Originally Posted by Caspian
...but what of the fact that these are renewable sources that require much less maintenance than a coal plant or oil refinery? Would that not more than make up for the fact that the initial cost is heavy - esp. when oil starts hitting $100/bbl?
The price comparisons I mention are levelized prices--meaning they include all costs of producing the electricity including paying off the equipment, paying for fuel, and paying for maintenance. I can only assume gasoline prices include the cost of maintenance on the oil refineries. And if they don't, someone's not doing their job.
I don't know what oil price it will take to make solar+hydrogen competitive. I just think there are other options that will make sense before solar+hydrogen. Even wind+hydrogen would make more sense. Solar will have to come down in price by 50% or more to really compete with other renewable options. Until then, it needs pretty hefty subsidies, or people that just like to do it because they think it's neat.
Originally Posted by earthNRG
Electrolysis (using electricity to break water into hydrogen and oxygen gas) is not the only method used to produce hydrogen. Currently it is reformed out of natural gas. This still uses a fossil fuel that is of limited supply. Another option being worked on is direct extraction of hydrogen form water using a solar device. There are others working on designing bacteria that "exhale" hydorgen (much like how plant life "exhales" oxygen).
A hydrogen economy is not dead in the water just because electrolysis is inefficiant. There are other ways that may work out better.
Yes, there are other ways to make hydrogen. I think we can rule out getting it from natural gas in the long term, since we're already seeing a natural gas shortage and it doesn't much reduce greenhouse gas emissions. Making it with biological processes is interesting, but will it work, when, and at what cost?
Electrolysis is not really that inefficient...80 or 90% is pretty darn good as far as energy processes go. But the losses don't end there. You also have to think about the efficiency of transporting the hydrogen (about 90%) and the fuel cell (50% in theory). The net efficiency of this is 38%. Not only are there losses, but there is a lot more equipment (some of it not yet available, or available only at very high prices): electrolyzer, hydrogen delivery infrastructure, and fuel cells.
Assuming you're starting with renewable electricity, why go through the added complication and losses of converting to hydrogen at all? The electric grid can get it to you at better than 90% efficiency. You can then charge a battery in your plug-in hybrid, which has an efficiency of about 64% considering losses in charging batteries and the efficiency of the electric motor. The net efficiency is 58%, and it can be done with technology and infrastructure that already exists.
I have my own cynical theory about why the notion of a hydrogen-powered cars continues to thrive:
1. It sound good, in a sound bite: "Hydrogen-powered car emits nothing but water!" But, you have to look past the headline to understand it either takes fossil fuels to produce that hydrogen (i.e., diminishing supply and resulting in emissions) or high-priced renewable energy.
2. Industry is behind it: "There's infrastructure to be built and new technologies to be developed. Who cares if this makes any sense? Bring on the government initiatives and funding!"
3. The Bush administration can use it as a stalling tactic: "We don't have to push car makers to improve fuel efficiency, and we can keep using oil, because we're working on the technology for hydrogen-powered cars. There's a bright future ahead!" Meanwhile, we do nothing, and if this doesn't work, Bush will be long gone before we figure it out.
Rather than focusing so much effort on hydrogen, why not start pushing up auto efficiency now, which will have an immediate effect, and pushing for plug-in hydrids, which are much closer to being a reality than fuel-cell cars?