It is very unlikely hydrogen and fuel cells replace oil. First off Hydrogen gas is explosive!
There are several ways to store hydrogen, most of which are quite safe and actually safer to store than gasoline. I remember reading about a company that stored hydrogen in compound and used a catalyst to release it on-demand, so I did a quick web search and found it,
Millenium Cell, Inc.. There's also a number of other methods that appear safe, Take a look at
this page, which also contains some nice straight-forward and basic information on fuel cells in general. Producing the hydrogen will be the big problem, and I suspect that electrolysis will be too expensive in terms of energy used, so they will produce it from the natural gas / methane. The good thing about this, while it does still produce carbon monoxide and/or carbon dioxide is that the release of these gasses can be controlled (and thus stored) when they are produced, making them available for any other industrial processes that use them, whereas today they are released into the atmosphere during combustion at the time they are used.
By the year 2050, fuel for transporation will come from methane hydrates (from the deep sea)
While methane hydrates ("MH") are a promising new source, and I think that there will be some use of this resource, I think your timeline is probably a bit agressive. We know relatively little about the effects of removing methane hydrates from the seafloor may have. There are indications that drilling for MH may destabilize the seafloor and cause massive landslides, potentially releasing the MH in an uncontrolled fashion. Methane, of course, is one of the key greenhouse gasses, and the atmospheric effect from such a release, while not catastrophic, would be noticable.
By 2050 there will be far fewer cars on the roads (few people will be able to afford them) and most of the interstates will be converted to electric rail (trains) for public transportation.
I strongly disagree with you on this - what data do you have that suggests people won't be able to afford cars? Interstates being converted to rail - that's moving backwards. First of all, the interstate highway system is NOT public transportation - its private use of public resources. Second, long-distance rail is only efficient for mass movement from point A to point B, as long as point A and point B are the same for everyone. Compare this to short-distance rail, such as New York subway, etc, where there are many stops, and is quite efficient. Third, the Interstate system is more than a public means of transportation - its an important (albeit rarely mentioned) military resource. In fact, one of the original reasons for developing the interstate system was to facilitate military movement. I believe that one of the guidelines while designing and building the interstates was to make them capable of providing a landing area for aircraft in case airfields were destroyed Fourth, the highway system is perhaps one of the most significant factors to why America is so prosperous and powerful as a nation today. Both power and prosperity require a strong economy, and the interstate system is a big big BIG reason why our economy is as strong as it is. Rest assured - the interstate system is not going away anytime soon. If you really want a nice overview of the benefits and effects the system has had on America as a country, take a look at
this report, titled
40 Years of the US Interstate Highway System: An Analysis
The Best Investment A Nation Ever Made. This report, while admittedly funded by a pro-Highway group, extolls the best of the American highways.
In 2050, few people will have full time jobs.
Again, what data do you have to support this? The only thing that would cause this is some kind of economic depression, so if you know something I don't, please inform me so I can sell all of my stocks.
