OVERVIEW

Boundless acknowledges and is well versed in the various biogenic carbon accounting methodological approaches within the clean technology and bioproducts industries. Thus, we understand the importance of selecting the most representative methodology, as well as the need to refine methodological calculations to comprehensively evaluate specific product and technology processes. To guide this decision-making process, Boundless has prepared the protocol presented herein to transparently document our approach to biogenic carbon accounting methodology selection and the various factors to consider during evaluation.

This protocol is meant to provide guidance for durable products (bio-based materials, biochar, bioenergy), soils, bio-fixation (microbial carbon fixation), trees, wood products, land conservation, economic sectors (agriculture, forestry, and energy), and municipal solid waste (MSW) regarding the calculation of carbon dioxide equivalent (CO2e) emissions and uptake throughout the life cycle. Figure 1 (below) illustrates the Boundless system boundary for biogenic carbon Life Cycle Assessment (LCA). It shows how carbon flows are tracked within a defined system, including carbon uptake from the atmosphere (via photosynthesis and microbial fixation) and carbon release back into the atmosphere (via combustion, respiration, and decomposition). The figure highlights that carbon storage and emissions are only included if they occur within the system boundary defined by the LCA study. This visual underlines a key principle: to correctly account for biogenic carbon impacts, it's essential to align the assessment boundary (e.g., cradle-to-gate or cradle-to-grave) with the physical lifecycle of the product or process being evaluated.

Figure 1: Boundless Biogenic Carbon LCA System Boundary

Biogenic carbon refers to carbon in gases emitted to the atmosphere from material of biogenic origin and to carbon removed from the atmosphere into biotic materials:

Carbon released arises from biotic materials through processes including but not limited to combustion, fermentation and respiration, and following disruption of soils (i.e. tilling).
Carbon removed refers to carbon removed from the atmosphere by incorporation into solid or liquid materials, primarily through biomass growth via photosynthesis and generation of biogas from biological processes.

Carbon storage and/or carbon re-emission should only be included in a LCA if these activities occur within the system boundary, as shown in the biofuel example below. However, it is best practice and specific methodologies recommend to include both removals and emissions (even if they are delayed in time) to avoid misinterpretation of results. Boundless’ protocol is to prioritize the adoption of LCA system boundaries encompassing the full life cycle of the product or circular system under study, that is, a “cradle-to-grave” or “cradle-to-cradle” approach. This is further explained in Step 3 of the Boundless Biogenic Carbon Accounting Protocol.

Biofuel System Boundary Example

If assessing a biofuel derived from corn on a cradle-to-gate (or well-to-pump in the fuels industry) system boundary, only carbon storage should be accounted for. However, if assessing the same biofuel on a cradle-to-grave (Figure 2) or well-to-wake/wheel in the fuels industry (Figure 3) system boundary, both carbon storage and carbon release should be accounted for as fuel combustion would have occurred.

Figure 2: Cradle-to-Gate and Cradle-to-Grave System Boundaries

Figure 3- Well-to-Pump and Well-to-Use System Boundaries for the Fuel Industry

In the latter scenario, the biogenic carbon emissions would essentially be given a net zero contribution as all biogenic carbon initially stored would then be released through the combustion of the fuel. Therefore, it is recommended to report both cradle-to-gate as well as well-to-wake/wheel results. In general, carbon released is accorded a weight of +1 kg CO2e per kilogram (kg) of CO2 released in the life cycle carbon balance. Carbon temporarily/permanently removed from the atmosphere is treated as sequestered and assigned a weight of -1 kg CO2 per kg of CO2 stored,.

Biogenic Carbon Accounting Protocol

The Boundless Biogenic Carbon Accounting Methodology Protocol is composed of four Steps:

Step One: Identify Relevant Carbon Accounting Methodology
Step Two: Perform Industry-Specific Research
Step Three: Calculate Biogenic Carbon Life Cycle Emissions
Step Four: Report Biogenic Carbon Life Cycle Emissions

Boundless’ Scientific Advisory Council and consortium of peer experts informed the development of the protocol.

Step One: Identify Relevant Biogenic Carbon Accounting Methodology

The initial phase of Boundless’ proprietary LCA methodology is to determine the project-specific proper taxonomy and climate terminology. This is guided by a customer kick-off call and Request for Information (RFI) to establish the system boundary, functional unit, and process inputs. This information gathering stage identifies project-specific biogenic carbon feedstock (raw materials), biogenic carbon process emissions, and biogenic carbon storage or conversion components. Identification of these biogenic carbon system process components informs the relevant carbon accounting methodology(ies) (refer to Table 1) to incorporate into the LCA.

Different types of biogenic materials and applications require distinct accounting methodologies due to the variation in carbon storage mechanisms, time horizons, degradation pathways, and sector-specific standards. In cases where a single study encompasses multiple types of materials or products (e.g., a bio-based composite including wood and biochar, or an integrated agricultural system with soil amendments and biomass energy), Boundless selects a hybrid approach by applying the most scientifically appropriate and methodologically accepted protocols to each component. These distinct carbon flows are calculated and reported separately, ensuring methodological consistency and transparency while maintaining an integrated life cycle perspective within the overall system boundary. This modular approach enables robust carbon accounting even in complex, multi-input systems.

Step Two: Perform Industry Specific Research

The next phase of Boundless’ proprietary LCA methodology is to conduct specific literature reviews and research to model the industry project-specific process or product. This includes review of the project’s biogenic carbon accreditation methodology required for carbon credit quantification. It should be noted, that while ISO 14067:2018 does not mandate specific durability horizons, it aligns with practices that track carbon for 100+ years for removals to be considered "permanent” and assess risks of reversal (e.g., biomass decay, forest fires).

Summary Biogenic Carbon Methodology for Carbon Accreditation Frameworks

Isometric: Biogenic Carbon Capture and Storage (Bio-CCS) processes (solid sorption, liquid solvent, membrane processes, electrochemistry, etc). Calculates impacts over a 1000-year durability claim and counterfactual carbon dioxide equivalents (CO2e).
Puro.earth: High-durability carbon removal from industrial bio-based processes. Issues CO2 Removal Certificates (CORCs) based on standardized methodologies, assuming 100+ to 1,000-year durability claims, especially for biochar and carbonated materials. Counterfactual estimates emphasize net-negative LCAs and long-term storage beyond natural decay.
Gold Standard: Biogenic sequestration with sustainable development goals (SDGs) integration (e.g., agroforestry, biogas). Life-cycle and land-use methodologies prioritize co-benefits alongside carbon removal. Typically targets 30–100 years; buffer pools may be used. Projects must demonstrate additionality and set conservative baseline to account for CO2e.
Verra (VCS): Biogenic carbon capture through forestry, agriculture, biomass, and biochar. Uses detailed methodologies (e.g., for biochar, afforestation) to quantify carbon removals and emissions reductions based on project-specific permanence requirements; some methods account for long-term storage (e.g., 100+ years). Counterfactual baselines and leakage are rigorously assessed to calculate net CO2e benefit.
Climate Action Reserve (CAR): U.S.-centric bio-based carbon offset projects (e.g., forest, organic waste, biochar). Prescriptive protocols with quantification and monitoring requirements. Biochar protocol targets long-term storage (>100 years). Counterfactuals modeled as emissions savings vs. business-as-usual scenarios.
American Carbon Registry: Market-based forestry, agriculture, and carbon removal via bio-based systems. Offers methodologies for quantifying and verifying long-term storage. Specific to methodology; biochar protocol supports 100+ year storage. Counterfactuals accounted for as a detailed baseline and additionality criteria.
Plan Vivo: Community-based land-use projects with biogenic carbon benefits typically realized within 30–50 years; buffers applied for risk. Counterfactuals are accounted for using simpler baseline assumptions but still conservatively estimated.

Step Three: Calculate Biogenic Carbon Life Cycle Emissions

The findings of Steps 1 and 2 inform the biogenic carbon accounting calculation used for the project-specific LCA.

As shown in the examples provided in Table 1, time dependence is a primary factor in biogenic carbon accounting calculations. In general, carbon released is accorded a weight of +1 kg CO2e per kg of CO2 released in the life cycle carbon balance. Carbon permanently removed from the atmosphere is treated as sequestered and assigned a weight of -1 kg CO2 per kg of CO2 stored.

Boundless applies biogenic carbon life cycle emissions calculation best practices per the European Union’s ALIGNED Guide on the Life Cycle Impact Assessment (LCIA) for bio-based products – Climate change. In summary, the ALIGNED Guide has five primary recommendations (refer to Figure 4):

Prioritize the adoption of LCA system boundaries encompassing the full life cycle of the product or circular system under study, that is, a “cradle-to-grave” or “cradle-to-cradle” approach (Figure 4). If not deemed as possible in the mark of the goal and scope of the study, or simply because there is no information on the use and end-of-life of the product, then a “cradle-to-gate” approach will be applied. Further truncated systems (e.g. “gate-to-gate” approaches) are not recognized as adequate to assess bio-based production.
Document and report separately the biogenic from nonbiogenic elementary flows during the LCI phase. This specifically applies to carbon flows.
If the product life cycle, including end of life phase, is greater than 100 years the biogenic carbon accounting will assess the climate change midpoint impacts scores with two indicators representative of two cultural perspectives: short-term (GWP20 or GWP100) and long-term (GWP500 or the GTP100 indicators) climate effects.
Implement the -1/+1 approach for biogenic CO2 flows accounting. Report climate scores of cradle-to-gate studies along with the biogenic carbon uptake used in the calculation as well as displaying separately the climate scores associated with contrasted scenarios for the use and end-of-life phases.
Default to include temporal effects in the calculation of climate scores associated with biobased production. As a minimum requirement, at least the biomass sourcing, production, use, and end-of-life phases will be documented separately.

Figure 4 ALIGNED recommendations for estimating climate impacts of biobased production – synthesis.

Step Four: Report Biogenic Carbon Life Cycle Emissions

The methodological approach and results with and without biogenic carbon stored must be presented in an impact assessment report. Figure 5 presents examples of biogenic carbon accounting results.

Figure 5 Examples of Boundless Biogenic Carbon Results

Figure 5.1 Biochar fertilizer product cradle-to-field system boundary

Note: Project-Specific Biogenic Carbon Breakdown reports the biogenic carbon stored separately than the fossil-based GHG Emissions Footprint, while the Biogenic Carbon Accounted includes contribution of stored carbon in the GHG Emissions Footprint value.

Figure 5.2 Carbon dioxide removal amendment product cradle-to-field system boundary

Figure 5.3 Biofuel product cradle-to-gate system boundary.

In addition, the following caveats (as applicable) will be included in the LCA report for transparency:

Nuances of indirect carbon cycle impacts from storage and re-emission are not accounted for.
Land-use change impacts associated with biomass cultivation should be accounted for, when applicable. For example, a crop protection product results in a smaller acre of land to produce the same amount of crop and the land no longer used for agriculture is repurposed for another use.
100% of the biogenic carbon is credited to the specific process (or product) assessed within the report.
If modeling cradle-to-gate, indicate that biogenic carbon released during use and end-of-life are not accounted for in the analysis.
For organic waste process inputs, the LCA will apply a "zero burden assumption" or per the European Union “Polluter Pays Principle”, which entails that waste materials enter the subsequent process without carrying any environmental burdens from their previous life cycle stages. Consequently, the environmental impacts associated with the production, distribution, and use phases prior to the waste becoming a resource are not attributed to the new process utilizing the waste material. Boundless will still include the impact of organic waste feedstock transportation.

Exhibit 1 - Soil Organic Carbon (SOC) Grow Media Methodology

Key Takeaways:

SOC Role in Carbon Sequestration: LCAs often overlook dynamic changes in SOC, which significantly impact GHG emissions, especially when using organic grow media like coconut coir, peat, hemp, and jute.
Carbon Contribution of Organic Grow Media and Additives: Different organic amendments contribute to SOC through Particulate Organic Carbon (POC) and Mineral-Associated Organic Carbon (MAOC). Compost additives enhance the formation of POC and MAOC, peat stabilizes carbon, while coconut coir, hemp, and jute (rich in lignin) primarily contribute to POC.
Mineralization & Carbon Retention: The mineralization rate affects carbon dynamics, with faster decomposition increasing CO₂ emissions. Rates vary from 1 millimol (mmol) CO₂/kg C per hour (hr) (such as peat, wood) to 25 mmol CO₂/kg C·hr (such as straw), influenced by soil carbon content, microbial activity, and moisture.
Challenges & Modeling Approaches: SOC sequestration modeling requires mass balance techniques, isotope tracing, and tools like RothC, C-TOOL, and CENTURY. Due to measurement inconsistencies and lack of standardization, the estimated carbon sequestration through crop yield improvements can be applied as an alternative approach.

Full Synopsis:

LCAs of agricultural systems have often overlooked the dynamic changes in SOC parameters, despite its significant role in carbon sequestration. Incorporating SOC parameters, particularly when organic grow media such as coconut coir, peat, hemp, and jute are used, can substantially influence GHG emissions estimates. This summary aims to provide best practices for calculating organic grow media SOC sequestration potential and examines the carbon contributions of various organic amendments.

To accurately estimate the carbon sequestration potential of organic grow media, it is crucial to understand their role in SOC formation. SOC consists of POC and MAOC, with different mechanisms influencing sequestration efficiency. The persistence of POC and MAOC in the soil depends on factors such as decomposition, microbial processing, and interactions with soil minerals.

Organic grow media contribute to SOC through both POC and MAOC pathways. For example, compost additives promote the formation of both POC and MAOC, which supports long-term carbon sequestration. Coconut coir, hemp, and jute, which are rich in lignin, primarily contribute to POC, while peat enhances the stability of carbon, aiding in MAOC formation.

The mineralization rate, which refers to the breakdown of organic matter by soil microorganisms, directly affects carbon dynamics. A higher mineralization rate leads to faster decomposition and greater CO2 emissions, potentially reducing the amount of carbon retained in the soil. The mineralization rate varies across different organic amendments, ranging from approximately 1 mmo) CO2/kg C·hr for materials like bark, peat, and wood, to around 25 mmol CO2/kg C·hr for materials such as straw. The mineralization rate is influenced by factors including the original carbon content of the soil, microbial populations, regional conditions, and soil moisture.

To integrate SOC sequestration into LCAs, it is essential to use robust modeling, time-sensitive calculations, and detailed soil analysis. Methods that account for the full soil profile and consider multiple time horizons will enable more accurate assessments of the carbon sequestration potential of organic grow media. The LCA model can integrate mass balance techniques, stable isotope tracing, and modeling as a comprehensive framework for quantifying SOC sequestration in soils amended with their organic grow media hemp-based and jute products. SOC changes can be modeled using tools such as C-TOOL, RothC, or CENTURY, which simulate carbon inputs and decomposition dynamics over time. For long-term SOC turnover the Bern Carbon Cycle Model can be applied to account for the decay of carbon in the atmosphere and soil over these horizons.

Published studies estimating SOC parameter changes in response to grow media applications are typically conducted over multiple years and include at least two crop cycles across multiple sites. These studies revealed inconsistencies in SOC content both between locations and across years, despite identical application methods, highlighting the challenges of accurately quantifying carbon sequestration through SOC measurements alone.

As an alternative approach, estimates of carbon sequestration can be conducted by measuring average increases in crop yield. By obtaining reliable estimates of crop yield improvements resulting from their product application, carbon sequestration can be approximated using the average carbon content of the harvested biomass.

It is not uncommon to face limitations due to the current state of the industry, as there is no universally accepted methodology for calculating SOC. As mentioned earlier, there are several potential pathways they could follow, but the lack of standardization makes it challenging to determine the most accurate and widely recognized approach.

To effectively measure SOC, it is recommended to access reliable soil sampling techniques, laboratory analysis, and predictive modeling tools that align with existing methodologies. They would also require expertise in carbon accounting and regulatory compliance to ensure their measurements are both accurate and credible. However, limitations such as variability in soil composition, differences in environmental conditions, and inconsistencies in measurement techniques could pose challenges. Additionally, evolving industry standards and the need for long-term data collection may further complicate their ability to establish a consistent and validated approach.