Abstract: A pollution-free propulsion engine includes a rotating arm, a hollow axle defining a fuel delivery chamber, and hydrogen and oxygen sources. The rotating arm is formed with a detonation chamber, an opening and two tubular ducts therebetween. The axle is inserted into the opening. A pair of holes is formed in the axle to establish paths of fluid communication from the fuel delivery chamber through the ducts and into the detonation chamber as the rotating arm turns. The hydrogen source comprises a thin palladium binding layer deposited onto an aluminum sheet. Hydrogen molecules that are trapped in the binding layer are released, and the hydrogen is fed into the delivery chamber, through one duct and into the detonation chamber. At the same time, oxygen is delivered into the detonation chamber through the other duct, and the oxygen-hydrogen combination is detonated to release energy, which is converted into mechanical energy.