Transcript Energy Resources Geothermal Energy: A Free Lunch? Environmental Problems of Geothermal Energy • It is Finite • Heat Sources Can Be Exhausted (Geysers, California) • Sulfur Emissions •

Energy Resources
Geothermal Energy: A Free Lunch?
Environmental Problems
of Geothermal Energy
• It is Finite
• Heat Sources Can Be
Exhausted (Geysers,
California)
• Sulfur Emissions
• Disposal of Mineralized
Brines
Technical Problems of
Geothermal Energy
• Corrosion
• Mineral Deposition in
Pipes
• Non-Productive gases
(Carbon dioxide,
methane, etc.)
• Low Temperatures
• Low Thermodynamic
Efficiency
Thermodynamic Efficiency
Thermodynamic Efficiency
• Eff. = (Ti - Tf)/Ti
• T = Degrees Kelvin = Degrees C + 273
• Ti = initial temperature
• Tf = final temperature
Thermodynamic Efficiency
Automobile Engine
• Ti = 1200 C = 1473 K
• Tf = 500 C = 773 K
• Eff = (1473 - 773)/1473 = 48%
Typical Steam Power Plant
• Ti = 700 C = 973 K
• Tf = 200 C = 473 K
• Eff = (973 - 473)/973 = 51%
Thermodynamic Efficiency
Geothermal Power Plant
• Ti = 150 C = 423 K
• Tf = 80 C = 353
• Eff = (423 - 353)/423 = 17%
Actual achieved efficiencies
• Automobile on Highway: about 5%
• Geothermal Plant: 5% or So, Sometimes
less than 1%
Nuke-u-lar Energy
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U-235 fissions to lighter nuclei
Naturally 0.7% in uranium ore
Must be enriched to 3-4% for reactors
Mining is conventional metal mining
Radium (decay product) is principal
problem in mine wastes
Radiation Hazards
• Problem in the body is ionization and creation of
free radicals
• Alpha particles (He nuclei) have +2 charge
– Do not penetrate skin
– Worst ionization problem if ingested
• Beta particles (Electrons)
– Weak penetration ability
– Moderate ionization problem
• Gamma Rays (High Energy photons)
– Great Penetrating ability
– Lowest ionization ability
Plutonium
• Produced in small amounts in civilian
reactors
• Toxicity of Plutonium is a Myth
– Chemically it is comparable to U, Th
– Ra and Rn are worse radiation hazards
– Chemical plus Radiation hazard high
• Main Problem: Long-lived waste product
• Security issue: Can be Chemically Separated
from Uranium
Nuclear Waste
• Contain until radiation decays to negligible
levels (Pu = 24,000 years)
• Possible Containment Schemes
– Yucca Mountain
– Crystalline Rock
– Salt Domes
– Subduction Zones?
– Space?
• Breeder Reactors?
– Security Concerns
Fossil Fuels
Coal Seams, Utah
Coal
• Delta, continental environments
– Autochthonous: Grew in Place
– Allochthonous: Transported Log Mats
• Carbonized Woody Material
• Often fossilized trees, leaves present
Plant Fragments Are Often Visible in
Coal
Coal Forms From Wood
Petroleum
A hydrocarbon molecule
What organisms make these?
Answer: None
Petroleum
• Lots of organisms make these, however
• Fatty Acids
• Probable source: Marine plankton
Hydrocarbons CnH2n+2
Name
Formula
Melts C
Boils C
Methane
Ethane
Propane
Butane
CH4
C2H6
C3H8
C4H10
-182
-183
-190
-138
-164
-88
-42
0
Pentane
Hexane
Octane
C5H12
C6H14
C8H18
-130
-95
-57
36
69
126
Decane
Eicosane
Triacontane
C10H22
C20H42
C30H62
-28
37
66
174
343
450
Hydrocarbons
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Methane = Natural Gas
Propane-Butane = Bottled Gas
Iso-octane (2,2,4 Trimethylpentane) = Gasoline
Cetane (Hexadecane = C16 H34) = Diesel Fuel
Kerosene = 12-15 Carbons
Mineral oil, petroleum jelly, paraffin wax = 20-40
Carbons
• Bitumen (Asphalt) ~ 50 Carbons
Iso-Octane (Gasoline)
Abiogenic Petroleum?
• 18Mg2SiO4 + 6Fe2SiO4 + 26H2O + CO2 →
12Mg3Si2O5(OH)4 + 4Fe3O4 + CH4
• Olivine + Water → Serpentine + Magnetite
+ Methane
• nCH4 + nFe3O4 + nH2O → C2H6 + Fe2O3 +
HCO3 + H+
• Methane + Magnetite → Ethane + Hematite
• Minority view in Russia
• Resurgence among U.S. Right Wing
Petroleum-Bearing Rocks, Utah
Petroleum Traps
Seismic Reflection Profile
Methane
Hydrate
Gas Hydrates
• Hydrocarbons trapped in cage of water
molecules
• Freeze above 0 C under moderate pressure
• Solid gas hydrates occur in marine
sediments (“yellow ice”)
• Potentially huge energy resource
• Possible role in climate change?
Energy Use, California, 1972
Energy Use, California, 1979
Energy Use, California, 1993
Energy Use, California, 1994
Energy Use, California, 2003
All You Need to Know
Economics
• 2000 WINNEBAGO CHIEFTAIN
SERIES M-36LP-DSL
• Average Retail Price: $51,600
• Suggested List: $140,851
• Source: NADAGuides.com (23 April 2010)
• Ten-Year Cost: $89,251
• @$300/day = 297 days = 30 days/year
Planning for the future has longterm benefits
Procrastination pays off Now
An Oil Drilling Bit
“World’s Richest Acre”
Offshore
Oil Rig
Offshore Oil Rig
Offshore Oil Rig
Deep-Water
Oil Rig
(Houston for
Scale)
Anchor Link for Deep Water Rig
Ocean Star, Galveston, Texas
Cutaway of Drill Bit
Soft Rock Bits
Derrick
Pipe Grappler
Drilling Floor
“Christmas Tree”
“Christmas
Tree”
Well Completion
Rocker
Oil Recovery
• Primary: Natural Pressure Forces Oil to Surface
– Recovery Rate 5 – 15%
• Secondary: Pumping and Pressurized Fluids
– Total After Secondary Recovery: 35-45%
• Tertiary: Solvents, Steam, Carbon Dioxide
– Total After Tertiary Recovery: 50-60%
• No Underground Resource Recovery Gets All
of the Resource
Where Does The Oil Go?
Oil Refinery
Where the Oil Is
The Geography of Oil
Why So
Much
Oil?
Hubbert Curves
• In 1956, Oil geologist M. King Hubbert noted that
rates of oil production follow a bell-shaped curve.
• Cumulative production follows a slanting S- curve
• Production lags discovery by about ten years.
Hubbert’s 1956 Prediction
Where We Stand Today
What if We Find More Oil?
• Even a huge
increase in total
oil has very little
effect on the
peak and
decline of
production.
• Why? We waste
most of it on
inefficient uses.
One Solution: Limit Production
Is There a Lot More Undiscovered Oil?
• 80 per cent of oil being produced today is from fields
discovered before 1973.
• In the 1990's oil discoveries averaged about seven
billion barrels of oil a year, only one third of usage.
• The discovery rate of multi-billion barrel fields has
been declining since the 1940's, that of giant (500million barrel) fields since the 1960's.
• In 1938, fields with more than 10 million barrels
made up 19% of all new discoveries, but by 1948 the
proportion had dropped to only 3%.
Oil Discovery Rates
U.S. Petroleum Use
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2009 - 7,121,644,500 barrels
2007 - 6,257,125,000 barrels
2006 - 6,384,780,000 barrels
2005 - 6,470,457,000 barrels
2004 - 6,410,770,000 barrels
2003 - 6,175,244,000 barrels
2002 - 5,945,585,000 barrels
= 19,498,000 barrels a day
= 1 billion barrels in < two months
Global Petroleum Usage
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2008 projection: 87 million barrels/day
= 31.8 billion barrels per year
= 1 billion barrels in 11.5 days
= 1000 barrels/second
U.S. = 25% of total
Oil Fantasies
“America is sitting on top of a super massive
200 billion barrel Oil Field that could potentially
make America Energy Independent and until
now has largely gone unnoticed. Thanks to new
technology the Bakken Formation in North
Dakota could boost America’s Oil reserves by an
incredible 10 times, giving western economies
the trump card against OPEC’s short squeeze on
oil supply and making Iranian and Venezuelan
threats of disrupted supply irrelevant” (Next
Energy News, 13 February 2008)
Realty Check
• 200 billion barrels @ 20 million barrels a
day = 10,000 days = 27 years
• Then what?
• Reality: maybe 10% of the oil is recoverable
with known technology
• The Bakken is a “tight” formation
• Horizontal drilling can increase yields
Canadian Oil Sands
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170 billion recoverable barrels
10 x larger total amount
Current production: 1.2 million barrels/day
Projected production in 2015 = 3 million
barrels per day
• 3 million barrels = 4 hours of U.S.
petroleum consumption
Some Relevant Quotes
The internal-combustion engine used for
automobiles is a fragile device compared with
other prime movers -- even compared with
the internal combustion engines used for
diesel- electric locomotives that have been
known to go over a million miles without
mechanical overhauling.
Some Relevant Quotes
... the energy-system efficiency of the motor car
with petroleum motor fuel is, thus, 5 percent
... no one is proud of this accomplishment -least of all the automotive-design engineers ...
The trouble is, every time the design engineer
manages to save a few BTU it is more than
spent answering the clamor for softer tires, for
radio, for better heaters, more lights, cigarette
lighters and possibly even air conditioning.
Some Relevant Quotes
Histories written a few centuries hence may
describe the United States as a nation of such
extraordinary technologic virility that we
succeeded in finding ways of dissipating our
natural wealth far more rapidly than any other
nation. At any rate, we are having a wonderful
time doing it. From the discussions in the
earlier chapters of this book it is clear that the
problem of energy for the United States is not
one of the dim future. It is upon us now.
Some Relevant Quotes
Our imports of petroleum are small but each
year they become larger. By 1960 they are
likely to be quite substantial. By 1970 they will
almost certainly be huge -- if foreign oil is still
available then in sufficient quantity... This tiny
period of earth's life, when we are consuming
its stored riches, is nearly over ... Fortunately
for us there is still time for fundamental
research [on alternative energy sources]. But
not too much time.
Some Relevant Quotes: Source
Eugene Ayres and Charles A
Scarlott, 1952; Energy Sources -The Wealth of the World,
McGraw-Hill, 344p.
Petroleum is a Syllogism
• There is a finite amount of it in the
world
• We are using it and not replacing it
• Therefore we will eventually run
out of it
• Any of this not clear?
The End of Cheap Oil
• Known petroleum can last at least a couple of
centuries more, but…
• It only flows through the rocks so fast.
• No amount of drilling will make it flow faster,
and careless drilling can shorten the lifetime
of an oil field.
• Sometime in the 21st century, global demand
will outpace production capacity and…
• Oil will go to the highest bidder.