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Using Solar Energy to Provide High- Temperature Heat and Electricity Solar thermal systems Photovoltaic (PV) cells Solar Cell Trade-Offs

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Producing Electricity from Moving Water Large-scale hydropower Small-scale hydropower 50% of West Coast electricity 7% of US electricity 20% of Worlds electricity Major environmental impacts High construction costs

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Impacts of hydropower on Species and People_______________ Dams can provide many human benefits but: Disrupts ecological services rivers provide; e.g. 119 dams on Columbia River have caused a 94% drop in wild salmon; removing hydroelectric dams will restore native spawning grounds Displaces millions of people worldwide as reservoirs flood traditional homelands No room for expansion in the US

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Producing Energy from Biomass Biofuels Biomass plantations Crop residues Animal manure Biogas Ethanol Methanol

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The Solar-Hydrogen Revolution Extracting hydrogen efficiently Storing hydrogen Fuel cells

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Geothermal Energy Geothermal reservoirs Dry steam Wet steam Hot water Molten rock Hot dry-rock zones

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Solutions: A Sustainable Energy Strategy

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Calculation of number of households supplied by a windfarm Assume 24 windturbines each generating 0.25 MW for 70% of time. In a year this amounts to 3.66 x 10 7 kwhr. If this figure is divided by average amount of electricity used by a consumer ie 10,607 kwhr in a year, Answer is 3600 consumers. But 166 of these wind farms = 1000Mw power station!

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Biofuel feedstocks Agricultural and forestry products: Grains -Corn, Wheat, Sorghum, Rice Sugar Cane Timber Production residues: Crop Residue Logging Residue Manure Processing products and by products: Corn Oil Rendered Animal Fat Milling Residue Energy crops: Switchgrass Willow Hybrid Poplar Not doing red items today

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Atmospheric CO 2 is increasing * Slide from Lecture on 11/27 Net increase of 3.2 gigatons of CO2 per year

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The Disadvantages of Ethanol The ethics of using food for fuel Production of large quantities of ethanol may require increased deforestation. Objectionable farming methods (fertilizers, factory farming, etc.) Cannot be transported in pipelines Potentially economically infeasible Contains less energy than gas

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The Benefits of Biodiesel A Net Energy Balance of 93% makes it efficient to produce. The exhaust emissions of sulfur oxides and sulfates from biodiesel engines are negligible. Biodiesel emits 40% less CO 2 than conventional diesel. Emissions of various other pollutants are also lower: CO by 48%, particulate matter by 47%, hydrocarbons by 67%. It is biodegradable, non toxic, and produces few emissions.

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The Disadvantages of Biodiesel NOx emissions from biodiesel are 10% higher than from diesel. Cost of production and cost of raw materials is high, although still lower than gasolines. Requires a great deal of land, which could lead to increased deforestation. When small quantities of water are added to biodiesel, it becomes less efficient and potentially dangerous.

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Efficiency for Production of Ethanol and Biodiesel

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Conclusions & Further Considerations We can conclude that ethanol and biodiesel are suitable alternatives to gasoline and conventional diesel, though there are a few significant caveats: Biodiesel & Ethanol may be too costly (in terms of input/output of energy & environmental effects in production) to be feasible as complete replacements. Clearly however, they are reasonable transitional alternatives with far more environmentally responsible Greenhouse Gas emission rates.

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A commodity: TiO 2 (titanium oxide) Extremely white, opaque, edible, dirt resistant. Used in paper, food, cosmetics, paint, textiles, plastics. World consumption: 4 million tons/yr. Cost: $2,000/ton. Total world value = $8 billion/yr. A 1% increase in production efficiency = 0.01*2*10 3 *4*10 6 $/yr = $80 million/yr.

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Molecules Small and simple: ammonia (NH 3 ) sulfuric acid (H 2 SO 4 ) ethylene (C 2 H 4 ) sugar (C 12 H 22 O 11 ) Large and complex: insulin C 257 H 383 N 65 O 77 S 6 Large and simple (polymers): polyethylene[-CH 2 -CH 2 ] n See www.psrc.usm.edu/macrog for a very good introduction to polymers.

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Ken YoussefiMechanical Engineering19 Popular Plastics Polyethylene (LDPE (low density) and HDPE (high density) Properties: good chemical and electrical properties, strength depends on composition Applications: bottles, garbage cans, housewares, bumpers, toys, luggage ABS Properties: dimensionally stable, good strength, impact and toughness properties, good resistance to abrasion and chemicals Applications: automotive components, helmets, tool handles, appliances, boat hulls, luggage, decorative panels Acetal (Delrin) Properties: good strength, good stiffness, good resistance to heat, moisture, abrasion and chemicals Applications: mechanical components; gears, bearings, valves, rollers, bushings, housings

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Ken YoussefiMechanical Engineering20 Popular Plastics Polycarbonates Properties: very versatile and has dimensional stability, good mechanical and electrical properties, high resistance to impact and chemicals Applications: optical lenses, food processing equipments, electrical components and insulators, medical equipments, windshields, signs, machine components Nylons Properties: good mechanical and abrasion resistance property, self- lubricating, resistant to most chemicals but it absorbs water, increase in dimension is undesirable Applications: mechanical components; gears, bearings, rollers, bushings, fasteners, guides, zippers, surgical equipments,

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Ken YoussefiMechanical Engineering21 Applications of Thermosetting Plastics Epoxies Properties: good dimensional stability, excellent mechanical and electrical properties, good resistance to heat and chemicals Applications: electrical components requiring strength, tools and dies, fiber reinforced epoxies are used in structural components, tanks, pressure vessels, rocket motor casing Phenolics Properties: good dimensional stability, rigid, high resistance to heat, water, electricity, and chemicals Applications: laminated panels, handles, knobs, electrical components; connectors, insulators

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Ken YoussefiMechanical Engineering22 Applications of Thermosetting Plastics Polyesters (thermosetting, reinforced with glass fibers) Properties: good mechanical, electrical, and chemical properties, good resistance to heat and chemicals Applications: boats, luggage, swimming pools, automotive bodies, chairs Silicones Properties: excellent electrical properties over a wide rang of temperature and humidity, good heat and chemical properties Applications: electrical components requiring strength at high temp., waterproof materials, heat seals

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Cracking One solution to this is to crack the long chain molecules into short chains. Two options are available: 1) Thermal cracking (using very high temperatures to break the bonds) 2) Catalytic cracking (using a catalyst to break the bonds at lower temperature)

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Zeolites Aluminosilicate compounds (Al, Si and O.) Honeycomb structure (huge surface area) for alkanes to be adsorbed on to. Circulated as powders in the cracker.

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Catalytic cracking Catalytic cracking uses heat, pressure and a catalyst to break larger hydrocarbon molecules into smaller, lighter molecules. Feed stocks are light and heavy oils from the crude oil distillation unit which are processed primarily into gasoline as well as fuel oil and light gases. The catalytic cracking processes, and also other refinery catalytic processing, produce coke which accumulates on the surface of catalyst and causes the gradually losses of catalytic properties (deactivation). Therefore, the catalyst needs to be regenerated continuously or periodically by burning the coke off the catalyst at high temperatures. A fluidized-bed catalytic cracking units (FCCU) are the most common reactor to use.

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Catalytic cracking

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