Compressed Air Engine

Compressed Air Engine  by Motor Development International, Luxembourg (MDI)



How the high-tech MDI engine works.

Air is compressed using an electric motor driving the engine in reverse.

From a compressed air tank the air is released and pushes the pistons of the engine. The engine then turns an electricity generator when demanded.

To increase the energy from the compressed air stored in the tank the air is heated in a burner as it leaves the tank increasing the volume of air.

Air Engine

by Motor Development International, Luxembourg (MDI)

  • Piston Engine
  • Well proven parts
  • Reversible
  • Becomes Compressor
  • 430 cc – 7 kW 20 kg
    1,000 cc – 60 kW 35 kg


MDI have created 2 compressed air engines which is the base of Automotive and Energy applications.

Small 7 kW Engine
@ 1,500 rpm, 45 Nm, 430 c.c.

The engines can be grouped together (‘banked’) so, by way of example for electricity production, if 8 engines were banked with each engine providing 7 kW of electricity the total electricity provided would be 56 kW.

Larger 72 kW Engine
@ 3,000 rpm, 230 Nm, 1,000 c.c

The engines can be grouped together (‘banked’) so, by way of example for electricity production, if 8 of the larger engines banked together would provide over 500 kW of electricity.


2 Modes of operation

  1. Air only
  2. Air + external combustion

Mono Energy – Mode 1

The pre compressed air in the tanks is transferred to a chamber (called “active”) which provides “work” before being expanded in the cylinders to perform the stroke phase. There are no polluting emissions generated and the use of renewable energy in the air filling stations allows the production of a completely clean energy loop (compression – expansion).

Dual Energy Engine – Mode 2
The engine is the same as the Mode 1 engine, however a burner is added between the compressed air storage tank and the engine. The burner provides a continuous low temperature combustion increasing the volume of the intake air and therefore increases the freedom and independence of the system. The performance of the engine in terms of torque and power remain identical to Mode 1.

This external continuous combustion at a controlled temperature at around 600°C does not produce nitrogen oxides or sulphur dioxides and eliminates any discharge of unburnt hydrocarbons. Although using a fossil fuel, it is never the less a clean engine. Unlike the internal combustion engine, it is totally insensitive to the load (throttle position) and provides unparalleled consumption efficiency.

AIRPOWER – Compressed Air Battery

The initial energy product is to be called Air Power, a standalone GenSet with a small air tank.

This is intended for emergency backup use.

We are currently working with MDI to develop the GenSet, combined with modular storage, as an alternative to battery storage, aimed at the solar energy storage market. Initial work indicates that it is viable for both on grid and off grid applications.