Executive Summary of Biochar Research

Water Conservation and Carbon Sequestration

By

Michael Maguire

OPR Intern and PhD Applicant

1.12.2016

Definition

Biochar, as outlined by the International Biochar Initiative, can be defined as “a solid material

obtained from the thermochemical conversion of biomass in an oxygen-limited environment.”

Biochar is essentially a charcoal-like material, derived from heating and thermally degrading organic matter such as animal manure, crop residue, root mass, natural

vegetation and biosolids.

Description “Biochar can be used as a product itself or as an ingredient within a blended product, with a

range of applications as an agent for soil fertility enhancement, improved soil water use efficiency, remediation and/or protection against organic and inorganic particular environmental

pollutants, and as an avenue for greenhouse gas mitigation” (International Biochar Initiative, 2014).

Academic Sources of Biochar Research

Dr. Sanjai Parikh, Associate Professor of Soil Chemistry at UC Davis. IBI Co-Founder: Dr. Johannes Lehmann, Associate Professor of Soil Sciences and

Biogeochemistry at Cornell University.

Dr. Jeff Novak, Research Soil Scientist with the United States Department of Agriculture – Agricultural Research Service.

Dr. Mark Johnson, Research Soil Scientist with the United States Environmental Protection Agency.

Dr. Milt McGiffen, Professor of Plant Physiology at UC Riverside.

Executive Summary of Research Findings

The available evidence indicates that biochar can effectively be used in soil (under the proper environmental conditions) to sequester carbon, increase soil water retention near root masses,

moderately increase soil fertility, and reduce the bioavailability of soil contaminants (such as heavy metals). According to Dr. Jeff Novak of the USDA, it is important to note that not all

biochars are equal nor function the same. Thus, in order to achieve any one or several of the particular outcomes stated above, each biochar has to be designed from a particular feedstock and subjected to various pyrolytic conditions, in order to achieve a desired interaction with a

particular soil type and its associated deficiency. Though there has been a significant increase in biochar research in the last few years here in California, particularly in reference to the work

being done in Dr. Sanjai Parikh’s lab at UC Davis, as well as in Dr. Milt McGiffen’s lab at UC Riverside; there is still more research that needs to be done in order to have a complete index to guide safe and effective biochar use in California’s 2,000 different soil types. Based upon the

available evidence, it appears that there is a lot of potential for biochar to play some role in addressing some of California’s most challenging environmental concerns.

For the purpose of this discussion, I will only address two claims in detail (below), water conservation and carbon sequestration. Additional claims have been addressed with a proper

scientific evaluation, and they can be viewed in the context of the full white paper, “Biochar: A Useful Tool to Advance Environmental Stewardship in California.”

1. Carbon Sequestration Findings and Data:

How Carbon is Stored in Biochar

According to Dr. Johannes Lehmann, “the carbon lattice structure made up of fused polyaromatic carbon rings (a stable molecular structure) is hypothesized to be the key

property that confers a resistance to mineralization (conversion from organic carbon to carbon dioxide via respiration) by soil microbes that utilize organic matter i.e., hydrocarbons, as food” (Lehmann et al, 2015). The energy required by microbes to

access the carbon in biochar appears to be greater than that acquired when it is released. In contrast, carbon compounds in the original biomass (feedstock) are a net positive

energy source and are more readily mineralized by soil microbes. In short, biochars can mineralize more slowly than the biomass they were produced from, which means that carbon in biochar becomes decomposable for soil microbes at a much slower rate than it

otherwise would have been, had the biomass not been charred.

See Appendix 1.1, for data set of biochar mineralization rates.

Understanding Biochar Persistence

Achieving sufficient carbon storage via biochar in a soil medium is highly dependent on

a series of variables and interactions related to the pyrolysis process, the physical and chemical characteristics of the source feedstock, as well as the soil-biochemical properties and climate conditions. Thus, it is important to note that the biochemical

properties of a specific soil type and the associated surrounding environment, have a significant influence on biochar persistence. “The term persistence, a measurable,

numerical parameter, e.g. expressed as mean residence time (MRT), is used to characterize the length of time that carbon in biochars remain sequestered in soils” (Lehmann et al. 2015).

Measuring Biochar Persistence

Source: Dr. Johannes Lehmann Biochar stability can be measured in several ways, however one method in particular has been widely used by researchers in recent

years. This method analyzes the hydrogen to carbon molar ratio found embedded in the

molecular structure of biochar particles. Stability can be determined by measuring the amount of hydrogen atoms present per carbon atom. The

lower the hydrogen to carbon molar ratio, the higher the stability/persistence will be for that

particular char. In contrast, the higher the hydrogen to carbon molar ratio is, the lower the

stability and persistence will be. According to the data presented in the graph (above), a hydrogen to carbon (H/Corg) molar ratio below 0.7 indicates an MRT of greater than

100 years, an H/Corg molar ratio of 0.5 indicates an MRT of roughly 500 years, and an H/Corg molar ratio of 0.4 indicates an MRT of 1,000 years. According to Dr. Jeff

Novak, “a surrogate for biochar’s resistance to mineralization is in its atomic oxygen to carbon (O/Corg) ratio. As feedstocks are pyrolyzed at higher temperatures, the O-containing volatile material vaporizes, leaving the C-enriched material behind. This C

accumulates and O is lost, so the O/Corg ratio should range from 0.4 to as low as 0.1.”

See Appendix 1.21-1.24, for data set of biochar persistence (MRT).

Achievable Carbon Offset Credits via Biochar Production in California

Over the last four years, drought conditions have taken a toll on forest tree populations

throughout California. In a recent study titled, “Progressive Forest Canopy Water Loss During the 2012–2015 California Drought,” published on November 30, 2015 by Dr. Greg Asner in the Proceedings of the National Academy of Sciences; an estimated 58

million trees have died primarily in the Sierra Nevada Mountains, the coastal ranges, as well as the southern and northern forests in the state. Over the next several years, these

trees are going to decompose and release a significant amount of greenhouse gas emissions and pose a serious fire hazard to rural communities.

In September 2015, under sponsorship of the Placer County Air Pollution Control District, the California Air Pollution Control Officers Association (CAPCOA) adopted a

Biochar Reporting Protocol that was designed to quantify the carbon offsets generated by biochar production. Based upon my calculations (using a conversion ratio from this protocol), if 9.48% (of 58 million) or 5.5 million trees were removed and converted into

biochar, the state could expect to sequester about 17,268,382.9 metric tons of CO2 equivalent in biochar, which is equivalent to removing 3,674,124.02 passenger vehicles

off the road in the State of California. At a current price of $13.16 per carbon credit (as of January 6, 2016), this would equate to about $227,251,919 in carbon offset credits.

See Appendix 1.3, Carbon Credit Projections via

Biochar Production (2015)

2. Soil Water Retention Findings

and Data:

Findings

Biochar is generally considered

to have similar properties to soil organic matter (SOM) and since

it is generally accepted that SOM positively affects soil moisture

content in agricultural lands, a similar affect is often reported for biochar.

For example, the graph (above) illustrates that it took significantly

more time (an additional 5 days) for the soil moisture content of a Norfolk sandy loam soil mixed with a

Switchgrass derived biochar, to drain and eventually dry to field capacity in

comparison to the non-biochar control plot (Novak et al., 2012). This finding suggests that a properly designed

biochar can significantly increase soil water retention, which could improve

the water use efficiency of farmland across California

See Appendix 1.4, for soil water retention data.

How Soil Holds Water

Soil water holding capacity is controlled primarily by soil texture and soil organic matter

content. Soil texture is a reflection of the particle size distribution of a soil. An example is a silt loam soil that has 30% sand, 60% silt and 10% clay sized particles. In general,

the higher the percentage of silt and clay sized particles, the higher the water holding capacity. The small particles (clay and silt) have a much larger surface area than the larger sand particles. This large surface area allows the soil to hold a greater quantity of

water. The amount of organic material in a soil also influences the water holding capacity. As organic matter increases in a soil, the water holding capacity also increases,

due to the affinity of organic matter for water.

How Biochar Improves Soil Water Retention

The biomass that biochars are

derived from can be modified during the thermochemical conversion process (pyrolysis),

to have a much larger surface area. This combination of

organic matter (that already has an affinity for water), with a higher surface area than non-

thermally degraded organic matter, are the key properties in

biochar that improve soil water retention. In the graph (top left),

biomass that is pyrolyzed at higher temperatures tend to yield biochars with a much higher surface area than those exposed to lower temperatures. In particular, biochars

derived from softwood and grasses tend to have significantly higher surface areas than biochars derived from sludge (or manure). However, biochars derived from grass tend to

have a very high ash content (see graph above), which could restrict nutrient availability to crops in alkaline soils. Thus, when designing biochars to improve soils with low water holding capacities, it would be wise to use a biochar created from a non-manure (or

sludge) type feedstock, and one that is produced at higher temperatures (between 500 and 700 °C), but with limited ash content (below 10%).

Surface Area and Ash Content Graphic Sources (above): Dr. Sanjai Parikh, UC

Davis Biochar Characterization Database. (http://biochar.ucdavis.edu/graph-data/)

Summary

The scientific literature supports the conclusion, that there is a lot of potential for biochar

to play some role in addressing some of California’s most challenging environmental concerns.

o Biochar can sequester carbon for a significant amount of time.

In Appendix 1.1 and 1.21-1.24, data supports this conclusion.

o Biochar can significantly improve soil water retention.

In Appendix 1.4, data supports this conclusion.

Despite these findings, more research is certainly needed in order to create a more complete index to guide safe and effective biochar use in California.

o A state sponsored research program could fill the existing gaps in the scientific

literature.

The capacity to design biochar to meet IBI or EBC standards exists.

o Biochar Now data is a great example (see Appendix 1.6 and 1.7)

A biochar-greenhouse gas quantification protocol exists (adopted by CAPCOA).

o A state sponsored research program could demonstrate the protocol’s

effectiveness in the field.

Existing Precedents for Biochar Product Standards and Enforcement

International Biochar Initiative (IBI), Standardized Product Definition and Product

Testing Guidelines.

o Version 2.0

o Adopted: October 27, 2014

European Biochar Certificate (EBC)

o Version 6.1

o Updated on June 19, 2015

IBI – EBC, Biochar Product Standards Comparison (Appendix 1.5)

Biochar Now, Colorado

o U.S. Environmental Protection Agency, Toxic Substance Control Act Inventory

Approved biochar (created by Biochar Now) for unrestricted use

CAS Registry Number: 1467719-78-3

Accession Number: P-13-0920

Definition: Carbonized wood at temperatures exceeding 550 C

o Army Corps of Engineers, Engineering Research and Development Center,

Environmental Laboratory.

“Our preliminary investigation showed the 3mm sized biochar, at a 10%

volume in the test soils, showed significant improvement for plant and

root mass growth over the growth found in the control soils.”

o OMRI Certification

Product Number: bcn-2856

o USDA Bio Preferred

Identification Number: 3437

o See IBI Certification Test Results (Appendix 1.6)

o See Water Retention Data (Appendix 1.7)

Biochar Reporting Protocol, California Air Pollution Control Officers Association

o A carbon offset quantification protocol, developed to adequately determine

carbon offsets generated by biochar use.

o Adopted: September 28, 2015

Appendix

1.1: Data set of biochar mineralization rates

1.21-1.24: Data set of biochar persistence (MRT)

1.3: Carbon Credit Projections via Biochar Production (2015)

1.4: Soil Water Retention Data

1.5: IBI – EBC, Biochar Product Standards Comparison

1.6: Biochar Now – IBI Certification Test Results

1.7: Biochar Now – Water Retention Data

Appendix 1.1

Source: Biochar for Environmental Management (2015)

Appendix 1.21

Source: Biochar for Environmental Management (2015)

Appendix 1.22

Source: Biochar for Environmental Management (2015)

Appendix 1.23

Source: Biochar for Environmental Management (2015)

Appendix 1.24

Source: Biochar for Environmental Management (2015)

Appendix 1.3

Carbon Credit Projections via Biochar Production (2015)

Species

By

Common

Name

Total

Acres

Affected

per

Species

(2014)

Percentage

of Total

Acres

Affected

Number

of Logs

per

Species

Log

Length &

Diameter

L = ft.

D = in.

big, small

Mean

Weight

per Log

(lbs) at

75%

MC

Mean

Weight

per Log

(lbs) at

0% MC

CO2 e

Sequestered

per Log

(metric ton)

Total CO2 e

Sequestered

per Species

(metric tons)

White Fir 258,948 27.58% 1,516,900 L: 150

D: 50, 28

54,352 31,058 3.94 5,976,586

Ponderosa

Pine

232,839 24.8% 1,364,000 L: 100

D: 48, 23

31,811 18,177 2.30 3,137,200

Jeffrey

Pine

125,740 13.39% 736,450 L: 150

D: 48, 24

28,540 16,308 2.07 1,524,451.5

Sugar

Pine

110,945 11.82% 650,100 L: 198

D: 60, 36

98,284 56,162 7.13 4,635,213

Lodgepole

Pine

105,599 11.25% 618,750 L: 90

D: 16, 8

3,300 1,885 0.2395 148,190.6

California

Red Fir

92,533 9.85% 541,750 L: 100

D: 48, 24

30,614 17,493 2.22 1,202,685

Douglas

Fir

12,008 1.279% 70,345 L: 200

D: 60, 36

130,114 74,350 9.44 644,056.8

Totals 938,612 99.969% 5,498,295 n/a n/a n/a n/a 17,268,382.9

Source: Species composition, acreage, and species specific size data provided by USDA Forest

Service, Region 5 Aerial Survey (2014).

Link to survey: (http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprd3841372.pdf)

These calculations were conducted to project the estimated CO2 equivalent savings and

associated carbon offset credits that could be generated from the production of biochar

derived from converting just 9.48% (5.5 million) of the estimated 58 million dead trees

throughout the State of California.

Conversion Data:

o In order to achieve a full metric ton of CO2 equivalent offsets, 3.571 Bone Dry

Tons (BDT) of biomass must be processed into biochar.

o One BDT = 2,000 lbs of woody biomass at 0% Moisture Content (MC)

o 0.9072 Metric Tons/ US Ton

o One Carbon Offset Credit = One Metric Ton of CO2 equivalent

o Estimated Log Weight Calculator, using USDA Forest Service data on log size

and dimensions.

Available at: http://www.woodweb.com/cgi-

bin/calculators/calc.pl?calculator=log_weight

Calculation Steps to convert biomass (BDT) to Metric Tons of CO2 e:

1. Convert biomass weight from 75% MC to 0% MC (Moisture Content).

2. Divide by 2,000 to convert biomass weight (at 0% MC) to U.S tons

3. Multiply that sum by (0.9072) to convert from U.S. tons to Metric Tons

4. Multiply that sum by (0.28) to convert to total CO2 e sequestered

In a scenario of which 5.5 million trees (comprised of the species mentioned above) were

removed from the state and converted into biochar, one could expect the following

carbon savings and associated carbon credits:

o 17,268,382.9 MT CO2 equivalent Sequestered = $227,251,919 in carbon offset

credits.

o Traded at $13.16 per carbon credit (as of January 6, 2016).

In a scenario of which all 58 million trees (comprised of the species mentioned above)

were removed from the state and converted into biochar, one could expect the following

carbon savings and associated carbon credits:

o 182,095,098 MT CO2 equivalent Sequestered = $2,396,371,000 in carbon offset

credits.

o Traded at $13.16 per carbon credit (as of January 6, 2016).

Average annual Carbon Dioxide (CO2) emissions from a passenger vehicle is about 4.7

metric tons

o CO2 emissions from a passenger vehicle account for an estimated 95-99% of all

tailpipe emissions.

o If 17,268,382.9 metric tons of CO2 equivalent was sequestered in biochar, it

would be equivalent to removing 3,674,124.02 passenger vehicles off the road in

the State of California.

o Source: U.S. EPA, Greenhouse Gas Emissions from a Typical Passenger Vehicle.

(http://www3.epa.gov/otaq/climate/documents/420f14040a.pdf\

Appendix 1.4

Improvement in soil moisture storage (mmH2O/mmsoil) on days 0, 2 and 6 after water

leaching (soil treated with 2% biochars).

Norfolk

soil+Biochar

Pyrolysis (°C) Day 0 Day 2 Day 6

Peanut Hull 400

500

0.05

0.05

0.28

0.27

0.16

0.15

Pecan Shell 350

700

0.04

0.04

0.25

0.26

0.14

0.15

Switch Grass 250

500

0.04

0.05

0.29

0.36

0.17

0.24

Hardwood 500 0.05 0.29 0.17

Control

(no biochar)

** 0.03 0.23 0.11

Source: Dr. Jeff Novak

Appendix 1.5

IBI – EBC, Biochar Product Standards Comparison

Appendix 1.6

Biochar Now – IBI Certification Test Results

Appendix 1.7

Biochar Now – Water Retention Data