Using Solar Energy to Provide High- Temperature Heat and
Electricity Solar thermal systems Photovoltaic (PV) cells Solar
Cell Trade-Offs
Slide 2
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
Slide 3
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
Slide 4
Producing Energy from Biomass Biofuels Biomass plantations Crop
residues Animal manure Biogas Ethanol Methanol
Slide 5
The Solar-Hydrogen Revolution Extracting hydrogen efficiently
Storing hydrogen Fuel cells
Slide 6
Geothermal Energy Geothermal reservoirs Dry steam Wet steam Hot
water Molten rock Hot dry-rock zones
Slide 7
Solutions: A Sustainable Energy Strategy
Slide 8
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!
Slide 9
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
Slide 10
Atmospheric CO 2 is increasing * Slide from Lecture on 11/27
Net increase of 3.2 gigatons of CO2 per year
Slide 11
Slide 12
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
Slide 13
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.
Slide 14
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.
Slide 15
Efficiency for Production of Ethanol and Biodiesel
Slide 16
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.
Slide 17
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.
Slide 18
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.
Slide 19
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
Slide 20
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,
Slide 21
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
Slide 22
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
Slide 23
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)
Slide 24
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.
Slide 25
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.