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Carnot Engines Redefining Heavy-Duty Power for a Decarbonized Future

The Challenge: How to replace the Diesel Engine?

At Carnot we are taking on the biggest challenge of our age; decarbonizing heavy-duty power and how to replace diesel engines. 

Hard-to-abate sectors — from shipping to long-haul road transport to remote power generation — face the biggest challenge in reaching net zero. Traditional internal combustion engine and especially diesel engines, waste much of their fuel energy as heat, and many cannot operate effectively on next-generation low-carbon fuels like hydrogen or ammonia.

Decarbonizing heavy-duty power requires technology that combines exceptional fuel efficiency with full fuel flexibility, without compromising on performance, reliability, or cost-effectiveness.

Carnot Engines – The World’s most efficient, multi-fuel engine

At Carnot Engines, we are developing the world’s most efficient engines. Conventional engines operate around 35% efficiency, where a Carnot Engine can operate at over 70% break thermal efficiency. By doubling fuel efficient, we half fuel consumption, delivering enormous cost savings to our customers.

A Carnot Engine can also work on any fuel, and switch anytime. A Carnot Engine can run on:

  • Hydrogen
  • Ammonia
  • Methanol
  • HVO/Biofuels
  • Biogas
  • LNG
  • Diesel

Our design targets >70% brake thermal efficiency — more than double the efficiency of many conventional diesel engines. By operating at higher temperatures and eliminating most cooling losses, Carnot Engines aim to dramatically reduce fuel consumption and slash greenhouse gas emissions across the toughest sectors.

Applications Across Multiple Sectors

Our technology is built for the hardest jobs in the most demanding environments:

  • Maritime power — main propulsion and auxiliary power units (APUs) for ships

  • Heavy-duty road transport — trucks, buses, and specialist vehicles

  • Off-grid and industrial power generation — remote mining, construction, and backup systems

These sectors demand high reliability, long service life, and global maintainability — our engines are being engineered to meet or exceed these benchmarks.

Driving Maritime Decarbonization

Shipping accounts for nearly 3% of global CO₂ emissions, and international regulations are tightening fast. Carnot Engines is working with leading shipping companies to demonstrate hydrogen and ammonia-fuelled engines in real-world maritime environments.

Upcoming trials include:

  • Hydrogen-powered auxiliary engine testing aboard a commercial vessel

  • Hydrogen Engines for Shipping with the UK’s first hydrogen auxiliary engine sea trials 

  • Ammonia-fuelled APU retrofit projects for improved efficiency and emissions reduction

  • Ammonia Marine Engines and Auxiliary power units 
  • Fuel-Flexible high efficiency engines
  • Decarbonised Port Power

Designed for the Net-Zero Transition

Our approach solves three critical barriers to decarbonizing heavy-duty power:

  1. Fuel flexibility — switch between low-carbon fuels as supply chains develop

  2. High efficiency — reduced fuel use means lower emissions and operating costs

  3. Modular scalability — from smaller APUs to MW-scale maritime powerplants

This combination allows operators to begin cutting emissions now while staying adaptable for future fuels and standards.

Carnot has won a £1.5m Energy Catalyst Grant converting rice straw biomass into energy.

Carnot is leading a consortium to develop the world’s first profitable rice-straw bioenergy demonstrator for a rural community in Lombok Island, Indonesia. Rice straw is separated from the grains during harvesting and either combusted or left to decompose, thus producing CO2 or Methane, the latter being an incredibly potent greenhouse gas.

With the support of local implementer Chakra Giri Energi Indonesia the project aims to identify alternative and valuable uses for waste rice straw. We will convert this harmful waste stream into:

    1. A valuable bio-energy feedstock
    2. A fertiliser source which is also sequestering carbon and
    3. Refined bio-fuel generating highly efficient clean power using Carnot technology which will create a revenue stream selling energy on the open market. 

Straw Innovations has created innovative technology that overcomes the barriers to harvesting it in all weathers, unlocking a potential 300Mt of rice straw generated in Asia every year. Rice straw has high ash content (around 20%), comprising about 75% silica. This, combined with other components in the straw (chlorine, potassium) causes melting and slagging / fouling in boilers when combusted. Hence, it is not an easy fuel to chop or combust.

PyroGenesys have developed a lower-temperature pyrolysis process which can convert rice straw into Biochar, a carbon-sequestering fertiliser that can be used by the rice farmers, and biofuel. The carbon sequestered can be traded on carbon removal markets. Surplus biofuel not used to generate electricity can be sold. Electricity is a low-value commodity and renewable electricity projects will typically require very large scale to be profitable and attract funding required from investors. PyroGenesys’ process solves this problem by opening up two very high-value revenue streams.

Carnot is developing ceramic engine gensets with double the efficiency of state-of-the-art diesel gensets, capable of operating on all fuels. These will provide electricity to the rice mills as their base load as well as electricity to a rural community. Integrating Carnot’s gensets enables revenues generated by biofuel sales to be maximised.

The Energy and Bioproducts Research Institute at the University of Aston is also supporting on the project by carrying out research into the fuel composition, emissions outputs and analysing outcomes at the end of each stage. 

Indonesia is the:

      • Is the world’s 5th largest GHG emitter.
      • Is the largest producer of biofuels worldwide.
      • Has mandated to convert a significant portion of its palm oil into FAME biodiesel.

There is a reluctance to move to renewable energy due to fossil fuel sunk costs/subsidies and no proven profitable off-grid low-carbon energy business model. This demonstrator project aims to be the catalyst to breaking the deadlock and unleashing investment into Indonesia’s enormous renewable energy potential.

Key project outputs:

      • Pilot-scale demonstration of business model feasibility
      • 200,000kg rice-straw feedstock;
      • 76,000kg value-added-biochar/53,200kg carbon sequestration/80,000kg biofuel;
      • 2.28MWh electricity provided to rice mill