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USDA REE Energy Summit USDA REE Energy Summit
Biochar as Part of a Carbon Negative Economy
Robert Brown Bioeconomy Institute
Department of Mechanical Engineering Iowa State University
USDA REE Energy Summit USDA REE Energy Summit
USDA REE Energ S mmit
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