Manifesto / E2 Power Systems

The case for combustion after fossil fuels.

The world is electrifying. That does not mean every machine will store all of its energy in batteries.

E2 is building a new rotary power architecture for applications where energy density, uptime and fuel flexibility still matter.

E2 pressure-pulse rotor architecture
Pressure-pulse architectureDelft, the Netherlands
The transition

Electrification is winning. That is not the end of the story.

Transport, industry, heating and computing are electrifying because electric machines are efficient and batteries keep improving. For a huge number of applications, direct electrification will be the best answer. E2's case cannot depend on that progress stopping.

The harder question begins when a machine has to carry a lot of energy and stay productive for a long time. A passenger car can sit parked for most of the day. A long-haul truck may operate for most of it. Construction equipment can spend a shift away from high-power grid access. Ships carry their energy for days or weeks.

As duty cycles become longer, storage mass, volume, replenishment time and infrastructure move from secondary details to system constraints. For high-utilisation vehicles, charging is not only an energy problem; it becomes an operating-system problem. Opportunity charging can preserve utilisation by moving charging into loading, unloading, driver breaks or depot dwell — but then sufficient electrical power has to exist at each place where the vehicle stops.

9%of global truck sales were electric in 2025.
−8%average battery price decline in 2025.

The point is not that battery-electric trucking is uneconomic. Many return-to-base operations can work with depot charging. The point is that the purchase price of the vehicle does not always describe the whole system required to keep that vehicle productive.

Heavy-duty BEV systemVehicle + battery → depot charging → grid connection → destination charging → public / en-route charging
There will not be one universal powertrain. There should not be.
The carrier

Electrons move energy well. Molecules carry it well.

Electricity is extraordinary when generation and demand are connected by a wire. The physics changes when the energy has to travel with the machine.

Chemical fuels store energy in molecular bonds. That physical advantage is why fuels transformed transportation in the first place. The climate problem does not invalidate that advantage; it invalidates our dependence on fossil carbon.

Hydrogen is one possible answer. It removes carbon from the molecule, but it does not remove the engineering constraints around storage, distribution, infrastructure and full-system efficiency. Hydrogen is exceptional by mass and difficult by volume. And today, low-emissions hydrogen is still a very small part of global production.

<1%of global hydrogen production was low-emissions in 2024.
120MJ/kg hydrogen LHV — high by mass, difficult by volume.

Hydrogen can become electricity through a fuel cell or mechanical work through combustion. Fuel cells can be highly efficient, but practical systems also require air, thermal and water management, power electronics and a balance of plant. Combustion can create pressure directly, but today's hydrogen combustion engines largely retain the piston, connecting rod, crankshaft and valvetrain architecture of the fossil-fuel engine.

We changed the fuel. We have not fundamentally changed the machine.
E2 architecture

Pressure first.
Rotation second.

E2 is developing a pressure-pulse turbine. A controlled quantity of fuel and air enters a combustion chamber. It burns. Pressure rises. That pressure is released as a controlled high-energy pulse. The resulting flow transfers momentum to an impulse rotor. The rotor turns.

01Fuel + airprepare energy
02Pressure pulserelease energy
03Momentum flowdirect energy
04Shaft rotationextract work
The machine

Separate combustion from rotation.

In a conventional piston engine, combustion and mechanical conversion are tightly coupled. Pressure acts on a piston, the piston drives a connecting rod, and the crankshaft converts that motion into rotation.

E2 takes a different route. Combustion creates pressure in a dedicated chamber. That pressure is released as a high-energy flow, and an impulse rotor converts the momentum of that flow directly into rotation.

This separation matters because the two sides of the machine can evolve independently. The combustor can change with the fuel, combustion strategy and operating conditions while the rotary power-conversion principle remains.

Today, propane gives us a practical way to develop and validate that architecture in the laboratory. Hydrogen is the long-term objective. E2 is not intended to become the answer for every vehicle, machine or energy system. It is being developed for a narrower class of duty cycles where sustained power, high utilisation, compact onboard energy and rapid replenishment remain important.

Within that class, the fuel landscape can still change. The objective is therefore not universal applicability, but architectural adaptability within the applications E2 is designed to serve.

Not one powertrain for everything. One adaptable architecture for the duty cycles that still need molecules.
The place

Go where carrying energy is difficult and sustained power is valuable.

There is no reason for E2 to compete where batteries already provide the best system. Urban vehicles with predictable routes, passenger cars with convenient charging and short-duration stationary storage can be better served by electrification.

E2 is being developed for harder duty cycles. Heavy transport, off-highway machinery, marine power and distributed generation are different industries, but they can share the same underlying requirement: sustained power where carrying and replenishing energy are part of the operating constraint.

Heavy transport applicationHeavy transportHigh-utilisation road duty
Off-highway applicationOff-highwayConstruction & industrial machines
Marine applicationMarineSustained onboard power
Distributed power applicationDistributed powerDispatchable generation

E2 is not claiming that one machine should replace every powertrain in these sectors. These are the places where the architecture may earn a role if it can demonstrate the required efficiency, durability, emissions, power density and economics.

The build

Start smaller than the ambition. Accumulate evidence.

New thermodynamic architectures should not begin by asking customers to trust them inside safety-critical machines. They should earn that trust.

E2 begins with laboratory-scale combustion, then sustained rotary power, then larger integrated systems, then thousands of operating hours, then machines in the field. Each development stage will retire a specific technical risk before the architecture moves to the next scale.

The first engine will not be the best engine. Neither was the first diesel engine, the first gas turbine or the first lithium-ion battery. New energy technologies improve through iteration: geometry changes, materials improve, valves become faster, thermal management improves, control becomes more precise and manufacturing becomes cheaper.

We are not trying to scale a CAD model. We are accumulating evidence.

The real question is not whether generation one beats a century of optimisation. It is whether the architecture contains enough fundamental advantage to make generation ten worth building.

The future

A machine for an uncertain energy future.

We are betting that the world will continue to need compact, dispatchable, energy-dense mechanical power — and that the machine producing it can be fundamentally better than the combustion engines we inherited.

Combustion is not the problem. Fossil carbon is. If combustion remains useful in a decarbonised world, there is no reason its architecture has to remain frozen in the twentieth century.

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Sources / Evidence

The claims should be inspectable.

Electrification and battery-market evidence

International Energy Agency, Global EV Outlook 2026, and IEA battery-market commentary (2026). These support the electric-truck sales and battery-price context used in this manifesto.

Hydrogen storage and low-emissions hydrogen

U.S. Department of Energy, Hydrogen Storage; International Energy Agency, Global Hydrogen Review 2025. These support the energy-density and low-emissions-production context.

BEV charging infrastructure

ICCT / ZEV Alliance and Transport & Environment research on truck charging, destination opportunity charging, depot charging, grid access and site constraints.

Pressure-gain combustion

NASA pressure-gain combustion analyses, including Humphrey-cycle and unsteady-combustion studies. These establish the thermodynamic concept; they do not establish E2 performance.