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Sized by energy balance, not tons per day.

What we ask you for, how the model translates it into hardware, and why the system arrives matched to your material.

Tons-per-day is a useful spec — after feedstock characterization. As a starting point, it can be misleading. It says almost nothing about how a system will behave on your feedstock, in your climate, on your worst day. This page describes how the Biogenic Refinery is actually sized: the energy-balance model, the inputs we ask for to determine whether a feedstock is qualified, how those inputs map to model selection, and how multi-unit deployments scale beyond a single system.

Talk to us about your feedstock See the field record
§ 01 Why not tons per day

The same wet-tons number can require different equipment.

A ton of dry wood and a ton of dairy-manure solids are not the same engineering problem. Treating them as equivalent leads to undersized heat exchangers, low-quality biochar, clinkers, and disappointed customers.

Tons-per-day may be useful after feedstock characterization. As a starting point it is misleading, because the same wet-tons number can require different equipment depending on what the material actually is.

Same wet-weight target, different sizing envelope

As a reference example, compare two feedstock conditions from the Model 4018 sizing table: a high-moisture biogenic stream at roughly 75% moisture and a dewatered stream at roughly 35% moisture.

Both can be described in wet pounds per day, but they do not create the same engineering load. The wetter stream consumes more recoverable energy in water removal. The drier stream carries less water but can shift the limiting factor toward volatile load, catalyst duty, biochar energy retention, and heat-exchanger loading.

That is why the table shows different sustained rates under different input-moisture conditions. The point is not that one feedstock is "better." The point is that wet tons per day is not the sizing variable. Feedstock energy, moisture, ash, volatile content, and intended biochar use determine the operating envelope.

§ 02 The Biomass Controls sizing equation

Throughput is what the energy balance allows.

The throughput a Biogenic Refinery can sustainably process falls out of an energy balance, not a brochure spec. Each pound of feedstock carries a certain amount of energy. Some of that energy dries the next batch. Some powers the system. Some is retained as durable carbon in the biochar. What is left is the heat the exchanger can recover.

The sizing equation
Hourly feedstock energy Energy required to remove water to target moisture Energy retained in biochar System electrical and thermal demand Jacket, loop, and stack losses Recoverable heat-exchanger load, per hour

If recoverable heat-exchanger load is positive at your design moisture, the system runs self-sufficiently. If it is negative, the system needs supplemental energy and the operating model is different. The energy balance tells us which.

§ 03 What we ask you for

The questions we ask up front are the questions an auditor will ask later.

To run the energy-balance model, we need to know what you have. Minimum inputs cluster into four buckets.

01 · Feedstock

Composition

  • Type — manure, biosolids, food residuals, agricultural residues, fibers, reprocessed char, with co-feedstocks where applicable
  • Particle size and bulk density — affects feeder design and pot residence time
  • Moisture content — as-received, range across seasons, and any upstream dewatering or drying
  • Calorific value — measured (bomb calorimeter) where available; estimated from composition otherwise
  • Ash content and composition — affects heat-exchanger fouling, catalyst protection, and biochar end-use
  • Halogens, metals, and contaminants — fluorine, chlorine, heavy metals, PFAS where applicable
02 · Process

Operating envelope

  • Throughput target on a wet basis (what you can deliver) and dry basis (what we'll process)
  • Drying target (if applicable) and dryer interface requirements
  • Hours-per-day target operating window
  • Seasonal variation in feedstock composition or supply
03 · Site

Site conditions

  • Climate range — ambient design temperatures, sub-freezing operation requirements
  • Utilities — electrical, water, fuel, and process-heat interfaces
  • Space and access — building, enclosure, or containerized; installation and service access
  • Permitting — emissions limits, biosolids regulations, EPR obligations, biochar end-use rules
04 · End use

Downstream intent

  • Biochar end use — soil amendment, durable carbon storage, construction additive, filtration, fuel. Affects target H:C ratio and certification path.
  • Carbon-credit path (if relevant) — methodology and registry: Puro.earth, EBC, Verra, CRCF
  • Recovered-heat use — drying, process heat, on-site power generation via ORC

Submit feedstock data through our project intake form, or send a representative sample and we will run characterization in-house.

Send us a feedstock summary
§ 04 How the model maps to hardware

From the energy balance to the system on your site.

Once the model is run, four things are determined: the heat-exchanger size and configuration, the catalyst duty, the pot configuration, and the deployment configuration.

  1. Heat-exchanger size and configuration

    The BTU/hr rating is the primary capacity spec. The configuration choice — forced-air or hydronic — depends on how you want to use the recovered heat.

    Forced-air delivers recovered energy as a hot-air stream. Best fit when feedstock moisture is below 35% and thermal energy is needed locally — direct integration with belt or rotary dryers, or space heating in cold climates.

    Hydronic delivers recovered energy as hot water or thermal oil through a non-pressurized loop. Best fit for indirect drying, process hot water, pasteurization, or feeding an Organic Rankine Cycle (ORC) for on-site electricity generation. Duratherm option for ORC/CHP applications.

  2. Catalyst duty

    The precious-metal catalyst is sized against the volatile-gas load driven off the feedstock at operating temperature. Catalyst duty is one of the limiting variables in the energy balance — it sets the maximum sustainable throughput regardless of pot capacity.

  3. Pot configuration

    The pyrolysis pot is the physical reaction volume. A full pot is a 16″ × 16″ × 16″ cube; feedstock enters through the top and exits the bottom as biochar. Pot count scales the system from a single full pot (Model 4018) up to a four-pot continuous-duty configuration (Model 99).

  4. Deployment configuration

    Indoor, enclosed, or containerized — selected against site conditions and the feedstock-handling envelope. Closed-loop deployments use recovered thermal energy to dry separated solids upstream of the carbonizer.

    Cold-climate deployments do not change the energy-balance equation; they change the configuration around it. Insulation, freeze protection, enclosure design, start-up logic, and recovered-heat routing are specified against the site's ambient design conditions.

§ 05 The Biogenic Refinery model line

Four standard models. BTU/hr is the headline spec.

Sustained throughput is set by the energy-balance model and is feedstock-specific. The four standard configurations differ in heat-exchanger output and pot count.

Model Architecture HX output (BTU/hr · kW) Heat-exchange options
209 3/4 pot · 12″ × 12″ × 16″ 200,000 · 58.6 kW Forced-air or hydronic
4018 Single full pot · 16″ × 16″ × 16″ 400,000 · 117.2 kW Forced-air or hydronic
600 Twin pot 600,000 · 175.8 kW Forced-air or hydronic
99 Four pot · continuous duty 990,000 · 290.2 kW Hydronic only
209200,000 BTU/hr
Architecture3/4 pot · 12″ × 12″ × 16″ · forced-air or hydronic · 58.6 kW
4018400,000 BTU/hr
ArchitectureSingle full pot · 16″ × 16″ × 16″ · forced-air or hydronic · 117.2 kW
600600,000 BTU/hr
ArchitectureTwin pot · forced-air or hydronic · 175.8 kW
99990,000 BTU/hr
ArchitectureFour pot · continuous duty · hydronic only · 290.2 kW
A note on model names

The naming history is honest about how we used to size and how we size now. The 209 came from a 20 lbs/hr nominal throughput target; the 4018 from 40 lbs/hr on a dry basis. As we moved to energy-balance sizing, BTU output became the more honest spec — hence the 600 (600,000 BTU/hr) and the 99 (990,000 BTU/hr). Designations may evolve as the platform improves.

§ 06 Feedstock moisture and throughput

How the same model produces different throughput.

Reference figures for Models 209 and 4018 at 20 hrs/day steady state, against a reference biogenic feedstock profile.

Input condition Model 209
community-scale ref.		 Model 4018
mid-scale ref.		 Preprocessing
4% solidsseptage 1,200 gal/day
4,500 L		 2,400 gal/day
9,000 L		 Dewatering required
80% moisturewet pit 240 gal/day
910 L		 480 gal/day
1,820 L		 Drying (bound-water removal)
75% moisturefecal sludge 1,600 lbs/day
720 kg		 3,200 lbs/day
1,440 kg		 Drying (bound-water removal)
60% moisturedry pit 1,000 lbs/day
454 kg		 2,000 lbs/day
910 kg		 Dryer sometimes required
35% moistureUDDT 600 lbs/day
275 kg		 1,200 lbs/day
550 kg		 No dryer required
0% moisturedry basis 400 lbs/day
180 kg		 800 lbs/day
360 kg		 No dryer required
4% solids
septage
Model 2091,200 gal/day · 4,500 L
Model 40182,400 gal/day · 9,000 L
Dewatering required
80% moisture
wet pit
Model 209240 gal/day · 910 L
Model 4018480 gal/day · 1,820 L
Drying (bound-water removal)
75% moisture
fecal sludge
Model 2091,600 lbs/day · 720 kg
Model 40183,200 lbs/day · 1,440 kg
Drying (bound-water removal)
60% moisture
dry pit
Model 2091,000 lbs/day · 454 kg
Model 40182,000 lbs/day · 910 kg
Dryer sometimes required
35% moisture
UDDT
Model 209600 lbs/day · 275 kg
Model 40181,200 lbs/day · 550 kg
No dryer required
0% moisture
dry basis
Model 209400 lbs/day · 180 kg
Model 4018800 lbs/day · 360 kg
No dryer required

Figures assume steady-state operation at 20 hrs/day and a reference biogenic feedstock energy profile. Actual rates are set by the site-specific energy-balance model and feedstock characterization. Models 600 and 99 are sized from the same energy-balance method. Their feedstock-specific throughput envelopes are provided after characterization and validation, rather than published as generic capacity numbers.

The wettest feedstocks aren't always the slowest.

Septage at 4% solids moves faster (in gallons-per-day) than wet-pit sludge at 80% moisture, because the energy balance is dominated by water removal at very high moisture levels and the system spends most of its time drying. Below ~35% moisture, the system runs without supplemental drying and throughput climbs.

The 35%-moisture line is the design target.

This is the moisture level at which most qualified biogenic feedstocks can operate without an upstream dryer. The heat exchanger is sized to bring incoming feedstock to approximately this target during the run, using recovered thermal energy. The final target depends on the feedstock's calorific value, ash, volatile content, system configuration, and site energy balance.

§ 07 A worked example

Same feedstock, two moisture levels, two very different system sizes.

This section walks through an actual energy-balance calculation for a representative project. The numbers are illustrative, not a quote. Real projects use the feedstock characterization in § 03, the same equation in § 02, and a model that's specific to your lab data, schedule, and site constraints. But the math here is the math we use.

The project

A mid-size US dairy, roughly 500–700 lactating head, currently composting separated manure solids on-site. The composting footprint is at capacity, the nutrient management plan is pressuring further volume reduction, and the operator wants an on-farm thermal solution that reduces disposal volume and produces a soil amendment they can use or sell. Upstream dewatering is not currently optimized; the solids stream comes off the screw press at roughly 75% moisture.

Feedstock characterization (lab analysis)
Moisture (wet basis)75%
Ash (dry basis)12%
Higher heating value (HHV, dry)18.0 MJ/kg
Volatile matter (dry)73%
Fixed carbon (dry)15%
Operating schedule & throughput

80 hours/week — five days × sixteen hours, an operator-attended schedule that doesn't require overnight staffing. Fifty productive weeks per year = 4,000 operating hours annually.

The dairy generates roughly 20 tons/week of separated solids that need disposal. Over 80 operating hours: 250 kg/hr wet throughput. That's the input to the energy balance below.

The energy balance at 75% moisture

Term Mass / basis Power (kWth)
In: Feedstock chemical energy 62.5 kg/hr dry × 18.0 MJ/kg HHV +312.5
Less: Energy retained in biochar product 17.5 kg/hr biochar × 26 MJ/kg −125.0
Equals: Combustible gas + tar energy (released in secondary chamber) +187.5
Less: Water evaporation (latent, 2.26 MJ/kg) 187.5 kg/hr × 2.26 MJ/kg −117.7
Less: Water sensible heating (20 → 100 °C) 187.5 kg/hr × 4.186 kJ/kg·K × 80 K −17.4
Less: Pyrolysis endothermic enthalpy ≈ 8% of feedstock energy −25.0
Less: Jacket and radiation losses ≈ 4% of feedstock energy −12.5
Less: Stack losses ≈ 8% of combustion heat −15.0
Less: System electrical demand motors, blowers, controls −8.0
Equals: Recoverable heat at heat exchanger (at 75% moisture) −8.1

At 75% moisture, this project sits at breakeven for self-sustained operation — the feedstock's chemical energy is fully consumed by water evaporation, pyrolysis enthalpy, and conduction losses. The system would run, the biochar would be produced, but the operator wouldn't have meaningful thermal output to recover.

What changes at 60% moisture

If the operator invests in upstream dewatering — improved screw press performance, supplementary solar drying, or a brief mechanical compression stage — and brings the feedstock to 60% moisture at the same 250 kg/hr volumetric rate, the energy balance shifts substantially.

Same 250 kg/hr feedstock At 75% moisture At 60% moisture
Dry mass per hour 62.5 kg/hr 100 kg/hr
Feedstock chemical energy 312.5 kW 500.0 kW
Water evaporation demand 135.1 kW 108.2 kW
Stack + jacket + system losses 35.5 kW 56.5 kW
Pyrolysis endothermic enthalpy 25.0 kW 35.0 kW
Biochar product (exits as product) 125.0 kW 200.0 kW
Recoverable heat at HX −8.1 kW +100.3 kW
The central insight

A 15-percentage-point reduction in moisture moves the system from breakeven to ~100 kW of recoverable thermal output. Tons per day looks the same in both columns. The engineering reality differs by an order of magnitude. This is why we don't quote from tons-per-day alone.

What this tells the operator

  1. 75% moisture is technically operable. The system will produce biochar, achieve volume reduction, and inactivate pathogens. But there's no usable thermal output to offset propane, grain drying, or electrical generation.
  2. 60% moisture transforms the economics. At the same volumetric throughput, the system now produces recoverable heat that can offset 100+ kW of farm thermal demand. If propane costs $1.50/gallon (≈ $0.055/kWh equivalent), that's roughly $22,000/year of avoided fuel cost.
  3. The right pre-treatment investment is the highest-leverage decision. Far more impactful than picking a different model line or adjusting operating hours. A $50,000 upstream dewatering improvement pays back in 2–3 years from thermal recovery alone, before counting biochar offtake value or composting capacity recovery.
Important caveats

This worked example uses representative values, not your project. Every real sizing model uses your feedstock's actual lab analysis, your actual operating schedule, and your actual site conditions.

  • The 28% biochar yield assumed here is typical for manures; your feedstock could yield 22–35% depending on lignin content, ash composition, and pyrolysis temperature.
  • The 8% stack loss assumes properly insulated heat exchange; under-insulated enclosures or older units can run higher.
  • The 18 MJ/kg HHV is a midpoint; lab results for separated dairy manure typically range 16–20 MJ/kg.
  • Pyrolysis endothermic enthalpy varies with feedstock — 5% to 12% of feedstock energy depending on volatile content and operating temperature.

Send your moisture, ash, HHV, volatile matter, particle size, bulk density, contaminant screen, intended operating hours, and intended biochar use. We model from there.

Start a sizing →

§ 08 Multi-unit deployment

Larger projects scale by adding units, not by building bigger ones.

A single Biogenic Refinery is a complete system. Larger projects deploy identical systems in parallel inside a shared site envelope.

Shared site envelope · permitting · operations Shared feedstock handling Unit 01 Heat exchanger Catalyst Pyrolysis pot Unit 02 Heat exchanger Catalyst Pyrolysis pot Unit 03 Heat exchanger Catalyst Pyrolysis pot KELV°N Shared biochar handling · recovered heat
Three identical units · shared site envelope · one data layer

Capacity scales linearly.

Each additional unit adds its own heat exchanger, catalyst, pot, and KELV°N® controller. There is no point at which scaling forces a fundamentally different machine, with different operating envelopes, different permitting, or different operator training.

Reliability scales linearly.

Single-machine failure does not take down the site. Maintenance windows are scheduled per-unit rather than as a plant-wide shutdown.

Permitting often scales smoothly.

Multiple identical units under the same emissions envelope are easier to permit than one larger custom system, especially where local emissions limits would force a thermal oxidizer above a particular throughput threshold.

Phased buildout matches phased financing.

Sites can install one unit, validate the operating model on their actual feedstock, then add capacity as the project case is proven out — without rebuilding the plant.

§ 09 Auditable and reproducible

The sizing math is not a black box.

The energy-balance model can be reproduced by any third party who runs the same feedstock characterization through the same equation.

The open-source QSDsan toolkit includes a Biogenic Refinery sanunit module that replicates the model and is available for independent verification. A 2022 peer-reviewed study in ACS Environmental Au modeled the Biogenic Refinery's financial viability and environmental performance across five country contexts using QSDsan, with 10,000 Monte Carlo simulations per scenario. The findings are reproducible by any verifier or offtaker who runs the same model on the same inputs.

In the sanitation scenarios modeled in the paper:

  • $0.05 / cap·day Per-capita treatment cost (mixed excreta, pit-latrine scenario)
  • 11–49 kg CO₂e Per-capita annual emissions — below the anaerobic-treatment baseline for the same feedstock
  • 40–44% Cost reduction when carbon is valued at $150 / Mg CO₂
Source: Rowles et al., ACS Environmental Au, 2022. DOI: 10.1021/acsenvironau.2c00022

The model is independently verifiable.

A buyer's engineering consultant, a regulator, or a carbon-credit auditor can run the same math against the same inputs and get the same result. This is uncommon in pyrolysis where vendor-specific sizing math is often proprietary.

The model improves with every deployment.

150,000+ hours of operational runtime, on three continents, in feedstocks ranging from human biosolids to dairy manure to spent mushroom substrate, in climates from tropical to Arctic — each run adds calibration data. The model that sizes your system today is more accurate than the model that sized the first system ten years ago.

§ 10 Common questions

What buyers usually ask about sizing.

How long does a sizing conversation take?
A first-pass sizing model — enough to confirm whether the project is in our envelope and which model line fits — typically takes one to two weeks after we have feedstock characterization data. A full sizing recommendation suitable for engineering commitment takes longer and usually involves at least one round of feedstock testing.
Do you need lab analysis of our feedstock, or can we send a sample?
Often both. A representative sample lets us run our own characterization (moisture, ash, calorific value, volatile fraction). Where the feedstock has known contaminants — halogens, metals, PFAS — we typically also request third-party lab results before final sizing.
Can the model handle feedstock that varies seasonally?
Yes. The energy-balance model is run across the operating envelope, not at a single design point. Sites with significant seasonal variation — e.g., dairy operations with a higher-moisture wet-season feed — are sized against the worst-case energy balance, with the heat-exchanger configuration chosen to handle the range.
Will you size a system without seeing the feedstock?
No. We will not quote without modeling, and we will not model without feedstock data. This is a deliberate position — under-characterized feedstocks produce undersized heat exchangers, surprised customers, and broken commitments. The first conversation is always about the material.
Is the sizing model proprietary?
The Biogenic Refinery hardware is protected by 21 issued patents and 5 pending. The energy-balance model itself uses standard thermodynamic principles; the open-source QSDsan toolkit includes a Biogenic Refinery sanunit module that replicates the model and is available for independent verification. We share the model output and assumptions with buyers; we don't hide the math.

More questions on the full FAQ page

Send us a feedstock summary — we'll return a sizing model, not a price list.

Composition, moisture range, daily volume, site conditions. We'll come back with an energy-balance model, an acceptance note, and the model line that fits.

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