Transcript Fuel Cells

Sustainable Energy Workshop for Science and
Technology Teachers (SEWFSTT)
Module 3:
BioFuels
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BioFuels
What are BioFuels?
• Petroleum – Crude Oil
– Mixture of hydrocarbons
• Longest – Paraffin wax
• Shortest – Natural gas
• Contaminants
– Sulfur, nitrogen,
etc.
– High energy density
– Liquid or Semi-Solid forms
• BioFuels
– General term for a variety of
fuels generated from biomass
• Solids: Wood, Coal
• Liquids: Biodiesel, Bioethanol
• Gases: Biogas, Bio-Hydrogen
The
CarbonNeutral
BioFuel
Cycle
Carbon neutral –
omits carbon rich
fuels that have
been sequestered
BioFuel Types
• First Generation
(NOW)
– ‘Farmed’ fuels
– Biodiesel
• Transesterfication of vegetable oils
– Bioethanol
• Fermentation process
– Biogas
• Recaptured from landfill
• Second Generation
(soon?)
– Less resource intensive feedstock
– Cellulosic ethanol
– Synthetic fuels from gasified
biomass
– Micro algae
Liquid Bio-Fuels
• Liquefied Coal
• BioEthanol
• BioDiesel
Cost prohibitive
Not carbon-neutral
Policy – Politics  Energy Chain
Petroleum Issues
• Discharge to Environment
• Resource Availability
• Combustion
Construction of a
refinery run-off barrier
– Pollution: By-products of combustion
» CO, CO2, NOx, SOx ---- and more!
• Carbon-neutrality
South Korean oil spill (2008)
NOx concentrations over Europe
Ground level Ozone
Energy Generation Combustion
Combustion includes thermal, hydrodynamic, and chemical processes
BioEthanol
Ethanol(ethyl alcohol) C2 H5OH
• Gasoline substitute favored by US
• Produced by sugar fermentation
• Clear, colorless liquid
How can it be
high octane if
octane is
CH3(CH2)6CH3
• High octane: increased engine efficiency &
performance
• Lower energy content than gasoline
– More fuel needed to travel equal distances
• Can be produced from a number of fuel sources
– Corn, waste straw, willow and poplar trees
– Future Goal: municipal solid waste, algal production
Ethanol can be produced from a
variety of sources
Corn
Poplar chips
Sugarcane
Switchgrass
(Overview)
Ethanol from Corn
Only a small portion of the starch
present in the corn is useful for
producing Ethanol
(Overview)
Ethanol
from
Corn
Ethanol
from Corn
Feed grain processing
• Increase surface area
for reactions
• Remove cellulosic
material – pure starch
• Slurry: piped through
processing plant
Corn
Starch
Starch vs. Sugar
C6 H10O5
amorphous, insoluble in water, no sweet taste
Macromolecule
•
Starch is a polysaccharide carbohydrate consisting of a large number of glucose
monosaccharide units joined together by glycosidic bonds.
– All plant seeds and tubers contain starch which is predominantly present as amylose and
amylopectin.
Monosaccharides:
simple sugars
(e.g. glucose)
Alton Brown’s TV show Good Eats
(Food Network) does a great job at
teaching about chemistry
Ethanol
from Corn
Cooking/Fermentation
• Starches converted to
simple sugars:
fructose, glucose,
sucrose, etc.
• Saccharification
(enzymes)
Starch
Sugar
(power-houses for many biological systems)
Glucose, Sucrose, Fructose, etc.
C6 H12O6
C12 H 22O11
• Saccarification (Hydrolysis)
•
Hydrolysis is a chemical reaction or process in which
a chemical compound is broken down by reaction
with water.
•
Cellulase refers to a class of enzymes produced
chiefly by fungi, bacteria, and protozoans that
catalyze the cellulolysis (or hydrolysis) of cellulose
Glucose: monosaccaride
with 6 carbons in a cyclical
structure
Ethanol
from Corn
Cooking/Fermenting
• Sugars digested –
Ethanol waste product
• Fermentation (yeast)
Sugar
Ethanol
Fermentation
(metabolic waste products)
• Yeast
(a variety of sources possible)
– Enzymatic
– Anaerobic process
– Temperature and PH dependent
Glucose
glycolysis
Pyruvate
Yeast is a Fungus (budding)
Ethanol
Acetyldehyde
Ethanol
from Corn
Extraction/Distillation
• “Beer” = 8-12% ethanol
• Separate Ethanol
• Increase purification
Ethanol+
Ethanol
Ethanol
from Corn
Extraction/Distillation
• “Beer” = 8-12% ethanol
• Separate Ethanol
• Increase purification
Clean-Up + Reuse ByProducts
E85/E10
• Ethanol increases the octane of fuel
• E10 – 10% ethanol blend (gasohol)
The logo from
e85tips.com
– Cars can run on up to 10% ethanol without
needing modifications
• E85 – 85% ethanol
– Only certain cars can run with this blend
• Changing a car to E85 is not as simple as
it seems (MotorTrend segment)
Activity: Ethanol Production
• BioEthanol generator demonstration
Combustion of Ethanol
Combustion of
Ethanol
Air is not pure oxygen
Simple fuel – Simple reaction
Waste products can also include nitrous oxides (NOxs)
Combustion of Gasoline
1. Hydrocarbons: this class is made up of unburned or partially
burned fuel (smog +toxic).
2. Nitrogen oxides (NOx): generated when nitrogen in the air
reacts with oxygen under the high temperature and pressure
conditions inside the engine. (smog + acid rain)
3. Carbon monoxide (CO): product of incomplete combustion
4. Carbon dioxide (CO2): an increasing concern as its role in
global warming as a greenhouse gas
5. Particulates: micron sized particles
6. Sulphur oxide (SOx) general term for oxides of sulphur,
mostly sulfur dioxide and some sulfur trioxide
Calorimetry Experiments
Bomb/Combustion Calorimeter needed
Can determine the molar heat of
combustion for any number of fuels
Activity: Energy Density of Ethanol
Energy Density of Ethanol
100% Ethanol = 24 MJ/L
MJ = mega-Joule = 1 x106 J of energy
Biodiesel is standard in
Europe
BioGas
• Landfill Gas
– Network of buried pipes – capped landfill
– Captures methane and directs it to purification
BioGas
• Agricultural Resources
• Large-scale farms
– Manure digesters (living systems)
BioGas Production Experiments
• Methane production
– Fermentation of … most anything
– Timeline: Weeks-to-Months
– Bacteria – anaerobic
• Manure is a good source …. Mmmm
• Safety concerns
Carbon-dioxide first
Methane later
Where is Ethanol produced
• U.S. – Ethanol from Corn
– Iowa, Illinois, Minnesota, Nebraska
• Brazil – Ethanol from Sugarcane
• Vehicles there have been running on 100% ethanol
for decades
Iowa corn processing and ethanol plants,
current and planned (10/26/06).
(3.8 billion liters) of ethanol a year
Existing and planned U.S. corn processing plants (8/30/06).
Local Production, Local Consumption?
Harvest – Ship to Processing – Processing – Ship to
Corrosion Issues
• Alcohols are more conductive
than gasohol - acts as an
electrolyte and promotes
galvanic corrosion
• Materials affected: brass, zinc, lead,
and aluminum.
• Corrosion products can damage or
block fuel system components
• Plastics and rubber
components degrade in the
presence of ethanol as well
Gasohol (1970's) bad press - complaints about engine problems, corroded fuel lines, etc.
Pipeline
A number of clues have arisen indicating a problem (area for research and development)
with increased ethanol use …..
Pipeline = Most Efficient Transport/Delivery System
+
Video mentions close proximity of
ethanol plant to natural gas
pipeline …. But focuses on rail and
truck in its content
+
Pipeline
A number of clues have arisen indicating a problem (area for research and
development) with increased ethanol use …..
•Water affinity problem
• Ethanol is water soluble
• Water accumulation in pipelines is normal
•Ethanol-related corrosion problems
• Result from how ethanol behaves in the pipe
• Lead to various forms of corrosion
• internal stress
• corrosion cracking
• Damage is accelerated at weld joints
We are still finding some of these things out --- and developing “fixes” as we go ...
Hallmark of BioFuels: Debate
Is it worth it? Are there other complicating issues? Are there other options?
Competition with Food Resources
• Being a ‘farmed’ fuel,
biofuels compete with
food supply
• Increased demand for
arable land
• Conversion of crops to
corn
• Increased cost of corn
propagates through
markets
One of the many issues associated with BioFuels that is currently ‘hot’
CO2 Payoff Questions
Hidden Costs
Fossil Fuel Requirements for Farming, Transportation of Materials ,etc.
Cellulosic Ethanol Production
Goal: Cellulosic Ethanol  10x