The Problem
Topic 4: Energy, Chemistry, and Society
The US, and most of the world, operates
in a petroleumpetroleum-based economy.
economy.
We depend of fossil fuels to meet our
energy needs, and without them, life as
we know it would cease to exist.
But the earth is rapidly exhausting its
fossil fuel supply.
Economic and Political Impact
of Petroleum Dependence
We spend $470,000 per minute (or $250
billion per year) on foreign oil.
z We use ~26 million barrels per day (about
3 gallons per day per person). ~ 60% is
imported oil.
z "We have a serious problem. America is
addicted to oil, which is often imported
from unstable parts of the world," State of
the Union 2006 President George W. Bush
z
Economic and Political Impact
z
"The energy abundance on which this nation
was built is over."
z
The balance of supply and demand "has
become so precarious that even small acts of
sabotage or local insurrection have a
significant impact on oil prices."
z
"Oil in the years ahead will remain an
important element of our energy future, but it
need no longer be the dominant player."
Economic and Political Impact
z
Alan Greenspan previously testified before
the Senate Foreign Relations Committee
on the world oil market and agricultural
sources of alternative fuels.
z
Quotes:
Environmental Impact
Most of this oil is combusted. The combustion
releases CO2 which contributes to global
warming since the plants that formed the fossil
fuel have been out of the carbon cycle for
millions of years.
1
II. Definitions
II. Definitions
z
TemperatureTemperature- measures the average speed
of molecules in an object.
z
3 scales: oF, oC, or K
IV. Energy from Reactions
Scenario I: The product has less E than
reactant
z
Energy (E)(E)- the ability to do work
z
WorkWork- movement against a force
III. Energy Sources/Conversion
Remember the 1st Law of Thermodynamics.
IV. Energy from Reactions
Ex. Hydrocarbon fuels like methane (CH4) burn in the
presence of oxygen to produce carbon dioxide and water.
The potential energy of the fuel is released in this
exothermic reaction called combustion.
2
IV. Energy from Reactions
Scenario II: The product has more E than
reactant.
The E difference is heat
absorbed by rx.
V. Jump-Starting a Reaction
Activation energy: E needed to initiate a rx
*higher act E = harder to initiate = slower
*Catalysts speed up rx by lowering Eact
E
rx
VI. ExplosivesExplosives-Brief Background
Properties of Gases
z Adding energy (heat) increases the
velocity of gas molecules and thus their
volume.
VI. ExplosivesExplosives-Brief Background
Why Explode? A Reaction Coordinate:
E
rx→
rx→
VII. Terrorist Bombs
53% increase from 19901990-1994!
z
VII. Terrorist Bombs
Theory: produce/expand enough gas to
cause damage
Material must meet requirements for explosives
Prevention?
3
VII. Terrorist Bombs
VII. Terrorist Bombs
Taggants:
Taggants: in theory help track down perpetrator
Taggants:
Taggants: Controversial
Microscopic plastic chips of layered colors
1970’
1970’s: US develops pilot program. Decide cost of
implementation and possible stability questions
outweigh benefits.
VIII. Calculating E Released/Absorbed
Heat of combustion:
combustion: the amount of heat
released during a combustion reaction.
z
Depends on the potential energy of fuel.
(how tightly molecules are held together)
VIII. Calculating E Released/Absorbed
VIII. Calculating E Released/Absorbed
Example: Propane (C3H8) has a heat of
combustion of 46 kJ/g.
Example: Propane (C3H8) has a heat of
combustion of 46 kJ/g.
A. How much E is released when 5 g
propane burns?
A. How much E is released when 5 g
propane burns?
5 g C3H8 x 46 kJ
= 230 kJ
1 g C3H8
4
VIII. Calculating E
Released/Absorbed
B. How much E is released when 5 mole
propane is burned?
VIII. Calculating E
Released/Absorbed
C. How much E is produced when enough
C3H8 is burned to release 1 mol CO2?
History of U.S. Energy Consumption by Source 1800-2000
IX. Types of Fuels
1 EJ = 1018 J
IX. Types of Fuels
4.5
IX. Types of Fuels
A. Coal
a mixture of compounds
z mainly C and H, but some N, O, and S
z
5
IX. Types of Fuels
IX. Types of Fuels
A. Coal
3 Types of Coal
z anthraciteanthracite- high ΔHcomb, hard, little S,
running out
A. Coal
z
Pros
Globally more coal
than oil
IX. Types of Fuels
Cons
zEnvironmental
damage?
zMiner Safety
IX. Types of Fuels
B. Petroleum
Over 87% of each 45 gallon barrel is used for transportation and heating.
B. Petroleum
z wide range of products obtained from
crude oil by distillation
This 1.25 gal
includes
nonrenewable
feedstocks for
all plastics,
pharmaceuticals,
fabrics and other
carbon-based
products.
Moonshine
Ingredients:
Ingredients:
One of the
drawbacks to
petroleum is
that it must
be refined (or
distilled)
before use.
1.
2.
3.
Grain or some source of carbohydrate
Water
Yeast (contains catalytic enzymes)
These three things yield a “sour mash”
mash”. Need to
concentrate ethanol.
4.8
6
IX. Types of Fuels
B.
z
Petroleum – from where does the U.S. import it?
Petroleum
Pros
More E/g than wood
or coal
Cons
•Import politics
•Cost of distillation
2005: U.S.
consumption was
almost 22 billion
barrels A DAY.
Over 60% of it was
imported.
The U.S. has 5% of the
world’s population, yet
consumes 25% of the oil
produced worldwide.
4.7
REVIEW
IX. Types of Fuels
Most of this oil is combusted. The combustion
releases CO2 which contributes to global
warming since the plants that formed the fossil
fuel have been out of the carbon cycle for
millions of years.
C. Ethanol
Note: the more oxygen a molecule contains,
the lower its heat of combustion
IX. Types of Fuels
C.
z
z
Pros
domestic
Cheap?
Ethanol
Cons
zLower mpg than
gas
D. Biodiesel
A domestic, renewable fuel for diesel engines
derived from natural oils like soybean oil
produced through transesterification (
↓viscosity). Vegetable oil reactant may have
been previously used for cooking.
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Economic and Political Impact
D. Biodiesel
z
What impact can biodiesel have?
z
Benefits of Biodiesel
Biodiesel Production: transesterification
z
z
z
z
z
z
z
-78.3% greenhouse gases
-55.4% particulates (soot)
-56.3% hydrocarbons
-8080-90% cancercancer-causing agents
-100% reduction of sulfurs (a major
component of acid rain.)
+5.8% increase in NOX emissions
If 5% (1.85 billion gallons) of the 37 billion gallons of
road use diesel were replace with biodiesel this would
equal the amount of oil imported from Iraq. National Biodiesel Board
Vegetable oil + methanol Æ FAME + glycerin
HEAT
Plant or animal oil
+
METHANOL
BIODIESEL
+
GLYCERIN
METHOXIDE
CATALYST
WFU has a Biodiesel CoCo-Op. Email
[email protected]
if interested.
IX. Types of Fuels
E.
z
z
Pros
domestic
Cheap?
Biodiesel
zLower
Cons
mpg than
gas
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