Module 3: BioFuels
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Sustainable Energy Workshop for Science and Technology Teachers (SEWFSTT)
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 Carbon-Neutral 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– Pollution: By-products of combustion
» CO, CO2, NOx, SOx ---- and more!
• Carbon-neutrality
South Korean oil spill (2008)
NOx concentrations over Europe
Construction of a refinery run-off barrier
Ground level Ozone
BioEthanol
• Gasoline substitute favored by US
• Produced by sugar fermentation• Clear, colorless liquid
• 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
OHHCalcoholethylEthanol 52)(
How can it be high octane if
octane is
CH3(CH2)6CH3
Ethanol from Corn
Only a small portion of the starch present in the corn is useful for producing Ethanol
(Overview)
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
• 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.
Alton Brown’s TV show Good Eats (Food Network) does a great job at
teaching about chemistry
5106 OHC
Macromolecule
amorphous, insoluble in water, no sweet taste
Monosaccharides: simple sugars(e.g. glucose)
Ethanol from Corn
Cooking/Fermentation
• Starches converted to simple sugars: fructose, glucose, sucrose, etc.
• Saccharification (enzymes)
Starch Sugar
Glucose, Sucrose, Fructose, etc.
• 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
(power-houses for many biological systems)
6126 OHC 112212 OHC
Ethanol from Corn
Cooking/Fermenting
• Sugars digested – Ethanol waste product
• Fermentation (yeast)
Sugar Ethanol
Fermentation
• Yeast (a variety of sources possible)
– Enzymatic– Anaerobic process– Temperature and PH dependent
(metabolic waste products)
Yeast is a Fungus (budding)
glycolysis
Pyruvate
Glucose
Acetyldehyde
Ethanol
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)
– 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)
The logo from e85tips.com
Combustion of Ethanol
Air is not pure oxygen
Waste products can also include nitrous oxides (NOxs)
Simple fuel – Simple reaction
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
Combustion of Gasoline
Calorimetry ExperimentsBomb/Combustion Calorimeter needed
Can determine the molar heat of combustion for any number of fuels
Energy Density of Ethanol
Biodiesel is standard in Europe
100% Ethanol = 24 MJ/LMJ = mega-Joule = 1 x106 J of energy
BioGas
• Landfill Gas– Network of buried pipes – capped landfill– Captures methane and directs it to purification
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
Existing and planned U.S. corn processing plants (8/30/06).
Iowa corn processing and ethanol plants, current and planned (10/26/06).
(3.8 billion liters) of ethanol a year
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.
PipelineA 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
+ +
PipelineA 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’