Decarbonising Process Heat: The Realistic Options

Electricity is the easy part. Most industrial sites have a credible path to lower emissions electricity, whether through the grid decarbonising, on site solar, or contracting.

Heat is harder, and it is frequently the larger share of a site's emissions. Processes needing steam or high temperature heat cannot simply be plugged in.

Hydrogen CHP appears in most conversations about this, and it is one option among several. Here is how the realistic options compare for an Australian industrial site making decisions now.

First: know your heat demand properly

Before comparing technologies, characterise what you actually need. The answer narrows the field immediately.

What temperature? Low temperature hot water, medium temperature, or high temperature steam. This is the single biggest determinant of what is feasible.

What quantity, and when? Continuous or batch, and the load profile through the day and year.

How is it delivered? Direct fired, steam, hot water, thermal oil.

How firm is the requirement? Can the process tolerate variability, or does it need absolute consistency?

Sites frequently discover during this exercise that a portion of their heat demand is low temperature and readily addressed, while a smaller portion is high temperature and genuinely difficult. Splitting the problem that way makes it tractable.

Option 1: use less

Unglamorous and almost always the best first move.

Heat recovery. Waste heat from one process feeding another. Most industrial sites reject substantial heat that could be captured.

Insulation and steam system maintenance. Steam traps, uninsulated pipework and leaks. Cheap to address and the savings are immediate.

Process optimisation. Temperature setpoints that have crept up over years, batch schedules that could be consolidated.

Why it comes first: every unit of heat you do not need is a unit you do not have to decarbonise, and it reduces the size of whatever you install next. It is also the cheapest emissions reduction available and it needs no new technology.

Option 2: heat pumps, for low and medium temperature

Underused in industry and frequently the right answer for the low temperature share of a site's demand.

An industrial heat pump moves heat rather than generating it, delivering considerably more heat energy than the electricity it consumes.

Suits: hot water, wash down, space heating, and increasingly medium temperature process heat as the technology develops.

Does not suit: high temperature steam.

Why it matters: for the portion of your demand it can serve, it is efficient, it uses electricity that can be decarbonised, and the technology is available now rather than prospective.

The practical approach on many sites: use heat pumps for everything below their capability, and address the genuinely high temperature remainder separately. That reduces the hard problem to its actual size.

Option 3: biogas, if you have a feedstock

If your site produces organic waste, you may already have a renewable fuel.

Food processing, meat processing, wastewater, agriculture. Anaerobic digestion converts that waste into gas which can fuel a CHP plant producing both electricity and heat.

Why it is often the strongest option: the fuel is on site, it is renewable, it addresses a waste disposal cost, and the technology is mature and available now.

The limitation: you need the feedstock, and the gas volume has to be meaningful relative to your demand.

For sites with this option, it usually beats hydrogen commercially and environmentally. See biogas power generation.

Option 4: biomethane, purchased or produced

Biogas upgraded to pipeline specification is functionally natural gas, and it can be used in existing equipment without modification.

As a producer: if you have surplus gas and no use for the heat, upgrading and selling may be worth more than burning it. See biomethane plants.

As a buyer: purchasing certified renewable gas allows you to decarbonise existing gas fired equipment without capital works. That is genuinely attractive for hard to electrify heat, and it depends on availability and price in your market.

The attraction: no equipment change required. Your existing plant runs on it.

Option 5: hydrogen

Now the realistic position.

Hydrogen is not currently a drop in fuel. It burns faster than methane, carries less energy per unit volume, has much wider flammability limits, escapes through seals that hold methane, and can embrittle some metals. An engine designed for natural gas is not an engine that runs on pure hydrogen.

Blends are the near term reality. Many modern engines tolerate modest hydrogen percentages with limited or no modification, and where a gas network begins blending you will encounter it whether or not you planned to.

Availability and price are the constraint, not the technology. Building a business case on hydrogen fuel cost today is difficult in most Australian contexts.

So the practical decision is not whether to run on hydrogen. It is whether the plant you buy now can be converted later without replacing it.

That reframing matters, because engines last a long time and the option costs little to preserve.

The questions to ask any supplier:

1. What hydrogen blend percentage does this accept as supplied, and is that warranted?

2. What modification is required for higher percentages?

3. Is the conversion path defined and priced, or aspirational?

4. What changes on the safety side: ventilation, detection, exclusion zones?

5. What happens to heat recovery, given different exhaust composition?

A supplier answering all five with specifics is offering something real. "Hydrogen ready" without those answers is a word.

How to sequence it

For most Australian industrial sites making decisions now:

1. Reduce demand. Heat recovery, insulation, steam system maintenance, process optimisation.

2. Electrify what you can. Heat pumps for low and medium temperature demand.

3. Use your own waste, if you have it. Biogas is the strongest option for sites with feedstock.

4. Buy renewable gas for the remainder, if available and priced sensibly.

5. Specify convertible plant. Where you are installing gas fired equipment now, buy plant with a defined and priced hydrogen conversion path.

6. Revisit periodically. The fuel landscape is moving and the right answer in five years may differ.

The mistake is waiting for a single technology to solve everything. The realistic path is layered.

Frequently asked questions

Should I wait for hydrogen before investing?

Generally no. Waiting costs you the savings the plant would have delivered meanwhile. Specify convertible plant and proceed on the fuel you have.

Can heat pumps produce steam?

Not conventionally. They suit low and medium temperature demand. High temperature steam needs another answer.

Is biogas better than hydrogen?

If you have the feedstock, generally yes on both cost and availability. Hydrogen matters most to sites without their own renewable gas.

Can I use renewable gas in existing equipment?

Biomethane upgraded to specification is functionally natural gas and works in existing plant. That is its main practical attraction.

What is the cheapest emissions reduction available?

Using less. Heat recovery and steam system maintenance, almost always.

How do I know what my heat demand profile is?

Metering and monitoring rather than estimating. Most sites have less data on heat than on electricity, and that gap is worth closing first.

Split the problem before you solve it

Most sites find their heat demand divides into an easy majority and a genuinely hard remainder. Sizing the hard part honestly is what makes it solvable.

See hydrogen CHP, CHP plants, heat pumps, or get in touch.