is copper oxide, cycling between CuO and Cu 2 O. Experimentally determined rate expressions for these reactions are needed for proper development, modeling, and scale-up of CLOU technology. The evaluation of rates for this system is not straightforward, however, since the equilibrium partial pressure of oxygen is appreciable and varies significantly in the temperature range of interest. This in turn affects the driving force for oxidation, and also affects rates of reduction. The study presented here aims to better understand the oxidation conversion characteristics, to decouple the influence of temperature and driving force for a range of carrier materials, and to offer suitable rate expressions. It is concluded that the well-documented decrease in oxidation rate at higher temperatures cannot be explained solely by the decrease in driving force, but that physical development of copper boundaries likely plays a more significant role at high temperatures.

An effective copper-based oxygen carrier for use in chemical looping with oxygen uncoupling (CLOU) has been developed, and its physical and reactive properties have been evaluated. The preparation method involves coating β-SiC support material with CuO and then baking the coated material at 980 °C which causes the β-SiC to convert to SiO 2 , thus enveloping the CuO. Variations of the preparation technique, including different forms of SiC, methods of CuO addition, and the order of CuO addition and baking, were tested. It was determined that preparation by rotary evaporation CuO deposition and final sintering produced superior carrier particles. Loadings as high as 60 wt % CuO were achieved. The carrier particles fluidized well, and for loadings to 40 wt % CuO, no agglomeration was observed at temperatures as high as 1000 °C. The particles retained reactivity over many oxidation and reduction cycles. The coat-then-bake preparation method using β-SiC is a viable candidate to be used as oxygen carrying material in CLOU.