US Energy Consumption vs. Renewable Energy Potential: A Comparative Study, Study notes of Water and Wastewater Engineering

Download US Energy Consumption vs. Renewable Energy Potential: A Comparative Study and more Study notes Water and Wastewater Engineering in PDF only on Docsity! 1 Energy in natural processes and human consumption - some numbers The average person in the US consumes 60 barrels of oil (2520 gallons) per year and on average this is 10,000 watts of power consumption (the calculation is made relatively easy by consulting tables below and keeping track of units: [2520 gallons /yr x 125 x 106 J/gallon ]/ [π x 107 sec./yr] = 1.00 x104 watts). It is a useful coincidence that the number of seconds in a year is π x 107 to within half of one percent. Rough Values of Power of Various Processes (watts) Solar power in all directions 1027 Solar power incident on earth 1017 Solar power avg. on U.S. 1015 Solar power consumed in photosynthesis 1014 U.S. power consumption rate 1013 U.S. electrical power 1012 Large electrical generating plant 109 Automobile at 40 mph…note this is not the output which only about 30% of the energy input..PBR 10 5 Solar power on roof of U.S. home 104 U.S. citizen consumption rate 104 Electric stove 104 Solar power per m2 on U.S. surface …this seems a little low…it’s 1342 watts per m2 outside the atmosphere, about 1000 watts per m2 at high noon on the ground, and on average (day and night) about 240 watts per meter2 absorbed at the ground. This is the average over the Earth too…PBR 102 One light bulb 102 Food consumption rate per capita U.S. 102 Electric razor 101 Energy Content of Fuels (in Joules) Energy Unit Joules Equivalent (S.I.) Docsity.com 2 gallon of gasoline 1.3x108 AA battery 103 standard cubic foot of natural gas (SCF) 1.1x106 candy bar 106 barrel of crude oil (contains 42 gallons) 6.1x109 pound of coal 1.6 x 107 pound of gasoline 2.2 x 107 pound of oil 2.4 x 107 pound of Uranium-235 3.7 x 1013 ton of coal 3.2 x 1010 ton of Uranium-235 7.4 x 1016 Energy Conversions Energy Unit Equivalent 1 Btu 1055 joules or 778 ftlb or 252 cal 1 calorie 4.184 joules 1 food Calorie 1000 calories or 1 kilocalorie 1 hp hr 2.68 x106 joules or 0.746 kwh 1 kwh 3.6 x 106 joules or 3413 Btu 1 eV 1.6x10-19 joules Fuel Requirements for a 1000MWe Power Plant =109 watts (2.4 1011 Btu/day energy input) =2.53x1014 joules/day = 2.9x109 watts = 2200 Mwatts thermal fuel energy Coal: 9000 tons/day of 1 "unit train load" (100 90 - ton cars/day) Oil: 40,000 bbl/day or 1 tanker per week (note: "bbl" means barrels) Natural Gas: 2.4 l08 SCF/day Uranium (as 235U): 3 kg/day Docsity.com 5 D-D fusion energy possible from worlds oceans 1031 Earth spinning 1029 Earth's annual sunshine 1025 Cretaceous-Tertiary extinction theory meteorite 1023 Energy available from earth's fossil fuels 1023 Yearly U.S. sunshine 1023 tidal friction (which drives the moon slowly away from Earth and lengthens the day steadily) 10 20 U.S. energy consumption 1020 Exploding volcano (Krakatoa) 1019 Severe earthquake (Richter 8) 1018 100-megaton H-bomb 1017 Fission one ton of Uranium 1017 E = mc2 of 1 kilogram 1017 Burning a million tons of coal 1016 Energy to create Meteor Crater in Arizona 1016 1000-MW power station (1 year) 1016 Hurricane 1015 Thunderstorm 1015 Atomic Bomb (Hiroshima) 1014 E = mc2 of 1 gram 1014 Energy to put the space shuttle in orbit 1013 Energy used in one year per capita U.S. 1012 Atlantic crossing (one way) of jet airliner 1012 Saturn V rocket 1011 Energy to heat a house for one year 1011 D-D fusion energy possible from 1 gal. of water 1011 One year of electricity for the average house 1010 Lightening bolt 1010 Burning a cord of wood 1010 One gallon of gasoline 108 100-W light bulb left on for one day 107 Human daily diet 107 One day of heavy manual labor 107 Explosion of 1 kg of TNT 106 Woman running for 1 hr 106 Candy bar 106 Burning match 103 Docsity.com 6 1AA battery (alkaline) 103 Hard-hit baseball 103 Lifting an apple 1 m 1 Human heartbeat 0.5 Depressing typewriter key 10-2 Cricket chirrup 10-3 Hopping flea 10-7 Proton accelerated to high energy (one trillion eV) 10-7 Fission of 1 uranium nucleus 10-11 Energy released in D-D fusion 10-12 Electron mass-energy 10-13 Chemical reaction per atom 10-18 Photon of light 10-19 Energy of room-temperature air molecule 10-21 Cost of Various Fuels Type Unit Cost $/Unit Cost $/Joule Uses Electricity 1Kwh=3.6x10 6J (3.6 MJ) $0.10 0.028 $/MJ = 2.8x10-8 appliances, motors Gasoline 1 gallon 2.00 0.013 $/MJ = 1.3x10-8 transportation Natural Gas 1 Therm 0.60 similar to gasoline heating AA battery 1 battery 0.80 0.8 x 10-3 portable electronics Milky Way candy bar 1 bar 0.60 0.60/MJ = 0.6 x 10 - 6 food (but note, although electricity is twice as expensive as gasoline per unit of energy, electric motors are typically much more efficient than gasoline engines, so that electricity as a fuel source can be competitive with gasoline). Worldwide Power Use - History "Developed" countries average (1990): • 1.2 billion people 7.5 kilowatts/per person = 9.0 terawatts The rest of the world (1990): • 4.1 billion people 1.1 kilowatts/person = 4.5 terawatts Docsity.com 7 (…we got a slightly different number for 2000…taking 400 exaJoules/year and dividing by 6 Billion people gave 2.11 kw per person..average power consumption..24 hrs a day!..has it changed? Here we used the interesting fact that there are π x 107 seconds per year…to a good approx. PBR) World Population (est.) (billion persons) Year Average Power Use (terawatts) 5.5 1990 13.5 3.6 1970 8.4 2.5 1959 3.2 2.0 1930 2.3 1.7 1910 1.6 1.5 1890 1 Areas and crop yields • 1.0 hectare = 10,000 m2 (an area 100 m x 100 m, or 328 x 328 ft) = 2.47 acres • 1.0 km2 = 100 hectares = 247 acres • 1.0 acre = 0.405 hectares • 1.0 US ton/acre = 2.24 t/ha • 1 metric tonne/hectare = 0.446 ton/acre • 100 g/m2 = 1.0 tonne/hectare = 892 lb/acre o for example, a "target" bioenergy crop yield might be: 5.0 US tons/acre (10,000 lb/acre) = 11.2 tonnes/hectare (1120 g/m2) Biomass energy • Cord: a stack of wood comprising 128 cubic feet (3.62 m3); standard dimensions are 4 x 4 x 8 feet, including air space and bark. One cord contains approx. 1.2 U.S. tons (oven-dry) = 2400 pounds = 1089 kg o 1.0 metric tonne (that is, 1000 kg) wood = 1.4 cubic meters (solid wood, not stacked) o Energy content of wood fuel (HHV, bone dry) = 18-22 GJ/t = 18-22 MJ/kg (7,600-9,600 Btu/lb) o Energy content of wood fuel (air dry, 20% moisture) = about 15 GJ/t (or 15 MJ/kg) ( or 6,400 Btu/lb) • Energy content of agricultural residues (range due to moisture content) = 10-17 GJ/t (4,300-7,300 Btu/lb) • Metric tonne charcoal = 30 GJ (= 12,800 Btu/lb) (but usually derived from 6-12 t air-dry wood, i.e. 90-180 GJ original energy content) • Metric tonne ethanol = 7.94 petroleum barrels = 1262 liters Docsity.com