Why couldn’t we use dust grain dispersion instead of fuel in a combustion engine?

Internal combustion engines work by igniting fuel under a compressed piston, which rapidly heats up the air and (therefore) causes a dramatic rise in pressure, pushing the piston out. The two most common engines are petrol (which use a spark plug to ignite the fuel) and diesel (which compresses air to much higher pressure under the piston, yielding a higher temperature that spontaneously ignites diesel fuel without a spark plug. We use oil-based fuels because it is much easier to inject into the engine than dust and because gasoline and diesel have long hydrocarbon chains that store lots and lots of energy that is suddenly released by combustion. Dust grains would not carry as much energy, yielding lower ignition temperatures (if they would combust at all), lower piston pressure and (therefore) lower power output. Low temperatures also mean lower [max. thermodynamic efficiency](_URL_0_), which mean more fuel consumption for less power and work. edit: link troubles: _URL_0_