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Undergraduate Certificate in Renewable and Sustainable Energy. Deadline March 1 //rasei.colorado.edu/ undergraduatecertificate. Energy news.
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Undergraduate Certificate in Renewable and Sustainable Energy Deadline March 1 //rasei.colorado.edu/undergraduatecertificate
Energy news Lawrence Livermore National Laboratory’s NIF laser facility delivered a burst of light with 1.9 megajoules = 1.9*106 J. How fast would a 2000 kg truck be moving to equal this? (Science 343, p. 721, 14 February 2014)
answer Lawrence Livermore National Laboratory’s NIF laser facility delivered a burst of light with 1.9 megajoules = 1.9*106 J. How fast would a 2000 kg truck be moving to equal this? ½ mv2 = ½ *2000*v2 = 1.9*106 all in metric Joules v2 = 2*1.9*106/2000 = 0.0019*106= 1900 v=43.5 m/sec = (43.5 m/sec * 3600 sec/hr) / (1000 m/km) = 157 km/hr!
Powerrrrrr! That 1.9 megajoules was discharged in 15 nanoseconds=15*10-9 sec. What was the power? Power = energy/time = 1.9*106 J/ 15*10-9 sec = 1.27*1014 Watts (average US power =1.3 * 1012 Watts. The energy for this burst was stored up in something like a battery for a while before the discharge.)
Today New ideas in transportation- hydrogen, fuel cells, electric cars, hybrid cars Friday: Chapter 9, Air Pollution, but not CO2, sulfur or lead All power point images are only for the exclusive use of Phys3070/Envs3070 Spring term 2014
3. (10 Points) Table 8.4 of your text lists the ‘energy density’ for several ways an automobile may carry the energy needed for travel. Explain to a smart, but ill-educated, national policy maker what she should do about the future of US automobile traffic, from these numbers. 4. (10 points) Plug and chug: What are the rolling and the aerodynamic drag forces on my Subaru Legacy, with a weight of 3423 pounds, a frontal area of 25 square feet, the CD of a Ford Escort, a Cr of 0.01, at 60 mph? 5. (10 points) How much total work is done, in foot-pounds and in kWh, to drive twenty miles at that speed? Don’t do it, but make a mental outline of how you would compute the fuel consumed from these numbers.
SWOT analysis S=Strength W=Weakness O=Opportunity T=Threat
Electric car-8.3.1 • Run from the burning of coal or natural gas • Multiply efficiency at coal plant (30%)x efficiency of transmission (90%)x efficiency of car electric motor(80%) = 21.6% • Compare to internal combustion, e=20% • Range? • Battery weight? • Battery charging time? • Battery cycles?
Example/Model 15 gallon fuel tank holds 15 gallons x 36.6 kWhr/gallon (text front cover page) =549 kWhr of energy. A 12 volt battery, charging at 10 amperes (DC), power = 12 V *10A = 120 W, holding the same energy needs 549 x 103 Watt -hr = 120 Watts x time Time =4575 hours to charge=191 days. At 100 Amps, 19 days.
Costs? At $3.00/gallon, the tank of gasoline costs $45. The electricity at $0.07/kW hr costs 549 kwh*$0.07/kwh= $38.43 ‘system efficiency’ both ~20%.
Nissan Leaf A sensor tells the driver 4.1 miles/ kWh=kiloWatt-hour. Some gasoline cars tell the driver mpg. How many mpg (equivalent energy) is 4.1 miles/kWh? Gasoline holds 36.6 kwh per gallon. 4.1 mi/kWh = (X miles/gallons) /36.6 kwh/gallon X= 4.1 miles/kwh * 36.6 kwh/gallons = 150 mpg (energy from the battery, not from the coal)
Hybrid car-8.3.3 • Gasoline engine– for energy density, range • Run at constant speed to generate electricity for the battery—greater efficiency • Electric motor runs wheels • Motor=generator, collect energy when slowing or going downhill. • Battery to store the electricity. Enough for a short trip without gasoline.
Direct conversion of fuel to electricity—skip the generating plant and transmission lines! The fuel cell. Electrolysis, backwards.
Fuel cell efficiency=electric energy out/fuel energy in Burn hydrogen at 25 deg C max 83%, useful 50% x motor 80% =40% Internal combustion engine Max (theory) 58 %, useful 20% Battery 90% x motor 80%=72% (21% from the coal)
Hydrogen as fuel 2H2 +O2 2 H2O + energy We can make H2, from coal : C +H2OCO + H2 Or natural gas: CH4+2H2O CO2 + H2 Or water: 2H2O 2H2 + O2 (electrolysis)
Energy density (Table 8.4) • Hydrogen 38,000 Watt hr/kg • Gasoline 13,000 • Battery 25 So the 549 KW-hr example above ( a 15 gallon tank of gasoline) would require a battery mass of 549,000 Watt-hr /25 Watt-hr/kg = 21,960 kg=22 tonnes !!
Energy densities H2 gas LH2 methane gasoline 10.2 9553 38.5 24,500 MJ/m3 • 114 50.5 34 MJ/kg H2 gas has 1/8 density of natural gas LH2 has 1/10 density of gasoline LH2 – liquid at -253 deg C=20 deg K at atmo. pressure H2 gas tank- 10,000 psi (700 atmospheres=700 times the density of STP hydrogen)
SWOT Electric car • Strength—short trips, efficient, CO2 production elsewhere • Weakness- heavy, no long trips, slow charge • Opportunity—battery technology • Threat-accidents
Hybrid • S- combines short range and long range options • W-twice as much machinery • O- fuel cells for efficiency • T- Fragility of fuel cells
Hydrogen S- moves the CO2 problem elsewhere else W-no hydrogen mines, energy density O- cheaper hydrogen, fuel cells T- pressures
Biodiesel US consumes 3 million bbl diesel/day Ground beef contains 10-20% fat. If we use ALL of that fat for biodiesel, how much beef need we eat in one year? Mass of beef x 0.15 = 3 x106bbl/day*365 day/year * 42 gal/bbl * 3.4 kg/gal =1.56x1011 kg of biodiesel/year M=this/0.15=1.0x1012 kg/year=1.0x109 ton/year (we mine 1.1x109 tons of coal/year)
Challenge! IF we ate that much beef (1.0* 109 tons/year), what is your daily share in pounds?
Bio Beef • IF we ate that much beef 1.0 109 tons/year, what is your share? 1.0*109tons/year *1/(365 days/year)*2000 pounds/ton / 320*106 people =0.017*10 9-6 = 17 pounds of beef per person-day.
Therefore? Nothing beats burning fossil petroleum for transportation. Or—does such combustion cause so many other problems that we must find substitutes ? Subsidize experiments—try things out. Accept the fact that some of these experiments may fail.
Friday Feb. 28 • Air pollution: smog, ozone, carbon monoxide, particulates, NOX,……… • Origin? Mitigation? Dr. Christine Wiedinmyer of NCAR //acd.ucar.edu/~christin/ Next week– Lead, sulfur, CO2 and consequences