The Harlow Connection

I've recently obtained, through a Freedom of Information request, a collection of documents relating to the proposed Xetrov installation at Tarmac's asphalt plant in Harlow, England. These include the technical application, engineering information, environmental assessments, the operating permit and Harlow Council's explanation of its decision.

There are some very interesting discoveries.

As I work through things, we must remember that Tarmac’s operation is different. It’s in a different country, operating under different legislation. Its Xetrov incinerator is intended to supply heat to an existing asphalt plant rather than a biosolids drying and fertiliser manufacturing facility. We cannot assume the equipment or operating conditions will be identical.

Nevertheless, both projects propose using Xetrov's vortex combustion technology to generate industrial process heat from waste. That makes Harlow a particularly useful comparison.

What the engineering documents reveal

The Harlow application provides substantially more technical detail about the Xetrov than we have seen in the Glan Devon application. To me, that in itself is revealing. Tarmac (the applicant) did not approach Harlow Council with an incomplete, under-designed and evolving concept. They provided substantial detail so the council officers could evaluate the proposal without guessing.

Fuel for the Xetrov Incinerator

The application specifies a maximum waste feed rate of 1,500 kg per hour, with incoming fuel required to meet defined specifications for moisture, particle size, calorific value and contaminants. The fuel must arrive pre-processed, ready for combustion.

The specifications are interesting. Harlow's Xetrov is not designed to accept just any waste delivered to the facility. Its fuel must meet defined physical and chemical requirements:

• Moisture content below 15%.

• Calorific value greater than 15 MJ/kg.

• Metal and glass content below 3%.

• Particle size below 14 mm³.

• No hazardous, infectious, liquid or malodorous wastes.

That particle-size specification is particularly interesting. The permit actually states cubic millimetres, which is a volume rather than a maximum particle dimension. That describes very small particles, about 2.4mm on each side if they are cubes or 3mm diameter for spheres.

The incoming fuel must be pre-processed into a suitable, relatively homogeneous material and delivered ready for combustion. Tarmac does not propose to undertake additional fuel preparation on site.

Now compare that with Glan Devon. BYV's May Waste Acceptance Framework identifies materials including treated timber, agricultural HDPE plastics, MDF and dried biosolids. It says that operating limits will be tested and refined during Stage 1.

But identifying waste types is not the same as specifying a fuel that can actually be fed into the incinerator. The Glan Devon application has not established a consistent physical fuel specification or resolved where all the necessary preparation would occur.

This raises some important questions. What size must the incoming waste particles be? What equipment will produce them? Where will that preparation take place? What happens to rejected material? What happens when the incoming waste doesn't meet the incinerator's requirements? And where is it coming from?

Harlow specifies the fuel its incinerator is intended to burn. At Glan Devon, those fundamental fuel requirements remain to be established through the proposed trial.

Jump Starter

There is also a significant piece of supporting equipment: an auxiliary diesel burner.

The Harlow Xetrov requires diesel heating during startup to bring the combustion system to at least 850°C before waste can be introduced. Normal operating temperatures subsequently exceed 1,100°C.

The diesel burner also has an important safety and process-control function. If temperatures fall below the required level, waste feeding must stop and the auxiliary burner must operate. Its role extends to shutdown and periods when incompletely burned waste remains in the combustion chamber.

This is not merely an optional starting aid. It is part of the system's required operating controls.

I have not identified an equivalent burner or its associated fuel requirements in the Glan Devon engineering information available to us. However, the Harlow evidence shows that its Xetrov requires an auxiliary heating system, not just for startup but also for controlling combustion during abnormal operations and shutdown.

Interestingly, BYV's Code Responses declare storage of approximately 10 tonnes of Class 3 Packing Group III flammable liquid, along with 40 litres of Packing Group II liquid. But what are these substances, and what are they used for?

Could some of this be fuel for an auxiliary heating system? We don't know. But if an auxiliary burner is required, where is it shown in the engineering design, what fuel does it consume, and have its emissions been included in the air-quality assessment?

Air pollution control is more than a filter

Another notable difference is the description of the Air Pollution Control (APC) system.

At Harlow, this includes urea injection for nitrogen oxide control, activated carbon for metals, dioxins and other contaminants, limestone for acid-gas control, and a baghouse filtration system. More chemical reagents and consumables.

The application even provides indicative reagent consumption rates: approximately 5–10 litres per hour of urea and 5 kg per hour of activated carbon.

It also identifies arrangements for collecting, storing, testing and disposing of combustion residues and APC materials. We haven’t seen the equivalent for BYV’s Glan Devon operation.

I know some of these controls are integrated into the existing asphalt operation. For example, limestone aggregate passing through the dryer performs part of the gas-cleaning function. That arrangement cannot simply be assumed to apply at Glan Devon. But while the arrangement may not be the same, the need to manage acidic fumes may well be similar.

What equipment will actually be installed at Glan Devon, what consumables will it require, and what happens to the contaminants it captures?

Harlow Council's approach is particularly interesting

Harlow Council did not treat the Xetrov as some novel device exempt from conventional waste-incineration requirements. It specifically classified and permitted the installation as a Small Waste Incineration Plant (SWIP).

Although Tarmac described it as a first-of-a-kind pilot, Council rejected the idea that a full-scale installation should avoid normal regulatory requirements through a research-and-development classification.

It also imposed an important operational restriction. The waste incinerator must generate heat for the asphalt manufacturing process. It is not authorised to operate independently as a general waste-disposal facility.

The permit includes detailed operating conditions, emissions limits, continuous monitoring requirements and commissioning obligations.

But perhaps the most interesting conditions concern automatic interlocks.

Waste feeding must stop if:

• Required combustion temperatures are not maintained.

• The limestone needed for pollution control is not passing through the dryer.

• Continuous emissions limits are exceeded.

• The gas-cleaning system fails or is disturbed.

• Continuous emissions monitoring equipment fails or is disturbed.

Council also refused to permit a period of abnormal operation during which the plant could continue despite certain equipment failures. If something goes wrong and the operation is off specified performance limits it must stop the incinerator.

These are not simply promises to manage problems. They are defined operating constraints with specific consequences when something goes wrong.

Council required an approved commissioning plan and firewater/drainage review before operation, followed by testing to demonstrate emissions compliance and verify combustion residence time. The permit establishes an operating framework, but commissioning is still needed to demonstrate that the actual installation meets its requirements.

And what about Xetrov's emissions data?

The Harlow air-quality assessment was not based on measured emissions from the proposed Harlow Xetrov installation. Instead, the modelling assumed emissions at the applicable waste-incineration limits. Effectively the application said “these are regulatory limits, the incinerator will meet those limits and when it does this is how the air quality model performs”. Instead of an evidence-based approach, it was a tacit assumption that the incinerator could and would comply.

Council accepted this approach, subject to subsequent commissioning and emissions verification.

That does not mean the modelling was necessarily inappropriate. But it does mean the Harlow approval is not evidence that this Xetrov installation has actually demonstrated compliance with those emissions limits.

This is particularly relevant to Glan Devon, where we have already questioned the representativeness of the Xetrov emissions testing used in BYV's air-quality assessment. A similar approach would be possible in Queensland but it would be unusual and, in my opinion, set a precedent that the Queensland government would be reluctant to adopt.

Now consider the location

This is where the comparison becomes especially interesting.

Harlow is an established industrial site, within an existing industrial and commercial area, with an existing permitted asphalt manufacturing operation.

Even there, the introduction of waste importation and incineration attracted separate planning scrutiny. Essex County's minerals and waste planning authority specifically identified the proposed thermal treatment system as materially different from the existing approved operation. A separate planning amendment was subsequently approved.

In other words, placing a waste incinerator inside an established industrial operation was not regarded as an insignificant change.

Now consider Glan Devon.

BYV proposes establishing an entirely new industrial facility on rural land identified as Class A agricultural land.

And the proposed operation is considerably more complicated than Harlow. It combines waste combustion with biosolids receival, drying, odour management, condensate and wastewater handling, mineral fertiliser blending, pelletising and product manufacture.

The relationship between these operations introduces additional engineering, environmental and operational questions.

There is also the unresolved planning question we have raised previously: Is the Xetrov waste incinerator genuinely ancillary to the proposed High Impact Industry, or does the development involve a separate Special Industry use that has not been adequately addressed?

Harlow's classification does not determine the answer under Queensland legislation. But it certainly reinforces the importance of examining what the Xetrov actually does, rather than simply accepting its description as a heat source.

The question for South Burnett

Harlow demonstrates that regulatory authorities can permit novel industrial technology while imposing extensive engineering, monitoring and operational controls.

It also demonstrates that calling a waste incinerator a heat generator does not make its waste-incineration function disappear.

And it reveals some common features of Xetrov's technology that warrant closer examination at Glan Devon: fuel preparation requirements, auxiliary heating, combustion temperature controls, automatic shutdowns, pollution-control equipment and the management of contaminated residues.

None of this establishes that the proposed Glan Devon plant cannot operate successfully.

But it leads to a rather obvious question.

If this level of engineering detail, regulatory scrutiny and operational control is considered necessary to introduce a Xetrov incinerator into an established industrial facility at Harlow, why would we contemplate establishing a more complex, integrated waste-processing operation on rural Class A agricultural land at Glan Devon?

And perhaps the more fundamental question is: Why should we be considering this location at all?

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