Turn fats, oils and grease into a bioenergy opportunity

A litre of grease-trap waste is not a litre of cooking oil.

Two collections with the same volume can contain very different amounts of usable organic material. Water content, solids, contaminants and the degradable fraction all affect the assessment.

A useful starting record includes:

- Material source and subtype. - Quantity and collection frequency. - Water or solids content, where known. - Seasonal changes. - Packaging, grit or other contaminants. - Current collection cost or sale value. - Existing contracts and availability. - Site location.

Already have a laboratory report or collection docket? Record its source, date and relevant measurements to improve the assessment.

Explore what your resource could become

Suitable FOG streams can be assessed for anaerobic digestion, often alongside other organic materials. Separately collected oils and fats may also have established material-recovery or liquid-fuel uses.

The best route depends on both technical suitability and the value of the alternatives.

Route A: Biogas for electricity and heat

Accepted organic material is fed into a suitable anaerobic digester. The resulting biogas is treated for its intended use and can fuel a combined heat and power system.

Potential outputs: Electricity and recoverable heat.

Commercial questions: Can electricity be used on site? Is there a useful heat demand? What gas treatment and connection arrangements are needed?

Route B: Biomethane

Biogas can be upgraded by removing carbon dioxide and other unwanted components to meet a defined gas specification.

Potential output: Biomethane for an appropriate local, transport or network-delivery route.

Commercial questions: What quality is required? Where is the buyer? What infrastructure, compression and delivery costs apply?

Route C: BioLNG

A suitable biomethane stream can undergo additional conditioning and liquefaction.

Potential output: Liquefied biomethane.

Commercial questions: Does the project have sufficient scale, a suitable buyer and a viable liquefaction and logistics arrangement?

Route D: Hydrogen via a further conversion process

A suitably treated biogas-derived methane stream may be assessed for hydrogen production through a dedicated conversion and purification process.

Potential output: Hydrogen meeting a specified end-use requirement.

Commercial questions: What technology, energy, water and purification inputs are needed? What is the full emissions boundary? Is there committed demand?

Route E: Oil recovery and liquid fuels

Suitable separately collected oils and fats may be directed to recovery or liquid-fuel processing, including biodiesel or renewable diesel supply chains.

Commercial questions: What specification does the processor require? What price, collection terms and existing contractual obligations apply?

Comparison note: These are alternative configurations. The same resource cannot be counted at full capacity in every output pathway simultaneously.

Co-products: assess separately

Biogenic CO₂: CO₂ separated during biogas upgrading may be assessed for recovery. Recoverable quantity does not establish saleable quality or a market.

Digestate: Anaerobic digestion also produces residual material. Its handling and potential use depend on the feedstock, treatment, quality and applicable requirements.

How the estimate is calculated

The calculation first converts your quantity into a consistent measurement basis. It then applies the supported feedstock and process assumptions to estimate methane production and the selected downstream output.

For a solids-based model:

Wet mass → dry solids → volatile solids → methane production → selected energy or product pathway.

For a suitable wastewater model:

Liquid flow → organic load → applicable conversion model → methane production → selected pathway.

For electricity:

Methane available to the generator × methane energy content × electrical efficiency = gross electricity.

Subtract included plant electricity use to estimate net electricity.

Important detail: Yield units matter. A value expressed per kilogram of volatile solids cannot be applied directly to a tonne of wet waste.

Illustrative electricity example

Example arithmetic only, not a FOG yield prediction.

Suppose an assessment establishes that 100 Nm³ of methane per day is available to a generator.

Using illustrative assumptions of:

- Methane energy content: 10 kWh/Nm³ on a stated lower-heating-value basis. - Electrical efficiency: 35%.

The calculated gross electricity is:

100 × 10 × 35% = 350 kWh/day.

If the included plant electricity demand is 50 kWh/day, the corresponding net result is:

350 − 50 = 300 kWh/day.

Explanation: This example starts with an assumed methane quantity. It does not tell you how many litres or tonnes of your material are required.

Use the engine’s actual gas reference conditions and compatible energy constants in live calculations.

Could your resource complement an existing digester?

FOG can be investigated as a co-feedstock alongside manure, food organics or wastewater solids. The assessment must consider the receiving plant’s design, capacity, operating conditions and material acceptance requirements.

More incoming organic material does not automatically mean better performance. The mixture and feeding approach need technical review.

Questions to explore:

- Is there a suitable receiving facility? - What quantity and composition can it accept? - Is pre-treatment or controlled storage needed? - How consistent is the supply? - What transport and receiving costs apply? - Who manages residual material?

Explore a mixed-feedstock pathway

Animal manure · Food waste · Wastewater and sludge

Look beyond energy output

An energy estimate is one part of the opportunity. A commercial assessment also considers what the resource costs to collect, transport, prepare and process, and what it is already worth.

- Current disposal or collection cost. - Existing sale value. - Collection and transport distance. - Storage and pre-treatment. - Receiving charges or gate-fee income. - Plant capital and operating costs. - Energy consumed by the process. - Local electricity, heat or gas demand. - Residual-material management. - Buyer requirements and contract terms.

Callout: Used cooking oil with an existing buyer has an opportunity cost. Compare the proposed pathway against the current arrangement.

Use your own prices and costs in the project economics tool. No indicative FOG sale price is assumed here.

Value disclaimer: Gross value is not profit. Prices, usable output and delivery costs require project-specific confirmation.

Start with the requirements for your location

Collection, transport, receiving facilities and trade-waste arrangements vary by location and activity. Record your postcode and existing service arrangements so the next assessment can identify the relevant requirements.

Check your local water utility’s instructions before changing grease-trap or trade-waste practices. In Sydney Water’s service area, waste oil must not be poured into drains or grease traps.

Feedstock regulations Supply and contracts

Avoid presenting a single national approval checklist as sufficient for every project.

Frequently asked questions

What does FOG mean in bioenergy?

FOG means fats, oils and grease. It includes different streams such as grease-trap waste, food-processing residues and separately collected cooking oil. Each needs its own assessment.

Can grease-trap waste generate electricity?

Suitable grease-trap waste can contribute to biogas production in an appropriate anaerobic digestion system. Treated biogas can fuel electricity generation. Output depends on composition, recoverable methane and generator performance.

How much electricity does one tonne of grease waste produce?

There is no reliable universal figure. One tonne may contain substantial water, while another stream may be concentrated organic material. Establish the composition and applicable yield before estimating electricity.

Is used cooking oil the same as grease-trap waste?

No. Used cooking oil is usually collected separately from frying operations. Grease-trap waste is a mixed collection containing water and other material. They may have different processing routes and commercial values.

Can fats and grease be mixed with manure?

Co-digestion may be possible at a suitable facility. The receiving plant must assess the mixture, quantity and feeding approach.

Can FOG contribute to biomethane production?

Yes, where it is suitable for digestion. The resulting biogas requires upgrading and treatment to meet the intended biomethane specification.

Does a digester produce hydrogen directly?

The pathway described here produces biogas first. Hydrogen requires a further dedicated conversion and purification process.

Can I add several feedstocks to the planner?

Yes. Enter each stream separately with its own quantity and available composition data. The report should retain each contribution and identify any unresolved mixture constraints.

What if I do not have laboratory results?

Enter what you know. The tool can identify missing information and use a clearly labelled screening assumption where supported. Otherwise, it will save the resource for further assessment.

Can I join a hub without building my own plant?

Potentially. A resource supplier may participate through collection or supply arrangements with a suitable project. This depends on compatibility, location, quantity, permissions and agreed commercial terms.

Sources and references

ARENA, Australia's Bioenergy Roadmap: resource availability appendix (2021)

Sydney Water, Retail food trade wastewater, What’s in your wastewater (publication date not stated; checked 30 October 2026)

Ampol, Brisbane Renewable Fuels Project: Market Context and Interim Report, 21 March 2025, Technology and feedstock selection (ARENA-hosted; checked 30 October 2026)

Build my FOG pathway

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