Fuel Life Cycle

• Determine low lipid content cut-off where biodiesel production is unfavorable

• Perform techno-economic analysis on biodiesel from trap grease

• Analyze FER sensitivity to allocation methods for co-products

• Optimize distillation conditions to reduce sulfur content, producing ASTM

biodiesel

Proposed System to Integrate Biodiesel Production

Introduction

Megan E. Hums1, Colin J. Stacy1, Dr. Richard A. Cairncross1, Dr. Sabrina Spatari2

Drexel University, 1Chemical and Biological Engineering & 2Civil, Architectural, and Environmental Engineering 3141 Chestnut St. Philadelphia, Pennsylvania 19104: megan.e.hums@drexel.edu

Conclusions

Feasibility and Environmental Impacts of the Production of Biodiesel from Grease Trap Waste

Biodiesel is a renewable fuel that can be produced from a variety of vegetable oils, animal fats, and waste greases. We utilize fats, oils, and greases (FOG) from commercial kitchen wastewater and convert it into biodiesel. Research at Drexel has demonstrated the technical feasibility of production of biodiesel from FOG; however, commercial feasibility is limited by the variability of its lipid content, which ranges between 2-30%, by volume. This poster presents a process for conversion of FOG to biodiesel.

• GTW-to-biodiesel is competitive with alternative biodiesels and low sulfur diesel

• Producing biodiesel under 10% lipid content is unfavorable due to process steam

requirement to separate lipids from grease

• Trap grease biodiesel FER is more favorable than soybean biodiesel >15% lipids

Acknowledgments Russell Reid * United States Department of Agriculture * Philadelphia Water Department

EPA P3 Design Award—SU-83352401 * GAAN RETAIN— Award No. P200A100117

EPA SBIR Grant—EP-D-14-09 * WERF Grant—U3R13

• Traditional biodiesels have high

negative impact due to

farming/harvesting of crops

• GTW does not include farming

step, but has a high impact due

to processing

• Impacts from GTW-to-biodiesel

process is dependent on lipid

content

Where, LHV= lower heating value, E=energy input, i=process step 1,2,3: 1=harvest/separation 2=conversion/purification 3=biodiesel transport

Future Work

TAG + Alcohol Biodiesel + Glycerol FFA + Alcohol Biodiesel + Water

Lipid content primarily affects steam requirement in separation step Below 10% lipids, process steam requirement increases steeply and FER decreases rapidly

Process steam requirements (Left ) From process analysis of each major process

step Here steam is produced by burning natural gas 𝐹𝐸𝑅 =

𝐿𝐻𝑉

𝐸𝑖𝑛𝑖=1

For >15%Lipids GTW Biodiesel has higher FER than Soybean Biodiesel For > 2% Lipids GTW Biodiesel has higher FER than Low Sulfur Diesel

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0% 5% 10% 15% 20% 25% 30%

0.0

0.1

0.2

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0.5

0.6

0.7

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0.9

Fo

ss

il E

ne

rgy R

ati

o (

FE

R)

Lipid Content of Waste Grease (%)

Pro

ce

ss

Ste

am

En

erg

y R

eq

uir

em

en

t

(M

J-n

atu

ral g

as/M

J-b

iod

iese

l)

Separation of lipids from grease

Conversion of lipids to biodiesel

Purification of biodiesel

Methanol Recovery

Soybean Biodiesel

GTW Biodiesel

Petroleum Diesel

Fossil Energy Ratio (Right) FER = a ratio of fuel energy output divided by fossil energy input: High FER values desirable

Conventional Biodiesel Production:

• Refined vegetable oils (Soybeans)

• Contain primarily triglycerides (TAG)

• Expensive feedstock cost

• Cheap processing

Alternative Biodiesel Production:

• Waste fats, oils, and greases (FOG)

• Contain primarily free fatty acids (FFA)

• Low to no feedstock cost

• More complex processing

Challenges:

1. Waste grease produced in limited quantity and location-dependent

2. Lipid content in grease is highly variable; 2-30% total waste volume

3. Sulfur concentration inhibits production of ASTM grade biodiesel

Biodiesel from Waste Greases:

1. Utilizes a low-value liability to make a high-value product

2. Reduces the processing burden on waste management systems

3. Has the potential to fuel 1 million vehicles

Utilizing Waste Greases for Biodiesel Production

Waste greases challenge wastewater treatment processes and lead to clogging and

sewer overflows. Lipids can be extracted from waste greases for production of

biodiesel.

a) Grease Trap Waste (GTW) from commercial kitchen effluent

b) Sewage Scum (SS) from primary tanks at wastewater treatment plants.

Alcohol/Water Content Study

Bubble Column Reactor (BCR)*

Reactor developed at Drexel University for biodiesel production

Novel Biodiesel Technology

0

10

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30

40

50

60

70

80

90

100

0 50 100

FF

A c

on

ten

t (%

)

Time (minutes)

Pure MeOH

90:10 MeOH:H2O

Pure EtOH

90:10 EtOH:H2O

Short-Path Distillation

Biodiesel is purified through distillation operating under a vacuum

(in collaboration with the USDA)

Crude FOG biodiesel is:

• Dirty

• High in sulfur content

• Difficult to separate

Short-path distillation purifies biodiesel:

• Under high vacuum: 1 mbar

• Low temperature:

• 115-190 °C @ 1 mbar

• 300-400 °C @ 1 mbar

• Reduces sulfur:

• Lipids: 300 PPM

• Crude: 201 PPM

• Residue: 776 PPM

• Biodiesel: 27 PPM

(ASTM grade = 15 PPM)

Life Cycle Assessment (LCA)

Method to evaluate energy usage and environmental impacts for a product

Operating Conditions:

• At 120 °C - Hotter than

boiling points of:

• Water (H2O)

• Methanol (MeOH)

• Atmospheric pressure

• MeOH rate 0.75 mL/min

0

1

2

3

4

5

6

7

0

20

40

60

80

100

120

140

160

180

0 0.05 0.1 0.15 0.2

Un

rea

cte

d M

eth

an

ol R

ati

o

Tim

e t

o 9

5%

FF

A C

on

ve

rsio

n

(min

)

Normalized MeOH Feed Rate (1/min)

Time to 95% conversion (left axis)

Excess MeOH at 95% conversion (right axis)

BCR is Robust for:

• Waste Greases (FFA)

• Various Alcohols

• Elevated Water Content

Conversion/Excess MeOH Study

Biofuels are renewable due to the

recycling of biogenic Carbon Dioxide (CO2)

Achieves >95% FFA Conversion in less than 2 hours

Atmospheric boiling points:

• FAME: 344 °C

• FFA: 360 °C

• TAG: 884 °C

Harvest

Use as

Vegetable

Oil

Disposal

Distribute

CO2

Emissions

Acidic Oil

(FFA)

Crude

Biodiesel

(FAME)

MeOH &

H2O Vapor

(MeOH)

Vapor

FFA

+

MeOH

H2O

+

FAME

MeOH

H2O

Ris

ing

Bu

bb

les

Hot wall

Cold wall High

vacuum

Crude

Biodiesel

Biodiesel

Residue

Wipers

*Stacy, C. J.; Melick, C. A.; Cairncross, R. A., Esterification of free fatty acids to fatty acid alkyl esters in a bubble column reactor for use as biodiesel. Fuel Processing Technology 2014, 124, (0), 70-77.