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Biochar as a viable carbon sequestration option Global and Canadian perspective

Darko Matovic

Department of Mechanical and Materials Engineering Queenrsquo s University 99 University St Kingston ON K7L 3N6 Canada

a r t i c l e i n f o

Article history

Received 11 January 2010

Received in revised form

19 August 2010

Accepted 18 September 2010

Available online 25 October 2010

Keywords

Biochar

Carbon sequestration

Global warming

Forestry

Forest 1047297re

Biomass

a b s t r a c t

Biochar production and mixing in soil are seen as the best options for atmospheric carbon sequestration

providing simultaneous bene1047297ts to soil and opportunities for distributed energy generation The prox-

imity of biomass source and biochar dispersal greatly reduces the energy and emissions footprint of thewhole process The viability of the whole biochar process is examined from two boundary points is there

enough biomass around to have signi1047297cant impact on the atmospheric CO2 levels and is there enough

soil area for biochar dispersal The answers are soundly positive both for the world as a whole and for

Canada for which a more detailed analysis was done However the massive adoption of biochar solution

is critically dependent on proper recognition of its carbon sequestration impact its soil improvement

potentials To that extent the International Biochar Initiative together with national chapters including

recently formed Canadian Biochar Initiative are actively promoting biochar related research and policy

framework This paper addresses the questions of availability of sources and sites that would bene1047297t

from its dispersal

2010 Elsevier Ltd All rights reserved

1 Introduction

Current trend in atmospheric CO2 concentration calls for

dramatic reduction in anthropogenic CO2 emissions in order to

avoid runaway scenario of potentially catastrophic temperature

and sea level rise The annual mean CO2 growth rate was signi1047297-

cantly higher for the period from 2000 to 2005 (41 01 Pgyr)

compared with the 1047298ux in the 1990s (32 01 Pgyr) even though

only 45 of combined anthropogenic emissions have remained in

the atmosphere the rest being naturally sequestered by terrestrial

and oceanic systems ([1] p 515) In addition to curbing the fossil

fuel and cement industry CO2 emissions several strategies for CO2

sequestration are being proposed A special IPCC report on carbon

capture and storage (CCS) [2] lists seven climate change mitigation

options carbon capture and storage energy ef 1047297ciency switch to

low-carbon fuels nuclear power renewable energy enhancementof biological sinks and reduction of non-CO2 greenhouse gas

emissions Of these options only enhancement of biological sinks

and CCS from biomass combustion products can remove CO2

already in the atmosphere Other mitigation options only reduce or

prevent further emissions CCS is energy intensive option requiring

additional emissions associated with carbon capture A natural gas

power plant (even when in combined cycle) emits equal or less

amountof CO2 than the one run on coal with CCS [3] It is estimated

that CCS in Europe in 2020 will result in an increase in theproduction cost of electricity by coal and natural gas technologiesof

30e55 [4] Little is known about the long-term storage issues [5]

from slow seepage into the atmosphere or sea water to the cata-

strophic release as in the case of LakeNyos disaster [6] Overall CCS

has manyobstacles toovercome if it was to become a viable carbon

emissions reduction strategy and even then the expected time

frame for full implementation may be around 2050 [2] Other

proposed methods include injecting CO2 into chemically reactive

rock even dead wood burial [7]

Production and deposition of biochar (or black carbon as it is

sometimes called [8]) into thesoil are rapidly gaining recognition as

a viable option in permanent carbon storage while its bene1047297ts to

soil fertility continue to emerge

A number of methods can be used for producing biocharModern biochar is a product that can be manufactured from

almost any uncontaminated organic matter such as crop residues

bark stem timber (logs) non-stem logging residues (bark

branches tree-tops) various grasses and agricultural plant resi-

dues The main processes for modern char production are fast or

slow pyrolysis (biomass heating without air or oxygen) or gasi1047297-

cation (run in the regime that leaves charcoal residue) Biochar

production is typically self suf 1047297cient in energy requirements and

can produce surplus energy as heat or biofuel for use in various

energy conversion processes including transportation and elec-

tricity production Tel thorn1 613 533 6824 fax thorn1 613 533 6489

E-mail address darkomequeensuca

Contents lists available at ScienceDirect

Energy

j o u r n a l h o m e p a g e w w w e l s e v i e r c o m l o c a t e e n e r g y

0360-5442$ e see front matter 2010 Elsevier Ltd All rights reserved

doi101016jenergy201009031

Energy 36 (2011) 2011e2016



This paper is focused on three aspects of biochar production

and dispersion

1 Can we offset the full annual CO2 level increase by using

biochar

2 How much carbon can be sequestered worldwide and in

Canada

3 Is there enough soil area for its dispersal

The anthropogenic impact on carbon dioxide atmospheric levels

can principally be attacked in three ways (a) CO2 production

reduction via phasing out fossil fuel use (b) CO2 capturing and

storage from the source and (c) CO2 capturing and storage from the

air Of course the overall strategy that is pursued now and will be

pursued in the near future is a mix of all three For completeness

we should add the fourth mechanism for the atmospheric CO2

reduction namely natural capture via terrestrial carbon cycle In

fact it is this last mechanism that is mostly counted on for climate

change mediation combined with emission reductions Direct

capture from the source (eg power plant 1047298ue gases) seems to be

favoured among all the capturing options by the policy makers

today although it is limited to large scale plants situated in good

location Currently most economically viable projects are thosethat combine CCS with oilgas extraction already practiced in US

Canada Brazil Turkey Hungary Croatia Norway and few other

countries [910]

Carbon capture from air is being contemplated on an industrial

scale by the closed-cycle sodium hydroxide absorption at a cost of

$500tC (USD) or by a combination of biomass with carbon capture

and sequestering at roughly half the cost [11] Signi1047297cant cost both

in energy and 1047297nance is associated with compressing carbon

dioxide and pumping it into the ground Biochar production and

distribution do not incur that cost at all and offer additional agri-

cultural and ecological bene1047297ts This triple bene1047297t puts is in

a unique position among various sequestration options it can be

produced by relatively simple processes (that need to be non-

polluting nevertheless) it can be produced wherever there isbiomass and soil (ie practically everywhere) and it improves soil

quality The role of biochar as a viable sequestration vehicle has

recently been recognized formally in the draft negotiating text for

the upcoming Copenhagen round of Climate Change talks

ldquoConsideration should be given to the role of soils in carbon

sequestration including through the use of biochar and enhancing

carbon sinks in drylandsrdquo [12]

What is the optimal amount of biochar addition to soil Kurth

et al [13] investigated different soils that have undergone 1e3

forest 1047297res in the last 100 years and found that they contain

between 03 and 09 of charcoal Estimates of the optimum in

agricultural soil range between 1 and 5 For purposes of this

study it is assumed that the charcoal is added to the soil at the 3

level to the top 30 cm ie 135 thaThe question of biochar interaction with soils while important

and even critical to the policy of biochar incorporation into arable

soils is beyond the scope of this paper A recent comprehensive

review done by the EU commission [14] found ldquo a small overall

but statistically signi1047297cant positive effect of biochar application to

soils on plant productivity in the majority of cases The greatest

positive effects were seen on acidic free-draining soilsrdquo M work

needs to be done in this area leading to more speci1047297c knowledge

about optimal conditions and concentrations in various agricultural

scenarios Black carbon is also seen as bene1047297cial in binding

anthropogenic hydrophobic organic compounds (eg persistent

aromatic hydrocarbons polychlorinated biphenyl pesticide and

herbicides) in soil responsible for 80e90 of total uptake of trace

HOC in soils [15] The negative effects of biochar on soil are mainly

avoidable (eg dust exposure during application soil compaction

and risk of passing the contaminants to the soil if biochar is

produced from contaminated source material esp if it contains

heavy metals) Other potential pitfalls such as the loss of minerals if

the crop residues are removed for char production to be dispersed

elsewhere can easily be avoided by the appropriate policies in

biochar production and use

2 Potentials for carbon removal world

Storing biochar rather than burning it forfeits 32 MJkg C of

heat energy This is certainly more than CCS penalty estimated at

10e30 for large power plants [2] However CCS can only be

applied in the very speci1047297c cases of large-scale power plants close

to suitable storage reservoirs Optimal siting for CO2 storage usually

invokes ef 1047297ciency penalty since combined heat and power (CHP)

utilization opportunities are lost It is often quoted that the large-

scale power plans have higher ef 1047297ciency and this is certainly true

if measured by the ratio of fuel caloric value to electricity produced

(up to 40) In reality smaller community-based CHP plants ach-

ieve much higher overall ef 1047297ciencies around 75 In addition

charcoal production can be done in a much more distributed way

eg on farms and forest grounds drastically reducing trans-portation costs and energy use both for biomass supply and for

charcoal dispersal An additional ef 1047297ciency penalty when biomass

is used in large energy plants is in transportation Lower caloric

value of biomass (per weight and especially per volume) means

that substantial amount of energy is lost in transportation

If we focus now on biochar production and distributionstorage

we 1047297rst ask if there is enough raw material available to have

a meaningful impact on the atmospheric carbon dioxide Fig 1

illustrates overall carbon budget for all planetary ecosystems

(atmospheric terrestrial and aquatic) ([1] p 515) The arrows with

numbers represent annual 1047298uxes in GtCyr while the numbers in

the boxes represent the totals contained in each reservoir (atmo-

sphere vegetation soil amp detritus fossil fuel reservoirs surface

intermediate and deep ocean marine biota and ocean bottomsurface sediments) The reservoir 1047297gures do not include the litho-

graphic storage estimatedat 20 PtC ie 998 of the total terrestrial

carbon [16] since it can be considered inert on a millennial and

shorter time scales Anthropogenic annual emissions of carbon due

to fossil fuel use and cement production are 72 03 GtCyr in

2000e2005 period as indicated in ref [1] Table 71 page 516 Of

this total 41 GtCyr remains in the atmosphere increasing the CO2

concentration while 31 GtCyr is being absorbed by terrestrial and

oceanic systems (1 GtCyr and 21 GtCyr respectively) as indicated

in Fig 1

To examine the potential for carbon sequestration via terrestrial

biomass conversion to biochar we will assume that the biomass

available for conversion is 10 of the net primary production (NPP)

currently estimated at 606 Gtyr [17] This estimate 1047297ts well withinthe range of 15 models reviewed in [18] placing NPP in the

444e663 GtCyr range Further calculations are summarized in

Table 1

As seen in the table 10 of NPP of biomass would be more than

suf 1047297cient to offset the entire annual CO2 increase in the atmosphere

(48 vs 41 GtCyr) The next question is where this amount of

biochar would be dispersed As will be discussed later the most

bene1047297cial use of biochar is in mixing it with soil As a soil constit-

uent it is both chemically stable and biologically bene1047297cial If we

assume adding 3 of biochar (by mass) into the top 30 cm of the

total agricultural land area (standing at w45 mil km2 worldwide

[19]) the capacity worldwide would be 600 GtC of biochar The

average soil density for this calculation was assumed to be 15 tm 3

(Loam with 40 sand 22 clay and 38 silt [20]) amounting to 135

D Matovic Energy 36 (2011) 2011e 2016 2012



tones of charcoal per hectare At the rate of 3 GtCyr this potential

reservoir would be available for 2 centuries The brief analysis

above has been done for natural new biomass growth only Even

more could be achieved by utilizing short rotation biomass crops

such as poplar and willow Estimates of that potential are outside

the scope of this paper

The deposition of biochar into agricultural soil seems to provide

several bene1047297ts to soil quality Laboratory research [2122] and

historical 1047297ndings [2324] indicate that incorporation of charcoal

into the soil has demonstrable bene1047297ts to soil fertility recognized

both in the laboratory and by traditional soil management practices

on a millennial scale This is particularly demonstrated in the

Amazon region of South America where the patches of dark

almost black soil are scattered in sizes from 05 ha to more than

120 ha Research into these soils con1047297rmed anthropogenic in1047298u-

ence in their creation mainly through systematic burning and

burial of organic material and ash and provided detailed soil

analysis data The effect of black carbon on the soil fertility is still

based mostly on anecdotal evidence albeit strong one McCann et

al [24] attribute the bene1047297ts to the introduction of charged (active)

surfaces and the increase in soil pH suppressing Al activity toxic to

soil biota Glasser et al [23] attribute longevity of black carbon in

the Terra preta soil to the carbon polyaromatic structure making it

chemically and microbially resistant able to survive in the envi-

ronment over thousands of years Complex structure and

morphology of the charcoal are illustrated by the sample taken

from a ponderosa pine forest in Northern Idaho which was

exposed to 1047297re 79 years prior to collection [25] Fig 2 As more

research is done in correlating the crops yield with mixing of bio-

char into the soil there will be more solid experimental evidence

and certainly additional best practice recommendations

Laird [26] offered an interesting paradigm change by arguing

that the biomass debate should shift from the current how much

Fig 1 The global annual carbon cycle with anthropogenic 1047298uxes adjusted for the 2000e2005 period showing the main annual 1047298uxes (arrows) and reservoir sizes (1047297gures in boxes)

All units are in GtC for reservoirs and GtCyr for 1047298uxes Pre-industrial lsquonaturalrsquo 1047298uxes and reservoir sizes are shown in black anthropogenic ones are shown in red Source IPCC

Fourth Assessment Report 2007 p 515 adjusted with Tables 71 and 72 data from the same report

Table 1

Potentials for worldwide carbon sequestration via biochar production and disper-

sion over agricultural land

Item Value CommentsNet primary production (NPP) 606 GtCyr Source [9]

Percentage of NPP for biochar 1000

Resultant biochar production 3 GtCyr Assume 50 of biomass

carbon is converted into

biochar

Carbon offset via combustible

products (60 of 50 biomass)

18 GtCyr Assume 60 emission

displacement ef 1047297ciency of

the combustion portion

(50 of biomass) The

remaining 40 (13 GtCyr)

is used up for running

pyrolysis

Annual increase in atmospheric

C due to fossil fuels and cement

industry

41 GtCyr Amount of CO2 that remains in

the atmosphere out of the

total of 72 GtCyr released

by humans

Fig 2 An electron micrograph of charcoal collected from a ponderosa pine forest in

Northern Idaho US which was exposed to 1047297re 79 years prior to collection Source

Brimmer 2006 [16]




can be harvested without doing too much damage into how to design

integrated agricultural biomass-bioenergy systems that build soil

quality and increase productivity so that both food and bioenergy

crops can be sustainably harvested

3 Potentials for carbon removal Canada

Canadian CO2 emissions history in a post-Kyoto period is illus-

trated in Fig 3 [27] It is clear from the graph that the trend of CO2

emissions has been the opposite from the Kyoto targets for the

most of the post-Kyoto period Small temporary drops in the 1991

and 2001 can be explained mainly by economic downturns while

the drop in the 2004e2006 period illustrates the major contribu-

tion of tar-sands to the overall Canadian emissions The data for

total above do not include land use land-use change and forestry

(45 Mt CO2 [27]) and Canadian share of international aviation

(w7 Mt CO2 assuming total aviation as 2 of total emissions ie

w15 Mt CO2 minus 77 Mt CO2 emissions from domestic aviation

already included in the total) These sources addup 50 Mt CO2yr or

67 of the reported total Together the new total becomes

w797 Mt CO2yr or 217 Mt Cyr (conversion factor 367 tCO2tC)

We will examine here if conversion of biomass from forest and

agricultural sources could offset this totalUsing the same assumptions as for the world production above

(Table 1) we would need approximately 271 Mt of bone-dry

biomass per year (producingw136 MtCyr of biochar for dispersal

ie converting 50 of the original biomass and offsetting additional

81 MtCyr of emissions by displacing fossil fuel ie 30 of the

original biomass e either as a syngas methane or liquid biofuel)

Where would that biomass potentially come from We next

examine 4 potential sources in Canada forestry resources forest

1047297re reduction pine beetle infested trees and agricultural residues

31 Forestry resources

The total forest area in Canada is 3101 Mha of which 2749 Mha

(88) is stocked (ie known to have signi1047297

cant tree population)

[28] The total biomass on the forested land is 29574 Mt (oven-dry)

or 29383 Mm3 [29] Based on these 1047297gures the average volume

density is 948 m3ha biomass density is 954 tha C density is

42 tCha and CO2 equivalent density is 187 tCO2ha How much of

that biomass is sustainably available annually There are various

ways to answer this question depending on the intended biomass

use harvesting strategy and the notion of ldquosurplusrdquo and ldquoresidualrdquo

biomass For example if the main product is roundwood for lumber

or pulp and paper the tree stems are the primary harvesting targetwhile bark three-tops and branches are residuals If the primary

product is biomass as energy source then bark and branches even

foliage becomes harvesting target especially if the biomass is

pelletized With biochar the focus is further shifted somewhat

depending on the biochar production strategy (larger centralized

vs small-scale distributed) Comparison and optimization of these

strategies are out of scope of this survey Instead two approaches

with different but comparable outcomes will be used as an

illustration

A well managed forestry resource is harvested in rotation fol-

lowed by replanting and regeneration Assuming that harvesting

occurs on average on a 100 yr cycle we can calculate sustainable

new biomass as an average density of a 100-year old forest (130 t

ha) over 1 of the total stocked area (275 M ha) to the total of 3574 Mtyr of biomass If we assume that half of that biomass can

be converted into biochar this gives 1787 Mtyr of biomass or 58

of the target amount of 271 Mtyr

Alternatively if we use the total annual new biomass estimate

[28] of 197 Mm3yr of merchantable timber corresponding to

199 Mtyr of biomass (factor 101 [29]) and again assume that half of

that is available for biochar conversion that would amount to

approx 100 Mtyr of biomass ie 37 of the target amount

32 Forest 1047297re reduction

Forest 1047297res are highly variable events with the immediate

impact on greenhouse gases (GHG) emissions For example in the

1990e

2007period an annual area under forest1047297

re in Canadavaried

Fig 3 Total Canadian GHG emissions [GtCO2 equivalent] Source [18]




between 063 and 71 Mha [30] with the average of 233 Mha

Compared to a typical harvested area of w1 Mha the average area

under the 1047297re is more than twice the total harvested area Using

average biomass density (954 tha) this represents the range of

60e676 Mtyr with the average of 222 Mtyr or 82 of the total

target biomass Can this amount or a portion of it be turned into

char instead of ash and dead biomass Fire is a central part of the

life cycle of many Canadian ecosystems Robust new trees quickly

emerge to replace the burnt aged forest In some species (eg Pinus

banksiana) it also opens the seed cones allowing the species to

reproduce and survive [30]

Annual CO2 emissions from forest 1047297res reported to the IPCC

were between 11 and 291 Mt CO2yr in a 1990e2007 time span

[31] These are apparently low values since the emissions corre-

sponding to the average forest density of 187 tCO2ha would be an

order of magnitude larger (117 and 1327 Mt CO2yr respectively)

Clearly only a small proportion of the biomass is immediately

burnt but the remaining dead biomass continues to release GHG

gases slowly in subsequent years For the most part converting

biomass into biochar and spreading it locally would have similar

ecological impact as the wild1047297re itself with one substantial

difference the organic carbon would be mostly converted into

inorganic black carbon instead of being pumped back into theatmosphere as CO2 thus it would be a long lasting carbon

sequestration vehicle How could that be done to what extent it is

feasible to replace naturally occurring 1047297re knowing fully well that

it is impossible to eliminate 1047297re altogether should be a subject of

intensive research technical innovation and public debate

Here we estimate that 20 of the total average area of forest

burnt annually could be converted to biochar enlarging the 1047297re

corridors and achieving similar ecological impact as if that area

burnt naturally but1047297xing the biomass carbon instead of releasing it

to the atmosphere either as an immediate release or a slow release

due to the dead biomass decay This amounts to 222 Mtyr biomass

representing 82 of the total target biomass that would fully offset

current Canadian GHG emissions

33 Pine beetle infestation

Another major tree killer in Canada (after wild1047297re) is the insect

infestation In Canada the mountain pine beetle infestation is the

most serious epidemic killing 9 10 and 7 Mha of forest in 2006

2007 and 2008 respectively [32] Total cumulative impact of the

epidemics is about 620 Mt of merchantable timber on 145 Mha

[33] If we consider all the biomass in that area as a biochar source

the amount is much larger Based on the average BC forest biomass

density of 169 tha [30] this would amount to 2450 Mt of biomass

or 1180 Mtyr just for 2008 This is conservative estimate of the

biomass density since mountain pine beetle destroys older forest

stands (60 years and more) while younger trees 1047297ght the beetle

more successfully The wide range of estimates associated withthese 1047297gures calls for further investigation and innovation in

handling this carbon source Of course this is not sustainable

source of biomass but nevertheless converting a portion of this

amount into biochar would prevent release of its carbon back into

the atmosphere At present we will take the 1047297gure of 271 Mtyr as

a plausible portion for several years ahead representing 23 of the

area affected but 100 of the target biomass amount

34 Agricultural land

For this survey no food stocks are considered as biochar sources

(grain oil seeds etc) Detailed analysis of strawstover availability

of various crops in [34] indicates that 44 Mtyr of agricultural

residues (out of the 56 Mtyr total) are sustainably removable

This would represent 16 of the target biomass While this may

look like a small amount comparedwith the other sources surveyed

above this is the ldquolow hanging fruitrdquo in terms of biochar operations

since the biomass is right where the biochar is needed most ie in

the farmersrsquo 1047297elds

35 Fast rotation silviculture

Fast rotation cellulosic crops such as poplar or willow represent

an intensive ldquofarmingrdquo of biomass either for energy chemical raw

material or sequestration vehicle via biochar McKenney et al [35]

conducted detailed analysis of land availability and possible

biomass production as a function of yield at 10e20 m3(ha yr) and

the price of at $10e50tCO2 (CAD) As the yield and sequestration

price go up so does the available land for rapid rotation silviculture

Here we adopt 16 m3(ha yr) yield and $25 (CAD) per ton of CO2

resulting in 52 Mha of land available to the total of 840 Mt of

biomass or 310 of the target

36 All sources combined

All sources are combined in Table 2 expressed as Mtyr and as

a percentage of the target amount of 271 Mtyr of biomass that

would offset total Canadian annual CO2 emissions

Clearly there is enough biomass to offset total Canadian GHG

emissions (574 times total annual target mass) Large potentials lay

in forest 1047297re mitigation through a ldquoslash and charrdquo strategy and in

fast rotation wood crops

The potentials for spreading the biochar lay in mixing it with

soil in brown soil remediation and depositing it in the forest 1047298oor

Historically forests have undergone periodic1047297resall acrossCanada

and adding charcoal to the forest 1047298oor would be similar to the

natural process of forest rejuvenation after the 1047297

re Looking at thearable land alone (675 mil km2 [19]) and using the same concen-

tration of 3 30 cm deep (135 tCha) the total agricultural soil

capacity would be 9113 MtC Given the need to sequester 136 MtC

yr this resource would be ldquo1047297lled uprdquo in about 67 years This is

much lower capacity than the worldwide one Despite the vast land

area of Canada (9 mil km2) agricultural land represents only 74

of the total Clearly other deposit sites should be looked upon and

there are plenty forest 1047298oor mine tailings (dry) and various brown

soil remediation sites Further research is needed in this area

4 Conclusions

Biochar is indeed a viable carbon sequestration option for the

planet as a whole as well as for Canada The overall biomass

Table 2

Sourcesof biomass in Canada in absoluteamounts andas a percentageof the pool of

271 Mtyr required to offset total Canadian GHG emissions from fossil fuels cement

industry and land use

Biomass source Mtyr of 271

Mtyr

Comments

50 of annual forest

biomass production

1787 66 Assumes 1 of the stocked forest

area harvested annually 130 tha

Forest 1047297

re reduction 222 82 Assumes 20 of burnt forest wasconverted to biochar at 945 t

biomass per hectare

Pine beetle infestation 271 100 23 of the biomass affected in

2008 (7 Mha)

Agricultural residues 44 16 Residues sustainably available

Fast rotation silviculture 840 310 Based on 16 m3ha yield and price

of $25 CAD per tone CO2

sequestered resulting in harvesting

area of 52 Mha

Total 15557 574




reserves seem to be suf 1047297cient to ful1047297ll the sequestration need and

still provide other substitutions for fossil fuel use

If 10 of the world biomass NPP is converted into charcoal

at 50 yield and 30 energy from volatiles it would sequester

48 GtCyr approx 20 more than the current annual increase of

atmospheric carbon at 41 GtCyr

Mixing biochar in soil at the rate of 135 tha (3 of the upper

30 cm layer) provides storage space that would last 2 centuries

Various studies indicate soil fertility increases with the addition of

biochar while the carbon so deposited remains chemically stable

for millennia Further research is needed to characterize best char

morphology for maximum bene1047297ts to soil and perhaps variations

to match various soil and climate conditions

Canada has large reserves of biomass available for biochar

production Combined sources from forest harvesting forest 1047297re

reduction mountain pine beetle infestation agricultural residues

and fast rotation silviculture provide the biomass source more than

5 times larger then the annual requirements of 271 Mtyr that

would fully offset total carbon emissions However the land

capacity to store that carbon is more limited especially when only

the agricultural land is considered

The review of potential biochar application worldwide and in

Canada presented here does not tackle the economic or the policyaspects of mass production distribution and application of biochar

These questions are of critical importance in any implementation

scenario but are out of scope of this preliminary survey

Further research is needed in biochar production its effects on

soil and other biochar storage options to name just the few here

More complete list of research areas is posted at the Canadian

Biochar Initiative web site [36]

Acknowledgements

The author thanks the reviewers whose constructive sugges-

tions assisted in revising the text and resulted in more coherent and

accurate account of the topics covered

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[2] Metz B Davidson O Coninck H Loos M Meyer L editors IPCC 2005 carbondioxide capture and storage Cambridge United Kingdom and New York NYUSA Cambridge University Press 2005

[3] Viebahn P Nitsch J Fischedick M Esken A Schuewer D Supersberger Net al Comparison of carbon capture and storage with renewable energytechnologies regarding structural economic and ecological aspects inGermany Int J Greenhouse Gas Control 2007121e33 doi101016S1750-5836(07)00024-2

[4] Tzimas E Peteves S The impact of carbon sequestration on the productioncost of electricity and hydrogen from coal and natural-gas technologies in

Europe in the medium term Energy 2005302672e

89[5] Holloway S Underground sequestration of carbon dioxide e a viable green-

house gas mitigation option Energy 2005302318e33[6] Le Guern F Sigvaldason GE The LakeNyos event and natural CO2 degassing

J Volcanol Geoterm Res 19893995e276[7] Zeng N Carbon sequestration via wood burial Carbon Balance Manage

200831 doi1011861750-0680-3-1[8] Fowles M Black carbon sequestration as an alternative to bioenergy Biomas

Bioenerg 200731426e32[9] ZEP European technology platform for zero emission fossil fuel plants (ZEP)

strategic overview EU March 2007

[10] Domitrovic D Current status of CO2 injection projects in Croatia carboncapture and storage response to climate change In Regional workshop for CEand EE Counties CO2Net East 27e28 Feb 2007

[11] Keith DW Ha-Duong M Stolaroff JK Climate strategy with CO2 capture fromthe air Clim Change 20067417e45

[12] UNFCCC Negotiating text for the Ad Hoc working Group on long-termCooperative Action under the convention Link httpunfcccintresourcedocs2009awglca6eng08pdf p 36 [accessed 250509]

[13] Kurth VJ MacKenzie MD DeLuca TH Estimating charcoal content in forestmineral soils Geoderma 2006137135e9

[14] Verheijen F Jeffery S Bastos AC van der Velde M Diafas I Biochar applicationto soils JRC scienti1047297c and technical reports EUR 24099 EN EU Commission2010 doi102788472

[15] Cornelissen G Gustafsson O Bucheli TD Jonker MTO Koelmans AA vanNoort PCM Extensive sorption of organic compounds to black carbon coaland kerogen in sediments and soils mechanisms and consequences fordistribution bioaccumulation and biodegradation Environ Sci Technol2005396881e95

[16] Klas D Biomass for renewable energy fuels and chemicals Acad Press 1998p 24

[17] Amonette JE Lehmann JC Joseph S Terrestrial carbon sequestration withbiochar a preliminary assessment of its global potential EOS Trans AGU200888(52) Fall Meeting Supplement Abstract U42A-06

[18] Cramer W Kicklighter DW Bondeau A Moiore III B Churkina G Nemry Bet al Comparing global models of terrestrial net primary productivity (NPP)overview and key results Glob Change Biol 19995(Suppl 1)1e15

[19] World Resources Roots of Resilience p 210 httppdfwriorgworld_resources_2008_roots_of_resiliencepdf [accessed 020509]

[20] Saxton KE Rawls WJ Romberger JS Papendick RI Estimating generalized soil-water characteristics from texture Soil Sci Soc Am J 198650(4)1031

e6

[21] Lehmann J Gaunt J Rondon M Bio-char sequestration in terrestrial ecosys-tems e a review Mitig Adapt Strat Glob Change 200611(2)395e419

[22] Rondon MA Lehmann J Ramires J Hurtado M Biological nitrogen 1047297xation bycommon beans (Phaseolus vulgaris L) increases with bio-char additions BiolFertil Soils 200743699e708

[23] Glaser B Guggenberger G Haumaier L Zech W Persistence of soil organicmatter in archaeological soils (Terra Preta) of the Brazilian Amazon region InRees RM Bell BC Campbell CD Watson CA editors Sustainable managementof soil organic matter CAB International 2001

[24] McCann JM Woods WI Meyer DW Organic matter and anthrosols in Ama-zonia interpreting the Amerindian legacy In Rees RM Bell BC Campbell CDWatson CA editors Sustainable management of soil organic matter CABInternational 2001

[25] Brimmer RJ Sorption potential of naturally occurring charcoal in ponderosapine forests in western Montana (MS thesis) Missoula MT U of Montana2006

[26] Laird DA The charcoal vision a win-win-win scenario for simultaneously

producing bioenergy permanently sequestering carbon while improving soiland water quality Agron J 2008100(1)178e81[27] Government of Canada Canadarsquos 2007 greenhouse gas inventory e

a summary of trends httpwwwecgccapdbghginventory_report2007som-sum_engpdf [accessed 281209]

[28] Lowe JJ Power K Gray SL Canadarsquos forest inventory 1991 the 1994 versionAn addendum to Canadarsquos forest inventory 1991 CFS information report BC-X-362 Paci1047297c Forestry Centre Victoria BC 1996

[29] Power K Gillis M Canadarsquos forest inventory 2001 CFS information report BC-X-408 Victoria BC Paci1047297c Forestry Centre 2006

[30] National Forestry Database Canadian council of forest ministers forest 1047297resbackground httpnfdpccfmorg1047297resbackground_ephp [accessed 281209]

[31] National Forestry Database Canadian council of forest ministers dynamicreport generated at httpnfdpccfmorgdynamic_reportdynamic_report_ui_ephp Dec 28 2009

[32] Walton A Hughes J Eng M Fall A Shore T Riel B et al Provincial-level of thecurrent mountain pine beetle outbreak update of the infestation projectionbased on the 2007 provincial aerial overview of forest health and revisions of the ldquoModelrdquo (BCMPB V5) Gov of British Columbia Forest Management

Branch 2008[33] Forests and Range Mountain pine beetle information infestation information

httpwwwforgovbccahfpmountain_pine_beetlefactshtminfestation[accessed 281209]

[34] Wood SM Layzell DB A canadian biomass inventory feedstocks for a bio-based economy Canada BIOCAP 2003

[35] McKenney DW Yemshanov D Fox G Ramlal E Cost estimates for carbonsequestration from fast growing poplar plantations in Canada For Pol Econ20046345e58

[36] Canadian Biochar Initiative Needed research httpwwwbiocharcaNeededResearchhtm [accessed 050509]




This paper is focused on three aspects of biochar production

and dispersion

1 Can we offset the full annual CO2 level increase by using

biochar

2 How much carbon can be sequestered worldwide and in

Canada

3 Is there enough soil area for its dispersal

The anthropogenic impact on carbon dioxide atmospheric levels

can principally be attacked in three ways (a) CO2 production

reduction via phasing out fossil fuel use (b) CO2 capturing and

storage from the source and (c) CO2 capturing and storage from the

air Of course the overall strategy that is pursued now and will be

pursued in the near future is a mix of all three For completeness

we should add the fourth mechanism for the atmospheric CO2

reduction namely natural capture via terrestrial carbon cycle In

fact it is this last mechanism that is mostly counted on for climate

change mediation combined with emission reductions Direct

capture from the source (eg power plant 1047298ue gases) seems to be

favoured among all the capturing options by the policy makers

today although it is limited to large scale plants situated in good

location Currently most economically viable projects are thosethat combine CCS with oilgas extraction already practiced in US

Canada Brazil Turkey Hungary Croatia Norway and few other

countries [910]

Carbon capture from air is being contemplated on an industrial

scale by the closed-cycle sodium hydroxide absorption at a cost of

$500tC (USD) or by a combination of biomass with carbon capture

and sequestering at roughly half the cost [11] Signi1047297cant cost both

in energy and 1047297nance is associated with compressing carbon

dioxide and pumping it into the ground Biochar production and

distribution do not incur that cost at all and offer additional agri-

cultural and ecological bene1047297ts This triple bene1047297t puts is in

a unique position among various sequestration options it can be

produced by relatively simple processes (that need to be non-

polluting nevertheless) it can be produced wherever there isbiomass and soil (ie practically everywhere) and it improves soil

quality The role of biochar as a viable sequestration vehicle has

recently been recognized formally in the draft negotiating text for

the upcoming Copenhagen round of Climate Change talks

ldquoConsideration should be given to the role of soils in carbon

sequestration including through the use of biochar and enhancing

carbon sinks in drylandsrdquo [12]

What is the optimal amount of biochar addition to soil Kurth

et al [13] investigated different soils that have undergone 1e3

forest 1047297res in the last 100 years and found that they contain

between 03 and 09 of charcoal Estimates of the optimum in

agricultural soil range between 1 and 5 For purposes of this

study it is assumed that the charcoal is added to the soil at the 3

level to the top 30 cm ie 135 thaThe question of biochar interaction with soils while important

and even critical to the policy of biochar incorporation into arable

soils is beyond the scope of this paper A recent comprehensive

review done by the EU commission [14] found ldquo a small overall

but statistically signi1047297cant positive effect of biochar application to

soils on plant productivity in the majority of cases The greatest

positive effects were seen on acidic free-draining soilsrdquo M work

needs to be done in this area leading to more speci1047297c knowledge

about optimal conditions and concentrations in various agricultural

scenarios Black carbon is also seen as bene1047297cial in binding

anthropogenic hydrophobic organic compounds (eg persistent

aromatic hydrocarbons polychlorinated biphenyl pesticide and

herbicides) in soil responsible for 80e90 of total uptake of trace

HOC in soils [15] The negative effects of biochar on soil are mainly

avoidable (eg dust exposure during application soil compaction

and risk of passing the contaminants to the soil if biochar is

produced from contaminated source material esp if it contains

heavy metals) Other potential pitfalls such as the loss of minerals if

the crop residues are removed for char production to be dispersed

elsewhere can easily be avoided by the appropriate policies in

biochar production and use

2 Potentials for carbon removal world

Storing biochar rather than burning it forfeits 32 MJkg C of

heat energy This is certainly more than CCS penalty estimated at

10e30 for large power plants [2] However CCS can only be

applied in the very speci1047297c cases of large-scale power plants close

to suitable storage reservoirs Optimal siting for CO2 storage usually

invokes ef 1047297ciency penalty since combined heat and power (CHP)

utilization opportunities are lost It is often quoted that the large-

scale power plans have higher ef 1047297ciency and this is certainly true

if measured by the ratio of fuel caloric value to electricity produced

(up to 40) In reality smaller community-based CHP plants ach-

ieve much higher overall ef 1047297ciencies around 75 In addition

charcoal production can be done in a much more distributed way

eg on farms and forest grounds drastically reducing trans-portation costs and energy use both for biomass supply and for

charcoal dispersal An additional ef 1047297ciency penalty when biomass

is used in large energy plants is in transportation Lower caloric

value of biomass (per weight and especially per volume) means

that substantial amount of energy is lost in transportation

If we focus now on biochar production and distributionstorage

we 1047297rst ask if there is enough raw material available to have

a meaningful impact on the atmospheric carbon dioxide Fig 1

illustrates overall carbon budget for all planetary ecosystems

(atmospheric terrestrial and aquatic) ([1] p 515) The arrows with

numbers represent annual 1047298uxes in GtCyr while the numbers in

the boxes represent the totals contained in each reservoir (atmo-

sphere vegetation soil amp detritus fossil fuel reservoirs surface

intermediate and deep ocean marine biota and ocean bottomsurface sediments) The reservoir 1047297gures do not include the litho-

graphic storage estimatedat 20 PtC ie 998 of the total terrestrial

carbon [16] since it can be considered inert on a millennial and

shorter time scales Anthropogenic annual emissions of carbon due

to fossil fuel use and cement production are 72 03 GtCyr in

2000e2005 period as indicated in ref [1] Table 71 page 516 Of

this total 41 GtCyr remains in the atmosphere increasing the CO2

concentration while 31 GtCyr is being absorbed by terrestrial and

oceanic systems (1 GtCyr and 21 GtCyr respectively) as indicated

in Fig 1

To examine the potential for carbon sequestration via terrestrial

biomass conversion to biochar we will assume that the biomass

available for conversion is 10 of the net primary production (NPP)

currently estimated at 606 Gtyr [17] This estimate 1047297ts well withinthe range of 15 models reviewed in [18] placing NPP in the

444e663 GtCyr range Further calculations are summarized in

Table 1

As seen in the table 10 of NPP of biomass would be more than

suf 1047297cient to offset the entire annual CO2 increase in the atmosphere

(48 vs 41 GtCyr) The next question is where this amount of

biochar would be dispersed As will be discussed later the most

bene1047297cial use of biochar is in mixing it with soil As a soil constit-

uent it is both chemically stable and biologically bene1047297cial If we

assume adding 3 of biochar (by mass) into the top 30 cm of the

total agricultural land area (standing at w45 mil km2 worldwide

[19]) the capacity worldwide would be 600 GtC of biochar The

average soil density for this calculation was assumed to be 15 tm 3

(Loam with 40 sand 22 clay and 38 silt [20]) amounting to 135








































Table 1







biochar






(50 of biomass) The



pyrolysis



industry




by humans



Brimmer 2006 [16]





















































illustration
















1990e


re in Canadavaried






































































































4 Conclusions



Table 2





Mtyr

Comments

50 of annual forest

biomass production



Forest 1047297


biomass per hectare


2008 (7 Mha)





area of 52 Mha

Total 15557 574

































Acknowledgements




References























e6


























































Table 1







biochar






(50 of biomass) The



pyrolysis



industry




by humans



Brimmer 2006 [16]





















































illustration
















1990e


re in Canadavaried






































































































4 Conclusions



Table 2





Mtyr

Comments

50 of annual forest

biomass production



Forest 1047297


biomass per hectare


2008 (7 Mha)





area of 52 Mha

Total 15557 574

































Acknowledgements




References























e6







































































illustration
















1990e


re in Canadavaried






































































































4 Conclusions



Table 2





Mtyr

Comments

50 of annual forest

biomass production



Forest 1047297


biomass per hectare


2008 (7 Mha)





area of 52 Mha

Total 15557 574

































Acknowledgements




References























e6























































































































4 Conclusions



Table 2





Mtyr

Comments

50 of annual forest

biomass production



Forest 1047297


biomass per hectare


2008 (7 Mha)





area of 52 Mha

Total 15557 574

































Acknowledgements




References























e6



















































Acknowledgements




References























e6




















fast growing poplar

Documents