10
Energy Consumption
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Consumption

No energy sources are truly clean


No not even solar
All humans activities require energy
Heat & cool buildings
 Illuminate buildings and streets
 Plant, harvest, & ship food


100 years ago energy sources were local

Wood, peat, dung, wind & water (windmills for grinding & sailing ships)
 Mostly
always derived and used for agriculture
 Energy sources were local
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Consumption

Now they are worldwide


Fossil fuels, nuclear energy, biomass & electricity
(large scale hydropower, wind, solar)
Energy is needed to capture energy
 Drill
& pump oil
 Mine coal & uranium
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Consumption and Policy

Advantages of energy source
 How
concentrated it is
 Versatility
 Safety
 Availability

Disadvantages of energy source
 Hazard
potential
 Environmental damage
 Cost
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Consumption Worldwide

Differs between developing and developed nations
 20%
of world’s population use 60% of the world’s energy
sources

Fun Facts
100 watts means 100 Joules/Second.
So in 24 hours, the bulb would use
24*60*60*100 Joules.
so that's 8,640,000 joules.
(8.6 million joules = 0.0086 gigajoules)
The energy of an average 3 mile-long lightning strike
is one billion to ten billion joules.
1gigajoule ^10,000,000,000 joules
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Efficiency vs Conservation

Efficiency
 Looks
at making stuff we use better at using energy
 Cars
more fuel efficient
 Washer, Dryer & Refrigerator

Conservation
 Looks
at using less by
 Sharing
(carpool)
 Shutting off lights when not in use (shutting off vampire draw)
Both efficiency and conservation accomplishes the
same goal = Using less power
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Efficiency

Amount of available energy in a source that is
transformed into useful work
1

Ranges from 0–100%
 Natural
gas (cooking) ~100%
 Natural gas (electricity) ~60%
 Incandescent bulbs ~2-3% (1)
 Fluorescent bulbs ~10% (2)
 Light-emitting diodes ~20% (3)
3
2
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Efficiency
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Intensity

Energy Intensity- energy use per $ of GDP
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Efficiency

Super-insulated buildings
use 70-90% less energy

NAECA sets national
standards for appliances
 Refrigerators
built post2001 are 75% more
efficient than those build in
1975
 Payback of $135/yr!
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Efficiency - Commercial
Buildings

High-performing buildings pay for themselves
 Energy
costs = 30% of budget
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Efficiency - Transportation

Most energy in gasoline is wasted
 Energy
lost in combustion to heat
 Energy lost in braking
 Energy lost in friction with road & wind
 Energy lost in moving weight of car (not passengers)
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Efficiency - Transportation

Modern Vehicle Design
 Use
of Kevlar and plastics to reduce weight
 Gasoline-electric hybrid engines (Prius & Leaf)
 Regenerative
braking recaptures lost energy
 Operate at lower temperatures

New Laws
 By
2020, all passenger vehicles must have ave fuel
efficiency of 35 mpg
 Including
minivans, light trucks and SUVs
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Conservation

Requires a change in behaviors and practices
 Reduce
commute length
 Use public transportation or bike to work
 Turn off lights when not in use
 Reduce temperature on thermostat at night

Some changes would be difficult
 Removing
subsidies
 Allow product prices to reflect true cost of production
(including energy costs)
 Increase price of gasoline to represent true price
© 2012 John Wiley & Sons, Inc. All rights reserved.
Benefits of Efficiency & Conservation

$$ savings (Easy cash savings)

Environmental benefits
 Dec.
CO2 emissions by million of tons /yr
 Dec. air pollution
 Dec. acid rain
 Slow global climate change
© 2012 John Wiley & Sons, Inc. All rights reserved.
Electricity


The flow of electrons in a
wire
Can be generated from
almost any energy source
 Energy source spins a turbine
 Turbine turns a generator
 Bundle
of wires spin around a magnet or vice versa
 Spinning

causes electrons to move in a wire = electricity
Source of electricity can be hundreds of miles away
 Environmental
the energy
impacts are far away from those who use
© 2012 John Wiley & Sons, Inc. All rights reserved.
Hydrogen and Fuel Cells

Hydrogen gas (H2)
 Comprised
of two hydrogen molecules
 Large amounts of available energy
 Explodes when combined with oxygen
releasing energy and forming water
© 2012 John Wiley & Sons, Inc. All rights reserved.
Hydrogen as a Fuel Source

Advantages
 Very
high energy density
 Can be produced from any electrical source
 Electrolysis
(see illustration on next slide)
 No
greenhouse gases and few other pollutants
 Can be use in vehicles

Disadvantages
 Highly
volatile (requires special storage)
 Relatively inefficient
© 2012 John Wiley & Sons, Inc. All rights reserved.
Electrolysis
© 2012 John Wiley & Sons, Inc. All rights reserved.
Future Applications of Fuel Cells

Hydrogen Fuel Cells Vehicles
H
not yet readily available as fuel source
 61 H fueling stations in US
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Storage

Many energy resources are not available when
we want them
 Too
little: Solar and wind can be intermittent
 Too much: Large coal and nuclear plants are most
efficient with constant energy output

Solution = storage of unused energy
 Less
than 100% efficient
 With each conversion, less energy is available
© 2012 John Wiley & Sons, Inc. All rights reserved.
Energy Storage






Superconducting Magnetic Energy Storage
Compressed Air Energy Storage
Electrochemical Energy Storage (Batteries)
Pumped Hydrogen Storage
Thermal Energy
Storage
Kinetic Energy
Storage (Flywheel)
© 2012 John Wiley & Sons, Inc. All rights reserved.
© 2012 John Wiley & Sons, Inc. All rights reserved.
US Energy Policy
Obj 1: Increase Energy Efficiency & Conservation
Requires many unpopular decisions

Ex: Decrease speed limit to conserve fuel

(US did this one time in the 1974. 55mph speed limit)
1974 Emergency Highway Energy Conservation Act



Eliminate government subsidies
Obj 2: Secure Future Fossil Fuel Energy Supplies

2 oppositions: environmental and economic
Obj 3: Develop Alternative Energy Sources
 Who
should pay for this? Gas taxes?
Obj 4: Meet the Above 3 Objectives Without Further
Damage to the Environment
© 2012 John Wiley & Sons, Inc. All rights reserved.