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Biochar as Part of a Carbon Negative Economy

Robert Brown Bioeconomy Institute

Department of Mechanical Engineering Iowa State University

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Bioeconomy Institute Goal: Securing sustainable supplies of

energy and carbon from biomass

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BEI Mission • Research

• Biomass production • Biomass conversion • Systems analysis

• Education • K-12 • Undergraduate • Graduate • Continuing

• Outreach • Producers • Industry • General Public

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BEI Proposal & Award Services

o Assist faculty and staff o Submittal and management o Targeting proposals related to

renewable energy, biobased products, sustainability,

o No cost to faculty

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Examples of Assistance o Broader Impact guidance/resources o Data Management Plans o Coordination & Management Plans o Post Doc Mentoring Plans o BEI Facilities & Equipment o Statement of Project Objectives

(SOPO) o Biosketch Templates o Current and Pending Support

Templates o Conflict-of-Interest Templates

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What is a Carbon Negative Economy?

• Economic activity reduces the amount of carbon dioxide in the atmosphere

• Distinct from goal of approaching carbon neutral status (that is, zero emissions of carbon dioxide)

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All economic activity generates greenhouse gas emissions

0

2

4

6

8

10

Gasoline fromPetroleum

Steel Cement Electricity fromCoal

Ethanol (E85)from Corn

Beef from Corn

Car

bon

Bur

den

(Mg

CO

2/$1

000

GD

P)

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We Live in a Petroleum Economy

CO2

Net Energy

Carbon Pool

Petroleum Economy

Atmosphere

Geosphere

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Reversing the Paradigm

CO2

Net Energy

Carbon Pool

Carbon Negative Economy

Renewable Energy

Atmosphere

Biosphere

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ISU’s Approach to a Carbon Negative Economy

• Terrestrial plants or aquatic species fix carbon as biomass

• Biomass is harvested and pyrolyzed to bio-oil and biochar

• Bio-oil is upgraded to drop-in fuels and other high value products with attractive economics

• Biochar is returned to croplands where it recycles nutrients, sequesters carbon and improves soil fertility

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Pyrolysis

11

Definition – thermal decomposition of organic compounds in the absence of oxygen

Temperatures in the range of 350-600 ⁰C

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Py Products • Gas – non-condensable gases like carbon

dioxide, carbon monoxide, hydrogen • Solid – mixture of inorganic compounds (including

plant nutrients) and carbonaceous materials known as biochar

• Liquid – mixture of water and organic compounds known as bio-oil recovered from pyrolysis vapors and aerosols (smoke)

Bio-oil

Biochar

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Definitions • Char – any carbonaceous residue from pyrolysis

including natural fires. • Charcoal - char produced from pyrolysis of

animal or vegetable matter in kilns for use in cooking or heating.

• Biochar – char produced specifically for application to soil for agronomic or environmental management.

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Glaser et al. 2001. Naturwissenschaften (2001) 88:37–41

Terra Preta Oxisol

Inspiration for ISU’s CNE: Terra Preta in Amazon Basin

Applied to the land, biochar serves as both soil amendment and carbon sequestration agent

• Created hundreds of years ago by pre-Colombian inhabitants of Amazon Basin

• Result of slash and char agriculture

• Much higher levels of soil organic carbon

• Far more productive than undisturbed Oxisol soils

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Biochar as Soil Amendment

Slide courtesy David Laird, ISU Agronomy

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Purported Benefits of Biochar • Recycling of nutrients

‒ Mostly K and P ‒ Some N but it may be unavailable to plants

• Improved soil fertility ‒ Enhanced cation exchange capacity (with time) ‒ Improved water retention ‒ Mycorrhiza enhancement

• Long-term carbon sequestration ‒ Measured in hundreds or even thousands of years

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15

20

25

Biochar added (g-char / kg-soil)

ECEC

(cm

ol k

g-1

)

ControlManure

0 5 10 20

Effective Cation exchange Capacity (0-3 cm)

18.1 18.8

20.8 18.8

21.6 20.5 21.7 23.1LSD0.05=1.34

b cb d

d d

b a

+20% Bulk density (day 483)

1.1

1.2

1.3

1.4

Biochar treatment (g/kg)

Bul

k de

nsity

(g c

m

)

ControlManure

0 5 10 20

a ab

c bc c cc c

-3

1.301.34

1.241.27

1.24 1.251.24 1.25

-7% Biochar added (g-char / kg-soil)

0

5

10

15

20

25

30

35

40

Charcoal treatment (g-char / kg-soil)

Org

anic

C (g

)

ControlManure

0 5 10 20

Organic C in Soil (whole column)

20.5 20.5

24.1 24.3

28.2 28.2

34.6 35.1

d d c cb b

a a

LSD0.05=0.94

+69%

1.5

1.6

1.7

1.8

1.9

2.0

Charcoal treatment (g-char / kg-soil)

Org

anic

N (g

)

ControlManure

0 5 10 20

Organic N in Soil (whole column)

1.73 1.751.74 1.79

1.81 1.84 1.85 1.89

de cd bc ac

ab a

LSD95 = 0.060

e de

+7%

Improves Soil Properties

Slide courtesy David Laird, ISU Agronomy

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Improves Volumetric Soil Moisture ISU Boyd Farm – moisture measured July 12, 2011

Slide courtesy David Laird, ISU Agronomy

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Increase in Water Retention May be Most Important Benefit of Biochar Application to Soils

<80 80-110 110-140 140-170 >170

Yield bushels/acre Moisture content (%)

<15% 15-20 20-25 25-30 >30

Slide courtesy David Laird, ISU Agronomy

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Biocharm www.biocharm.com

Soil Reef www.soilbiochar.com

GroChar www.Carbongold.com

Horticultural Applications of Biochar are Near-term, High Value Opportunities

Slide courtesy David Laird, ISU Agronomy

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Biochar Solutions www.biocharsolutions.com

Mine land reclamation is another important niche opportunity for

early biochar applications

Slide courtesy David Laird, ISU Agronomy

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Lignocellulosic Biomass

Lipid-rich Biomass

Pyrolysis

Extraction

Sugars

Phenolic chemicals

Biochar

Pyrolysis

Lipids

Residue

Upgrading Fuels & Chemicals

Ammonia Biochar

Upgrading

Upgrading Fuels &

Chemicals

Two Major CNE Pathways Being Considered for Wide Scale Applications

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Production of Biochar • Can traditional charcoal making be used to

produce biochar? • How do processing conditions affect yield

and quality of biochar? • Do we want processes that maximize yield

of biochar? • What technologies are available to

sustainably produce biochar?

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Traditional Charcoal Making Is Not Sustainable

• Contributes to deforestation: Need to use residues • Generates air pollution: Need to minimize emissions • Low carbon conversion: Need to utilize more carbon

Kiln type CO (g kg-1)

CH4 (g kg-1)

NMOC1 (g kg-1)

TSP2 (g kg-1)

Uncontrolled batch 160-179 44-57 7-60 197-598 Low control batch 24-27 6.6-8.6 1-9 27-89 Controlled continuous 8.0-8.9 2.2-2.9 0.4-3.0 9.1-30

1NMOC – non-methane organic compounds 2TSP – total suspended particulates

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Effects of pyrolysis heating rate and temperature on biochar

‒ Heating rate affects biochar yields ‒ Slow pyrolysis yields 25-40 wt% char ‒ Fast pyrolysis yields 12-10 wt% char

‒ Pyrolysis temperature affects biochar quality ‒ Biochar produced at very low temperature is not

recalcitrant to mineralization ‒ Biochar produced at very high temperature can be

phyto-toxic at least in first season of application ‒ Best quality biochar produced at 400-600°C

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Do We Want to Maximize Char Production to Build a CNE?

Slow pyrolysis maximizes char production and has lower capital costs

Fast pyrolysis maximizes bio-oil production and has higher capital costs

Pyrolysis gas substitutes for natural gas

Bio-oil upgraded to gasoline & diesel

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Not if We Want to Make a Profit Slow Pyrolysis

To achieve 10% IRR, product biochar would have to sell for $346

per metric ton (no thanks)

Fast Pyrolysis To achieve 10% IRR product

gasoline would have to sell for $2.68 per gallon (sounds like a deal)

Internal Rate of Return Internal Rate of Return 10% 10%

Char Yield (27; 36; 45 wt% feed) Bio-oil Yield (40; 53; 66 wt% feed)

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Modern Pyrolyzers: Bubbling Fluidized Bed

• Heat supplied externally to bed

• Good mass & heat transfer • Gas residence times shorter

than char residence times

Gas, Char, and Oil Vapors and Aerosol

Freeboard

Fluid bed

Fluidizing gas

Biomass

Feeder

Distributor plate

Heat

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Bubbling Fluidized Bed Pyrolyzer at ISU (includes fractionating bio-oil recovery system for value-added products)

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Modern Pyrolyzers: Auger Reactor

• Heat carrier and biomass mixed by auger

• Suitable for small scale

• Requires heat carrier heating and circulation system

Dual co-currently rotating screws mix and convey

heat carrier and biomass

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Modern Pyrolyzers: Free Fall Reactor

• No heat carrier • Little to no carrier gas • Simple design –no

moving parts • Requires small

biomass particles • May be suitable for

distributed pyrolysis operations and small scale

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Recovery of Bio-oil as Stage Fractions

Stage fractions have distinctive physical and chemical properties

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Value-Added Applications of Bio-Oil Fractions • Phenolic oligomers from lignin

‒ Green gasoline and diesel ‒ Bio-asphalt ‒ Bio-oil co-firing fuel

• Sugars from polysaccharides

‒ Fermentation substrate • Light ends from polysaccharides

‒ Fermentation substrate ‒ Gelled fuel

Pyrolysis sugars

Catalytic upgrading to green gasoline

and diesel

Paving bike path with bio-asphalt

Bio-Oil Co-firing Fuel

Gelled fuel (acetate + alcohol)

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ISU’s Initiative for a Carbon Negative Economy

• Established in 2011 with support from the ISU College of Engineering Venture Fund

• Purpose is to secure significant funding of interdisciplinary research into CNE

• Initiative has won $2 million from the Stanford Global Climate and Energy Program to model agronomic, engineering, and economic aspects of CNE

• Launching CNE demonstration at pilot-scale

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Outline of CNE Demonstration

• Bio-oil and biochar produced at Stine Seed Co. pyrolyzer (after retrofit)

• Bio-oil used to produce co-fire fuel for ISU physical plant

• Biochar applied to farm fields in cooperation with Soybean Promotion Board

• First-phase funding provided by Iowa Energy Center, Iowa legislature, and Stine Seed

Land application of biochar

Bio-oil co-firing fuel

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Lignocellulosic Biomass Pyrolysis

Bio-Oil

Biochar

Pathway for CNE Demonstration

Light Ends

Heavy Ends Co-Fire Fuel

Fermentation

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• Stine Seed has informally collaborated with ISU for several years ‒ Biochar demonstrated on Stine farms ‒ Company has experimented with prototype 30 tpd fast

pyrolyzer

• Stine Seed has agreed to: ‒ Let ISU use his pyrolyzer for research ‒ Pay for retrofits to pyrolyzer ‒ Provide 1-2 operators ‒ Provide discounted feedstock ‒ Work with ISU on field demonstrations

Partnership with Stine Seed

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Working with ISU Physical Plant • David Miller and Jeff Witte indicate that bio-oil

co-fire fuel (BCF) would require no retrofit of ISU boilers

• Agreed to have evaluate co-firing performance of BCF using their boiler model

• President Leath has endorsed the project

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Comparing CO2 Emissions

Note 1: Bio-fuel oil is the heavy ends of bio-oil; the light ends are used for acetate-based products

Fuel type Kg CO2eq/kg Oil

Residual Oil 0.543

Fuel Oil 0.622

Biofuel oil (with biochar sequestered to agricultural lands) -2.85

Note 2: Burning Bio-fuel Co-firing product would result in a 56% reduction in CO2 emissions relative to burning coal.

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Where Should We Grow Biomass?

Highest Annual Precipitation

Highest Annual Solar Irradiance

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Shaded areas contain some of the most weathered and leached soils in the world

Tropics Have Limited Soil Fertility

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Where the CNE really pays off

Highest Human Development Need

‘Much of the current debate on bioenergy […] obscures the sector’s huge potential to reduce hunger and poverty …If we get it right, bioenergy

provides us with a historic chance to fast-forward growth in many of the world’s poorest countries, to bring about an agricultural renaissance and

to supply modern energy to a third of the world’s population.” –Jacques Diouf, Director-General, UN Food and Agriculture Organization

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Backyard Biochar Horticulture

Red Pots: Biochar Yellow Pots: Control

R. C. Brown, 2012

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Biochar-treated tomato plants matured three weeks earlier than untreated plants

Red Pots (biochar):

2.5 kg

Yellow Pots (control): 0.36 kg

R. C. Brown, 2012

Harvested Tomatoes for Week of July 24, 2012

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Additional Resources on Pyrolysis and Biochar