My understanding was that the (currently) most efficient means of producing hydrogen gas was a catalyzed splitting of water, but I could be wrong.
Regardless, you have to get the hydrogen somewhere. So, even if the ony byproduct of the splitting itself is O2, you still have to get power from somewhere, which currently (usually) means producing CO2. I wasn't trying to answer any questions about actually generating the power supply, so much as concerns about what happens when you start dumping so much water vapor into the atmosphere. --Doom Robert Munn wrote: > http://en.wikipedia.org/wiki/Fuel_cell > > 'Hydrogen combustion, like that of petroleum, is limited by the Carnot > efficiency <http://en.wikipedia.org/wiki/Exergy_efficiency>, but is > completely different from the hydrogen fuel cell's chemical conversion > process of hydrogen to electricity and water without combustion. Hydrogen > fuel cells emit only water during use, while producing carbon dioxide > emissions during the majority of hydrogen production, which comes from > natural gas. Direct methane <http://en.wikipedia.org/wiki/Methane> or natural > gas <http://en.wikipedia.org/wiki/Natural_gas> conversion (whether IC or FC) > also generate carbon dioxide emissions, but direct hydrocarbon conversion in > high-temperature fuel cells produces lower carbon dioxide emissions than > either combustion of the same fuel (due to the higher efficiency of the fuel > cell process compared to combustion), and also lower carbon dioxide > emissions than hydrogen fuel cells, which use methane less efficiently than > high-temperature fuel cells by first converting it to high-purity hydrogen > by steam reforming. Although hydrogen can also be produced by electrolysis > of water using renewable energy, at present less than 3% of hydrogen is > produced in this way.' > > > > What I take from this is that hydrogen fuel cells product CO2 during the > extraction of hydrogen from natural gas, but product water during chemical > conversion of the hydrogen to electricity. Sounds like this isn't even close > to being commercially viable right now. > > > On Feb 11, 2008 6:30 AM, Ben Doom <[EMAIL PROTECTED]> wrote: > >> I suppose it would depend largely on what the fuel was derived from. >> Hydrogen fuel cells run on H2 that is largely generated by (wait for it) >> splitting watter. You get what you give. >> >> Methane fuel cells, however, are another story entirely. >> >> --Doom >> >> Robert Munn wrote: >>> Bye bye biofuels. >>> >>> Fuel cells are an interesting option, but I don't know if anyone has >>> seriously thought through what it would do to the atmosphere if every >> car on >>> the planet was emitting water as a by-product of its fuel cells. I >> wonder >>> how much water that would be. Seems like it could alter weather patterns >>> rather significantly. >>> >>> On Feb 8, 2008 6:02 AM, Cameron C wrote: >>> >>>> So far I've been leaning towards Ethanol as a good bridge fuel between >>>> gasoline and *whatever*. I think I just changed my mind. Not because >>>> we are burning our food (Munn), but because it's really actually not >>>> good for the environment. There have been some studies stating this in >>>> the past, and they've always been questionable to me - but this one >> just >>>> broke the camel's back.... >>>> >>>> http://online.wsj.com/article/SB120241324358751455.html?mod=cfcommunity >>>> >>> >>> >> > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;160198600;22374440;w Archive: http://www.houseoffusion.com/groups/CF-Community/message.cfm/messageid:253898 Subscription: http://www.houseoffusion.com/groups/CF-Community/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=11502.10531.5
