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What is Decentralised SAF?

The SAF bottleneck that no one is talking about: why untapped renewable power could decide the future of sustainable flight.

Across the aviation sector, sustainable aviation fuel (SAF) is viewed as the most practical and scalable route to cutting emissions in the near term. Yet despite strong policy momentum and rapidly growing demand, production capacity continues to lag. Much of the industry’s attention has focused on technology readiness, feedstock supply, and capital cost, but another question is now coming to the forefront:

What type of SAF production model can realistically scale — and how would it work in a world where renewable electricity is unevenly distributed?

This is where the decentralised model will play an important part. It offers a fundamentally different approach to producing SAF, one that aligns closely with the renewable energy system that is becoming increasingly more distributed. As Mel Courtney, CEO of ClimaHtech Green Flight, discussed on The SAF Podcast, decentralisation is emerging not just as a technical choice, but as a strategic response to the limitations of centralised refinery thinking.

To understand why, we first need to examine the real bottleneck in SAF production: clean electricity.

The Renewable Power Paradox

The growth of renewable energy across the UK and Europe has been remarkable. In 2024, the IEA reported that renewables generated around 50% of Europe’s electricity, while fossil fuels supplied about 25%, roughly half their share compared to a decade ago. This is a remarkably fast change in Europe’s energy makeup that has been made possible by distributed renewable generation in the form of wind and solar energy.

However, this growth of renewables has exposed a structural tension in the energy system. Thousands of wind, solar, and hydro sites produce clean electricity, but the grid often cannot accommodate it. As Mel Courtney outlined on CATAGEN’s episode of the SAF Podcast, around 50% of onshore windfarms in the UK have less than 10 MW of nameplate capacity, and if load and capacity factor is considered, the reality is these windfarms are producing about 2 MW of electrical power on average. This accounts for over 4,000 sites in the UK alone.

This is the paradox the SAF sector must confront. SAF produced through power-to-liquid pathways requires significant amounts of renewable electricity, but the traditional model assumes that this electricity can flow into a single, large refinery through a stable, high-capacity grid connection. In reality, renewable electricity generation is fragmented across many smaller sites, flowing intermittently depending on location, season, and grid conditions. These are not compatible with each other and is limiting the number of traditional plants that are being developed as they cannot access the renewable energy needed to produce SAF.

What Is Decentralised SAF?

The decentralised SAF flips conventional refinery logic, providing complementary SAF production methods that maximise renewable energy assets using technology that can be deployed closer to where the renewable electricity is generated.

Refineries are considered centralised because they concentrate all fuel-production processes into single, massive facilities that rely on large, continuous energy inputs, complex infrastructure, and long distribution chains to serve wide geographic regions.  

In contrast, a decentralised model of SAF production distributes smaller, modular units close to local renewable energy sources and airports, enabling flexible, efficient, regionally based fuel generation.

This is a natural progression of decentralisation of power. Large, single-site operations were well suited to the centralised power station model, this has changed as economies decarbonise to a distributed, geographically dispersed energy system. Technology that can adapt and work with this distributed network of smaller generation sites is the next step in decarbonising areas with high renewable energy potential.

This approach is built on four principles:

1.Production follows the power — facilities move to where renewable electricity already exists or can be accessed easily.

2. Modularity enables scale — growth comes from deploying more units in more locations, not expanding a single plant.

3. Grid dependency is reduced — units can operate on constrained, curtailed, or behind-the-meter power as they can be deployed close to renewables.

4. Regionalisation improves resilience — localised SAF supply reduces transport emissions and infrastructure risk, improving energy security and resilience.

Explore Green Flight's decentralised SAF supply

In essence, decentralisation means rethinking SAF not as a single mega-facility, but as a network of distributed production nodes, each sized to match the renewable resources around them.

How the Model Could work in Practice

ClimaHtech Green Flight’s modular systems embody this decentralised approach. Each unit includes:

  • Electrically driven chemical reactor technology.
  • Reverse water-gas shift and Fischer-Tropsch reactors powered by renewable electricity.
  • Integration for H2 and CO₂ inputs, such as the BIOHGEN technology to produce SAF from biomass (non-HEFA) or electrolytic H2 and DAC CO2 for e-SAF.
  • Output of one to ten million litres of neat SAF per site annually optimised to match available renewable power.
  • A power requirement of roughly 1.8 MW per 1M litres of SAF, suitable for ~50% (>4,000) of the UK’s windfarms that produce around 2MW of electricity due to load factors. This enables SAF production to ‘scale out’ across a huge number of renewable sites.
  • CATAGEN’s control and safety systems allow for remote, 24/7 operation, maximising uptime and minimising labour costs.

Because the unit size is matched to the scale of common renewable generation assets, these systems can slot into a variety of locations:

  • Wind farms producing excess electricity
  • Solar sites with seasonal peaks
  • Local grids where industrial-scale connections are not feasible or infrastructure constraints that stop renewable electricity being fully utilised
  • Airports seeking local SAF production to meet uplift requirements

This level of flexibility is what allows decentralised systems to scale quickly: deployment can happen where conditions are optimal without waiting for multi-year grid upgrades or development of mega-scale renewable projects such as offshore wind farms.

Why the Decentralised SAF Model Matters
  1. Accelerates time-to-market
    Large refinery projects often take years to reach FID, and several more to build. Smaller decentralised units can be prefabricated and deployed in parallel, dramatically shortening deployment.
  2. Unlocks underutilised renewable power
    Curtailment is not just an energy inefficiency; it is a missed economic opportunity. Decentralised units can convert this lost electricity into high-value molecules that support aviation’s decarbonisation.
  3. Reduces infrastructure risk
    Grid connections are often the most expensive and uncertain part of project development. Decentralised systems reduce dependence on large-scale infrastructure, enabling projects that would otherwise be unviable while also reducing the time to deploy.
  4. Spreads financial risk
    Multiple smaller projects with lower upfront capital requirements are more accessible to private equity, infrastructure funds, and regional investors. This provides more access to SAF production capacity to more parts of the SAF ecosystem.
  5. Supports regional resilience
    Decentralised SAF production can supply local airports directly, reducing transport emissions and aligning with upcoming airport-level SAF mandates, and providing energy security. SAF can be produced locally in areas with renewable energy, reducing reliance on imported fuel.
 
Why Decentralise SAF Now

To meet the ambitious SAF mandates set by the UK, EU, and beyond, we need a broad portfolio of solutions working together to meet the industries need for sustainable fuel. All approved SAF pathways have a vital role to play in decarbonising aviation at scale. A collaborative, diversified approach is essential, and decentralisation is a powerful part of the solution.

Explore decentralised SAF supply for your operations

Check out the clip below of Mel Courtney on The SAF Podcast, discussing how decentralised SAF production can tap into existing renewable electricity. 

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