biochar and biochar systems – specificity and flexibility · dr saran sohi [email protected] uk...

Dr Saran [email protected]

UK Biochar Research CentreUniversity of Edinburgh, UK 1

Saran Sohi and Ondrej MasekSchool of GeoSciences, University of Edinburgh

UK Biochar Research Centre (UKBRC)www.biochar.ac.uk

Biochar and biochar systems – specificity and flexibility

FOREBIOM Workshop, Eskisehir, 6th June 2014

1. Properties and function2. Flexibility in properties3. Specificity of properties4. Systems definition5. Conclusions

Outline



Biochar properties – native and non-native

Photo: Ondrej Masek

• Some functions common to soil organic matter, but without the turnover of carbon (so some long-term / permanent effects of single additions);

• The material stability of biochar carbon does not mean that biochar is inert – in fact it is multi-functional;

• Initial properties are also NOT necessarily a guide to longer-term function, e.g. beyond first year.

Are functions synergistic, additive and exclusive? Are they predictable? Can they be manipulated?

We developed a screening toolkit (a set of functional tests) to help examine this…

Biochar functions in soil



ConclusionsExamining consistency and specificity of properties through twelve standard biochars…

Photo: Ondrej Masek

Consistency in the conversion phase

Masek et al., in prep



Function versus properties

Sohi et al. In Prep.

Type Function Purpose Durationphysical porosity bulk density years;

texture water retention changingchemical base minerals pH and nutrient months;

(ash) recycling decreasingchemical exchange N-use efficiency decades;

capacity GHG mitigation increasingchemical adsorption hydrophobic days;

(micropores) compounds saturatedbiological volatiles hormesis <days;

induced resist. exhaustedbiological microbial stable surfaces decades;

attachment saturated

Biochar is multifunctional. These functions are not constant over time…




Potential flexibility of biomass conversion using pyrolysis – but also specificity to the system used.

Investigated by statistical (multi variable) approach:

�30 samples from 30 production facilities

�HTC, microwave, fast, slow, gasification, batch, continuous, rotary, auger, downdraft, updraft, etc.

�Scales from grams to tonnes per hour with nominal operating conditions

�Hardwood, softwood, waste wood, wood pellets, straw, sludge, digestate, municipal waste, etc.

The range in biochar (functional) propertiesalso “influenced by 13 pyrolysis parameters”1

1 Cordner Peacocke, British Biochar Foundation meeting, June 2013

Blanket 100-yr stability values assumed in LCAs

• Quantifying the specific 100-yr stability of biochar refines – and often increases – the C abatement value…

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000 1200

Sta

ble

C (

%)

Reported pyrolysis temperature (oC)

• Taking carbon storage function as an example: screening 100-yr carbon stability by accelerated ageing; “pyrolysis temperature” is not adequate as sole predictor of function...

– the range for one (functional) property




Studies of pyrolysis<>properties using different single materials using one set of equipment – clear trends emerge, e.g…

Predictability for pure feedstock materials?

0

1020

30

40

5060

70

8090

100

300 400 500 600 700

Pyrolysis temperature

Car

bon

stab

ility

(%

)

Willow slow heat rate (stable%)Willow fast heat rate (stable%)Willow slow heat rate (fixed C%)Willow slow heat rate (fixed C%)

Crombie et al., unpublished data

Multiple functions obtained by mixing and blending?

Sohi et al. (2014) In: Biochar for Environmental Management, 2nd Ed.



ORS straw large scaleBarley straw bales small scale

waste wood (large-scale) Sawmill residues

Arboricultural arisings Wheat straw bales large scale

barley straw bales large scale

greenwaste, domestic food (large-scale)

ORS straw small scale

Forestry residue (chips) Short rotation coppice (chips) (large-

-300

309298

298229229

125

-117

Ø 178

-200

-100

0

100

200

300

400

500

298

229

Short rotation forestry (chips)

138196

-220

-117

416404360

342309

Commercial & industrial (C&I) animal & vegetable waste (l Imported Canadian forestry (chips) Miscanthus (chips) (large-scale) SRC chips (small scale)

wheat straw bales small scale

sewage sludge (large-scale)

cost (£ per tonne CO2e)

Cost(£ tC-1)

vedo

m

Cumulative C sequestered

GBP t-1biochar

Feedstock is no.1 of thirteen influences – choice afecetd by feedstock price – and biochar value

VeDom

arge scale

Shackley et al. 2011. Carbon Management, 3:335–356

Viable feedstock will often be mixes.

If these mixes vary over time (e.g. seasonal changes in green waste) - how will product properties be affected?

Can we predict – rather than make and analyse –biochar in all permutations of mixing?

Mixing and blending…?



0

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60

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100

Post-Pyro450

Post-pyro550 deg

Pre-pyro550 deg

Post-pyro700 deg

Pre-pyro700 deg

Sta

ble

C (

% b

ioch

ar C

)

Expected

Actual

Interactions between feedstock types occur during pyrolysis and after…

UKBRC - In Prep.

USE PHASE

environmental context

transport, storage distribution and application of biochar

quality of products quantity of products

transport and infrastructure

socio-economic context

deployment equipment

LAND SYSTEM(contaminated and degraded)

CLIMATE SYSTEM(C abatement)

ENERGY SYSTEM(export or transport for us

of energy co/products)

markets

regulations and standards

FARMING SYSTEMAgriculture Horticulture

Research focused narrowly on production processes and biochar function in end-use context




WASTE SYSTEM

production, transport, storage and preparation of feedstock

FARMING SYSTEM

processing technology

feedstock availability

land availability tenure and

ownership

labour supply

transport and infrastructure

environmental context

socio-economic context

BIOMASS PHASE

CONVERSION PHASE

conversion of prepared feedstock to biochar and co-products

environmental context socio-economic

context

technology innovation

labour supply

effects of processing conditions effects of processing conditions


Aspects of system spatial scale and structure overlie the socio-economic context and system categories:

• Reach – what is the maximum separation of any two elements in biomass, conversion and use?

• Ubiquity – over what spatial / geographic range does the system replicate?

• Intensity – what proportion of land or production within a region is involved in the system?

• Directionality – is biochar used on land that produces the biomass or is there a net transfer?

Feedstock and system characteristics



Tokyo sewage sludge pyrolysis plantPhoto: Ondrej Masek

Biochar production – physical (unit) scale

Pyreg containerised systemPhotos: Jim Hammond

Biochar production – physical (unit) scale



Biochar will not be at the centre of the connected wider systems. Acceptance into systems affected by:

• Markets – existing products, brands and current / future resource supply / contracts;

• Social – end-user acceptability: familiarity (risk, quality,…), future availability, equity / equality;

• Policy – public perceptions and priorities, leadership and risk, time horizons;

• R&D – high rates of technology innovation.

Inter-disciplinary programmes essential, engaging business, industry, regulators and policy makers.

Opportunities must be assessed alongside “fit”

• Biochar for bulk use from major non-virgin biomass sources (e.g. sewage sludge) – use nutrient value and require rules for matching; needs standards / management of feedstock and process;

• Biochar as a (minor) ingredient to distributed products e.g. growing media, fertiliser, animal feed. Function will be facilitated / engineered / positioned, with added value exceeding additional cost.

Initial use may be inversely proportional to the ultimate scale of production and use. This changes the relevant stakeholders and investors in R&D – but all experience supports later large / very large scale use...

Conclusions



University of Edinburgh

Prof Stuart Haszeldine

Researchers

Simon ShackleySarah GreenwoodKyle CrombieAndrew CrossClare PetersUKBRC team

Sponsors:

Acknowledgements

biochar and biochar systems – specificity and flexibility · dr saran sohi [email protected] uk...

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