2. BIOETHANOL
Bioethanol has a number of advantages over conventional fuels. It comes from a renewable
resource i.e. crops and not from a finite resource. Another benefit over fossil fuels is the
greenhouse gas emissions. Also, blending bioethanol with petrol will help extend the life of
diminishing oil supplies and ensure greater fuel security, avoiding heavy reliance on oil
producing nations. By encouraging bioethanol’s use, the rural economy would also receive a
boost from growing the necessary crops. Bioethanol is also biodegradable and far less toxic that
fossil fuels. In addition, by using bioethanol in older engines can help reduce the amount of
carbon monoxide produced by the vehicle thus improving air quality. Another advantage of
bioethanol is the ease with which it can be easily integrated into the existing road transport fuel
system.
Bioethanol is an alcohol made by fermenting the sugar components of plant materials and it is
made mostly from sugar and starch crops. With advanced technology being developed, celluosic
biomass, such as trees and grasses, are also used as feedstocks for ethanol production. Ethanol
can be used in petrol engines as a replacement for gasoline; it can be mixed with gasoline to any
percentage. Most existing car petrol engines can run on blends of up to 15% bioethanol with
petroleum/gasoline. Ethanol has a smaller energy density than gasoline, which means it takes
more fuel (volume and mass) to produce the same amount of work. An advantage of ethanol
(CH3CH2OH) is has a higher octane rating than ethanol‐free gasoline available at roadside gas
stations which allows an increase of an engine's compression ratio for increased thermal
efficiency.
3. Market potensial and co produce chemicals
The market potential for bioethanol is not just limited to transport fuel or energy production
but has potential to supply the existing chemicals industry. A number of chemicals are
produced in the ethanol industry serving a wide range of uses in the pharmaceuticals,
cosmetics, beverages, and medical sectors as well as for industrial uses.
Co‐produce the following chemicals along with fuel ethanol :
1. Acetaldehyde (raw material for ether chemicals e.g. binding agent for paints and dyes)
2. Acetic acid (raw material for plastics, bleaching agent, preservation)
3. Ethyl acetate (paints, dyes, plastics, and rubber)
4. Ethanol 95 % (foods, pharmaceuticals, fuel ethanol, detergents)
5. Thermol (cold medium for refrigeration units and heat pumps)
6. Ethyl alcohol (spirits industry, cosmetics, print colours and varnish
7. Isopropyl alcohol (IPA) (cleaning agent for electronic device, solvents)
INTRODUCTION TO BIOETHANOL PRODUCTION UNIT
Ethanol is produced from biomass by hydrolysis and sugar fermentation processes.
• Biomass is pretreated with acid and enzyme to produce sugar.
• Sugar is then fermented into ethanol.
• Ethanol produced contains a significant amount of water, which is removed by using the
fractional distillation process.
4. REACTION STEPS
1. Hydrolysis reactor: the feedstock is heating (190°C) at high pressure (12.1 atm)
with an acid catalyst (H2SO4). Most of the hemicellulose is converted to xylose.
2. Saccharification reactor: an enzymatic reaction occurs, which converts most of
the cellulose to glucose.
3. Fermentation reactor: most of the glucose and the xylose are converted to
ethanol and carbon dioxide.
Process Flow Diagram of the Process Development Unit
Depending on the biomass source the steps generally include :
1.Storage 6. CO2 storage and ethanol recapture
2.Cane crushing and juice extraction 7. Evaporation
3.Dilution 8. Distillation
4.Hydrolysis for starch and woody bio 9. Waste water treatment
5.Fermentation with yeast and enzim 10.Fuel storage
5. Material Compatibility
Corrosive chemicals can be a large problem for a lot of these plants and storage. It is important
to understand that biofuels have significantly different characteristics from petroleum gasoline
and diesel. Higher percentage ethanol blended fuels do not have the same compatibility
characteristic of conventional fuels when it comes to storage and dispensing.
Bioethanol is electrically conductive and that => corrosivity
Ethanol blends are subject to “phase separation” which create corrosive condition *)
Bioethanol swells some elastomer 100% ‐, hardness and tensile strength may decrease and
then suddenly fails catastrophically
Water contamination makes bioethanol more aggressive (water facilitates electrical
conductivity, water accelerates oxidation, water may contain corrosive contaminants)
Bioethanol is more aggressive in acidic condition
Bioethanol is a solvent that attacks elastomers
(source : UST (under ground storage tank )CONVERSION FOR STORAGE AND DISPENSING OF BIOFUELS
www.waterboards.ca.gov)
Metallic materials : soft metals such as zinc, brass or alumunium, which are commonly found in
conventional fuel storage and dispensing system, are not compatible.
*) Picture :
phase separation in a steel (80 – 88% ethanol
(ethanol‐water phase in bottom of the tank
Source : www.waterboards.ca.gov
6. Ethanol can accelerated corosion in steel system by scouring or loosening deposits on the
internal surfaces of the tank and piping. If an area of corrosion exists, the ethanol can accelerate
(scour) the corroded area and cause perforation. Soft metals such zinc, brass, copper, lead and
alumunium these metals will degrade or corrode which may damage engine‐parts and may
result in poor vehicle driveability. Even if parts do not fail, running an ethanol‐fuelled vehicle
with contaminated fuel may cause deposits that could eventually harm the engine.
Nonmetallic material that degrade when in contact with fuel ethanol include natural rubber,
polyurethane, cork gasket material, polyvinylchloride (PVC), polyamides, methyl‐metaacrylates
plastics, polyester‐bonded fiberglass laminates.
PVDF Compatible plastics material with Bio Fuel
• PVDF exhibit low permeation levels to most fuel while still having good dimensional
stability and having low weight gain
• PVDF are one of the best resins you can use over a wide range of fuels
‐ Nylon physical properties deteriorate and permeation levels become high with high levels
of ethanol in fuel
‐ HDPE where performance deteriorates with higher toluene and iso octane concentration
• Biofuel is often not stabilized have a larger effect on materials that don’t have as broad of
a range of chemical resistance as PVDF resins. PVDF resistance to fuel mixture such as –
bio diesel, aromatic hydrocarbons, aliphatic hydrocarbons and alcohols
• PVDF have outstanding retention of its physical properties in fuel service and can give
extended service life when compare to other materials
• PVDF can withstand to high temperature –short term 150°C and continuous to 140°C
(length of service depends on contact time and chemical mixture involved)
7. Study :
No change in dimension after immersion No change in weight after immersion
at 40⁰C in biodiesel at 40⁰C in biodiesel
Graphic : PVDF gain is minimal (<0,1%) in Diesel and Biodiesel fuels for a period of 16 weeks
Kynar resins (PVDF) shows excellent resistance to biodiesel blends. PVDF immersed up to 3000 hrs in biodiesel
blends at 40°C, have seen no loss of physical properties minimal length change and minimal swelling. PVDF
repels diesel, biodiesel and their blends. (Source:fueling containment system www.arkema‐inc.com)
Typically plastics materials such as polyethylen will swell in presence of gasoline and diesel. Long‐term exposure
results then in a loss of the mechanical resistance of these plastics. Because of these fluoropolimers nature
PVDF does not absorb diesel and keep its strength and physical properties.
