Yes I was wondering too. When I saw the commercials with Alan getting a page "from a number that had been disconnected for 20 years" I thought nothing of it. It seemed obvious that the programs (or Flynn inside the computer) just hacked into the pager system over the internet and sent a page with a number they faked up (actually, now that I think about it you could always type any number you wanted when paging, real or not).
But The Grid was not connected to the internet or anything else, so how did CLU page Alan?
Ah but why does the postal service "need to make this trip anyway"? If you cut out all the bulk stuff, they would probably only need to send a truck once a week. It would be way more convenient for me to only have to go out to my mail box once a week, and nobody is going to send anything urgent via regular mail (they always suggest it could take about 2 weeks anyway, and they don't guaranty even that).
The only reason we need daily USPS service is because our box would be overflowing with all the crap mail we don't want anyway, which is only sent because it is so preposterously cheep. Raise the rates, all the stupid crap mail everyone hates goes away, you can slash your operating expenses to almost 1/6 of what they currently are, and I only have to walk over to the mailbox once a week. Its pretty much win all around, except for postal workers.
Most modern natural gas turbines are "combustion turbines", which means they don't generate steam to turn the turbine*. Instead they use the hot exhaust to directly turn the turbines. The modern designs I have worked with generally have a "duel fuel" option, allowing them to run off of diesel fuel as well. They can also run off of syngas, which is basically the same as natural gas (but synthetic not natural), which is made from coal. And I know of one that was modified to run off of hydrogen (it was at a refinery that produced hydrogen as a by-product of refining).
Combustion turbines can burn basically anything that is a gas or can be atomized, it is a question of tweaking there combustion settings, comparable to making a car run off alcohol or whatever.
*Most combustion turbines I've work with are "combined cycle" which means they've added a Heat Recovery Steam Generator (HRSG) to boil water from the exhaust of the combustion turbine. The steam is then used to turn a steam turbine generator to produce even more power.
If you want to put yourself on the map, publish your own map.