Oh.....
It's not either or, you need both, in order to operate........ That doesn't sound cool! Well for this purpose, sounds way hip for other purposes... Like clean air and such.
"Uses deisel as a liquid spark plug"
"Bi-Fuel System operates by blending both diesel fuel and natural gas in the combustion chamber. This is achieved using a fumigated gas-charge design, whereby natural gas is pre-mixed with engine intake-air and delivered to the combustion chamber via the air-intake valve. The air-gas mixture is ignited when the diesel injector sprays a reduced quantity of diesel fuel into the chamber."
