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8/10/2019 Energy Units
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Energy has its own vocabula
8/10/2019 Energy Units
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Energy and Power are of
used interchangeably, but th
mean slightly different thing
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Energy: quantity
Ability to do work
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Energy Has Many Units
Scientific Units:
!Fuels:
!BTU = British Thermal Units
!Quad = 1 quadrillion (BTU)
!Joules (J, kJ, MJ,)
!Calories
!Electricity:
!kWh = kiloWatt-hour
!MWh = MegaWatt-hour
!GWh = GigaWatt-hour
Proxy Units:
!Volume: assumes a particular
volumetric energy density
!barrels of energy (boe),
!barrels of oil equivalent (boee),
!cubic feet,
!Mass: assumes a particular
gravimetric energy density
! tons of energy,
! tonnes of oil equivalent (toe),
!kg of energy (kgoe)
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Power is a Rate of Energy
Power: work performed over a period of time
!Or energy produced over a period of time
!Or energy consumed over a period of time
!Its a rate not a quantity
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Power is a Rate of Energy
Units:
!Watt (W, kW, MW, GW,)
!Horsepower
kiloWatts of energy is nonsensical
Power density: W/m2
!Heat flux density, irradiance,
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Energy = Power !Time
A light bulb consumes energy at a rate of
Its instantaneous power consumption is
After 1 hour, it has consumed 100 Wh or 0
After 10 hours, it has consumed 1 kWh
!Note: power consumption at a house is roughly 14 kW
!Note: a humans nominal power consumption is 100 W
de.wikipedia, original upload 26 Jun 2004
by de:Benutzer:KMJ
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Energy = Power !Time
Example: A nuclear plant has a power capacity of 1 GW
!After 1 hour, generates 1 GWh of electricity
!After 1 year, generates 8,760 GWh of electricity
! NOTE: 8,760 hours per year
Converting from GWh to kWh
!1 GWh = 1 million kWh
!Total U.S. electricity in 2011: 4,000 billion kWh
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There is a Difference Between
Primary and Secondary Energy
Primary energy:original/unconverted fuel sources
!petroleum
!natural gas
!coal
!biomass
!water, wind, solar,
Secondary energy:converted/stored en
!electricity
!hydrogen
!pumped hydroelectric
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Energy Notation
Scientific Prefix Multiplier English Roman Numerals
m = milli 1/1,000 thousandth
c = centi 1/100 hundredth
d = deci 1/10 tenth
da = deka 10 ten X
h = hecto 100 hundred C
k = kilo 1,000 thousand M
M = mega 1 x 106 million
G = giga 1 x 109 billion
T = tera 1 x 1012 trillion
P = peta 1 x 1015 quadrillion
E = exa 1 x 1018 quintillion
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Energy Notation
MW = megaWatts = 1 million watts
MMBTU = million BTU = thousand, thousand BTU
MMBBLS = million blue barrels = thousand, thousand barrels
MMBD = million barrels per day = thousand, thousand barrels
!also sometimes noted mbd
!BOE = barrel of energy or barrel of oil equivalent
!MMBDOE = million barrels per day of oil equivalent (an amount of energy)
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We Have Some Fortunate Conversion
Natural Gas
The energy content of 1,000 SCF ofnatural gas is approximately 1 million BTU
!SCF = standard cubic foot
!MCF = thousand cubic feet (also mcf or Mcf or mil)
!1,028 BTU per cubic foot
!1,000 SCF = 1 MCF = 1.028 MMBTU
Price is often given in MCF or MMBTU
!The energy content is the same within 3%
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We Have Some Fortunate Conversion
TonsA ton is about a tonne
English system:!Ton = dry ton = short ton = 2000 lbs
Metric/SI system:!Tonne = metric ton = metric tonne = MT = 1,000 kg
1 kg = 2.2 lbs1 metric ton = 1000 kg = 2200 lbs = 1.1 tons
1 metric ton = 1 tonne = 1.1 tons!Only wrong by 10%
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We Have Some Fortunate Conversion
Large Scale Energy Units
An Exajoule and Quad are about the same
Metric/SI system:
!1 Exajoule (EJ) = 1 quintillion Joules = 1 1018J
English system:
!1 Quad = 1 quadrillion BTU = 1 1015BTU
1 EJ = 0.948 Quad
100 Quads = 105 EJ
!Accurate within ~5%
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Data Sources
Energy is highly politicizedpay attention to sources
Guide for evaluating sources
Sample authoritative sources
!Governmental agencies
!Industry and trade associations
!NGOs and watchdog groups