biochar as a pyrolysis byproduct - harvesting clean energy

8/9/2019 Biochar as a Pyrolysis Byproduct - Harvesting Clean Energy

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Harvesting Clean Energy Biochar As A

Pyrolysis Byproduct

Harvesting Clean Energy Biochar As A

Pyrolysis Byproduct Hal Collins, USDA-ARS

Vegetable and Forage Crops Unit24106 N. Bunn Rd.Prosser WA 99350

Harvesting Clean Energy Conference, Portrland, OR, January 29, 2008


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Total U.S. Land base: 2,268 million acres *

8181Public13294Urban/Swamps/desert20458Cropland26588Grasslands/range

33747Forests%M acresArea

from Vesterby and Krupa, 2001; Alig et al., 2003

*Includes 369 million acres of Alaska and Hawaii.

Table 1. Acres by land category.


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Total U.S. Cropland: 458 million acres

+337.036.035.0CRP

+667.063.060.6Pasture

+363.061.061.7Hay/alfalfa

89.7

57.2

72.0

81.8---- Million acres ----

2005

87.0

57.3

75.5

78.3

2006

%

-1772.0All other

+560.4Wheat

-1663.6Soybeans

+2093.6Corn (grain)

Increase/decrease2007Crop

www.nass.usda.gov, 2008.

Table 2. Acres planted.


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Biochar

What is Biochar? - carbon-rich solid a byproduct of low-temperature pyrolysisof biomass.

- also known as charcoal,biomass derived black carbon, Agrichar.

- formed under complete or partial exclusion of oxygenat low temperatures betweenabout 400 and 500 C.

- Origins - has been used for centuries- Cooking, health, water purification, etc

Active research into soil benefits was renewed by Johannes Lehmann at Cornell University in about 1998 resulting from studies of Terra preta soils of the Amazon.

Peanut hull biochar


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Figure 5. The properties of biochar greatly depend upon the productionprocedure. Temperature effects on C recovery, CEC, pH and surface area.from Lehmann (2007), Front. Ecol. Environ. 5:381-387.

Characteristics of biochar


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Any source of biomass: Rice husks Nut shells (groundnut, hazelnut, macadamia nut,

walnut, chestnut, coconut) Bagasse from sugar cane production Olive or tobacco waste Wood chips, sawdust, bark, etc Animal manure Peanut hull Grasses and corn stover Other sewage sludge tires, peat, lignite, coal

Potential feedstocks of biochar

* Not all organic biomass is suitable for producing biochar

Household, municipal and industrial waste may contain

heavy metals or organic pollutants which could causeenvironmental contamination by land application of theresulting biochar.


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What we know: Terra Preta

fine dark loamy soil - up to 9% carbon , (adjacent soil 0.5% C)- high nutrient content and high fertility

- 3 times the phosphorous and nitrogen

developed over thousands of years by humanhabitation correspond to ancient settlements

results from long-term mulching of charcoal production from hearths and bone fragmentswith soil application

persistents in soil, recalcitrant, resistant todecomposition.

Marris. 2006. Nature 442: 624-626; Lehmann, et al., 2003. Plant Soil 249: 343-357; Lehmann,et al., 2003. Kluwer Academic Publishers. 105-124.

Terra preta do indio or the black earth of the Amazons

forest fires and slash-and-burn

contributevery low amounts of charcoal (~3%)


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Figure 3. Biochar particles in a dark earth from the Amazon,with dimensions of several tens of microns to submicrons. Upper left side shows a quartz grain, inset shows separated biochar

particles. Note the coatings of biochar particles with minerals intheir natural assemblage.

from Lehmann, (2007), Front. Ecol. Environ. 5:381-387.

What we know: Terra Preta


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from Lehmann, (2007), Front. Ecol. Environ. 5:381-387.

Low temperature pyrolysis with biochar C sequestration


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Figure 1 . Schematics for biomass or bio-char remaining after charringand decomposition in soil. from Lehmann et al., 2006. Mitigation Adap.Strat. Glob. Change 11: 403427 .

C Sequestration Potential of Biochar


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Long-term:What are the sources of biochar?

Forest Resources- logging debris 67 M dry T y -160% recovery Converted to biochar = 10 M T Carbon

- forest thinning 60 M dry T y -1at most 30% collected 18 MT

Converted to biochar = 4.5 M T Carbon- Primary wood processing mills 91 M dry T y -1

bark, saw mill slabs, edgings, sawdust, etc.

< 2 million dry tons availableConverted to biochar = 0.4 M T Carbon

- Secondary wood processing mills 16 M dry T y-1

millwork, containers, pallets, etc.recovered from urban MSW DOE Billion Ton Report, 2005


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Available Urban Wood residues 63 M dry T y -1

28.034.462.3Total

6.07.313.2Wood (MSW)

1.78.09.8Woody yard

11.716.127.7Demolition

8.63.011.6Construction

AvailableRecovered/Un-useableGeneratedMaterial

Converted to biochar = 7 M T Carbon

(McKeever, 2004)Expected to increase 30%.

Total Forest resources available for biochar production~ 88 M dry T y -1 of 296 M dry T y -1 inventoried. (30%)

Total biochar produced = 22 M T Carbon y -1

Land Application @ 10 T acre -1 = 2.2 million acres


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Crop residues (corn stover, small grain residues)- DOE estimated 428 M dry T of residues. (2006)- 28% (120 M dry T) will be available for conversion- ignore ethanol industry, convert by pyrolysis

Converted to biochar = 27 M T Carbon


Dedicated crops (perennial, switchgrass, poplars, etc.)- DOE reports potential production for 377 M dry T - Yields range from 5-10 T acre -1- Acreage needed: 38 - 75 M acres

- ignore ethanol industry, convert by pyrolysisConverted to biochar = 85 M T Carbon

Total biochar produced = 112 M T Carbon y -1

Land Application @ 10 T acre -1 = 11.2 million acres


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Washington State

Forest Resourceslogging debris 1.9 M T y -1forest thinning 0.5 M T y -1

mill residues - 5.2 M T y -1 @10% = 0.5 M T y -1urban wood 0.8 M T y -1

3.7 M T y -1

Converted to biochar = 0.8 M T Carbon

Crop Residues - 2.2 M T y -1 @ 20% = 0.4 M T y -1

Converted to biochar = 0.1 M T Carbon

Total biochar produced = 0.9 M T Carbon y -1

Land Application @ 10 T acre-1

= 90,000 acresWA State, Biomass Inventory and Bioenergy Assessment, 2005


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Richard Haard Four Corner NurseriesBellingham, WA

Lehmann et al., Cornell University

Brazil

Agronomic Applications

Potting soil


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Figure 5. The properties of biochar greatly depend upon the productionprocedure. Temperature effects on C recovery, CEC, pH and surface area.from Lehmann (2007), Front. Ecol. Environ. 5:381-387.

Characteristics of biochar


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Figure 4. Adsorption of phosphate to biochar (produced fromRobinia pseudoacacia L at 350C for 16 hours). from Lehmann(2007) Front. Ecol. Environ. 5:381-387.

Adsorption of phosphate to biochar


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Nutrient Content of Biochar

C-content - 75-85% largely unavailable todecomposition; microbial activity?

C/N ratio 12-40 100 lbs biochar has ~8-10 lbs N net mineralization is low, due to physical

protection. Tends to NH 4 form.

P content 0.08%

Other nutrients (S, Mg, Ca, micronutrients)?


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USDA-ARS Integrated Cropping SystemsResearch Field Station , Paterson, WA

Switchgrass Trials


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Why the interest in Biochar?COMPOSITION OF U.S. DEMOLITION WASTE

(Source: Chatterjee-U.S. Army, as cited in SPARK, 1991)


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Dedicated perennial biomass crops- DOE reports potential production for 377 M dry t.- Yields of switchgrass range from 5-10 t acre -1

- Acreage needed: 38 - 75 M acres- Potential ethanol 75 M acres = 30 billion gals

Sources of new acres- Probably not from corn, soybean, wheat acreage.- CRP lands 37 million acres nation wide.

7 M acres converted to corn production. 20 M acres converted to switchgrass.@ 5T DM/acre yields 8 billion gals ethanol

- Other marginal croplands (pastures, hay/alfalfa). 130 M acreage available?

Long-term:Where will the acres come from?


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Corn Stover Biomass


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Nutrient Corn (lbs/A) Wheat (lbs/A)

N 115.00 (grain 136) 27.20P 2O 5 40.00 6.80

K2O 167.00 47.60

Ca 30.00 8.16Mg 23.00 4.08

S 16.00 6.80

Cu 0.06 0.01Mn 1.72 0.22

Zn 0.34 0.20 from Hatfield, 2008, Fluid Journal

As with switchgrass nutrients would be delivered to the refinery,potential for nutrient recovery and reuse.

Table 5. Average export of nutrients from soil with removal of cornstover and wheat residues.


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Switchgrass: Nutrient Removal

Estimate of nutrient removal based on 2006 production levels.Biomass yield: 10.1 T acre -1 (Kanlow cultivar)Planted: 24,750 acres (to support 20 gal facility)Total Biomass Harvested: 250,000 T

Nutrient % lbs acre -1 T*

Nitrogen 1.22 245 3,050

Phosphorus 0.15 31 375Potassium 1.51 305 3,775Calcium 0.27 54 675Magnesium 0.24 48 600Sulfur 0.05 10 125Other (Fe, B, Mn, Cu, Zn)


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Using pyrolysis under controlled conditions, carbon in the organic biomassis captured in the biochar (roughly 50%) and bioenergy co-products suchas biofuels (roughly 50%).

Pyrolysis produces optimum biochar in the absence of oxygen and mostoften with an external heat source. Gasification systems produce biochar in smaller quantities in a directly heated reaction vessel with the addition of

air.

The efficiency of carbon conversion from biomass to biochar is related tothe type of plant matter used.

Production of biochar could sequester approximately 50% more initialcarbon than that retained after burning or direct application (with biologicaldecomposition) of biomass.


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Adsorption capacity depends ona) physical and chemical characteristics of theadsorbent (carbon);b) physical and chemical characteristics of theadsorbate (the food or beverage);c) concentration of the adsorbate in liquidsolution;

d) characteristics of the liquid phase (e.g. pH,temperature)e) amount of time the adsorbate is in contact withthe adsorbent (residence time).


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Comparison to Activated Charcoal

Activated charcoal is charcoal that has beenmade from wood or other materials that havebeen exposed to very high temperatures in an

airless environment.Treated with oxygen, opens upmillions of tiny pores between the

carbon atoms.

The use of special manufacturing

techniques results in highly porous charcoalsthat have surface areas of 300-2,000 m 2 g -1.

Are widely used to adsorb odorous or colored

substances from gases or liquids.

biochar as a pyrolysis byproduct - harvesting clean energy

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