biogas
Enable an agent to recognise a biogas stream, assess its composition and condition, and determine what treatment and evidence are needed for a proposed use.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to recognise a biogas stream, assess its composition and condition, and determine what treatment and evidence are needed for a proposed use.
Biogas is a combustible gas mixture, composed principally of methane and carbon dioxide, produced by the anaerobic microbial decomposition of organic matter.
It can be Specify representative sampling and analysis for a defined biogas stream.; Compare measured gas quality with a named appliance or receiving-system specification.; Identify drying, sulfur removal or other cleaning needs from measured deficiencies.; Estimate fuel-energy delivery using compatible heating-value and flow measurements.; Flag changed composition or operating conditions that require reassessment.; Determine when upgrading warrants a linked biomethane product assessment..
Distinguishing features
Evidence traces gas formation to biological decomposition under anaerobic conditions; methane content alone cannot distinguish biogas from fossil natural gas.
The material is a variable mixture rather than pure methane, so constituent analysis is required instead of assigning methane's properties to the whole stream.
Production history distinguishes biogas from syngas generated through thermochemical conversion, even where both contain combustible constituents.
Treatment history and the receiving product specification determine whether the material remains described as biogas or should be linked to a biomethane model.
Landfill origin can identify a biogas subtype; the collection facility is a separate thing from the gas it supplies.
Scope
+ Biological origin and traceability of a defined gas stream or batch
+ Methane, carbon dioxide and other constituent concentrations
+ Moisture, contaminants and composition variability
+ Pressure, temperature, energy content and reference conditions
+ Treatment state and suitability for a specified receiving application
+ Stream-specific hazards and applicable gas-quality identity
- Digester design, microbial community management and digestion process control
- Feedstock production, waste collection and digestate management
- Upgraded biomethane product certification and distribution-system operation
- Engines, boilers, upgrading equipment and storage-vessel design
- Whole-facility lifecycle assessment and renewable-energy credit accounting
Characteristics
- Gas origin
- Producing process, facility, feedstock classes and collection point Establishes biological provenance and helps identify contaminants that require investigation.
- Stream identity and sampling interval
- Stream or batch identifier, sampling location and time interval Connects measurements to the actual gas being assessed.
- Major constituent composition
- Methane, carbon dioxide, nitrogen, oxygen and other measured gases in mol% or vol%, with wet or dry basis stated Supports identification, energy calculations and detection of dilution or air ingress.
- Contaminant profile
- Species-specific concentrations, such as ppmv or mg/m³, with reference conditions, methods and detection limits Determines treatment needs and compatibility with downstream equipment.
- Water content
- mg/m³ at stated reference conditions, or water dew point in °C at stated pressure Indicates condensation potential during transport, compression or cooling.
- Physical delivery condition
- Temperature in °C, absolute pressure in kPa, and presence or absence of condensate or entrained material Makes composition and handling assessments relevant to actual operating conditions.
- Heating value
- MJ/m³ or MJ/kg, with higher or lower heating value and reference basis specified Quantifies usable fuel energy without assuming a fixed methane fraction.
- Gas flow
- kg/h or m³/h, with actual or reference temperature and pressure stated Supports matching the available gas supply to treatment and consumption capacity.
- Treatment state
- Raw, dried, desulfurised, otherwise cleaned, or upgraded; treatment sequence recorded Distinguishes completed treatment from demonstrated outlet quality.
- Fitness for intended use
- Unassessed, meets specified limits, fails specified limits, or evidence insufficient Makes acceptance dependent on a named application and current evidence.
- Applicable regulatory identity
- Jurisdiction, supply form, applicable classification or specification, and supporting document Avoids treating a variable mixture as a universally identified pure substance.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 17 findings · 27 questions.
Biological origin and stream boundary Establishes why the material is biogas and which gas quantity the model describes.
Composition alone cannot establish biological origin, and measurements from different collection points may describe different mixtures.
Formation and provenance
Connects the gas to its biological formation and collection history.
Anaerobic origin evidence
Record evidence of biological formation separately from assumptions based on methane content or a supplier label.
- What producing process and records establish that this gas originated through anaerobic biological decomposition? provenance
- Has gas from fossil, thermochemical or other sources been blended into this stream? boundary
Material and product boundaries
Defines the assessed stream and its relationship to cleaned biogas and biomethane.
Stream and upgrading boundary
Identify the collection or delivery point, treatment stage and criteria used to change the product designation.
- Which sampling point and time interval define the biogas represented here? boundary
- Which specification or naming convention determines when this upgraded stream is assessed as biomethane? definition
Composition and energy quality Describes the combustible mixture and the evidence behind its energy properties.
Biogas does not have one fixed composition or heating value.
Major gas fractions
Records constituent fractions on a consistent analytical basis.
Composition basis and completeness
Keep constituent measurements, moisture basis and unmeasured balance explicit.
- What are the measured methane, carbon dioxide, oxygen and nitrogen fractions, and which other gases were measured? measurement
- Are results reported on a wet or dry basis, and what fraction remains unexplained within measurement uncertainty? measurement
Fuel energy and variation
Relates fuel properties to the measured stream and its variation over time.
Usable energy evidence
Record heating value and flow with compatible reference conditions and an assessment of temporal representativeness.
- What heating value and gas flow were measured or calculated, using which methods and reference conditions? measurement
- How much do methane fraction and energy delivery vary across the intended operating interval? measurement
Moisture and trace contaminants Captures constituents and entrained material that can constrain biogas use.
Acceptable methane content does not establish acceptable moisture, sulfur or trace-contaminant levels.
Water and condensation
Assesses moisture against the pressure and temperature path the gas will experience.
Condensation potential
Record water content, dew point and observed liquid carryover without treating these as interchangeable measurements.
- What water content or water dew point is established, and at what pressure? measurement
- Will the proposed cooling or compression path produce condensate or require additional moisture removal? action
Source-dependent contaminants
Defines a contaminant investigation appropriate to the feedstock, collection system and intended use.
Contaminant panel and residuals
Assess hydrogen sulfide, other sulfur species, siloxanes, ammonia, halogenated compounds and entrained material where relevant; do not presume their presence or absence.
- Which contaminants require analysis given this gas's origin and the receiving equipment's requirements? boundary
- What concentrations and detection limits are established at the delivery point after any treatment? measurement
Condition and hazard assessment Relates the gas's measured state to release, ignition and exposure concerns.
Biogas hazards depend on composition and handling conditions rather than the material name alone.
Pressure and release state
Records the conditions needed to assess containment and a potential gas release.
Delivery state and release context
Connect actual pressure, temperature and gas inventory to the receiving environment and its handling assessment.
- What absolute pressure, temperature and connected gas inventory characterise this stream at the handling boundary? measurement
- What receiving-environment assessment establishes the controls needed for a potential release? action
Combustibility and exposure
Keeps ignition, oxygen displacement and constituent toxicity separately assessable.
Mixture-specific hazard evidence
Require applicable hazard evidence for the mixture and its constituents, including methane, carbon dioxide and hydrogen sulfide where present.
- Which measured constituents and applicable classification sources establish the stream's combustion and exposure hazards? provenance
- Which monitoring and handling requirements follow from the assessed composition and use environment? action
Treatment and use acceptance Connects treatment history and verified gas quality to a specific use decision.
A treatment label cannot demonstrate that biogas meets an appliance, purchaser or network requirement.
Cleaning and upgrading evidence
Tracks which constituents treatment targets and whether the resulting gas was verified.
Verified treatment state
Record completed treatment stages, outlet measurements and evidence of changing treatment performance.
- Which drying, sulfur removal, trace-contaminant removal or carbon dioxide separation stages has this gas undergone? provenance
- Which outlet measurements demonstrate treatment performance, and when must they be renewed? measurement
Application-specific acceptance
Assesses the gas against a named destination and applicable requirements.
Use decision and quality gaps
Record a supported acceptance decision, including unmet limits and missing evidence, for the intended use.
- Which equipment specification, supply agreement or jurisdictional requirement governs this proposed use? provenance
- Does current evidence support acceptance, further treatment or withholding the stream from that use? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- This description is recalled knowledge, not source-verified research; composition ranges are indicative rather than acceptance specifications.
- Biogas is a variable mixture: do not assign methane's chemical identifiers, melting point or boiling point to the whole mixture.
- Check applicable standards, hazard classification and contaminant limits for the actual composition, intended use and jurisdiction.
- Which of these check these first hold for the sense of biogas this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Agricultural digester gas
- Sewage-sludge digester gas
- Landfill gas
- Food-waste digester gas
- Industrial wastewater digester gas
- Which of these kinds and varieties hold for the sense of biogas this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Fuel for combined heat and power generation
- Fuel for boilers and process heating
- Cooking fuel in appropriately designed biogas appliances
- Feedstock for upgrading to biomethane for gas-grid injection or transport fuel
- Which of these real-world use hold for the sense of biogas this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Methane volume fraction - Approximately 50-70 in many digester gases; feedstock and operating conditions can produce values outside this range - % by volume, dry basis
- Carbon dioxide volume fraction - Approximately 30-50 in many digester gases; varies with methane content and other constituents - % by volume, dry basis
- Lower heating value - Approximately 18-25 for dry gas containing 50-70% methane - MJ/m³ at 0 °C and 101.325 kPa
- Which of these typical measurements hold for the sense of biogas this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- Methane-containing biogas can form flammable or explosive mixtures with air.
- Hydrogen sulfide contamination can cause acute poisoning and cannot be reliably assessed by smell.
- Leaks or accumulation in confined spaces can create oxygen-deficient atmospheres; carbon dioxide also presents an inhalation hazard.
- Moisture and sulfur compounds can corrode equipment, while condensate can obstruct gas lines.
- Siloxanes in some feedstocks can generate silica deposits during combustion, damaging engines and other equipment.
- Which of these failure modes and hazards hold for the sense of biogas this model covers, and on what evidence? provenance
Regional variation
Recalled without web access and unsourced; every item is a lead to verify.
- Gas-grid acceptance requirements and transport-fuel specifications differ between jurisdictions and network operators.
- Feedstock availability and waste-management practices influence local gas composition and contaminant profiles.
- Some usage treats landfill gas as a distinct category, while broader technical usage includes it within biogas.
- Which of these regional variation hold for the sense of biogas this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- Biomethane - Biomethane is methane-rich gas obtained through upgrading or other biological production routes; raw biogas retains substantial carbon dioxide and usually requires contaminant removal.
- Natural gas - Natural gas conventionally denotes gas from geological reservoirs; biogas is identified by its production through anaerobic decomposition of organic matter.
- Syngas - Syngas is principally a mixture of hydrogen and carbon monoxide, whereas biogas is principally methane and carbon dioxide.
- Anaerobic digestion - Anaerobic digestion is the biological process that produces biogas, rather than the gas mixture itself.
- Digestate - Digestate is the residual liquid and solid material from anaerobic digestion, rather than its gaseous product.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of biogas this model covers, and on what evidence? provenance
What the second pass must settle
- Does the existing Vercy catalogue already cover biogas, landfill gas or biomethane in a model that should be linked rather than duplicated?
- Which authoritative definitions should govern the boundary between biogas, cleaned biogas and biomethane across the intended jurisdictions?
- Which mixture identifiers, safety classifications and constituent exposure limits apply to the actual supply form and jurisdiction?
- Which source-specific contaminants, sampling methods and measurement frequencies are necessary to establish representative gas quality?
- Which receiving-use specifications supply the actual acceptance limits for energy properties, moisture, sulfur, oxygen and other contaminants?