Comparison of automobile fuel technologies

	Gasoline	Ethanol	Diesel	Biodiesel	Compressed air	Hydrogen (internal combustion)	Electric	Hydrogen (Fuel cells)
Net output for single unit of input		1.3		3.2	≈0.25 × source of compressed air		0.9 × source of electricity	0.17 to 0.85 × source of electricity
New Infrastructure needed to be practical		Ethanol pipeline (ethanol corrodes conventional oil pipeline)			compressed air stations	hydrogen stations	chargers in parking zones	hydrogen stations
Current state of development	well developed, common	Production Obstacles need to be overcome	well developed, less common	Production Obstacles need to be overcome	well developed, uncommon	Production Obstacles need to be overcome	Charging time need to be overcome	Technological/Production Obstacles need to be overcome

[edit] Total chemicals emitted relative to gasoline

	Gasoline	Ethanol	Biodiesel	Compressed air	Hydrogen (internal combustion)	Electric	Hydrogen (Fuel cells)
carbon dioxide	100%	≈ 100%	22%	Depends on source of compressed air	Depends on source of electricity, typically (Hydro)carbons such as oil, natural gas	Depends on source of electricity	Depends on source of electricity
carbon monoxide	100%	< 100%	50%	Depends on source of compressed air	Depends on source of electricity, typically (Hydro)carbons such as oil, natural gas	Depends on source of electricity	Depends on source of electricity
benzofluoranthene	100%		44%	Depends on source of compressed air	Depends on source of electricity	Depends on source of electricity	Depends on source of electricity