Carbon Recycling technology (CRT), Zero emission, Bae load power, Zero fossil fuel
Author Archives: ahilan@cewt.tech
Professional chemical engineer,specializing on clean energy and water technologies.He has more than 35 years of industrial experience in various process industries.Bulk of his experience were in R&D and commercialization.He has few innovative National and International patents on desalination and power generation. His latest patent is to store renewable energy such as solar, wind and geothermal in the form of SNG (synthetic natural gas) to generate base load power. You can eliminate the usage of fossil fuel and substitute with SNG with Zero Carbon emission.
He is also a writer on Eastern philosophy, especially on Advaita Vedanta. He believes that science and Vedanta are two sides of the same coin. Science applies to this physical world, and it has its limitations. However, spirituality transcends science and the physical realm. It is your TRUE NATURE.
Carbon credits have become an important part of the global response to climate change.
They can create a financial value for reducing, avoiding, or removing greenhouse gas emissions. They can also help direct capital toward projects that might otherwise struggle to attract investment.
But there is a fundamental distinction that is sometimes lost in the discussion:
A carbon credit is an accounting instrument. Carbon itself is a physical material.
Understanding the difference requires us to follow the carbon.
Consider a facility consuming natural gas.
Carbon enters the system physically as hydrocarbons. Combustion converts that carbon primarily into CO₂. The CO₂ then crosses the plant boundary and enters the atmosphere unless it is captured.
A carbon credit may change the facility’s reported or compensated emissions position.
It does not, by itself, change that physical carbon pathway.
That distinction does not make carbon credits meaningless. It simply tells us what they can—and cannot—do.
Three different questions
When evaluating any climate strategy, it is useful to separate three questions.
Net zero asks: What is the balance between greenhouse-gas emissions and removals across a defined accounting boundary and period?
Decarbonisation asks: How are we reducing the carbon intensity or greenhouse-gas emissions associated with an activity?
Defossilisation asks: Are we reducing and ultimately ending the transfer of additional geological carbon into the active atmosphere–biosphere–ocean system?
These questions overlap, but they are not identical.
A company may improve its reported net emissions through high-quality credits while continuing to consume fossil carbon.
It may decarbonise a process substantially without completely eliminating fossil feedstock.
And a system may pursue defossilisation by changing where its carbon originates and how carbon physically circulates through the system.
The terminology matters because each describes a different aspect of the problem.
Follow the physical carbon first
Before discussing credits, certificates or offsets, draw the system boundary.
Then ask:
Where does the carbon enter?
Is it geological, biogenic, atmospheric, or recycled?
Where does it go?
How much becomes product?
How much is captured?
How much is recycled?
How much is permanently stored?
And how much ultimately reaches the atmosphere?
Those are physical questions.
They require mass balances, measurement, and clearly defined boundaries.
Only after establishing that physical carbon inventory should we apply the accounting framework.
This is particularly important because one tonne of CO₂ represented in an accounting system and one tonne of CO₂ physically moving through an industrial process are related concepts—but they are not the same thing.
Measurement strengthens carbon accounting
For industrial systems, the strongest carbon accounting begins with physical measurement wherever practical.
Gas flow can be measured.
Gas composition can be measured.
Carbon entering and leaving a process can therefore be calculated from actual operating data.
For example, where natural gas, hydrogen-rich synthetic gas or recycled gas streams are involved, composition matters. Methane, carbon monoxide, carbon dioxide and hydrogen contribute differently to the carbon and energy balances.
This is why instrumentation such as flow measurement and gas chromatography can become important not only for process control, but also for carbon accounting.
The objective should increasingly be:
Follow the carbon physically, reconcile the mass balance, and then apply the accounting rules.
Carbon credits still have a role
High-integrity carbon credits can support activities such as verified carbon removal, methane abatement, ecosystem restoration, and other genuine emissions-reduction projects.
But their role should be clearly understood.
They are mechanisms for assigning economic and accounting value to defined climate outcomes.
They should not become a substitute for understanding the physical system producing the emissions in the first place.
For industrial decarbonisation, the hierarchy therefore matters:
Measure the physical flows.
Reduce avoidable emissions.
Change the underlying carbon pathway where technically and economically possible.
Use credible accounting mechanisms for what remains.
The climate challenge ultimately exists in the physical world, not in the ledger.
Carbon accounting is essential for measuring responsibility and progress.
But if we want to understand whether an energy system is genuinely changing, there is an even simpler question to begin with:
Where did the carbon come from, where did it go, and will we need to extract more geological carbon to run the system again?
Follow the carbon, and the distinction becomes much clearer.
A framework for following carbon, energy, and consequences across the whole system
1. Start with the fundamental physical reality
Carbon is matter. In ordinary industrial chemical processes, carbon atoms are neither created nor destroyed. They are transformed from one chemical form to another and transferred from one location or reservoir to another.
Combustion illustrates this clearly:
CH₄ + 2O₂ → CO₂ + 2H₂O
The carbon contained in methane has not disappeared. It has simply moved into CO₂.
Methanation demonstrates another transformation:
CO₂ + 4H₂ → CH₄ + 2H₂O
Again, the carbon remains.
Carbon does not disappear when it crosses an engineering, corporate, geographical or regulatory boundary. We must continue following it.
2. The system boundary is necessary – but it can also mislead us
Engineers need boundaries. Without them, mass balances, energy balances and process calculations would be impossible. But nature does not recognise the boundaries we draw on process-flow diagrams.
A power station may reduce its stack emissions by capturing CO₂. From the plant boundary, this appears to solve the emissions problem. Holistic Process Engineering asks the next question: Where did the carbon go?
If it was compressed, transported, and injected underground, the carbon has not disappeared. Its location and physical state have changed.
Properly designed geological storage is intended to retain CO₂ for very long periods, and monitoring technologies exist to evaluate containment. The holistic point is that moving a material beyond the visible boundary of one process cannot, by itself, be considered the end of our responsibility for that material.
3. Follow the Carbon rather than only Follow the Emission
Instead of asking only, “How much CO₂ came out of the stack?”, ask: “Where did the carbon originate, where is it now, and where will it ultimately reside?”
The climate problem arises fundamentally from continually transferring carbon from a geological reservoir into the active carbon cycle.
Reducing emissions is necessary, but the deeper destination should be defossilisation: progressively ending the requirement for continual extraction of additional geological carbon.
4. CCS changes the destination, but does not eliminate the carbon
This can substantially reduce atmospheric emissions when it operates successfully. Holistic Process Engineering, however, requires assessment of the entire chain: capture efficiency, energy penalty, compression, transportation, injection, reservoir behaviour, monitoring, leakage risk and long-term responsibility.
Design performance should never be confused with demonstrated sustained operating performance. A FEED study specifying a high capture percentage is an engineering design objective; it is not equivalent to a facility demonstrating that performance continuously for 10 or 20 years. The same standard must ultimately apply to CRT.
5. History tells us that the carbon question is not new
The scientific foundations extend back well over a century. Eunice Newton Foote demonstrated the heat-retaining behaviour of CO₂-rich air in 1856. Svante Arrhenius quantitatively investigated the relationship between atmospheric CO₂ and temperature in 1896.
In 1912, the now-famous “Coal Consumption Affecting Climate” item publicly explained that burning enormous quantities of coal was adding CO₂ to the atmosphere and could increase Earth’s temperature.
In 1985, Carl Sagan testified before the United States Senate about fossil-fuel CO₂ and greenhouse warming.
The important lesson is not that humanity suddenly discovered the carbon problem recently. Our understanding has progressively strengthened over more than a century. The engineering question now is: What are we going to do differently with the carbon?
6. Separation is useful – but separation does not terminate responsibility
Process engineering depends on separation. We separate CO₂ from flue gas, hydrogen from mixtures, water from process streams, and contaminants from products. There is nothing inherently wrong with separation.
The problem arises when separation is mistaken for resolution.
Separation can be a process operation, but it cannot be the boundary of our responsibility.
What we separate conceptually remains connected physically.
7. There is another possible carbon pathway: circulation
Methanation itself is not a new experimental chemistry. Industrial methanation and synthetic natural gas production have decades of experience, including large coal-to-SNG installations.
A simplified coal-to-SNG pathway is: Coal → gasification → syngas → gas treatment → methanation → SNG
The fundamental carbon issue remains the continuing introduction of new geological carbon and the eventual release or disposal of carbon from the process.
This raises a logical engineering question: If CO₂ can be captured, and captured carbon can be converted with hydrogen into methane, why must disposal necessarily be the final destination of the captured carbon?
8. CRT changes carbon from a waste stream into a circulating inventory
Conceptually, the proposed Carbon Recycling Technology (CRT) pathway is:
The intention is not to destroy carbon. Instead, the objective is to manage carbon as an inventory.
Once the circulating inventory has been established, additional carbon should ideally be required primarily to replace measurable carbon losses rather than continually supplying the gross quantity circulating through the system.
9. CRT must be subjected to the same standard
Holistic thinking cannot be used to criticise CCS while exempting CRT from rigorous measurement.
If CEWT claims high carbon circulation, a demonstration plant must prove it through a whole-system carbon balance:
Every significant pathway should be instrumented. The system should measure carbon entering, carbon converted, carbon combusted, carbon captured, carbon recycled, carbon lost, and carbon make-up required.
A Carbon Recirculation Ratio may ultimately become an important CRT performance indicator, but its precise definition should be established rigorously during engineering and demonstration.
10. Technology readiness must distinguish components from architecture
The relevant question is not simply, “Has CRT operated commercially for 20 years?” It has not.
Instead, each element should be assessed independently. Methanation, syngas production, hydrogen production, CO₂ separation, CO₂ compression, gas turbines or engines, and heat recovery are established industrial operations at varying levels of commercial maturity.
The novel element is primarily the integration of these operations into sustained carbon recirculation, carbon-inventory management, and dynamic plant operation.
A technically defensible description is:
CRT is a novel system architecture integrating predominantly established industrial unit operations, with sustained closed-loop carbon recirculation and integrated system performance requiring demonstration.
11. Data, logic, intuition and engineering each have a role
Data tells us what has happened. Logic asks whether our explanation is internally consistent. Scientific knowledge establishes the governing physical laws. Engineering determines whether an alternative can actually operate.
Within Holistic Process Engineering, spiritual intuition provides another perspective: intuition sees the whole before we divide it into individual analytical pieces.
These do not have to compete. A holistic engineering process can move through:
The intuition may originate the idea. Ultimately, nature determines whether the engineering works.
12. Follow both carbon and energy
Carbon cannot be considered independently of energy. Converting CO₂ back into methane requires hydrogen and therefore substantial energy.
Consequently, circulating carbon is environmentally meaningful only if the energy required to maintain that circulation is simultaneously accounted for.
This leads to the broader principle:
Follow the Carbon and Follow the Energy simultaneously.
A solution that closes one material loop while creating an unsustainable energy requirement somewhere outside the selected boundary would not satisfy Holistic Process Engineering.
The central proposition
We create boundaries to understand nature. Nature does not obey the boundaries we create.
Carbon does not know whether it has crossed a power-station fence. It does not recognise corporate ownership or national borders. It does not disappear because it has moved beyond human sight.
Dealing with carbon emissions holistically therefore means continuing to follow the carbon – and the energy associated with it – until the consequences across the whole system are understood.
This provides the philosophical and scientific foundation for Follow the Carbon, defossilisation, and the continuing development and demonstration of CRT.
Here the objective is to prevent captured carbon from entering the atmosphere by isolating it durably underground.
The relevant system questions therefore extend beyond capture efficiency.
How much CO₂ was actually captured?
How much energy was required for capture, compression and transport?
What emissions occurred elsewhere in the system?
How much CO₂ reached the storage formation?
How securely is it retained?
How is the stored inventory measured and monitored?
The Global CCS Institute reported 77 commercial CCS facilities operating globally and another 47 under construction as of July 2025, while the IEA’s March 2026 database tracks large-scale capture, transport, storage and utilisation projects worldwide.
CCS is therefore moving increasingly from concept toward infrastructure.
But infrastructure does not remove the need for carbon accounting.
It makes accurate physical accounting even more important.
Capture and utilisation
Another pathway is:
CO₂ → capture → conversion → product
This is usually described as carbon capture and utilisation, or CCU.
But “utilisation” covers very different carbon outcomes.
Captured CO₂ might enter a material in which carbon remains bound for a long period.
Or it might be converted into a fuel that is subsequently combusted, returning the carbon to the atmosphere.
Both pathways use captured CO₂.
They do not necessarily provide the same climate service.
This is why the word utilised tells us less than it first appears.
We have to keep following the carbon.
If captured CO₂ becomes a fuel:
Where does the carbon go when that fuel is used?
If it becomes a material:
How long does the carbon remain there?
If it is subsequently recovered:
Can it enter another useful cycle?
The carbon molecule does not know whether we called the process “capture”, “utilisation” or “recycling”.
It simply moves from one reservoir to another.
Capture is not necessarily carbon removal
This distinction is particularly important.
Capturing CO₂ from a fossil-fuel process generally prevents some geological carbon from entering the atmosphere.
That can substantially reduce emissions.
But it is not physically identical to removing carbon that was already present in the atmosphere.
atmosphere → capture or biological uptake → durable storage
In the first case, the objective is largely to prevent a transfer.
In the second, the objective is to reverse a previous transfer from the active carbon system.
Both can matter.
But they should not be counted or described as though they are the same physical process.
The energy must also be followed
Capturing carbon requires energy.
So carbon analysis alone is insufficient.
We must simultaneously ask:
Where did the capture energy come from?
Capture systems may require heat, electricity, compression, pumping, refrigeration, regeneration of solvents or sorbents, and downstream CO₂ conditioning.
That additional energy has its own physical origin.
If supplying it creates additional emissions, those belong inside the system boundary.
This does not make carbon capture inherently good or bad.
It simply means the meaningful metric is not the gross amount of CO₂ entering the capture equipment.
The meaningful result is the net carbon outcome across the complete system.
Net zero, decarbonisation and defossilisation
Carbon capture also demonstrates why these terms should not be used interchangeably.
Net zero describes a balance between greenhouse-gas emissions and removals across a defined boundary.
Decarbonisation reduces emissions or emissions intensity. Capturing and permanently storing fossil CO₂ can therefore be an important decarbonisation pathway, particularly for difficult industrial processes.
Defossilisation asks a different upstream question:
How much newly extracted geological carbon does the system continue to require?
A process can become substantially decarbonised through capture while continuing to consume fossil carbon.
That is not a contradiction.
It simply means decarbonisation and defossilisation are measuring different changes in the physical system.
Understanding that distinction can improve both policy and engineering decisions.
Perhaps we need to measure carbon pathways, not just captured tonnes
The global carbon-management sector is expanding.
The IEA reports that more than 30 CCUS projects reached final investment decisions during the past two years, and investment exceeded US$5 billion in 2025. Projects currently under construction could nearly double operational capture capacity by 2030.
As that infrastructure develops, perhaps our language needs to become more precise too.
A tonne of CO₂ captured is an important engineering measurement.
But it is not yet the complete carbon story.
We should also ask:
Where did that carbon originate?
How much was actually captured?
What energy was required?
Where was the carbon transported?
Was it stored, converted, released, or recirculated?
How long did it remain outside the atmosphere?
And did the pathway reduce the requirement to extract another unit of geological carbon?
Carbon capture gives us control over a carbon stream.
What we do with that control determines the outcome.
So don’t stop at the capture plant.
Follow the energy.
Follow the carbon — all the way to its destination.
Hydrogen is increasingly described as one of the building blocks of the energy transition.
Green hydrogen. Blue hydrogen. Renewable hydrogen. Low-carbon hydrogen. Clean hydrogen.
These labels can be useful.
But from an engineering perspective, perhaps there is an even simpler place to begin:
Where did the hydrogen come from?
And immediately after that:
Where did the energy used to produce it come from?
Hydrogen carries energy — it does not create it
Hydrogen is an energy carrier and industrial feedstock, not a primary source of energy.
To produce hydrogen, energy has to come from somewhere else.
Water can be split through electrolysis using electricity.
Natural gas can be converted through steam methane reforming.
Coal can be gasified.
Other chemical and biological pathways are possible.
The hydrogen molecule may ultimately be identical.
But the physical pathway producing it can be very different.
That means evaluating hydrogen solely by the fuel at the point of use can hide much of the system that matters.
We have to follow the energy upstream.
Follow the energy
Consider renewable hydrogen produced by electrolysis.
The simplified pathway is:
renewable resource → electricity → electrolyser → hydrogen → storage/transport → end use
At each conversion and handling step, there can be energy requirements and losses.
IRENA notes that electrolysis, and particularly subsequent reconversion of hydrogen into electricity or other energy forms, involves inherent conversion losses. This is one reason direct electrification can be preferable where it is technically and economically practical.
That does not make hydrogen inefficient in every application.
It means the appropriate question is not:
“Is hydrogen good or bad?”
It is:
“What function are we asking hydrogen to perform?”
Hydrogen may be particularly valuable where direct electrification is difficult — including some industrial processes, chemical production, long-duration energy storage and production of hydrogen-derived fuels.
The system boundary determines the answer.
Then follow the carbon
Hydrogen itself contains no carbon.
But hydrogen production can have a substantial carbon footprint.
The IEA reports that global hydrogen production still remains dominated by unabated fossil fuels. Low-emissions hydrogen production reached almost 1 Mt in 2025, while total hydrogen demand surpassed 100 Mt.
So saying simply:
“This process uses hydrogen”
does not tell us its carbon impact.
We need to know how that hydrogen was produced.
For fossil-derived hydrogen, follow the geological carbon entering the production system.
For hydrogen produced with carbon capture, follow both the captured carbon and the residual emissions across the defined boundary.
For electrolytic hydrogen, follow the electricity.
Then follow the carbon associated with producing that electricity.
The colour assigned to hydrogen is secondary to the physical flows underneath it.
Hydrogen can move carbon as well as energy
There is another dimension that receives less attention.
Hydrogen can react with carbon-containing molecules to produce fuels and chemicals.
For example:
CO₂ + 4H₂ → CH₄ + 2H₂O
Here hydrogen becomes part of a carbon-management pathway.
The important questions then become:
Where did the CO₂ originate?
Where did the hydrogen originate?
Where did the energy originate?
What happens to the carbon in the methane after use?
Does it enter the atmosphere?
Is it captured?
Is it stored?
Is it reused?
And does the overall system require another unit of geological carbon to replace it?
Now we are no longer simply discussing hydrogen.
We are examining a carbon-and-energy system.
Why low-emissions hydrogen is struggling to scale
The physical system also helps explain some of today’s commercial difficulties.
The IEA reports that low-emissions hydrogen production grew by about 20% in 2025, but persistent barriers remain: high costs, uncertain demand, regulation and insufficient infrastructure. Only around 20% of newly signed low-emissions hydrogen offtake volumes in 2025 were backed by firm contractual commitments.
This should not necessarily be interpreted as hydrogen failing.
It may instead indicate that hydrogen needs to be deployed where its system value justifies the additional conversion steps and infrastructure.
The objective should not be to maximise hydrogen production.
The objective should be to use hydrogen intelligently where it helps transform the underlying energy and material system.
Net zero, decarbonisation and defossilisation
Hydrogen also demonstrates why these three concepts should not be treated as synonyms.
Net zero describes a balance between greenhouse-gas emissions and removals across a defined boundary.
Decarbonisation describes measures that reduce emissions or emissions intensity.
Defossilisation asks a different upstream question:
Can we progressively reduce the requirement for newly extracted geological carbon?
Renewable hydrogen can contribute to decarbonisation and defossilisation when it replaces fossil-derived hydrogen or enables industrial pathways that require less new fossil carbon.
But simply introducing hydrogen into a system does not automatically accomplish either.
The complete material and energy flows have to be examined.
Beyond the colour of hydrogen
Perhaps the hydrogen debate has become too focused on colours.
Green.
Blue.
Grey.
Pink.
Turquoise.
Those classifications can help describe production pathways, but they should not replace physical analysis.
Instead, ask:
Where did the hydrogen come from?
Where did the energy come from?
Where did the carbon come from?
Where did the carbon end up?
And finally:
Did this system reduce the amount of new geological carbon that had to enter the economy?
Hydrogen may become extremely important in the energy transition.
But its value will ultimately be determined not by its colour, nor by the molecule alone.
It will be determined by the system in which we use it.
Clean Energy and Water Technologies Pty Ltd (CEWT) Status: Preliminary internal assessment Purpose: Investor, government, EPC/EPCM, technology-partner and project-development discussions
1. Purpose of this Assessment
This assessment establishes a structured and defensible Technology Readiness Level (TRL) position for CEWT’s Carbon Recycling Technology / Carbon Circular Management System (CRT/CCMS).
A fundamental distinction is made between:
Component Technology Readiness — the maturity of the individual physical technologies incorporated into CRT/CCMS; and
Integrated System Readiness — the maturity of the specific CEWT process architecture that integrates those technologies into a managed carbon-recirculation system.
This distinction is essential because CRT/CCMS does not depend primarily upon the invention of a new turbine, chemical reactor, compressor, heat exchanger, CO₂ separation process or methanation reaction.
Its principal technological innovation lies in the integration and control of established and emerging industrial processes so that recovered carbon is maintained as a managed circulating inventory rather than continually replaced by newly extracted fossil carbon.
Accordingly, the TRL of the overall CRT/CCMS system should not automatically be equated either with:
the highest TRL of its individual components; or
the lowest maturity associated with demonstrating the complete integrated architecture.
Both levels of readiness must be reported separately.
2. Commercial Relevance of TRL
The Carbon Gap / Carbon Management Europe paper identifies Technology Readiness Level as a measure of technological maturity extending from early research through demonstrated operation.
For buyers and financiers, however, TRL has a broader commercial significance because it affects certainty of delivery.
The paper considers five broad approaches:
TRL 4–6 — early-stage technologies;
TRL 6–7 — pre-commercial scale-up;
TRL 4–9 — segmented portfolios;
TRL 7+ — near-commercial projects; and
TRL 8–9 — commercially ready projects.
The trade-off is therefore between technological diversity and delivery certainty.
For CEWT, the implication is that the objective should not be to assign the highest possible TRL to CRT prematurely. The objective should be to demonstrate a credible pathway through successive levels of integrated-system validation until the overall system achieves commercially bankable readiness.
3. CRT/CCMS System Definition
For purposes of this assessment, CRT/CCMS comprises the integration of the following principal functions:
Energy conversion
RSNG / methane-rich fuel is converted into electricity and recoverable thermal energy through a suitable prime mover.
Carbon recovery
CO₂ generated during energy conversion or associated process operations is separated and recovered rather than discharged as the intended normal carbon pathway.
Hydrogen-rich synthesis-gas production
Hydrogen-rich syngas and/or supplementary hydrogen is generated or supplied to provide the reducing hydrogen required for carbon conversion.
Methanation
Recovered CO₂ and/or CO reacts with hydrogen to regenerate methane-rich fuel.
Water recovery
Water generated through methanation and combustion/process reactions is separated and recovered where practicable.
Carbon inventory management
Carbon is managed as a circulating process inventory, with make-up carbon determined primarily by unavoidable system losses rather than by the gross amount of carbon circulating within the plant.
Energy integration
Electricity, process heat, steam, oxygen, hydrogen, water and other energy/material streams are integrated across the plant to reduce external energy and resource requirements.
Process control and safety
The complete system is operated using conventional industrial control, protection, isolation and safety systems appropriate to hydrogen, syngas, methane, oxygen and CO₂ service.
4. Component-Level Technology Readiness
The following ratings are preliminary engineering classifications rather than independent third-party TRL certifications.
CRT/CCMS subsystem
Preliminary component maturity
Assessment
Gas turbine / gas engine power generation
TRL 9 class
Commercially established equipment operating globally on natural gas and related gaseous fuels.
Heat recovery / steam generation
TRL 9 class
Mature commercial technology extensively deployed in combined-cycle and industrial applications.
CO₂ compression to moderate process pressure
TRL 9 class
Industrial gas compression is mature; CRT duty and pressure must nevertheless be engineered for the selected capture/methanation system.
Conventional CO₂ separation / solvent capture
TRL 8–9 class at component level
Commercially deployed separation principles and equipment exist. Performance within the specific CRT exhaust composition remains project-specific.
Cryogenic CO₂ separation
High component maturity, application dependent
Established industrial separation principles; the particular exhaust-stream application requires vendor confirmation and performance validation.
Steam methane reforming
TRL 9 class
Mature industrial hydrogen/syngas production technology.
H₂-rich syngas production
TRL 8–9 class depending on configuration
Industrial syngas generation and conditioning are established; CEWT’s target composition and integration require project-specific engineering.
Water electrolysis
TRL 8–9 class at equipment level
Commercial electrolysers exist; economics and dynamic integration remain project-specific.
CO₂ methanation
High component maturity
Methanation chemistry and industrial reactor technology are established. Required operating conditions and guarantees must be confirmed by the selected licensor.
Oxygen production — cryogenic ASU
TRL 9 class
Mature large-scale industrial technology.
Oxygen production — PSA/VPSA
TRL 9 class for applicable purity/range
Mature technology subject to required flow and purity.
Process heat integration
TRL 9 engineering discipline
Conventional process engineering practice; specific CRT integration remains to be demonstrated.
Established industrial storage technologies, subject to fuel composition and regulatory requirements.
Water separation and recovery
TRL 9 class
Conventional industrial process technology.
Important qualification
These ratings describe the underlying technologies, not CEWT’s integrated CRT/CCMS system.
They must therefore never be presented publicly as evidence that the overall CRT system itself has reached TRL 8 or TRL 9.
5. Integration-Specific Technology Elements
The areas requiring CRT-specific validation are substantially different from the mature underlying hardware.
They include:
5.1 Closed carbon-material balance
The complete plant must demonstrate that recovered carbon can be repeatedly returned to the fuel-production pathway and that the circulating carbon inventory can be quantified.
5.2 Carbon inventory management
The relationship between:
gross circulating carbon;
captured carbon;
temporary carbon inventory;
unavoidable process losses;
make-up carbon; and
product or purge carbon
must be demonstrated dynamically as well as through steady-state mass balance.
5.3 Methanation integration
The interaction among:
captured CO₂;
CO-containing synthesis gas;
hydrogen;
methanation reactor;
water removal;
methane conditioning; and
recycled fuel
must be demonstrated as an integrated operating system.
5.4 Hydrogen balance
Hydrogen demand must be validated under realistic operating conditions, including:
syngas-derived hydrogen;
supplementary renewable or low-fossil hydrogen;
transient operation;
process losses; and
hydrogen required to compensate for carbon-cycle losses.
5.5 Energy balance
A complete integrated energy balance must confirm the relationship between:
fuel energy;
gross electrical output;
internal power consumption;
hydrogen-production demand;
CO₂ capture demand;
compression;
oxygen production where applicable;
methanation heat;
recovered thermal energy; and
exportable electricity and heat.
5.6 Dynamic operation
The carbon loop must be demonstrated during:
start-up;
normal operation;
load changes;
shutdown;
restart;
temporary capture interruption;
methanator interruption;
hydrogen-supply variation; and
abnormal process conditions.
5.7 Carbon-loss accounting
A defensible CRT demonstration must measure rather than merely calculate carbon losses.
Relevant measurements should include:
stack carbon;
purge streams;
fugitive methane;
vented CO₂;
process drains where applicable;
start-up/shutdown releases; and
carbon entering or leaving stored inventories.
6. Preliminary Integrated-System TRL Position
Based on CEWT’s current project-development status, the overall CRT/CCMS architecture should not presently be represented as TRL 7, 8 or 9.
The individual constituent technologies are predominantly high-TRL technologies.
However, the complete CEWT carbon-recirculation architecture has not yet been demonstrated as an operating integrated plant at commercially relevant scale.
A defensible present description is therefore:
CRT/CCMS is an integrated system architecture built predominantly from high-TRL industrial technologies, while the integrated carbon-recirculation configuration itself remains at pre-commercial demonstration readiness.
For internal planning purposes, CEWT should presently treat the integrated CRT/CCMS system as approximately TRL 4–5, subject to independent review of the available engineering evidence.
This rating recognises that:
the process architecture has been defined;
stoichiometric relationships have been developed;
material and energy balances have been developed;
major equipment categories have been identified;
established technology suppliers are being engaged;
project-specific engineering is progressing; and
a commercial-scale demonstration project is being developed.
It also recognises that:
no complete CRT/CCMS loop has yet operated;
integrated steady-state performance has not yet been demonstrated;
dynamic carbon inventory management has not yet been demonstrated;
measured carbon-loss performance is not yet available;
long-duration operating stability has not yet been established; and
integrated performance guarantees have not yet been demonstrated.
The TRL 4–5 designation should therefore be treated as a provisional integrated-system assessment, not as an externally certified rating.
7. Proposed CRT/CCMS TRL Progression
Current stage — approximately TRL 4–5
Evidence should include:
defined process architecture;
process-flow diagrams;
overall mass balance;
overall energy balance;
principal reaction stoichiometries;
equipment list;
preliminary controls philosophy;
preliminary operating philosophy;
process simulations;
vendor engagement;
preliminary safety assessment; and
identification of all significant carbon entry and exit points.
Next objective — TRL 6
CEWT should target TRL 6 through an integrated pilot or demonstration system operating in a relevant process environment.
The demonstration should physically integrate, at minimum:
carbon-containing fuel input;
controlled energy conversion or representative combustion;
CO₂ recovery;
CO₂ conditioning;
H₂-rich gas supply;
methanation;
water removal;
methane/RSNG conditioning;
fuel recycle;
continuous carbon-flow measurement; and
integrated process control.
The critical result would not simply be methane production.
It would be evidence of continuous carbon recirculation through the complete process sequence.
Commercial demonstration objective — TRL 7
TRL 7 should correspond to operation of an integrated CRT/CCMS demonstration under conditions representative of the intended commercial application.
The demonstration should establish:
continuous operation;
representative scale;
validated carbon balance;
measured capture efficiency;
measured carbon losses;
hydrogen consumption;
electrical parasitic load;
methane-production performance;
fuel-quality stability;
transient response;
safety-system performance;
start-up/shutdown procedures;
reliability; and
preliminary operating cost.
Achieving this milestone would be particularly important because commercially oriented carbon markets and financiers increasingly associate TRL 7+ with credible delivery capability.
TRL 8
TRL 8 should require completion and qualification of the integrated commercial system design together with sufficiently extensive demonstration evidence to support:
final engineering;
vendor guarantees;
EPC contracting;
financing due diligence;
permitting;
operating procedures;
performance testing; and
independent engineering review.
At this stage, residual risk should principally be project-execution risk rather than fundamental technology-integration risk.
TRL 9
TRL 9 should only be claimed after CRT/CCMS has operated successfully as a complete commercial system under normal industrial conditions.
Evidence should include sustained operation demonstrating:
carbon recovery;
carbon recirculation;
system reliability;
operating availability;
process safety;
fuel quality;
carbon-loss performance;
hydrogen consumption;
internal energy demand;
maintenance requirements; and
commercial operating performance.
8. Critical Distinction: Technology Risk vs Integration Risk
The principal CRT development risk should be described as integration and system-performance risk, rather than fundamental scientific risk.
A conventional early-stage technology may require proof that a new physical phenomenon, catalyst, material or reactor can perform its intended function.
CRT is different.
Most of the physical transformations required by CRT already occur commercially in separate industrial processes.
The development question is therefore:
Can these established process operations be integrated, controlled and economically operated so that carbon functions as a repeatedly circulating system inventory while external fossil-carbon make-up is progressively reduced to the amount required to compensate for unavoidable losses?
This distinction materially affects how the project should be assessed by:
investors;
governments;
lenders;
insurers;
EPC contractors;
technology licensors; and
independent engineers.
9. Proposed Technology Readiness Matrix
CEWT should maintain a formal Technology Readiness Matrix for every demonstration project.
Each subsystem should be scored against the following categories:
Category
Evidence required
Technology maturity
Existing commercial installations and operating references
Scale maturity
Evidence at comparable throughput
Feed compatibility
Demonstration with relevant gas composition
Product specification
Ability to meet required outlet specifications
Integration maturity
Evidence of operation with upstream/downstream CRT systems
Dynamic performance
Start-up, shutdown and load-following behaviour
Safety maturity
HAZID/HAZOP/SIL and operating safeguards
Vendor guarantee
Availability and scope of performance guarantee
Commercial maturity
Budget price, schedule and contractual availability
Carbon-accounting maturity
Ability to measure all material carbon flows
Energy-performance maturity
Demonstrated auxiliary-energy consumption
Project readiness
Engineering, permits, procurement and constructability
10. Evidence Register
Every TRL claim should ultimately be supported by an evidence register containing, where available:
patents and patent applications;
engineering calculations;
process simulations;
BFDs;
PFDs;
UFDs;
P&IDs;
heat and material balances;
equipment data sheets;
vendor correspondence;
technology-provider proposals;
test reports;
pilot operating data;
independent engineering reports;
HAZID studies;
HAZOP studies;
SIL assessments;
emissions measurements;
carbon-flow measurements;
energy-consumption measurements;
product-gas analyses;
reliability data;
performance guarantees; and
commercial operating records.
No TRL advancement should be based solely on narrative description.
11. Recommended CEWT Public Position
Until an independent readiness assessment has been completed, CEWT should avoid statements such as:
“CRT is TRL 8.”
or
“CRT is commercially proven.”
A more defensible formulation is:
CEWT’s Carbon Recycling Technology integrates predominantly mature industrial technologies including power generation, carbon capture, synthesis-gas production, methanation, compression, heat recovery and industrial process control. The principal development requirement is demonstration and validation of these technologies as an integrated carbon-recirculation system.
For more technically sophisticated audiences:
CRT has a high component-level technology readiness but a lower integrated-system readiness. CEWT’s demonstration programme is specifically intended to close that integration-readiness gap and establish measured carbon, hydrogen and energy performance under commercially relevant operating conditions.
12. Strategic Objective
CEWT’s technology-development programme should therefore be structured around one clear objective:
Move CRT from high component maturity but pre-commercial integrated-system readiness to TRL 7+ through measured demonstration of the complete carbon-recirculation loop.
This is more credible than attempting to argue that CRT is already commercially mature.
Immediate development target:TRL 6 through integrated pilot/demonstration operation.
Critical commercial threshold:TRL 7+, supported by relevant-scale operating evidence and independently verified carbon and energy balances.
Ultimate objective: TRL 8–9 commercial qualification and operation.
The central proposition is therefore:
CRT does not require every industrial technology within the plant to be reinvented. It requires the integrated carbon-recirculation architecture to be demonstrated.
That distinction should form the foundation of CEWT’s technology-readiness, demonstration, and bankability strategy.
Ref: Carbon Gap (European Carbon Management Guide)
Concept Brief – Feasibility and Validation Program
Opportunity
Land-constrained cities face a growing challenge: how to strengthen food resilience without increasing dependence on land, water, and increasingly complex external supply chains.
Controlled-environment vertical farming offers one pathway, but its potential should be considered as more than an agricultural technology.
CEWT proposes evaluating an integrated urban food infrastructure platform in which dependable energy, controlled agriculture, cooling, water recovery, and controlled carbon dioxide utilisation are designed as one interconnected system.
Integrated concept
Dependable Energy → Controlled Agriculture → Local Food
Multi-level cultivation can substantially increase productive growing area within a limited physical footprint. Environmental control enables year-round production, while hydroponic water recirculation and recovery of moisture removed during dehumidification create opportunities to reduce net water requirements.
Controlled quantities of suitably conditioned CO₂ may also be supplied to the growing environment as a productive biological input. Rather than designing each requirement independently, the objective is to optimise the complete energy–water–carbon–food system.
Proposed feasibility and validation program
CEWT proposes an initial Singapore-based feasibility and validation program bringing together appropriate scientific, engineering, infrastructure and commercial expertise.
• suitable crops and realistic production yields;
• multi-level cultivation configuration and land productivity;
• lighting and electrical-energy requirements;
• cooling, humidity control and environmental management;
• plant transpiration and condensate-water recovery;
• hydroponic water and nutrient recirculation;
• controlled CO₂ enrichment requirements;
• opportunities for useful heat recovery;
• potential integration with existing urban infrastructure;
• CAPEX, OPEX and production cost; and
• commercial scalability and contribution to urban food resilience.
Potential 1 MW demonstration
Subject to successful scientific, engineering and commercial validation, the program could progress to a potential 1 MW integrated demonstration facility.
Preliminary CEWT engineering screening indicates that a 1 MW-class module could potentially support approximately 9,000 m² of effective multi-level cultivation area and production in the order of 700 tonnes per year of leafy vegetables.
These are preliminary engineering screening estimates only and are specifically intended to be tested and refined through the proposed feasibility and validation program.
The demonstration would evaluate the complete integrated system rather than simply the agricultural production component.
The initial objective is therefore not to propose construction of another vertical farm. It is to determine whether integrated design can materially improve the technical and commercial performance of controlled urban agriculture by managing energy, cooling, water and carbon as interconnected resources.
Strategic proposition
Land and resource constraints can become drivers of infrastructure innovation. A successful demonstration could establish a replicable model for highly urbanised and resource-constrained cities seeking greater resilience from limited physical resources.
Energy → Water → Carbon → Food An integrated infrastructure platform for resilient cities.
Clean Energy and Water Technologies Pty Ltd (CEWT) | Melbourne, Australia Ahilan Raman | Managing Director | ahilan@cewt.tech
Part 4: Hydrogen Powers the Future; Carbon Enables the Cycle
The energy transition is increasingly looking to hydrogen as a future energy carrier. That direction has merit—but hydrogen alone does not answer one of the more fundamental questions facing the transition:
What do we do with carbon?
Carbon is not inherently the problem. Carbon is an essential element in fuels, chemicals, materials, agriculture and life itself. The deeper problem is our continuing dependence on new geological carbon extracted from coal, oil and natural gas and transferred into the active carbon cycle.
This distinction is increasingly entering mainstream scientific discussion. In January 2026, Nature explicitly argued that achieving net zero means eliminating dependence on fossil fuels rather than eliminating carbon itself, noting that carbon-based fuels and carbon-containing products will remain necessary in a net-zero economy.
That is where hydrogen and circular carbon potentially become complementary.
Hydrogen supplies energy. Carbon provides a carrier.
Renewable hydrogen can provide chemical energy without introducing new carbon into a process. But hydrogen is difficult and costly to store, transport, and integrate into some existing industrial and energy infrastructure.
Carbon, by contrast, can form highly useful molecules such as methane and methanol.
Instead of treating captured CO₂ simply as a waste requiring disposal, we can ask a different engineering question:
Can recovered carbon become an inventory that is repeatedly circulated?
For methane synthesis, the underlying chemistry is well established:
CO₂ + 4H₂ → CH₄ + 2H₂O
Hydrogen supplies the reducing energy. Carbon provides the molecular framework for the methane.
The resulting methane can then be stored, transported, and used through established gas infrastructure. If its carbon is recovered rather than continuously released, it can potentially be returned to the synthesis process.
The important input progressively becomes energy, rather than replacement fossil carbon.
Follow the carbon, not merely the fuel label
Consider two methane molecules.
Chemically they may be identical.
One molecule may contain carbon freshly extracted from a geological gas reservoir.
The other may contain carbon recovered from an engineered process and circulated for its second, tenth, or hundredth cycle.
Calling both simply “natural gas” or “methane” misses the fundamental difference in their carbon pathways.
This is why I believe future energy accounting needs to examine three things separately:
Fossil Carbon Intensity (FCI) — how much fresh geological carbon enters the system.
Carbon Circularity (CC) — how effectively recoverable carbon is retained and reused.
Carbon Emissions Intensity (CEI) — how much ultimately reaches the atmosphere.
A system can therefore improve its carbon performance not merely by changing the fuel label, but by progressively reducing the amount of new fossil carbon crossing its system boundary.
We can express that transition through a simple measure:
where FCI₀ represents the fossil-carbon intensity of the reference system.
At the starting point, FCI = FCI₀ and defossilisation progress is zero.
As recovered carbon increasingly substitutes for newly extracted carbon, FCI declines.
If fresh geological carbon input eventually becomes negligible, defossilisation approaches 100%.
Renewable hydrogen becomes increasingly important
There is another reason to distinguish hydrogen from carbon.
Today, global hydrogen production itself remains overwhelmingly fossil-based. The IEA reports that global hydrogen demand exceeded 100 million tonnes in 2025, while low-emissions hydrogen production was still below 1 million tonnes. Electrolysis capacity is growing rapidly, but low-emissions hydrogen represents only a little over 1% of expected global production in 2026.
So simply saying “hydrogen” does not establish defossilisation.
We must also follow the hydrogen.
As renewable hydrogen expands, however, an interesting possibility emerges. Renewable hydrogen can increasingly provide the energy required to convert recovered CO₂ and CO back into useful carbon-based energy carriers.
The transition can therefore move in two directions simultaneously:
Fresh fossil carbon ↓
Renewable hydrogen ↑
while the existing carbon inventory continues circulating.
This changes how we think about carbon capture
Traditional carbon capture discussions often end at:
Capture → transport → permanent storage.
Permanent geological storage will undoubtedly have applications.
But there is another pathway:
Capture → recover → regenerate → reuse.
These approaches need not be competitors. Different carbon streams will require different solutions.
The important conceptual change is to stop assuming that every captured carbon atom is necessarily waste.
Some carbon may be permanently stored.
Some may become chemical feedstock.
Some may become materials.
And some may potentially remain within deliberately engineered energy cycles.
This broader idea is gaining attention beyond energy systems. Research published in 2026 is examining the replacement of fossil feedstocks with alternative carbon sources—including captured CO₂—in industrial clusters, while Nature has described the need for sustainable non-fossil sources of carbon for the chemical economy.
The destination is not a carbon-free civilisation
Such a civilisation is neither realistic nor desirable.
The destination should instead be an economy that requires progressively less new geological carbon.
Hydrogen can supply increasing amounts of the energy required to make that possible.
Carbon can continue doing what carbon does exceptionally well: forming molecules, carrying energy and providing essential industrial feedstocks.
But rather than continually extracting it, using it once and releasing it, we should increasingly ask whether we can manage carbon as an inventory.
That leads to a different vision of the energy transition:
Hydrogen powers the future. Carbon enables the cycle. Defossilisation determines whether we have actually broken our dependence on fossil extraction.
The next chapter will examine how this principle can move from a framework into an engineered system through Carbon Recycling Technology (CRT).
Sources: Nature, 6 January 2026 and 18 February 2026; International Energy Agency, Global Hydrogen Review 2026, published 18 June 2026; Scientific Reports, 26 January 2026.
The energy transition has created an expanding vocabulary.
Renewable energy. Green hydrogen. Blue hydrogen. Carbon capture. Net zero. Decarbonisation. Carbon removal. Synthetic fuels. Circular economy.
Each term has a purpose. But sometimes the labels make the underlying engineering harder, rather than easier, to see.
There may be a simpler question:
Where did the carbon come from, where does it go, and what happens to it next?
In other words:
Follow the carbon.
Carbon Is Not the Fundamental Problem
Carbon is one of the fundamental elements of life and industry.
It is present in fuels, chemicals, plastics, construction materials, agriculture, and countless products essential to modern society.
The problem is not simply that we use carbon.
The fundamental problem is the continuing transfer of additional geological carbon from underground reserves into the active atmosphere, oceans and biosphere.
Consider conventional natural gas.
Carbon is extracted from a geological reservoir as methane:
CH₄
It is combusted:
CH₄ + 2O₂ → CO₂ + 2H₂O + energy
The carbon atom has not disappeared.
It has simply moved.
Geological reservoir → natural gas → combustion → atmosphere
Once we look at the system this way, the distinction between carbon and fossil carbon becomes extremely important.
Capture Changes the Destination — Not Necessarily the System
Carbon capture can intercept CO₂ before it reaches the atmosphere.
That is important.
But then we must continue following the carbon.
If the CO₂ is captured and permanently stored underground:
fuel → CO₂ → capture → geological storage
we have changed its destination.
If instead the captured CO₂ is combined with hydrogen and converted into another useful molecule:
CO₂ + 4H₂ → CH₄ + 2H₂O
the carbon becomes fuel again.
The pathway becomes:
CH₄ → energy → CO₂ → CH₄
Now something fundamentally different has happened.
The carbon is no longer necessarily treated as waste.
It has become a circulating process inventory.
From Carbon Capture to Carbon Circulation
This distinction deserves more attention.
Traditional thinking often treats CO₂ as the final waste product of combustion:
Extract → combust → capture → dispose
A circular-carbon system asks whether another architecture is possible:
Carbon can therefore be considered in much the same way engineers consider other controlled inventories circulating through industrial processes.
There will never be a perfectly closed physical system.
There will be losses.
There will be purge streams, maintenance losses, leakage and other practical limitations.
The meaningful engineering question is therefore not whether carbon can circulate literally forever.
It is:
How many times can the same carbon inventory perform useful work before replacement carbon is required?
That changes the metric.
Instead of measuring only the gross amount of carbon passing through a plant, we should also measure the amount of new carbon entering the system.
This Is Why Defossilisation Matters
Decarbonisation and defossilisation are related, but they are not identical concepts.
Some industries will continue to require carbon-containing molecules.
The objective cannot therefore always be to eliminate carbon itself.
A more fundamental objective is to progressively eliminate dependence on newly extracted fossil carbon.
That is defossilisation.
Imagine that an industrial system circulates 100 units of carbon and loses one unit during each cycle.
The gross carbon throughput may remain approximately 100 units.
But the requirement for new carbon is approximately one unit to replace the loss.
The important number is therefore not merely the carbon circulating inside the system.
It is the make-up carbon crossing the system boundary.
As losses decline, dependence on virgin carbon declines.
That is a very different way of measuring progress.
Follow the Carbon — and Follow the Hydrogen Too
Hydrogen provides another useful example.
Hydrogen is frequently described according to how it is produced: green, blue, grey, and other classifications.
But again, labels alone do not describe the complete system.
Ask instead:
Where did the energy used to produce the hydrogen come from?
How much electricity was required?
What happens to the oxygen produced by electrolysis?
How is the hydrogen compressed, stored, and transported?
What molecule ultimately uses the hydrogen?
And what happens to that molecule afterwards?
This becomes particularly interesting when electrolysis is integrated with other processes.
Electrolysis produces hydrogen and oxygen:
2H₂O → 2H₂ + O₂
The oxygen is not an insignificant side stream.
By mass, approximately eight kilograms of oxygen are produced for every kilogram of hydrogen.
If an adjacent industrial process requires oxygen, that coproduct can potentially become part of the overall system architecture.
The correct question is therefore not simply:
“What is the cost of green hydrogen?”
It is:
“What is the performance and economics of the complete integrated system in which that hydrogen and its coproducts are used?”
The Same Principle Applies to Power
A power plant is normally compared using metrics such as efficiency, emissions intensity, and cost per megawatt-hour.
Those metrics remain essential.
But system boundaries matter.
A high-efficiency plant that continually requires newly extracted fossil carbon has a different long-term material flow from a system that captures and repeatedly circulates a controlled carbon inventory.
Likewise, a lower-efficiency process that simultaneously performs CO₂ separation may be providing a function that another generation technology requires as an additional downstream process.
Comparisons therefore need consistent system boundaries.
Follow the energy — but also follow the carbon.
And It Applies to Data Centres
The same thinking is becoming increasingly relevant to AI infrastructure.
A data centre cannot be understood simply by asking whether its electricity contract is renewable.
Coal, oil and natural gas have accumulated underground over geological timescales. We extract them, use their energy and molecular value, and transfer part of that geological carbon into the active atmosphere–biosphere–ocean system.
The problem is therefore not that carbon exists.
Carbon is fundamental to life, fuels, chemicals, materials and natural ecosystems.
The important question is the flow of additional carbon between reservoirs.
For more than a century, industrialisation has continuously moved carbon in predominantly one direction: from geological reservoirs into the active carbon cycle.
That is the physical flow we ultimately need to change.
Net zero is the destination
Net zero defines an atmospheric outcome.
Anthropogenic greenhouse-gas emissions must ultimately be balanced by anthropogenic removals so that human activity no longer produces a continuing net increase in atmospheric greenhouse gases.
That objective is essential.
But net zero does not, by itself, prescribe the engineering architecture required to achieve it.
Two systems can both have a net-zero objective while having very different physical energy and carbon flows.
This is why we also need to distinguish decarbonisation from defossilisation.
Decarbonisation asks:
How can we reduce greenhouse-gas emissions?
Defossilisation adds another question:
How can we progressively reduce the continual introduction of newly extracted geological carbon into our energy and industrial systems?
These objectives are related, but they are not identical.
Electrification is a pathway, not the destination
Electrification is one of the most powerful tools available to us.
Electric vehicles can replace internal-combustion engines. Heat pumps can replace combustion heating. Electric industrial processes can replace fossil-fired equipment.
But electrification does not make energy demand disappear.
It transfers that demand to the electricity system.
The complete question therefore becomes:
How is the additional electricity generated, transmitted, stored and firmed?
The same principle applies to hydrogen.
Hydrogen can be enormously valuable in steelmaking, chemicals, heavy transport, energy storage and other applications where direct electrification may be difficult.
But hydrogen is an energy carrier and industrial feedstock, not an energy source.
Its environmental outcome depends on how it is produced.
So rather than asking whether a technology is labelled renewable, hydrogen, electric or low-carbon, we should examine the complete physical system.
Follow the energy. Follow the carbon.
Carbon avoidance, removal — and circulation
Carbon markets commonly distinguish between two important activities.
Avoidance prevents emissions that otherwise would have occurred.
Removal takes CO₂ already present in the atmosphere and stores it durably.
Both have important roles.
But increasingly there may be a third carbon-management concept worth considering:
circulation.
Instead of treating carbon as something that passes through an industrial system once before becoming waste, what if recovered carbon could increasingly be treated as an inventory?
The physical architecture could begin moving from:
extract → use → emit
toward:
use → recover → reuse → recover → reuse
No engineered system will circulate material perfectly. There will be losses, degradation, energy requirements, and make-up inputs.
The meaningful question is therefore not whether a system can become literally 100% circular.
It is:
How much new resource extraction can repeated recovery and reuse displace?
That may ultimately be one of the most useful measures of circularity.
Carbon as inventory
This changes how we think about captured carbon.
If CO₂ is simply captured at one location and released somewhere else later, little has been achieved atmospherically.
If it is permanently stored, it can represent carbon storage or removal depending on its origin and the applicable accounting framework.
But if carbon can be recovered and repeatedly reused within an engineered system, another outcome becomes possible:
reduced demand for new geological carbon input.
This suggests that future carbon management may need to consider at least three physical pathways:
Avoid it. Remove it. Circulate it.
And each requires different measurement.
For avoidance:
What emissions genuinely did not occur?
For removal:
How much atmospheric carbon was removed and durably stored?
For circulation:
How much new carbon input was displaced through repeated recovery and reuse?
These concepts should not be confused or double counted.
But neither should physically different carbon-management pathways be forced into the same conceptual category.
Measurement must follow the physics
This also has implications for carbon accounting.
Installing equipment does not guarantee an environmental outcome.
A carbon-capture plant does not prove how much carbon was ultimately prevented from reaching the atmosphere.
An electrolyser does not automatically prove that hydrogen is low-carbon.
A renewable-energy contract does not necessarily describe the instantaneous electricity supplying a facility.
And circulating carbon cannot simply be counted repeatedly as carbon removal.
The strongest measurement systems should therefore reconcile the actual physical flows across a clearly defined boundary.
For carbon, that means understanding:
**carbon entering the system
opening carbon inventory − carbon leaving in products − carbon recovered and retained − carbon released = closing carbon inventory**
In other words:
Where did the carbon actually go?
Measurement, reporting and verification should increasingly answer that physical question.
The same principle applies to AI
Artificial intelligence provides a useful contemporary example.
Much of the discussion about AI’s environmental footprint focuses on data-centre electricity consumption, cooling and water.
Those are important.
But AI is also an optimisation technology.
If AI makes fossil-resource extraction more productive, its carbon consequences may extend far beyond the electricity consumed by the servers performing the computation.
If AI instead improves renewable integration, industrial efficiency, methane detection, carbon capture, resource recovery or material circulation, its enabled impact may move in the opposite direction.
So perhaps the question should not simply be:
Is AI sustainable?
Instead:
What physical energy and material flows does AI cause to change?
Again:
Follow the energy. Follow the carbon.
From carbon accounting to carbon management
Carbon accounting remains essential. Organisations need credible inventories, common standards and transparent reporting.
But the next stage of the transition must increasingly move from accounting for carbon to engineering carbon flows.
That means designing power systems, industrial plants, transport systems, buildings and data centres so that they require progressively less virgin fossil-carbon input for every unit of useful output.
It also means recognising that renewable energy, electrification, hydrogen, efficiency, carbon capture, storage, removal and carbon circulation are not necessarily competing philosophies.
They are engineering tools.
Their value should be judged by measurable system outcomes.
A simple test
Whenever we encounter a proposed climate solution, perhaps we should ask five questions:
Where does the energy come from?
Where does the carbon come from?
Where does the carbon go?
How much new geological carbon does the system require?
What changes when the complete system boundary is considered?
Those questions cut through many labels.
The energy transition is ultimately not a transition between fashionable technologies.
It is a transformation of physical systems.
Net zero defines the destination. Decarbonisation measures progress toward it. Defossilisation changes the underlying carbon flow.
And one of the simplest ways to see whether that transformation is genuinely occurring may be:
