Every once in a while I get asked the question about the connection between hydrogen cars and greenhouse gases, so I thought I would address the issue here. Jeff from Fallbrook, California sent in the following question:
Jeff: “Since water vapor is the major greenhouse gas causing global warming, how would a hydrogen car with emissions of water vapor be considered green?”
Hydro Kevin: Water vapor is the major ingredient in greenhouse gases, but it is also the major ingredient in clouds and in turn rain as well. The role of water vapor in greenhouse gases and in turn the greenhouse effect is one that is controversial and heavily debated by atmospheric scientists.
Many scientists subscribed to the theory of the positive feedback loop in which more water vapor is absorbed into the higher levels of the atmosphere and in turn absorb more heat and have a warming effect. But, scientists also have a hard time analyzing and simulating the formation of clouds that have a cooling effect on the planet.
According to the National Oceanic and Atmospheric Association (NOAA), “As water vapor increases in the atmosphere, more of it will eventually also condense into clouds, which are more able to reflect incoming solar radiation (thus allowing less energy to reach the Earth’s surface and heat it up).”
In regard to fuel cell manufacturers there is research currently being conducted to recycle the water vapor for use back into the fuel cell. In addition, water vapor doesn’t have to come out the tailpipe of a hydrogen car. The manufacturers could design a system where the water vapor is cooled and ported into a holding tank.
The water in this holding tank could then be disposed of or it could be put to further use. One use would be to recycle the water through an electrolysis system, create hydrogen and run it through the fuel cell again. In this kind of closed loop system, the issue of greenhouse gases does not even arise.