Bio-oil Sequestration
Prototype Protocol for Measurement, Reporting, & Verification

Overview
This prototype protocol is intended for use within voluntary carbon markets. Bio-oil sequestration involves the conversionof waste biomass to bio-oil via processes such as fast pyrolysis1, followed by injection of the bio-oil into deep geologicalformations for permanent storage. “Bio-oil” is intended here to broadly encompass fast pyrolysis oil, biocrude, slurries containing biochar, and other organic compounds derived from biomass.
Over 100 Gt CO₂2 is exchanged between the atmosphere and biosphere annually via photosynthesis, respiration, decomposition, and combustion. Through appropriate selection of biomass residue feedstocks that would otherwise decompose
or combust, the conversion of biomass to bio-oil and the permanent geological storage of the embodied carbon is a net
removal from the atmosphere.

Figure 1 Bio-oil sequestration directs part of the natural cycle of carbon dioxide into geological storage.

1 Fast Pyrolysis is a method of heating organic material to high temperatures in the presence of little or no oxygen to produce syngas, bio-oil, and biochar. Other processes,
such as hydrothermal liquefaction, can also produce bio-oils.
2 Biomass: Impact on Carbon Cycle and Greenhouse Gas Emissions, Carly Green, Kenneth A. Byrne, in Encyclopedia of Energy, 2004

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1Measurement and verification are essential to credit any process claiming carbon sequestration; without them, any claims
that carbon is being permanently removed from the atmosphere are suspect, and could result in unaccounted reversal andpossible environmental and commercial penalties.
This proto-protocol outlines a framework for measuring, reporting, and verifying (MRV) bio-oil sequestration.

Process Flow and Carbon Accounting
SYSTEM BOUNDARIES
Measuring the amount of carbon captured and sequestered relies on life-cycle analysis (LCA); an LCA study involves
establishing baselines and conducting a thorough inventory of the energy and materials required by all the processes involved in capturing and sequestering the carbon and calculating their corresponding greenhouse gas (GHG) emissions to
the environment. An LCA assesses cumulative potential environmental impacts and is conducted only for processes within
set system boundaries.
For instance, life cycle analysis for renewable diesel made from soy oil typically includes measuring emissions resulting
from the following processes:
Farm practices involved in growing and harvesting soybeans (biomass production)
Soybean transportation to the crush plant (biomass transport)
Soybean crushing and oil extraction (biomass conversion)
Transportation of soy oil to a renewable diesel facility (biomass transport)
Renewable diesel production (biomass conversion/fuel production)
Transportation of the finished fuel to its destination (fuel transport)
Combustion of the renewable diesel (fuel end use)
Direct or indirect land-use changes resulting from growth of soybeans (biomass production)
If the project were to capture and sequester the CO₂ produced during the fuel production stage, the LCA would include
measuring emissions from the following additional steps:
CO₂ capture at renewable diesel production
CO₂ liquefaction and transport to sequestration facility
CO₂ injection into storage
Monitoring costs and measured CO₂ returns
In the case of bio-oil sequestration, system boundaries include emissions resulting from the following processes:
Biomass production and collection, including direct and indirect land use change
Transportation of biomass to the facility
Conversion of biomass to bio-oil
Transportation of the bio-oil to the sequestration facility
Subsequent injection into a geological formation for storage and potential leakage
In some cases, if the biomass were to be transported to an alternate disposal site in the baseline, the net difference for thetransportation to the facility may be compared to the baseline and accounted for.
This protocol does not consider production of co-products, such as biochar and energy products such as heat and electricity. No deductions are given for displacement from co-products. Correspondingly, all increases in upstream biomass
emissions from the baseline are allocated to the bio-oil product.

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2

CALCULATION OF NET CARBON REMOVAL
Analyses of life cycle emissions, such as the one above, are estimated using models and inventories, some of which havebeen adopted by regulators such as the California Air Resources Board (CARB). CARB has a protocol for CO₂ sequestration3 that is integrated with the Low Carbon Fuel Standard (LCFS) regulation4. CARB’s LCA for fuels is conducted using
measurements of emissions and calculations based on actual biomass transportation, production, transportation, conversion and fuel end use/disposal data.
Bio-oil production and sequestration require biomass and energy inputs and outputs of stored carbon (bio-oil), CO₂ (fromconversion, transport, and injection energy use), biochar (by-product), and low volumes of other GHGs. Once an LCA model is created, then the net amount of removed CO₂e is calculated as:
Net Removed CO₂e = ∑ CO₂e in the injected bio-oil- ∑ CO₂e emissions from biomass production- ∑ CO₂e emissions from biomass collection- ∑ CO₂e emissions from biomass transport- ∑ CO₂e non-process-biomass emissions from the conversion process- ∑ CO₂e of non-CO₂ biomass-based process emissions- ∑ CO₂e emissions from bio-oil transport- ∑ CO₂e emissions from bio-oil injection- ∑ CO₂e from fugitive emissions
The LCA baseline is grounded on baseline measurement and assessment in the absence of the project. In some cases, forexample, waste biomass which serves as biomass feedstock for the project would be left in its natural environment, suchas the field or forest floor, or transported to landfills, where it would decompose and produce CO₂ and methane. Insteadof these greenhouse gasses being released into the atmosphere in the baseline scenario, bio-oil production and injection
sequesters CO₂e underground.
In calculating the CO₂e emissions from biomass production, feedstock specific pathways are required. These pathways
capture emissions impacts of biomass utilization for the project as compared to the baseline. For example, in-field cornstover degradation can contribute to the nutrient content in the soil and its removal may result in an additional fertilizer
requirement during the planting season. Any actual increase in fertilizer use would contribute to the CO₂e from biomass
production and must be included in LCA.
If the baseline for the biomass is landfilling or decaying under anaerobic conditions, there may be production of methane in
the baseline, a greenhouse gas with a high global warming potential (GWP). The LCA for the process should track reduced
methane if measured, but not include avoided methane as part of the CO₂e balance calculation (instead, that should betracked separately due to uncertainty around methane generation counterfactuals and future accounting practice).
The timing of decomposition and subsequent GHG release associated with the baseline scenario is dependent on several
factors. Studies on corn stover, for example, show 60-70% of the biomass decays within the first year, and 75-80% by year
2, and 80-90% by year 55. Physically, the decomposition timing is short with respect to the long arc of climate change
and project lifetime, and can be safely ignored from an impact perspective. Similarly for accounting purposes, consistent
with established methodology such as the World Resources Institute’s GHG Protocol’s guidance related to dead organic
material (DOM), the timing delay associated with the baseline case CO₂ emissions from degradation does not requireamortization across the years in which the degradation would have otherwise occurred, and is appropriate to be claimed
at the time of intervention6.
Industry standard methodologies exist (such as the Argonne National Laboratory GREET models used for biofuel LCA) to
calculate the material and energy flows for biomass production arising from factors such as decreased soil carbon intensity

3 https://ww2.arb.ca.gov/sites/default/files/2020-03/CCS_Protocol_Under_LCFS_8-13-18_ada.pdf
4 https://ww2.arb.ca.gov/sites/default/files/2020-07/2020_lcfs_fro_oal-approved_unofficial_06302020.pdf
5 https://cdnsciencepub.com/doi/10.4141/cjss2010-055#T0002
6 https://ghgprotocol.org/sites/default/files/standards/GHG%20Protocol%20Agricultural%20Guidance%20%28April%2026%29_0.pdf

Bio-oil Sequestration · Carbon Direct | EcoEngineers3

or increased fertilizer replacement rates7. These flows will be used to calculate the emissions impact associated with biomass production and will be added to the total emissions for the LCA. Industry standard methodologies must be applied to
calculate the biomass production emissions based on specific project attributes, including the location and biomass type.

LAND-USE CHANGE (DIRECT AND INDIRECT) CONSIDERATIONS
Direct land use change occurs when landscapes are altered for biomass production. For instance, a forest may be cleared
to support production of a new biomass crop, or an annual cropping system may transition to a perennial cropping system.
Indirect land use change occurs when other landscapes are altered as a consequence of biomass production throughmarket-mediated effects. For instance, a forest may be cleared as a result of higher prices when food-producing land isdiverted to produce biomass or carbon removal services. Estimates of indirect land use change for common crops havebeen estimates by the CA ARB8, while estimates of both direct and indirect land use change have been included in the
GREET model9. Direct and indirect land use change must be estimated as part of each feedstock-specific pathway.

SUMMARY
In summary, emissions from the following processes must be measured for the LCA of bio-oil sequestration. All CO₂eemissions from the processes should be conservatively estimated. Any unaccounted-for carbon (e.g. lost biomass along
the way) is assumed to be emitted as carbon dioxide.
Emissions from biomass production, including changes from baseline state, if any.
Emissions from harvesting and transportation of biomass from its source using standardized values for a vehicle type,
fuel type and transport distance.
CO₂-equivalent GHG emissions from bio-oil production, calculated based on the energy consumed in the process(directly when fossil fuels or indirectly when electricity), and any other GHGs created by the process, such as NOx.
CO₂ emissions from biomass and bio-oil transport, calculated from standardized values for a vehicle type and transport distance.
CO₂ emissions at the injection site, calculated based on energy usage, energy source standardized emissions
values10, and operating times.
Bio-oil carbon injected into storage as measured via elemental carbon content (ASTM5291) and bio-oil weight orvolume.
Any fugitive emissions must be deducted from the total net removed carbon dioxide.
Step

Biomass
Production

Biomass
Harvesting

Biomass
Transport

Conversion
to bio-oil

Bio-oilBio-oilInjection

Bio-oilStorage

Measurement

Modeled via
e.g. GREET

Modeled via
e.g. GREET

Measuredbill of lading,
distances

Measuredflue stackemissions,fossil fuel use

Measured flue stackemissions, fossil fueluse

Measuredenergy use

Measuredenergy use

Frequency

Per feedstock per
region

Per feedstock per
region

Per loadPer
pyrolyzer,
continuous
flueemissionsindicator

Amount with certified
truck scale or flow
meter, carbon with
3rd party lab perpyrolyzer-feedstock
pair each year

Per injection
well

Per formation

7 https://greet.es.anl.gov/publication-feedstocks-13
8 See table H5 of https://ww2.arb.ca.gov/sites/default/files/classic/fuels/lcfs/iluc_assessment/iluc_analysis.pdf
9 https://greet.es.anl.gov/publication-cclub-manual-r4
10 The CARB regulation has standard emission values for different regions in the US and globally.

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4Figure 2 Illustration of a potential LCA for bio-oil sequestration, including likely emissions, monitoring and verification requirements.

Injection Protocol
The fate of any fluids injected into the subsurface is directly a function of the site geology and the sum of well completion
history in the injection area. Any project proposing to inject CO₂, bio-oils, or complex biomass-bearing solutions must
understand the local geology and wells (both proposed and existing). In the US, the EPA regulates subsurface injection
through the underground injection control (UIC) program in order to safeguard drinking water under the Safe Drinking
Water Act. That regulatory process requires both an understanding of local geology, proposed wells, and in some cases
neighboring wells.
The geological storage of the bio-oil must be assessed, and should be modeled leveraging injection rates, pressures,volumes, and fluid composition and geophysical approaches such as active or passive seismic data, to understand thelikely extent of the bio-oil injection. The geochemical compatibility of the bio-oil with the formation must be verified as partof the permitting process through empirical demonstration, e.g. core testing or brine sampling. The injected fluid is likely
to undergo an increase in viscosity as it polymerizes—see inset box below. Operators must monitor injection regularly todemonstrate both proper storage of injectate for carbon accounting purposes and ensure safe drinking water compliance.

Bio-oil Sequestration · Carbon Direct | EcoEngineers5Consistent with the CCS protocol under the California Low Carbon fuel standard, bio-oil must be injected into a well that isconstructed and completed to “prevent the movement of fluids into or between any unauthorized zones”.11 Bio-oil injection
wells must be constructed to meet USEPA requirements for Class I, II, or V wells under the Underground Injection Control(UIC) Program, depending on the context for injection. The existing UIC standards specify minimum operating, monitoring,and reporting requirements for such wells.12
The monitoring plan should include, but not necessarily be limited to, the following:
A comprehensive characterization of the sequestration site, including traditional subsurface geologic interpretation
using regional geological studies, cores, well logs/seismic data and other reservoir characterization approaches todesign the monitoring plan.
An operational protocol for regular pressure and fluid testing in existing and new wells to address plume migration andfluid conversion. This should include above-injection-zone monitoring or well-bore monitoring for small variations inpressure or temperature in overlying units.
A bio-oil sequestration injection site must be assessed before injection, flowmeter measurements taken as bio-oil is injected13, and subsequent post-injection monitoring completed to ensure that de minimis fugitive carbon escapes the reservoir
during a timeframe that is acceptable to the regulatory body. A performance-based time for post-injection site care (PISC)
is recommended, although a 10 year period is likely to be more than sufficient due to the negative buoyancy and viscosityof bio-oils (see inset box).

SUBSURFACE CHANGE OF BIO-OIL
As a non-wetting phase, bio-oils are expected to react very little in the subsurface. Many bio-oils have a higher density than water, which prevents return to the surface. Laboratory tests suggest that viscosity is likely to increase overtime in the subsurface, also preventing return. The higher density and viscosity of bio-oils is fundamentally different
from either natural hydrocarbons or pure-phase CO₂, which are both buoyant and low-viscosity.
It is possible that some reservoirs contain chemo-autotrophic microbes that could break down a fraction of the biooils into CO₂ and methane, which are less dense than water and could be buoyant. Current scientific understanding
suggests that the rates of microbial bio-oil conversion would be slow and the volumes very small and thus would notpresent a material risk. However, conventional monitoring (e.g., above injection zone monitoring or well-bore monitoring) would be sufficient to identify any potential chemosynthetic byproducts and provide a basis for remediation.
Under all circumstances, risk of subsurface return would be near zero provided competent well completion in accordance with conventional regulations.

Monitoring and Verification
Monitoring and verification is performed by an independent third party against a monitoring plan. This ensures that theoperation is being carried out according to plan and that the calculations of the amount of carbon injected and stored arecorrectly assessed.
Biomass feedstock sources and transportation distances must be assessed from auditable records. The mass and energybalance at the bio-oil production facility must be calculated using data from actual metered inputs and outputs. Injectionof bio-oil must be metered, and the amount of CO2 equivalent credited must be assessed by the verifier over regular timeintervals.

11 https://ww2.arb.ca.gov/sites/default/files/2020-03/CCS_Protocol_Under_LCFS_8-13-18_ada.pdf
12 https://www.epa.gov/uic/underground-injection-control-regulations
13 If all volumes are trucked, it is acceptable to document truck volumes and safe disposal (c.f., no spillage), especially for small volumes. Flow metering would be preferred,especially if the well is in continuous operation.

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6Metering must be shown to be accurate and reliable14, and records must be maintained for at least ten years. Monitoredsites are observed during and after injection.
Auditing inputs to assess injected carbon must be performed quarterly (and should be performed monthly) and credited
once the amount of GHG carbon is verified. Site visits should be required as part of the annual audit cycle.

Reversal Risks
Bio-oils are not buoyant in the subsurface, meaning they pose almost no real risk of reversal. Any minor risks can be best
managed through conventional well completion practice for UIC compliance. There is a small chance of microbial alteration of injected bio-oils which must be similarly anticipated and managed. Site selection and well completion have thelargest impact on potential risks and should be managed actively in design and operation.
Theoretical reversal risks include migration of the bio-oil out of the geological storage formation or leakage of GHG formedby chemical reactions or anaerobic digestion. The reality of these risks depends on the bio-oil composition (biomass feedstock and conversion process), formation geology, pre-existing microbiota, reservoir operation, and drilling and completion
practice. Fundamentally, these risks are minute and can be managed through conventional drilling and completion practiceand standard monitoring approaches. This very low (near-zero) risk profile is below the already low risks of CO2 storage,
which must manage questions of buoyancy and chemical reactions. The risk of biomethane production is extremely small
due to (a) lack of wettability, (b) nutrient limits, and (c) low viscosity (which constrains ability to migrate).

Conclusion
Carbon accounting, monitoring, and verification are well-understood principles in everyday use. Extending the principles
to bio-oil production and sequestration can result in the removal of greenhouse gasses from the atmosphere and lay thefoundation for the creation of carbon credits from such processes.

14 Metering should be to industry-standard 95% confidence level or better.

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7Authors
CARBON DIRECT
Dr. Erica L. Belmont
Dr. Julio Friedmann
Dr. Matthew Potts
Dr. Daniel Sanchez

ECOENGINEERS
Roxby Hartley
Salman Khan
Andrew Schaper

Reviewers
CHARM INDUSTRIAL
Peter Reinhardt
Katie Holligan
Jennifer Anderson
Shaun Kinetic
Kelly Kinetic

AD HOC GROUPMax Tuttman

STRIPE/FRONTIER
Nan Ransohoff
Zeke Hausfather
Joanna Klitzke

CARBON180
Rory Jacobson

CLEARPATH
Savita Bowman

SCS ENGINEERS
Julie O’Leary

LOWERCARBON CAPITAL
Ryan Orbuch

www.carbon-direct.com | www.ecoengineers.us

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