Mike Cowdery, Corporate Electric & UCCI
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 Introduction
 Why engineering a sustainable future
matters
 Energy sources
 Where does energy come from?
 Energy alternatives
 Renewable energy options
 Other alternative energy sources?
 Conclusions
Some material courtesy Tom Murphy UCSD
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Why engineering a sustainable future matters
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Our per capita energy consumption is many times that of the rest of
the world
Most energy comes from fossil fuels - a short, finite lifetime
What will our future hold?
 Will it be back to a simple life?
 Or will we find new ways to produce all the energy we want?
 Or will it be somewhere in the middle?
energy usage
Fossil fuels
People, animals,
firewood
2000BC 1000BC
0
1000
2000
3000
Nuclear,
geothermal,
solar energy
OR
People, animals,
firewood
4000
5000
6000
year
4
1018 Joules/yr
158
Percent of Total
40.0
Coal*
Natural Gas*
Hydroelectric*
Nuclear Energy
92
89
28.7
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23.2
22.5
7.2
6.6
Biomass (burning)*
Geothermal
Wind*
1.6
0.5
0.13
0.4
0.13
0.03
Solar Direct*
Sun Abs. by Earth*
0.03
2,000,000
0.008
then radiated away
Source
Petroleum*
* Ultimately derived from our sun
Courtesy David Bodansky (UW)
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Cayman
Many countries in the world lie in this quarter-circle!!
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Energy usage
Energy use is directly
correlated with economic
prosperity
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Pasterze Glacier, Austria, 1874
Pasterze Glacier, Austria, 2000
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We are
borrowing
money from
China to buy oil
from the Gulf and it all goes up
in smoke!
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
Kinetic Energy: the energy of motion
K.E. = ½mv2
KE of wind can be used (e.g. windmills, sailing
boats, etc.)
Example: wind passing through a square meter
at 8 meters per second (18mph)
 Each second we have 8 cubic meters
 Air has density of 1.3 kg/m3, so (8 m3)(1.3 kg/m3) =
10.4 kg of air each second
 ½mv2 = ½(10.4 kg)(8 m/s)2 = 333 J
 333J every second  333W per square meter (but to
get all of it, you’d have to stop the wind)

Stronger winds  more power (~ v3)
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Raising a Weight W through height h against gravity
requires an energy input (work) of E = W = F ·h = mgh
Rolling a boulder up a hill gives it gravitational potential
energy
The higher the cliff, the more kinetic energy the boulder
will have when it reaches the ground
mgh
becomes
h
Conservation of
energy:
½mv2 = mgh
v2 = 2gh
½mv2
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Evaporating 1g of water takes 2,250J
Raising 1g of water to top of the troposphere (10,000 m,
or 33,000 ft):
mgh = (0.001 kg)(10 m/s2)(10,000 m) = 100 J
 A tiny bit of PE remains, IF rain falls on suitable terrain
(e.g. higher than sea level)
 hydroelectric plants use this tiny left-over energy
 damming concentrates PE in one location
 401015 W of solar power goes into evaporation
 Gravitational PE given to water vapor in the atmosphere
(per second):
mgh = (1.61010 kg)(10 m/s2)(2000 m) = 3.21014 J = 320
TW
 US uses only 1.25% of that available


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Pumped storage
2012
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A GLOBAL WAVE ENERGY RESOURCE ASSESSMENT. Andrew M. Cornett.
Proceedings of the Eighteenth (2008) International Offshore and Polar
Engineering Conference Vancouver, BC, Canada, July 6-11, 2008.
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Electrostatic energy (associated with
charged particles, like electrons) is stored
in the atomic bonds of substances.
 Rearranging these bonds can release
chemical energy (some reactions require
energy to be put in)
 Typical numbers: 100–200 kJ per mole
 a mole is 6.0221023 molecules/particles
 typical molecules are tens of grams per
mole  several thousand Joules per
gram


Burning a wooden match:
 releases about 1055 Joules
 a match is about 0.3 grams
 Energy release >3kJ/g (3kJ/g)



Burning coal releases about 20kJ/g
of chemical energy
Burning gasoline yields about 39kJ/g
Very few substances yield over
about 45kJ/g
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CUC's power system
comprised of 17
generating units (15
diesel and two gas
turbine) - capacity 151.2
MW
 Electricity price heavily
dependent upon fuel cost

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Shale gas = natural gas
formed trapped within shale
formations.
 An increasingly important
source of natural gas in the
US & rest of the world.
 In 2000 shale gas provided
1% of U.S. natural gas
production; by 2010 it was
over 20%
 U.S. government's Energy
Information Administration
predicts by 2035, 46% of the
US NG from shale gas.

Source: New York Mercantile Exchange
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Are fossil fuel resources finite/known??
May be too much fossil fuel - prices may be
too low, not too high
Availability, not cost
Abundant low-cost “conventional” oil
(Middle East) has limited other sources
The revolution in shale gas/shale oil has been
transformational in the US
Is there another way forward, using
cheaper gas without increasing emissions?
 Yes –for the next couple of decades
 Switching from coal to gas is cheap – &
cuts emissions by roughly half!
 Does not solve climate change but gets
emissions down much faster and
cheaper than wind farms
Source: BP energy outlook
2030, Jan 2012
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Human energy derived from food (stored
solar energy in the form of chemical energy).
 Energy sources recognized by our digestive
systems:
 Carbohydrates: 17kJ/g (4 Cal per g)
 Proteins: 17kJ/g (4 Cal per g)
 Fats: 38kJ/g (9 Cal per g - like gasoline)
 A 2000 Calorie per day diet means 20004184
J = 8,368,000 J per day, corresponds to 97
Watts of power
 This product has 150 Calories = 636 kJ:
enough to climb about 1000 meters (64 kg
person)

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Biomass: any living organism
40x1012 W out of the 174,000x1012 W
incident on the earth from the sun goes
into photosynthesis
 0.023%
 this is the fuel for virtually all biological
activity
 half occurs in oceans


Compare this to global human power
generation of 12x1012 W, or to 0.6x1012 W
of human biological activity
Fossil fuels represent stored biomass
energy
1.5% Solar Energy
Conversion Efficiency
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How much land to replace US oil?
 Cornfield ~ 1.5% efficient at turning
sunlight into stored chemical
energy
 Conversion to ethanol is 17%
efficient
 Growing season is only part of year
(say 50%)
 Net efficiency ~ (1.5% x 17% x 50%)
= 0.13%
 Need 4x1019 J/yr to replace
petroleum - this is 1.3x1012 W
 thus need 1015 W input (at 0.13%)
 at 200 W/m2 insolation, need 5x1012
m2, or (2,200 km)2 of land
 that’s a square 2,200 km on a side
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Einstein theory of relativity:
E = mc2
 Relates mass to energy
 one can be transformed into the other
 physicists speak generally of massenergy
 Seldom experienced in daily life directly
 Happens at large scale in the center of
the sun, and in nuclear weapons and
reactors
 Happens in all energy transactions, but
the effect is tiny!

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The energy equivalent of one gram of material
(any composition!!) is (0.001 kg)(3.0108 m/s)2
= 9.01013 J = 90,000,000,000,000 J = 90 TJ ≡
568,000g gasoline
If one gram of material undergoes a chemical
reaction, losing about 9,000 J of energy, how
much mass does it lose?
9,000 J = mc2, so m = 9,000/c2 =
9103/91016 = 10-13 kg
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4 protons:
mass = 4.029
energy
4He
nucleus:
mass = 4.0015
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Helium nucleus is lighter than the four protons!
Mass difference is 4.029  4.0015 = 0.0276 a.m.u.
 1 a.m.u. (atomic mass unit) is 1.660510-27 kg
 difference of 4.5810-29 kg
 multiply by c2 to get 4.1210-12 J
 1 mole (6.0221023 particles) of protons  2.51012 J
 typical chemical reactions are 100-200 kJ/mole
 nuclear fusion is ~20 million times more
potent!
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Energy reaching the Earth’s atmosphere
is 174 x 1015W → 89 x 1015W at surface
 Compare to total energy production
on earth of 3.31012 W
Even a small fraction of could solve
world energy problems!
Single-crystal silicon: η~15–18%
 expensive (grown as big crystal)
Poly-crystalline silicon: η~ 12–16%
 cheaper (cast in ingots)
Amorphous silicon (non-crystalline)
 η~ 4–8%
 “thin film”, easily deposited on a wide
range of surface types
Max. Si PV efficiency around 23%

We’ve now seen all the major energy
alternatives:
 kinetic energy (wind, ocean currents)
 gravitational PE (hydroelectric, tidal, wave)
 chemical energy (batteries, food, biomass, fossil fuels
(incl. shale gas)→ heat energy (power plants))
 mass-energy (nuclear sources, sun’s energy)
 radiant energy (solar energy)

WHAT WORKS HERE?
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
Renewable = anything that won’t
be depleted
 sunlight (the sun will rise again

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
tomorrow)
biomass (grows again)
hydrological cycle (will rain again)
wind (sunlight on earth makes more)
ocean currents (driven by sun)
tidal motion (moon keeps on
producing it)
geothermal (heat sources inside
earth not used up fast)
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Current electricity cost in GC is about
CI$0.35 per kWh
PV output: assume 5 hours peak-sun
equivalent per day = 1800 h/y
 one Watt delivers 1.8 kWh in a year
 installed cost is CI$5 per peak Watt
capability
 panel lasts at least 25 years, so 45
kWh for each Watt of capacity
 CI$0.111/kWh
 Assuming energy inflation a few %
per year, payback is ~ 6
years
 thereafter: “free”
 $$ up front = loss of investment
capability
 Cost today is what matters to many
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The sun is not always shining!
100% energy availability is not fully
compatible with direct solar power
 Hence large-scale solar implementation
must address energy storage techniques
 small scale: feed solar into grid & let
other power plants take up slack
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Methods of storage:
 conventional batteries (lead-acid)
 exotic batteries (need development)
 hydrogen production (consume later,
transport)
 Pumped storage/global electricity grid?
(not for Cayman)
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OTEC uses heat stored in ocean waters
The temperature of the water varies:
 top layer normally warmer than that
nearer the bottom
Works best when there is at least 20°C
difference
 This ΔT often found in tropical areas
 Closed cycle uses low-boiling point
fluid (e.g. ammonia)
 Warm ocean water is pumped through
a heat exchanger to vaporize the fluid
 Energy extracted in a turbine
 Cold water pumped through a second
heat exchanger to condense vapor to
be recycled through the system
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About 1/3 of US annual energy usage for transportation
Gasoline is a good fuel
 Around 40kJ/g
 engine efficiency only around 20%
Problems with ethanol (from corn)
Solar cars are impractical, at 1–2 horsepower
Electric cars need batteries (but can use solar as a
source of electricity)
 batteries store only 0.14 to 0.46 kJ/g
 some gain in fact that conversion to mechanical is
90% efficient
Desperately need a replacement for portable gasoline
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2012: Legislation changed
 HSEVs now available (e.g.
Wheego) meeting US
crash-test standards
 14 businesses have signed
letters of intent for solarpanel powered EV
stations
 Cayman Automotive +
UGO Stations + Corporate
Electric working on
installation plan

Equipment required:
 Solar panels, inverter and charger etc.
 Mounting, installation & infrastructure

Energy exchange with electricity grid
 Sunshine = power generation to car charger or send
electricity grid
 Car charging: from solar electricity or grid

Vehicle energy costs (Grand Cayman
experience):
 Gasoline: 22mpg @ $6/gallon = 27c/mile = $2430/y
 Mains electricity: 14kWh, 40 miles = 12c/mile = $1080/y
 Electric (solar): 0c/mile = $0/y
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Technical
▪ Type 1, 2 or 3 – charge
times
▪ Power source
▪ CUC
▪ Renewable –
solar/wind
 Mechanical/structural
▪ Withstand to natural and
man-made hazards
Aesthetics
 Local or remote PV array
 Harmonisation with
surroundings

Nuclear energy
 Fission
 Fusion

Fission energy release:
 85%: kinetic energy of fission
products (heat)
 15%: ke of neutrons +
radiation energy (γ)

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Energy release: E = mc2
1g equivalent:
 21.5 kilotons of TNT
 568,000 USG of gasoline
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
Structure of the atom
 Nucleus
▪ Protons
▪ Neutrons
 Electrons
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Modern small reactors:
 Simple design;
 Mass production economies;
 Reduced siting costs.
High level of passive or inherent safety
Many safety provisions necessary in
large reactors are not necessary in the
small designs.
Hyperion: Uranium-nitride fuelled, leadbismuth cooled small reactor
70 MWt, 25 Mwe
Claimed to be modular, inexpensive,
inherently safe, and proliferationresistant.
Could be used for heat generation,
production of electricity, and
desalination.
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
Do nothing
 Maintain dependence on diesel, gasoline

Use more natural gas - rely on shale gas/oil from
overseas
 Global warming?

Become more energy-independent
 Economy benefits
 Renewables: solar, OTEC
 Transportation: electric vehicles
▪ Solar-assisted?
 Nuclear: Small modular reactor technology
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 Energy cost
 Energy security of supply
 Environment & climate change
 Land use
 Safety
 Waste
 Employment
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