5 research outputs found

    Montana Kaimin, March 5, 1981

    Get PDF
    Student newspaper of the University of Montana, Missoula.https://scholarworks.umt.edu/studentnewspaper/8304/thumbnail.jp

    Spatially-Explicit Life Cycle Assessment of Sun-to-Wheels Transportation Pathways in the U.S.

    No full text
    Growth in biofuel production, which is meant to reduce greenhouse gas (GHG) emissions and fossil energy demand, is increasingly seen as a threat to food supply and natural habitats. Using photovoltaics (PV) to directly convert solar radiation into electricity for battery electric vehicles (BEVs) is an alternative to photosynthesis, which suffers from a very low energy conversion efficiency. Assessments need to be spatially explicit, since solar insolation and crop yields vary widely between locations. This paper therefore compares direct land use, life cycle GHG emissions and fossil fuel requirements of five different sun-to-wheels conversion pathways for every county in the contiguous U.S.: Ethanol from corn or switchgrass for internal combustion vehicles (ICVs), electricity from corn or switchgrass for BEVs, and PV electricity for BEVs. Even the most land-use efficient biomass-based pathway (i.e., switchgrass bioelectricity in U.S. counties with hypothetical crop yields of over 24 tonnes/ha) requires 29 times more land than the PV-based alternative in the same locations. PV BEV systems also have the lowest life cycle GHG emissions throughout the U.S. and the lowest fossil fuel inputs, except for locations with hypothetical switchgrass yields of 16 or more tonnes/ha. Including indirect land use effects further strengthens the case for PV

    Investigating the Energy-Water Usage Efficiency of the Reuse of Treated Municipal Wastewater for Artificial Groundwater Recharge

    No full text
    This project investigates the energy-water usage efficiency of large scale civil infrastructure projects involving the artificial recharge of subsurface groundwater aquifers via the reuse of treated municipal wastewater. A modeling framework is introduced which explores the various ways in which spatially heterogeneous variables such as topography, landuse, and subsurface infiltration capacity combine to determine the physical layout of proposed reuse system components and their associated process energy-water demands. This framework is applied to the planning and evaluation of the energy-water usage efficiency of hypothetical reuse systems in five case study regions within the State of California. Findings from these case study analyses suggest that, in certain geographic contexts, the water requirements attributable to the process energy consumption of a reuse system can exceed the volume of water that it is able to recover by as much as an order of magnitude

    Life Cycle Assessment of Solar Photovoltaic Microgrid Systems in Off-Grid Communities

    No full text
    Access to a reliable source of electricity creates significant benefits for developing communities. Smaller versions of electricity grids, known as microgrids, have been developed as a solution to energy access problems. Using attributional life cycle assessment, this project evaluates the environmental and energy impacts of three photovoltiac (PV) microgrids compared to other energy options for a model village in Kenya. When normalized per kilowatt hour of electricity consumed, PV microgrids, particularly PV–battery systems, have lower impacts than other energy access solutions in climate change, particulate matter, photochemical oxidants, and terrestrial acidification. When compared to small-scale diesel generators, PV–battery systems save 94–99% in the above categories. When compared to the marginal electricity grid in Kenya, PV–battery systems save 80–88%. Contribution analysis suggests that electricity and primary metal use during component, particularly battery, manufacturing are the largest contributors to overall PV–battery microgrid impacts. Accordingly, additional savings could be seen from changing battery manufacturing location and ensuring end of life recycling. Overall, this project highlights the potential for PV microgrids to be feasible, adaptable, long-term energy access solutions, with health and environmental advantages compared to traditional electrification options

    Chemical Recycling of Polyethylene by Tandem Catalytic Conversion to Propylene

    Get PDF
    Although polyethylene (PE) and polypropylene (PP) are by far the world’s largest volume plastics, only a tiny fraction of these energy-rich polyolefins are currently recycled. Depolymerization of PE to its constituent monomer, ethylene, is highly endothermic and conventionally accessible only through unselective, high-temperature pyrolysis. Here, we provide experimental demonstrations of our recently proposed tandem catalysis strategy, which uses ethylene to convert PE to propylene, the commodity monomer used to make PP. The approach combines rapid olefin metathesis with rate-limiting isomerization. Monounsaturated PE is progressively disassembled at modest temperatures via many consecutive ethenolysis events, resulting selectively in propylene. Fully saturated PE can be converted to unsaturated PE starting with a single transfer dehydrogenation to ethylene, which produces a small amount of ethane (1 equiv per dehydrogenation event). These principles are demonstrated using both homogeneous and heterogeneous catalysts. While selectivity under batch conditions is limited at high conversion by the formation of an equilibrium mixture of olefins, high selectivity to propylene (≥94%) is achieved in a semicontinuous process due to the continuous removal of propylene from the reaction mixture
    corecore