The importance of feedstock choice

When planning a commercial pyrolysis project, it’s easy to get caught up in the sophisticated engineering of the plant itself. However, the true foundation of every BCR project's effectiveness and profitability is the feedstock.

The choice of raw material dictates the nature of the biochar, the capital expenditure (CapEx), the day-to-day operational logistics and, ultimately, the revenue potential. In this blog, we break down three of the most important considerations when it comes to feedstock planning: chemical properties, moisture levels, and supply chain security.

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Chemical properties

The chemical composition of the feedstock (the input) directly determines the characteristics of the biochar (the output). The goals of each specific project will dictate what kind of material should be looked for.

- High fixed carbon (e.g. woody feedstocks): A high fixed carbon content translates directly into more carbon sequestered within the biochar. If the project's primary business model relies heavily on generating high-value carbon removal credits (CORCs), sourcing a clean, carbon-dense woody biomass is key.

- Higher ash/lower Carbon (e.g. agricultural residues): Materials with lower fixed carbon or higher ash content can still produce valuable biochar. If the project's main objective is generating large volumes of biochar for soil amendment on local agricultural lands, these alternative feedstocks are highly suitable and often cheaper.

Moisture Content

The moisture content of a feedstock is one of the most critical considerations when planning a pyrolysis project. As a rule of thumb, a typical pyrolysis system operates optimally with an input moisture content between 10% and 15%. Because most raw biomass sits far above this threshold, handling moisture requires careful financial and engineering calculations.

Forestry waste typically sits between 45% to 50% moisture, requiring significant drying. Fortunately, the pyrolysis process itself generally generates enough excess thermal energy to power its own drying function for materials with this moisture content.

However, if we look at much wetter inputs like biogas digestate or sludges (often exceeding 65% moisture), there isn’t enough heat generated by the plant to dry the material autonomously. While entirely possible to process, these projects require an additional, secondary heat source, namely a dryer to process this wet feedstock before it enters a pyrolysis chamber, or a parallel pyrolysis line running on a dryer feedstock.

A dryer is often therefore a large and crucial part of a pyrolysis plant. The higher the input moisture, the larger and more robust the drying system must be to maintain throughput, directly increasing upfront equipment costs.

The final consideration when it comes to moisture content are the logistics and emissions involved with transportation. If transporting feedstock to a facility there are not only costs to transport the raw material but also the unwanted water within it. High-moisture feedstock spikes logistics costs and increases a project's transport emissions, undermining both financial margins and introducing some carbon-accounting leakage.

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Supply Chain & Access

The most successful, bankable pyrolysis projects generally have a structural relationship with their feedstock source. Relying entirely on the open market for biomass introduces significant project risk.

The good foundation for project design often involves one of two models:

- Internal sourcing: The pyrolysis plant acts as a biomass valorization solution within an exisiting organization, utilizing residues generated by an existing business arm like a sawmill or food processing facility.

- Strategic co-location: Setting up the plant directly adjacent to a trusted partner's facility. Co-location ensures a long-term, secure supply of raw material and often grants access to feedstock at below-market rates by eliminating regional shipping logistics.

Feedstock choice acts as the anchor for the entire business model of a pyrolysis plant. It controls what equipment needs to be purchased, how thee logistics operate, and how much money one stands to make from carbon markets and biochar offtakes.