Biofuels Lec 2: Biodiesel-Part 1

Chemical Engineering Department | University of Jordan | Amman 11942, Jordan

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Dr.-Eng. Zayed Al-Hamamre

Biofuels

Lec 2: Biodiesel-Part 1


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Content

Diesel Fuel

Biodiesel

SVO and Oilseed Processing

Production Methods


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Energy Use

• What do we use energy for?

– Heating & Cooling

– Lights, appliances, cooking, household uses

– Manufacturing

– Transportation


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Transportation Fuels

• Two fuels dominate the transportation fuel market:

– Diesel

• Biodiesel can be used to supplement or replace diesel fuel

– Gasoline

• Diesel Fuel Facts

- Widely available

- Diesel engines are common

- Refining and transportation infrastructure is well developed

- Consumers know about diesel


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Diesel Fuel

• Recent Developments

– New diesel fuel standards (low sulfur diesel)

• New diesel burns cleaner (good)

• Lubricity is reduced (bad)

– Retail diesel prices have increased

• Why?

– Demand has been growing

– Refining capacity is strained

– Transportation capacity is strained

– Higher fuel quality standards


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Characteristics of Petroleum Diesel

• Produced from petroleum

• Product of distillation of crude oil

• Amber in color

• Immiscible

• High boiling point of > 300°F (> 149°C)

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Property of DOE, reprinted with permission


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• Low vapor pressure: 0.40 mmHg

• Flash point between 100°F & 160°F (38°C & 71°C)

• Specific gravity between 0.82 & 0.95

• Vapor density > 1

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Characteristics of Petroleum Diesel

• Exposure:

− Irritation to eyes

− Damage to respiratory system

• Class B firesCopyright 2008, TEEX/ESTI


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History of Biodiesel

• Using vegetable oil as fuel in dieselengines isn't a new idea. RudolfDiesel's first engines were built torun on peanut oil in 1892.

• Since then many researches havetaken place to improve theperformance of the biodiesel whenit’s burned in the engine.


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• Alternative Fuel derived from

from renewable sources like new

and used vegetable oils and

animal fats

• Contains no petroleum but be

blended with petroleum diesel

• Produced domestically from

renewable resources

• Biodegradable, Decays in natural

conditions (approximately the

same as sugar);

What is Biodiesel ?


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• Biodiesel can be blended with diesel fuel

o Low-level blends (≤20% biodiesel) can be used in almost any

existing diesel engine

o High-level blends (>20% can be used in most new diesel engines

What is Biodiesel ?

• Biodiesel be produced in small or large quantities

o Small-scale producers generally use vegetable oil

• Nontoxic Fuel; practically does not contain some sulfur

and cancerogenic benzene

• Provides significant reduction in harmful emissions in an atmosphere at burning, both in engines of internal combustion, and in technological units;


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• Lower energy content than Diesel

o Biodiesel: 118,296 BTUs per gallon

o No. 2 Diesel: 129,500 BTUs per gallon• Source: National Biodiesel Board

• Energy Lifecycle

o 3.2 units of energy are produced for each energy unit usedSource: NREL

What is Biodiesel ?

• Only used in diesel engines

• Immiscible


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• Will biodiesel damage my engine?

– No…if the biodiesel meets the standards of ASTM 6751

– One exception:

• Biodiesel can damage certain natural rubber engine components over time

– Older engines may require the replacement of fuel lines and some gaskets

– These components are unlikely to fail immediately but may fail with increased biodiesel use

What is Biodiesel ?


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Characteristics of Biodiesel• Liquid varying in color

• Immiscible

• High boiling point of 360–640°F (182–338°C)

• Low vapor pressure: < 2 mmHg

• Flash point 199°F (93°C)

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• Specific gravity between 0.86 & 0.90

• Vapor density > 1

• Less hazardous in terms of flammability

• Has high temperature of ignition (more than 100 °С), that makes its

use rather safe

• Increases cetane number of fuel and its greasing ability, that essentially increases a resource of the engine;


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Biodiesel-Blended Fuels

• Can be used alone / blended

− B20: 20% biodiesel

− B99: 99% biodiesel

− B100: pure biodiesel

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Property of DOE, reprinted with permission

• Mixing biodiesel fuels:

- At the plant

- Splash mixed in tanker trucks

- Line-mixed


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SVO and WVO

• Straight Vegetable Oil is not biodiesel

– This includes Waste Vegetable Oil

• Diesel engines can be modified to run on vegetable oil

– Some users who have modified engines have reported long term problems using SVO

• Biodiesel can be used in any diesel engine with no modifications to the

vehicle.


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To get a diesel engine to run off of straight vegetable oil a conversion

needs to be done to the vehicle;

o A parallel fuel system is required.

o start the vehicle off of diesel, and once it heats up, the coolant

from the engine can be used to heat the vegetable oil.

o Once the vegetable oil is heated to a certain temperature, and its

viscosity is lower, then can switch to using the vegetable oil.

• Raw vegetable oil requires all sorts of engine, tank, and fuel line modifications

SVO and WVO


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Main Problems:

o These fuels are too thick.

• The must be thinned to function in a diesel engine

−How? By heating or a by chemical reaction (the chemical

reaction is the biodiesel production)

• Problem is worse the lower the temperature

• Modified engines still typically use SVO in conjunction with

diesel for start up and shut down

• No government incentives for SVO and WVO

SVO and WVO


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Types of Oil seeds

• Major U.S. Oilseed Crops

– Soybean

– Cottonseed

– Sunflower

– Canola/Rapeseed

– Flaxseed

– Safflower

• Other oil producing crops

- Corn

- Peanut

- Camelina

– Palm

– Olive

– Coconut


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Crop Ave. Oil Content

Soybeans ≈ 22%

Canola ≈ 40%

Flaxseed ≈ 38%

Safflower ≈ 35%

Sunflower ≈ 42%

Mustard ≈ 36%

Types of Oil seeds


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Oilseed Processing• The Oilseed Processing Industry:

– Separates the “whole seed” into 2 or more products

– The difference between the cost of the seed and the value of the products created is the “crushing margin”

o Two General Methods

• Solvent Extraction

− Standard technology for facilities with daily capacities of greater than

300 tons per day

− Commonly used in conjunction with some form of mechanical

extraction

o Mechanical Extraction

− Typically used for facilities with daily capacities of less than 150 tons

per day


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Simple extraction of materials

Biomass

Extraction

Purification

Usage

Palm oil press


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Solvent Extraction

• Nearly all commercial soybean processors use solvent extraction technology


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• The basic process:

– Seed Preparation

• Removal of foreign objects

• Removal of seed hulls or shells for some seeds

– Pre-Pressing

• Seed is crushed through a mechanical press

– Pre-Pressing removes some oil from high oil content seeds

Solvent Extraction


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– Solvent Application

• Solvent (hexane) is applied to the pre-pressed material

• The solvent bonds to the oil in the material

– Solvent & oil mixture is removed from the meal

– The oil is then separated from the solvent which is reused in the process

Solvent Extraction


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• Benefits:

– Solvent Extraction is capable of recovering of 99% of the oil contained in the seed

– Lowest cost per ton for commercial processing

• Challenges:

– Large capital investment

– Not feasible for small-scale processing

– Environmental concerns

Solvent Extraction


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http://www.organix.net/organix/supercritical.htm

Super Critical Oil Extraction

• Most efficient method.

• Uses carbon dioxide at critical pressure and temperature (CO2 is almost a liquid).

• Carbon dioxide.

• Rapid diffusion of the oil.

• Very expensive process.


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Mechanical Extraction


– Seed Preparation

• Removal of foreign objects

• Removal of seed hulls or shells for some seeds

– Extraction

• Seed is processed by a mechanical press

– Removing 65-80% of oil contained in the seed


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• Required Equipment

– Mechanical Press

– Power source for the press

– Seed Bins

– Meal Bins

– Oil Tanks

– Pumps, Filters, Plumbing

Mechanical Extraction


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Example

• On-Farm Example:

– If you plant 100 acres of canola,

– with an average yield of 1,100 lbs per acre,

– your production is approximately 55 tons

• The 55 tons of seed will yield approximately:

- 4,200 gallons of oil

- 36 tons of meal

* Assuming: The seed has 38% oil content and press recovers 75%

of the oil content in the seed.

Acres : A unit of land area equal to 0.405 hectare .


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• On-Farm Example:

– If you plant 100 acres of safflower,

– with an average yield of 800 lbs per acre,

– your production is approximately 40 tons

Example


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Biodiesel = FAME

• Fatty Acid Methyl Esters (FAME)

• Fatty acids taken from oils or fats

• Reacted with MeOH• Washed, dried to remove

impurities• Must comply with fuel

standards (U.S., European, etc.)

• Variety of blends, from B5 to B100

FAME


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Chemistry of Oils and Fats

• Fatty acids are long-chain carboxylic acids

• A glycerol bonded to 3 fatty acids is called a triglyceride

• Oils/fats contain triglycerides and unbonded, or free, fatty acids (FFA’s)

A Fatty Acid

A Triglyceride


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Biodiesel Production Process

Source: Brent Schulte, University of Arkansas. Biomass Magazine April 2008.


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Production Methods

1. Direct use and blending

simplest method, 80% of petroleum heat content, ready available feed stock, viscosity too high, reactivity of unsaturated hydrocarbons

2. Micro emulsions

Utilizes alcohol solvents to reduce viscosity, causes carbon and laquer deposits on engine parts

3. Thermal cracking

Yields both biodiesel and gasoline, biodiesel produced similar to petroleum, negates emissions benefits


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Production Methods

4. Transesterification

– Most common production method

– can be used as a continuous process, more easily meets biodiesel fuel standards, expensive alcohol catalyst

– Uses vegetable oils and animal fats as feed stocks

– The reaction of a fat or oil with an alcohol to form esters (biodiesel) and glycerol


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• Most common process

• Most economical

• Low pressure (20psi)

• Low temperature (150oF)

• No intermediate steps

• High conversion rate (98%)

Base-catalyzed Transesterification


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Base-catalyzed Transesterification

• Possibility of formation soap if there is a high free fatty acids (FFAs)content in triglycerides.

• Excessive water can hydrolyze to form FFAs.

• Recycling of catalyst is challenging and not cost effective.

• Glycerol is in the crude form and has very little value.


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Transesterification

• First observed in 1850’s

• One main reaction for biodiesel production

• Exchanges an ester’s functional group

• Must be catalyzed, either base or acid

• R’ (below) is methyl, and it replaces glycerol group

• Viscosity is reduced significantly

Transesterification


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Schematic of the Transesterification process

Biodiesel 100%

Glycerin


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Transesterification Reaction

Catalyst (KOH)

Biodiesel

GlycerolMethanol

Fatty Acid Chain

Glycerol

Triglyceride


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Free Fatty Acids Interfere With Biodiesel Production

Catalyst (KOH)

Soap

Glycerol

Methanol

Glycerol

Free Fatty Acid

Methanol


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Formation of Soap

• Formation of soap inhibits the separation process and alsodeactivate the catalyst.

Source: Gerpen et al., 2004. Biodiesel Production Technology


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Hydrolysis of Triglycerides

• At high temperature, water can hydrolyze triglycerides andform free fatty acids (FFAs).



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• Acid catalyzed transesterification is very slow compared to base-catalyzed transesterification.

• Suitable for oil that has higher FFAs.

• This process uses strong acid to catalyze esterification of the FFAsand transesterification of triglycerides.

• The process does not produce soap with high FFAs because no metalis present.

• Esterification of FFAs is generally faster but produces water.

Acid-catalyzed Transesterification



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Enzyme-Catalyzed Transesterification

• Use enzymes to produce esters from triglycerides.

• Relatively longer period of reaction.

• Expensive to produce because of the cost of enzymes.

• No commercial plant using enzymes to produce biodiesel.

• Catalyst separation issue can be solved easily.


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• Liquid is defined as supercritical when its temperature and pressureare above critical points.

• Supercritical temperature and pressure for methanol are 240 oC and1140 psia, respectively.

• No Catalyst is required but can be used.

Supercritical Transesterification


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Biodiesel Feedstocks

Traditional The most common form of Biodiesel is that made by the transesterification of vegetable oils

• In the US, soybeans provide the most common feedstock

• In Europe, rapeseed [canola] provides the most common feedstock

Other Common Feedstocks

• Sunflower oil is commonly used in France and Eastern Europe

• Palm Oil is common in Malaysia

• Used cooking oil is quickly becoming a common feedstock

• Tallow is also becoming common and contains highly Saturated Fatty Acid Triglycerides.


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Feedstock Selection

Material FFA Content Cost

Refined oils (soybean, etc.)

0 - 1% High

Waste oils (fry grease) 2 – 7 % Low

Animal fat (lard) 5 – 30 % Low

Yellow grease 7 – 30 % Moderate

Brown grease > 30 % Very Low

Source: Kemp, William H. “Biodiesel Basics and Beyond.” p. 108


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Effect of Water Content and FFA

Source: Ayhan Demirbas, 2008. Biodiesel: a

realistic fuel alternative for diesel engines


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High FFAs Feedstocks

• Put excess catalyst to form soap and soaps are stripped usingcentrifuges (“caustic stripping”).

• Acid-catalysis followed by base-catalysis process.

• Acid catalyzed transesterification.


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Procedure for High FFA Feedstocks

• Measure FFA level.

• Add 2.25 g methanol and 0.05 g sulfuric acid for each gram offree fatty acid in the oil or fat.

• Agitate for one hour at 60-65ºC.

• Let the mixture settle. Methanol-water mixture will rise to thetop. Decant the methanol, water, and sulfuric acid layer.

• Take bottom fraction and measure new FFA level.



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Catalyst Selection

• Acid or base catalyst• Base is faster, more economic• With high FFA, base catalyst will produce soap• Base catalyst also produces glycerol as coproduct• Acid catalysis can fix the soap problem• Most commercial processes use base catalysis


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Methanol Vs. Ethanol

• Ethanol is more expensive than methanol.

• Lower ethyl ester conversion.

• Ethanol is difficult to recycle.

• Viscosity of the ethyl ester is slightly higher than that of methyl ester.

• Cloud and pour points are slightly lower than that of methyl ester.


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1. Oil Extraction or Clean and heat biolipid (WVO )

2. Titration the WVO sample. (Optimal PH7)

3. Determine the Amount of Methanol and Catalyst

4. Mix the bioalcohol and catalyst in exact amount

5. Combine methanol/caustic with biolipid at 50 C, mix and heat for several hours (Transesterification Process)

6. Separate biodiesel and glycerol and remove (recovery) alcohol

7. Crude Biodiesel Purification

Production


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• Pre-Reaction Equipment

– Oil Storage Tank

– Alcohol Storage Tank

– Catalyst Storage

– Biodiesel “Reactor”


Production


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• Post-Reaction Equipment

– Settling tanks and/or Separating Equipment

– Washing Equipment

– Drying Equipment

– Biodiesel Storage Tank

– Glycerin Storage Tank


Production


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Micro Scale Biodiesel Processor

(100 gallons or less per batch)Small Scale Biodiesel Processor

(75-300 gallons or less per batch)

Biodiesel Processor


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Commercial Processing Unit for Home Made Biodiesel


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Biodiesel Processor

• Processing 4,200 Gallons

– 40 gallon processor: 105 batches



Industrial Biodiesel System 40.000 ton/year – Client: Brasil Ecodiesel


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20 May, 2006 2006 Eastern Biofuel

Industrial Biodiesel System 100.000 ton/year – Client: Brasil Ecodiesel


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Production


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Final Products

• Biodiesel

– On-Farm Use

• Blended Fuels

• Fuel Quality Important

• Vehicle Modifications

– May need to replace natural rubber fuel lines and gaskets

100 lbs. of Soybean oil +10

lbs Methanol

=

100 lbs. Soy biodiesel

+10 lbs of Glycerol


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• Crude Glycerin

– No Ready Market for Crude Glycerin

– Quantity produced is 10% to 20% of biodiesel production

– Contains Methanol & Catalyst

– Possible Uses:

• Compost

• Fuel Oil

• Refine to Pharmaceutical Grade Glycerin

Final Products


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Biodiesel – Final Product


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Biodiesel 100%

Glycerin


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BioDiesel is here



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Washing and Drying


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• Compared to petroleum diesel, reduced emission of:

--Unburned hydrocarbons

--Carbon monoxide

--Particulate matter

--Sulfur oxides

• Overall ~50% less than that for diesel fuel

Biodiesel Emissions


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• Biodiesel reduces most problematic emissions

• NOx (greenhouse) emissions are increased

• Led to regulatory problems with TCEQ

• Can be addressed with NOx reducing additives -70%

-60%

-50%

-40%

-30%

-20%

-10%

0%

10%

20%

0 20 40 60 80 100

Percent Biodiesel

Ch

ang

e in

em

issi

on

NOX

PM

CO

VOC

Source: U.S. EPA

Biodiesel Emissions


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Think about the environment

Biodiesel Emissions


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Biodiesel Emissions


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Biodiesel Advantages

• Produced from renewable materials – eco friendly / closed CO

cycle.

• Local & self production – less reliance on foreign oil.

• Contains practically no sulfur (0.001%) – non toxic.

• Considerably decreases emissions (up to 50%).

• Easily decomposes – does not harm soil or ground water.

• Biodiesel is not hazardous material (flashpoint above 110°C).

• Eligible as fuels under international standards & specifications

(world-wide).

• Eligible for CDM (Clean Development Mechanism - Kyoto Treaty)


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• High energy return and displace petroleum based fuels.

• Biodiesel reduces life-cycle greenhouse gas emissions.

• Biodiesel reduces tailpipe emissions except NOx.

• Biodiesel improves air quality and has positive impact in humanhealth.

• Biodiesel improves engine operation and easy to blend.

Source: NREL , 2008. Biodiesel Handling and Use Guide

Biodiesel Benefits


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Biodiesel Drawbacks

• Biodiesel can be corrosive to rubber materials.

• Biodiesel cannot be stored in concrete lined tanks

• Biodiesel is not necessarily more economic than regular diesel. Depend on the plants, their related processes and, other incentives.

• Biodiesel can last up to 6 months. In 6-12 months need to be treated.


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Biodiesel Storage

• Biodiesel should be stored 5-10 degrees F above cloud point.• Above ground fuel systems should be protected with insulation,

agitation, heating systems, or other measure.

Test Method

CloudPoint

ASTM D2500

Pour Point ASTM D97

Cold Filter Plug Point

IP 309

B100 Fuel oF oC oF oC oF oC

Soy Methyl Ester 38 3 25 -4 28 -2

Canola Methyl Ester 26 -3 25 -4 24 -4

Lard Methyl Ester 56 13 55 13 52 11

Edible Tallow Methyl Ester 66 19 60 16 58 14

Inedible Tallow Methyl Ester 61 16 59 15 50 10

Yellow Grease 1 Methyl Ester -- -- 48 9 52 11

Yellow Grease 2 Methyl Ester 46 8 43 6 34 1


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Biodiesel Transportation

• Should not be contaminated

• Trucks or railcars should be washed from previous load to prevent mixing with leftover residuals or water.

• In cold weather can be shipped in several ways

– Hot for immediate delivery (80-130 F)

– Hot (120-130 F) in railcars for delivery within 7-8 days

– Frozen in railcars equipped with steam coils

– Blended with winter diesel, kerosene or other low cloud point fuel

Documents

Biofuels Lec 2: Biodiesel-Part 1