THE NET ENERGY OF BIOFUELS Dario Cordisco Melachroini Makrelli Miriam Peces EPROBIO 16th June 2011

Index 

Introduction



Net Energy  EROI  FER  PRR



Examples  Biodiesel



from soybean

Conclusions

INTRODUCTION

NET ENERGY

EXAMPLES

CONCLUSIONS

INTRODUCTION 

Bioenergy: Any kind of energy from natural resources.



Biofuel: Renewable energy source produced from natural materials (biomass). Biofuels

1st generation

2nd generation

3rd generation

4th generation

3

INTRODUCTION

NET ENERGY

EXAMPLES

CONCLUSIONS

Generation

Feedstocks

Examples

1st generation

Sugar, wheat, starch, animal fat

Bioalcohols, biodiesel, biosyngas, biogas.

2nd generation

Non-food crops, corn, wood, solid waste

Bioalcohols,bio-oil, biohydrogen,

3rd generation

Algae

Vegetable oil, biodiesel.

4th generation

Vegetable oil, biodiesel

Biogasoline Demirbas et al., 2010

4

INTRODUCTION



NET ENERGY

EXAMPLES

CONCLUSIONS

PROS AND CONS

Global Bioenergy Partnership, 2009

5

INTRODUCTION

NET ENERGY

EXAMPLES

CONCLUSIONS

Are biofuels convenient in terms of energy?

6

INTRODUCTION

NET ENERGY

EXAMPLES

CONCLUSIONS

NET ENERGY BALANCE 

Net energy balance (NEB): Technique for evaluating the amount of energy delivered to society by a technology to the total energy required to obtain it.

NEB = E supplied - E required 7

INTRODUCTION



NET ENERGY

EXAMPLES

CONCLUSIONS

Energy Return on Investment (EROI): tool of net energy analysis to compare the amount of energy delivered by a fuel.

EROI =

E supplied by fuel E required to obtain fuel

EROI > 1 Advantageous EROI < 1 Disadvantageous Charles A.S., 2009

8

INTRODUCTION

EXAMPLES

CONCLUSIONS

Fossil Energy Ratio (FER): the energy output of the final biofuel product to the fossil energy required to produce the biofuel.

FER =

E output renewable fuel E input fossil fuel

6 5

Fossil energy ratio



NET ENERGY

4 3 2 1 0 Cellulosic ethanol biorefinery

Corn ethanol

Gasoline

Electricity

Sheehan et al., 2003

9

INTRODUCTION

EXAMPLES

CONCLUSIONS

Petroleum Replacement Ratio (PRR): Reflects the degree of reliance on petroleum for a given energy carrier

Liquid fuels delivered to user PRR = Petroleum energy used Petroleum replacement ratio



NET ENERGY

20 15 10 5 0 Cellulosic ethanol biorefinery

Corn ethanol

Gasoline

Farell et al., 2006

10

INTRODUCTION

NET ENERGY

EXAMPLES

CONCLUSIONS

EXAMPLES 

Biodiesel from soybean Agriculture Application rate

Input

Manufacture energy

Total energy use

kg ha−1

MJ kg−1

MJ ha−1

MJ L−1a

Seeds

–

–

184

0.46

Nitrogen

4.9

46.8

230

0.57

Phosphorus

16.0

14.1

225

0.56

Potassium

26.8

8.9

238

0.59

Sulfur

0.4

8.9

3

0.01

Herbicide

2.9

476.7

1421

3.52

Diesel fuel

–

–

1582

3.92

Agricultural capital

–

–

705

1.75

Total

4588

11.37

11

INTRODUCTION

NET ENERGY

EXAMPLES

CONCLUSIONS

Machinery Shipping weight

Production energy Soybean

Mg

MJ ha−1 yr−1

GJ

MJ L−1

Tractor (4WD)

14.6

612

97.9

0.24

Tractor (MFWD)

7.5

314

50.2

0.13

Sprayer (27.4 m)

10.3

433

69.3

0.17

Swather

4.9

203

32.6

0.08

Combine

13.6

569

91.1

0.23

Pick-up header

1.5

64

10.2

0.03

Flex header

2.6

108

17.2

0.04

Semi-tractor

11.8

494

79.1

0.20

Hoe drill (13.7 m)

9.3

388

62.1

0.16

Chisel plow (11.6 m)

4.6

191

30.6

0.08

Field cultivator (13.7 m)

5.1

214

34.3

0.09

Bins (3×)

9.5

399

63.9

0.16

Auger

0.8

34

5.5

0.01

Agriculture buildings

9.1

381

61.0

0.15

Total

105.0

4405

705.2

1.76

12

INTRODUCTION

NET ENERGY

EXAMPLES

CONCLUSIONS

Oil extraction Inputs

Energy input

Canola

MJ Mg−1

Soybean

Canola

MJ L−1

Soybean

MJ ha−1

Crushing

1037

3.11

6.90

1644

2838

Feedstock transfer

107

0.32

0.71

170

294

Process heat

160

0.48

1.07

254

438

Conditioning

16

0.05

0.11

25

44

1320

3.96

8.79

2093

3614

Total

Transesterification Inputs

Energy input

Soybean

MJ L−1

MJ ha−1

Biodiesel processing

13

Process heat

0.32

131

Agitation

0.03

13

Methanol

4.86

1997

Catalyst

0.13

55

Washing/dryin g

0.07

28

Biodiesel total

5.31

2324

INTRODUCTION

NET ENERGY

Life cycle inventory

EXAMPLES

CONCLUSIONS

Total (BTU)

Bio-diesel fraction (BTU)

Agriculture

26,769

4,544

Soybean transport

4,291

728

Soybean crushing

23,151

3,930

Biodiesel conversion

18,772

15,467

Biodiesel transport

1,027

1,027

Total Energy Input for Biodiesel Adjusted for Coproducts

25,696

Biodiesel Total Energy Output

117,093

Net Energy Value

91,397

EROI

2,05

FER

4,56

14

INTRODUCTION

NET ENERGY

EXAMPLES

CONCLUSIONS

Invest or not to invest on biofuels?

15

INTRODUCTION

NET ENERGY

EXAMPLES

CONCLUSIONS

CONCLUSIONS 

Main goal  reduce energy costs



EROI it’s very general



To make biofuels attractive FER and PRR

EROI not enough to determine sustainability of the whole process being necessary to study other indicators as well as environmental and economic aspects 16

Thank you for your attention