Renewable energy can replace fossil fuels in many sectors, but industrial heat remains one of the toughest challenges. Electricity powers light industry and buildings effectively, but high-temperature heat for manufacturing still relies heavily on fossil fuels. Emerging technologies, including iron fuel, green hydrogen, and advanced electrification, are closing that gap. A full transition is possible, but it will take time, investment, and the right technology mix for each application.
Sticking with fossil fuels for industrial heat is putting your decarbonisation targets at risk
Industrial heat accounts for roughly two-thirds of all energy used in industry, and around 80% of that heat still comes from burning fossil fuels. For sustainability managers, this is where the emissions problem lies. While companies have made real progress in reducing Scope 2 emissions through green electricity, Scope 1 emissions from on-site combustion remain stubbornly high. Every year of delay widens the gap between current emissions and net-zero commitments, making future transitions more expensive and more disruptive. The practical fix is to start evaluating drop-in clean-heat technologies now, before regulatory pressure or carbon pricing forces a rushed decision.
Waiting for the “perfect” clean energy solution is slowing down progress that could start today
Many industrial operators are holding off on clean-heat investments because no single solution looks like a perfect replacement for natural gas. That wait-and-see approach has a real cost: delayed emissions reductions, growing exposure to carbon pricing, and the risk of being locked into fossil fuel infrastructure for another decade. A more productive approach is to assess which technologies can integrate with your existing setup now, even partially, and build from there. Incremental decarbonisation beats indefinite deferral every time.
Can renewable energy fully replace fossil fuels in industry?
Renewable energy can fully replace fossil fuels in industry, but not all at once and not with a single technology. Different industrial processes require different solutions. Electrification works well for low-temperature applications, green hydrogen suits some high-temperature uses, and newer carriers like iron fuel address gaps where neither electricity nor hydrogen is practical.
The honest answer is that the transition will be technology-specific and sector-specific. A food-processing plant has different heat requirements than a pulp and paper mill or a specialty chemicals producer. What works at 150°C may not work at 1,000°C. This is why a portfolio of clean energy technologies matters, rather than placing all investment behind one approach.
The direction of travel is clear. Costs for renewable energy are falling, policy pressure is increasing, and commercial-scale alternatives to fossil fuels are moving from demonstration to deployment. For most industrial operators, the question is no longer whether to transition, but which technology to adopt and when.
Why is decarbonising industrial heat so difficult?
Industrial heat is hard to decarbonise because it often requires very high temperatures, continuous supply, and large volumes of energy—conditions that most renewable alternatives struggle to meet cost-effectively. Unlike electricity generation, where the switch to renewables is well advanced, heat production for heavy industry has fewer ready-made solutions.
Several factors compound the difficulty. Many industrial processes require heat above 500°C, sometimes reaching 1,500°C or more. Electric resistance heating and heat pumps become less practical at these temperatures. Green hydrogen can reach those temperatures but faces infrastructure and cost barriers in many regions. Biomass is constrained by supply and land-use concerns.
There is also an infrastructure challenge. Industrial boilers and furnaces represent large capital investments with long operational lifespans. Replacing them entirely is expensive and disruptive. Technologies that can integrate with existing infrastructure, rather than requiring a full replacement, are far more attractive to operators managing both emissions targets and production continuity.
What renewable alternatives exist for high-temperature industrial heat?
The main renewable alternatives for high-temperature industrial heat are green hydrogen, electrification, biomass, and iron fuel. Each has different temperature capabilities, infrastructure requirements, and cost profiles. No single option fits every industrial use case, which is why most decarbonisation roadmaps combine more than one approach.
Here is a practical overview of the main options:
- Green hydrogen: Can produce very high temperatures and is carbon-free when produced from renewable electricity. The main barriers are availability, storage, transport infrastructure, and current cost.
- Electric boilers and heat pumps: Well-suited for low to medium temperatures. Practical up to around 200 to 300°C for most commercial systems. Limited by grid capacity and electricity costs at scale.
- Biomass: A proven technology for high-temperature heat, but constrained by sustainable supply, land-use competition, and emissions from combustion that vary by feedstock.
- Iron fuel: A solid-state energy carrier that burns at up to 2,000°C with zero direct CO₂ emissions. The combustion by-product, iron oxide, is regenerated back into iron fuel using hydrogen, creating a closed cycle. Designed to integrate with existing boiler infrastructure.
The right choice depends on your process temperatures, existing infrastructure, grid access, and supply-chain logistics. For many operators in food and beverage, specialty chemicals, and pulp and paper, a combination of electrification for lower-temperature needs and a high-temperature solution like iron fuel or hydrogen can cover the full range.
How does iron fuel technology work as a clean energy carrier?
Iron fuel technology uses fine iron powder as an energy carrier. When burned, it produces high-temperature heat with zero direct CO₂ emissions. The only combustion by-product is iron oxide, which is then regenerated back into iron powder using hydrogen, completing a closed, circular cycle. It works like a rechargeable battery, but for industrial heat.
The process runs in four stages:
- Storage and transport: Iron powder is stored and transported as a safe, solid-state material to industrial sites. It does not require pressurised containers or cryogenic conditions.
- Combustion: The iron fuel burns inside an industrial boiler, generating a flame of up to 2,000°C. This heat produces steam, hot water, or hot air for industrial processes. The only by-product is iron oxide.
- Collection: Iron oxide is collected from the boiler chamber, stored safely, and transported to a production facility for regeneration.
- Regeneration: The iron oxide is converted back into iron fuel using low-carbon hydrogen, ready to be used again.
We have demonstrated this technology at megawatt industrial scale in the Netherlands, reaching Technology Readiness Level 7. Our Iron Fuel Boiler achieves up to 95% energy efficiency, and the system produces just 10 kg of CO₂ per megawatt-hour of thermal energy, attributable only to a pilot safety flame rather than the combustion process itself. You can read more about how Iron Fuel Technology works on our technology page.
Which clean energy option is best for replacing fossil fuels in industrial boilers?
There is no single best option for all industrial boilers. The right technology depends on your required process temperatures, existing infrastructure, access to electricity or hydrogen, and total cost of ownership. For high-temperature applications where electrification is impractical and hydrogen infrastructure is limited, iron fuel is a strong candidate. For lower-temperature processes, electric boilers or heat pumps are often more straightforward.
When evaluating options, the most relevant criteria are usually these:
- Temperature range: Does the technology reach the temperatures your process requires?
- Integration: Can it work alongside your existing boiler setup, or does it require full replacement?
- Supply reliability: Is there a dependable fuel or energy supply available at the scale you need?
- Cost competitiveness: How does the total cost compare to your current fossil fuel spend, including carbon pricing?
- Emissions profile: What are the direct and lifecycle CO₂ and NOₓ emissions?
Iron fuel scores well across several of these criteria for high-temperature industrial heat. It integrates with existing boiler infrastructure rather than replacing it, produces zero direct CO₂ during combustion, and is designed to be cost-competitive with fossil fuels. For operators in sectors like food and beverage, specialty chemicals, or pulp and paper, it addresses the specific gap that electrification and hydrogen often cannot fill. Explore the industrial heat solutions available to see how different technologies compare for your sector.
When will renewable energy fully replace fossil fuels in heavy industry?
A full replacement of fossil fuels in heavy industry is realistically targeted for around 2050, aligned with net-zero climate commitments. Progress will not be uniform. Some sectors and processes will transition earlier, particularly where electrification or hydrogen is already cost-competitive. High-temperature and hard-to-abate applications will take longer and require technologies that are only now reaching commercial scale.
Several factors will determine the pace. Policy frameworks like the EU Emissions Trading System are already making fossil fuels more expensive, which strengthens the business case for alternatives. At the same time, the commercial availability of clean-heat technologies matters enormously. Technologies at the pilot stage today need to reach full commercial deployment within this decade to contribute meaningfully to 2050 targets.
Iron fuel is one example of a technology that has moved beyond the laboratory. With demonstration facilities operating at Technology Readiness Level 7 in the Netherlands and the first commercial contract signed, the timeline from pilot to broad deployment is now a question of scaling, not invention. The transition will not happen overnight, but the building blocks are in place. Companies that start evaluating and adopting clean-heat technologies now will be better positioned as regulatory and cost pressures intensify through the 2030s.
How RIFT helps industrial companies replace fossil fuels with clean heat
We develop and supply Iron Fuel Technology for industrial heat applications, giving companies a practical route to decarbonise high-temperature processes without replacing their existing boiler infrastructure. Here is what we offer:
- Drop-in integration: Our Iron Fuel Boiler is designed to complement existing fossil fuel boilers, reducing disruption to operations.
- Zero direct CO₂ emissions: Iron fuel combustion produces no carbon dioxide, with ultra-low NOₓ emissions as well.
- Up to 95% energy efficiency: Our boiler system matches or outperforms many conventional fossil fuel systems.
- Long-term fuel supply: We offer supply agreements that give operators reliable access to iron fuel at cost-competitive pricing.
- Proven at scale: Our technology has been demonstrated at megawatt industrial scale and is backed by over €113 million in funding.
If you are evaluating clean-heat options for your facility, we are ready to talk through what iron fuel could mean for your specific processes and emissions targets. Get in touch with our team to start the conversation.