6 Responses

1. Water vapor is dynamically balanced by the atmosphere, if your hydrogen car adds a little vapor to one location the relative humidity increases by that amount and that much less water evaporates off of nearby water sources like puddles, ponds, and lakes.

2. Water vapor is not a greenhouse gas according to the listing published by the IPCC (Intergovernmental Panel on Climate Change). A better reason to question the viability of H2-powered vehicles is “where does the hydrogen come?” H2 is not present in the atmosphere in significant pressures/volumes to power an engine. H2 itself must be generated from some other energy consuming process, like electrolysis.

3. Evaporated H2O (water vapor) is a gas that absorbs and re-emits infrared radiation in Earth’s atmosphere, thereby increasing temperatures. For all intents and purposes, it acts like a greenhouse gas.

   Part of the reason Hydrogen is (was) being pursued as an alternative fuel source was due to California’s Zero Emissions Vehicle mandate. In order to convince the California Air Resources Board (CARB) that big auto manufacturers would meet the ZEV mandate (without producing electric cars) was that they would produce hydrogen fuel cell vehicles – they just needed a few years to get them to market. Well, those few years have passed, and we are no closer to having fuel cell vehicles ‘on the road’ then we were in 1997. Once again, big auto says they are at least 10 years off. …And will still be 10 years away 10 years from now.

   But because they are ‘still working on hydrogen’ CARB has let them off the hook – they don’t need to actually produce zero emissions vehicles – they just need to look like they might someday. Eventually. In 10 years or so. Maybe.

   One of the problems with hydrogen is that hydrogen is in scarce supply and producing it requires vast amounts of energy. Climate-friendly production of liquid hydrogen on a large scale presupposes a virtually unlimited supply of ecologically produced electricity — something not likely to materialize in the near future.

   Energy is lost in the process of separating hydrogen from the molecules that bind it. This means that the energy stored in hydrogen (H2) will always be much less than the original energy spent to split the hydrogen out of water, methane, gasoline or your molecule of choice. Using methane (natural gas – most cost/energy efficient) the energy value of the hydrogen gas is only about 60-70% of the energy (typically electricity) spent to produce the steam in the steam reformation process. Another 30-40% is lost in the process of separating the hydrogen atoms from the carbon molecules in natural gas, and during the process of compressing and liquefying (most space-efficient storage state) the hydrogen so that it can be carried in a vehicle. Once the hydrogen is finally available for use, the fuel cell has only a 50% electrical efficiency, which means the fuel cell will only convert about 50% of the hydrogen into electricity to power the electric motor that turns the wheels of a fuel cell car. The other 50% is lost in heat.

   Forcing the transition to a hydrogen-based economy within the next three to four decades is not an economically sound idea. Approximately 95% of the hydrogen produced in the U.S. is made via natural gas reforming in large central plants. The U.S. currently imports about 15% of the natural gas it uses. Producing large amounts of hydrogen from natural gas in the long term would only trade U.S. dependence on imported oil for U.S. dependence on imported natural gas.

   There is a persistent myth that Joe Citizen can just produce his own hydrogen with water and a battery. Creating hydrogen from water (using electricity) is much less efficient than creating hydrogen from natural gas, and is not considered viable due to excessive cost. The pint or two of low pressure hydrogen gas that Mr. (or Mrs.) citizen could produce at home during a day using the ‘free’ methods advocated by others here would move a hydrogen fuel cell car no more than a few blocks.

   Beyond the seemingly simple task of splitting hydrogen out of water with electricity, there are the factors of compressing the hydrogen once it is produced, cooling the hydrogen to a liquid state and then powering the cryogenic storage tank and vehicle delivery pumps. If stainless steel tanks and delivery piping are used (almost mandatory due to the extremely high pressures used) there will be issues with hydrogen embrittlement of the metal, and maintenance will become an expensive issue in the ‘homebrew’ hydrogen system.

   Of note (and not ever reported by the Fool Cell press) is that producing hydrogen from natural gas -does- result in greenhouse gas emissions. In central station hydrogen production from natural gas reforming, the mass of CO2 emitted is 2.51 times greater than the mass of hydrogen produced, or about 0.36 pounds (1/3 lb) of CO2 per fuel cell vehicle mile.

4. water vapor as stated is not a greenhouse gas.
   the use of hydrogen makes sense in theory by breaking down water to its components hydrogen & oxygen then bring them back together in a combustion chamber for ignition “byproduct water” start again ” consider this do you really want to drive a hydrogen bomb ”
   refer to tom’s answer for specifics
   nice one tom :-)

5. Hydrogen does not emit a greenhouse gas when it burns, water vapor is not a greenhouse gas. The problem is hydrogen does not exist in nature. We have to make hydrogen fuel from something else and that requires a lot of fuel.

   Most hydrogen is made from natural gas and making the hydrogen from natural gas produces a lot of greenhouse gas, (mostly carbon dioxide)

   Hydrogen can also be made with electricity and water but lots of fuel is used to make the large amounts of electricity required.

   No greenhouse gas is made by the hydrogen fuel vehicle while it is running but a lot of greenhouse gas was made making the hydrogen.

6. Are you kidding me? The major oil producers will continue to (behind the scenes) fight alternative fuels because they do not want to cut their oil profits. Besides, do you really think that the DHS (Dept of Homeland Security) want Joe Public having access to hydrogen? If you are in manufacturing, then by now you will have received a document that is required to be filled out reagrding the quantities of certain chemical and products used at your facility. They also want to know who is responsible for the purchase of these materials (never mind that any employee can walk out of the back door of your facility with a quantity of chemical large enough to make a homemade explosive device).