1

Biofuels

Prof. Johan E. Hustad

Department of Energy and Process EngineeringNTNU

Norway

2

Biofuels are hot again - this time it’s the global warming

3

Introduction Characterisation, resources Fuel prices, trade, politics

Process routes and options

Technologies and cycles Combustion/Co-combustion Gasification/gasification-combustion

Producer gas impurities and gas/particle cleaning

Examples of projects at NTNU/Sintef

Biofuels for transport

Poly/tri-generation biomass systems

Conclusions

Outline

4

Biofuels – some examples

Wood

Chips

Pellets

Charcoal

5

6

Brenselanalyser

Direkte Analyse (Proximate Anlysis)- Fuktighet (moisture content) [vekt%]- Flyktige Bestanddeler (volatile matter) [vekt%]- Fast Karbon (fix-C) [vekt%]- Aske (ash) [vekt%]

Analysen gjøres på rått brensel

Elementanalyse (Ultimate Analysis)- Karbon C [vekt%]- Hydrogen H [vekt%]- Oksygen O [vekt%]- Nitrogen N [vekt%]- Svovel S [vekt%]

Analysen gjøres på tørr og askefri basis (DAF)

Brennverdi (Heating Value) [MJ/kg]

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8

Motivation

9

33 TWh

20 TWh

Forest Biofuels in Norway

Kilde: SSB, NIJOS, Petter Heyerdahl (UMB)

FUEL MARKET POTENTIAL

WOOD FUEL PRICES (Euro/MWh)

EU-Politics, regulations

•RES increase from 6% (1997) to 12% (2010)

RES-E incr. from 14% (1997) to 22% (2010)

Energy Performance Certificate in Buildings (Savings, Space Heat., DH, reduce FF)

Solid Biofuel Standardisation – CEN TC-335

Biofuels Directive to replace gasoline and diesel by 2% in 2005, 5.75% in 2010 and 20% in 2020

14

Energy from biomass. Routes and options

bio-diesel

methanol

FT-liquids

substitute natural gas

ethanol

oil

biomass

& biomass waste

& energy crops

electricity

work

&

movement

Hydrogen (H2)

FUELS INTERMEDIATE PRODUCTS / SECONDARY ENERGY CARRIERS

FINAL PRODUCTS

engine

engine

engine

engine

engine

eng/turbine

Combustion + steam cycle or Stirling

extraction

fermentation

pyrolysis

hydrogasif. or digestion

gasification

biological processes

synthesis

Synthesis gas (CO + H2)

reforming

eng/turbine

fuel cell

generator/engine

15

Small scale combustion

16

Medium/Large scale combustion

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5 – 100 MW

Fluidized bed

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Waste combustion

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Co-combustion – Pulverized fuel

Gasification

GAS CLEANINGUPGRADING

FEEDSTOCKSYN-GAS

FEEDSTOCK

AIR (STEAM)

ASH LCV: 4-6 MJ/Nm3 (air)MCV: 10-15 MJ/Nm3 (steam)Naturgass: 40 MJ/Nm3

SOFCFUEL CELL

GASENGINE

GASTURBINE

COMBUSTION

HOMOGENEOUS REACTIONS

CO2, H2O,,,NOx

CO, CO2, H2, H2O,,,NOx

HETEROGENEOUSREACTIONS

PYROLYSIS

Char, Tar, CO, CO2, H2, H2O, CxHy,NOx

H2O

DRYING

FEEDSTOCK

FEEDSTOCKOXIDIZER

FEEDSTOCKLCV-GAS FEEDSTOCKEMISSIONS

FEEDSTOCKASH

FEEDSTOCKOXIDIZER

SNTEF project - CFD-modeling of gasification/combustion

[energy from biomass]

RENEWABLE ENERGY NETWORK AUSTRIA

CHP- Plant Güssingelectricity

heat

To Synthesis Plants

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Gasification – co-combustion natural gas

Steam turbine

BoilerBurner

Combustionchamber

Air

Compressor

Natural gas

Gas turbine

Gasifier

Biomass

Flue gas

Natural gas

Supplemental firing

Biomass gasProcess steam

SINTEF project - Duct burner: Co-fire of natural gas and syngas

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Gasification –co-combustion coal

Air inlet

Biomass feeding

Gas analysis

Filter

Flare Motor

Generator

Product gas (H2+ CO)

Gasification reactions

C(s) + H2O + heat CO + H2

C(s) + CO2 + heat 2CO

Biomass gasification for heat and power production

Stratified downdraft gasifier

Reactor dimensions

Diameter: 100 mm

Height: 500 mm

Feeding rate

4-6 kg/h wood pellets

Air supply

6-8 Nm3/h (8-10 kg/h)

• Controlled and stable operation.

• Air excess ratio: 0.25-0.30

• 23-26% CO, 14-16% H2, 1.5%CH4, 46-49%N2, 8-11%CO2

• 10 -14 Nm3/h of product gas.

• Energy output: ~18 kWth

•Low heating value: 5.3 - 5.7 MJ/Nm3

• Cold gas efficiency: 52-64 %

• Tar content: 3 g/Nm3

( )nCOc pkr 2=

COb

COf

COfc

pkkp

kk

pkr

3

12

3

1

21

1 ++=

nth order Langmuir-Hinshelwood

fk CCOOC +→ 3)(

)(2 1

12 OC

k

kCOC

b

ff +

fk CCOOC +→ 3)(

)(2 1

12 OC

k

kCOC

b

ff +

Reaction kinetics and models

COMBINED HEAT & POWER

Stirling engine

Micro turbines

Organic Rankine cycle

Unsuitable for

biomass

Suitable for

biomassFuel cells

Nordic Seminar- Thermochemical Conversion of Biofuels, Trondheim 21 Nov. 2000, Norway

IntroductionBioSOFC – Project contents and goal

Goal: Technology development for integrated SOFC, biomass gasification and high temperature gas cleaning

Normal operation

Cleaned gas

Coarse sandFine sand

Dust cake

Uncleanedgas

Particulate gas cleaning in combustion and gasification processes

- The Panel Bed Filter, working principle -

Regeneration

Cleaning pulse

Dust cake

Nordic Seminar- Thermochemical Conversion of Biofuels, Trondheim 21 Nov. 2000, Norway

Panel Bed Filter

• Glass cover for the thermocouple

• Glass disc to avoids flow towards top/gasket

H2S removal reactor

Sorbent screening:– Temperture curves, flow rates, fuel gas

concentrations, influence of water

SOFC unit

Cooling cup

SOFC

Detail of the upper part

Single cell test I - Setup

OCV @ different feed composition1000C

0.7620.7640.7660.768

0.770.7720.7740.776

50 75 75 0 20050 50 75 25 20050 25 75 50 20050 0 75 75 200

N2+H2+CO2+CO+Air[ml/min]

Single cell test I - Results

50+0+75+75+200 [ml/min] N2+H2+CO2+CO+AIR 1000C

0.68

0.7

0.72

0.74

0.76

0.78

0 0.5 1 1.5Current [A]

Cel

lVo

ltag

e [V

]

Voltage drop:

0.089V per 1A

Power:

0.69W @ 1A

Single cell test I - Results

50+75+75+0+200 [ml/min]N2+H2+CO2+CO+AIR 1000C

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 0.5 1 1.5 2 2.5 3 3.5

Current [A]

CellV

olta

ge [V

]

Voltage drop:

0.054V pr 1A

Power:

0.72W @ 1A

Single cell test I - Results

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Three different technologies will coexists for production of biofuels

Hydrolysis Fermentation Distillationsett inn bilde

av hvete

Bioethanol

sett inn bilde av rapsolje

Esterification Separation

Biodiesel

Gasification Catalysed synthesis Distillation

Biodiesel

Biodiesel

Bioethanol

Biomass to liquid (BTL)

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Both agricultural and wood based materials are involved in biofuels production

Biomass to liquids (Second generation)

Biodiesel

Rapeseed

Europe, Canada, China, Russia

Palm

Indonesia, Malaysia, Nigeria

Jatropha

Africa, South Eastern Asia, India

Switchgrass Miscanthus StrawBagasse

Bioethanol

Sugar cane

Brazil, India, China, Colombia

Corn

US, China

Sugar beet

Europe, China

Wheat Europe,

India, China, US

Wood

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Bioethanol and biodiesel have different properties

Bioethanol• CH3CH2OH• Can be blended with gasoline (up to ~10%) or used in special cars• Commercially available• Brazil is the largest consumer

Biodiesel• Depends on raw material, typically C10H22 to C15H32

• Can be used in today’s diesel cars• Commercially available from agricultural crops• Germany is the largest consumer

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World production of bioethanol eight times that of biodiesel

0

3

6

9

12

15

18

2001 2003 2005

Mtoe

0

3

6

9

12

15

18

2001 2003 2005

Mtoe

Production of bioethanol dominated by Brazil and US Production of biodiesel dominated by Europe

BrazilUnited StatesRest of the world

GermanyFranceRest of the world

Source: IEA World Energy Outlook 2006

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Gasification of biomass is flexible with respect to raw materials and end products

Gasification

Fischer-Tropschprocess Biodiesel

Methanol production

DME-production

Hydrogenproduction

Methanol

Dimethyleter

Hydrogen

Wood/Wood waste

Agricultural materials

Sewagesludge

Biogas

Organicwaste

Black liquor

1

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Syntetic fuels - Choren

[energy from biomass]

RENEWABLE ENERGY NETWORK AUSTRIA

0

1

2

3

4

5

6

7

8

9

5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41

Cn

Con

cent

ratio

n [M

ol %

]

FT-Diesel

FT-product in off gas (condensed)

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Wide range in LCA results (1)

63% GHG savings per v-km

16% GHG savings per v-km

Concawe, et al., 2004.

[energy from biomass]

RENEWABLE ENERGY NETWORK AUSTRIA

BiomassGasification

Producer Gas (gas engine, gas turbine,

fuel cell)

Synthetic NaturalGas (BioSNG)

FT-Fuels(BioFiT)

Methanol

Hydrogen

Others (e.g.DME)

Biomass

The basic concept –“Green Chemistry”

[energy from biomass]

RENEWABLE ENERGY NETWORK AUSTRIA

Efficiencies in Case of Polygeneration

0

20

40

60

80

100

Gas engine BIGCC FT FT POLY BioSNG BioSNG POLY

Synfuel Electricity District heatCHP-plants Fischer-Tropsch Bio-SNG

Fuel orientation

Fuel orientation

%

[energy from biomass]

RENEWABLE ENERGY NETWORK AUSTRIA

BioSNG-production BioFiT– liquid fuel production

Biomass

Biomass gasification

Fischer-Tropsch BioFiTSlurry bed reactor Temperature 200-300°C Pressure 20-30 barCapacity ~ 10 Nm³/h Catalyst 2005: Iron

2006: Cobalt

nCO + 2nH2 = nCH2 + nH2O

Conclusions

• Biofuels can be utilised in a large range of processes and by the use of many different technologies at different scales.

• Biofuels will play an increased importance in the energy system in the future.

• Biofuels is the only renewable energy resource which can be used in both heat, electricity and transport applications.

• The most important processes will be combustion and gasification. • Combustion and co-combustion will be most important for heat,

power and CHP applications.– Particles, UHC, CO small plants– Fouling/slagging (Cl, K, S, Na) larger plants

• Gasification/combustion/co-gasification can be the source of both (heat), electricity and transport fuels including hydrogen– Gas cleaning like tars, H2S, particles, alkali metals and chlorine

compounds • Gasification also has the potential for advanced processes like

high temperature fuel cells.