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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.

Zero emission auxiliary engine

As society becomes increasingly aware of our environmental footprint, global industries are coming under unprecedented pressures to chart a course to a sustainable future. Shipping, the backbone of the global economy, delivers over 90% of global trade or 11 billion tons of goods annually and does so at incredibly low cost & high reliability but is no exception to the transition.

Heavy Fuel Oil (HFO) and Light Fuel Oil (LFO) accounted for 82% of all fuel used by the marine industry in 2020 according to the IMO, contributing to 940 million tonnes of CO2 emitted annually by the industry, more than 2.5% of global emissions.

The maritime industry must join the battle to reduce environmental pollution by adopting new innovative technologies. However, the challenge lies with a highly cyclical and competitive nature of the sector where profit margins are often low and the need to comply with the regulations that can’t keep up with the latest decarbonising technology is mandatory. It takes a company with the vision to commit to the change and we have partnered with the UK based Carisbrooke Shipping Ltd. for the advancement of our project.

Decarbonising with Carisbrooke Shipping

Carisbrooke Shipping Ltd. Is a family-owned business with over 50 years in business and has a long-standing commitment to innovation. The company’s philosophy is to lead the industry by building new, more efficient vessels to replace the existing ones and around 100 vessels were built at shipyards all over the world. Their previous project featured optimised bow design improving fuel efficiency by 20% compared to the existing similar ships on the market at that time.

Currently their Fleet Operation Centre uses wide range of tools from AI assisted Weather Routing, Voyage Optimisation and Just-In-Time arrival concept to in-house sea-going and engineering expertise in order to successfully maximise performance and reduce emissions in line with the CII-related targets.

When further exploring decarbonising, Carisbrooke evaluated a wide range of technologies for their auxiliary fuel systems, such as fuel cells, batteries, hybrid fuel and emission removal of fossil fuels. However, each of them had significant drawbacks and could not meet the stringent space, cost and maintenance requirements. In comparison, Carnot’s technology high reliability, ease of maintenance, low cost of ownership lead to the selection of the Carnot solution as the powertrain of choice.

The Kimberly C

With Carisbrooke and Concept Green Solutions, we co-developed a zero-emission auxiliary power unit to be used onboard the Kimberly C, a 6,805 DWT general cargo vessel. The system is containerised within a 20-foot container, mounted on the bow. One container has the 200 kW Carnot Engine and core generation machinery with fuel stored separately. See below a snapshot of the core configuration of the system.

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Hydrogen : Ammonia fuel blends

We also worked closely with the University of Southampton to review numerous different fuel combinations. What we were exploring was the most practical, economical and zero emission fuel types. Ultimately what we identified was a specific hydrogen and ammonia fuel blend. This combination results in a lower cost of operation when compared to diesel, is easier to store and manage the fuel, emits zero emissions and provides the best path to approved certification from IACS registered regulatory bodies.

For this project we partnered with DNV & Concept Green Solutions to develop & review a safety concept for the low flashpoint plant, fuel storage and operation onboard an existing vessel. They provided their expertise on how to best configure the system to comply with Classification Society regulations. This project enables us to set this technology on the path to full Type Approval and widespread utilisation within the industry. 

Shipping is a highly regulated industry with a unique set of technical challenges. Whilst ammonia is becoming more common, the guidelines for hydrogen as a fuel are far less defined. Carnot is currently partnering with the class societies to design the new approved framework which the key and is ongoing part in our development program.

Decarbonising marine power systems

The core objective of this project however was emission reduction. To quantify our impact, we worked closely with the University of Strathclyde who calculated that for each Carnot Engine replacing an equivalent diesel-powered unit, the annual savings are as follows:

      • 1,740 tons of CO2e
      • 470 tons of PM 2.5
      • 375 tons of SO2
      • 178 tons of NOx

Annual CO2 reduction 1,740 tons

One of the main advantages of the Carnot solution is in the tremendous scaling opportunities. For example, if we consider that there are 55,000 vessels worldwide with two zero emission auxiliary engines onboard, this represents saving of 191,400,000 tons of CO2e per annum, or 20% globally.

Our ambition is to deliver this solution for harbour & sea trials onboard.  We look forward to sharing the results from these trials in the next 12 months!

This hugely exciting project will demonstrate our ability to help decarbonise a hard to abate sector, whilst reducing OPEX and meeting the IMO’s challenging regulatory framework. We anticipate delivery of a cost-effective power plant, at scale and in a very short space of time.

If you would like to find out more about this project, interest in utilising such technology or discuss collaboration opportunities, please reach out to us via the form below or via the socials

With thanks to all our partners

& Concept Green Solutions