U.S. Department of Energy - Energy Efficiency and Renewable Energy

Fuel Cell Technologies Office

Water Emissions from Fuel Cell Vehicles

Hydrogen fuel cell vehicles (FCVs) emit approximately the same amount of water per mile as vehicles using gasoline-powered internal combustion engines (ICEs).

How far will one gallon go and how much water will it produce?How far will one gallon go and how much water will it produce?Gasoline Internal Combustion Engine Vehicle converts to 25 mpg1 gallon gasoline = 2.7 kg of fuel (may be represented approximately as CH2)CH2 + 3/2 O2  converts to  CO2 + H2O   (water)2.7 kg + 9.3 kg  converts to  8.5 kg + 3.5 kg3.5 kg water/25 miles = .14 kg water/mileHydrogen Fuel Cell Vehicle converts to 60 mpgge1 gallon of gasoline equivalent of hydrogen very nearly equals 1.0 kg H2H2 + 1/2 O2 converts to H2O (water)1.0 kg + 8.0 kg converts to 9.0 kg9.0 kg water/60 miles = .15 kg water/mile Note: The calculations above assume that a gasoline ICE vehicle averages 25 miles per gallon and a hydrogen FCV averages 60 miles per gallon of gasoline equivalent (gge) of hydrogen. (One gge of hydrogen has the same energy content as a gallon of gasoline [in terms of their lower heating values] and is approximately equal to one kilogram [kg] of hydrogen.)  The fuel cell is a valuable system because it is 2.4 times as energy efficient as traditional combustion systems, achieving 2.4 times as many miles per gallon of gasoline equivalent.