Contrary to the situation discussed here, with telecom there were not physical\chemical limitations with transmissions.

As it was correctly pointed, current limitation is with fundamental laws of physics and chemistry and with material science as well.

10x increase of battery density with the same weight would be sufficient to transfer most passenger cars to electric ones. But it won't be sufficient for heavy-duty trucks (25x increase required) and planes (50x increase required).

Considering battery efficiency\density increase in last 30 years, unless there are fundamental discoveries in physics\chemistry, chances that you will see electric power replacing fuel is quite slim in next 50-100 years.

About 3x for liquid hydrogen.
Anything colder than liquified natural gas is very difficult to handle and liquid hydrogen specifically is extremely dangerous. Ask SpaceX on that...
https://en.wikipedia.org/wiki/Liquid_nitrogen#Safety
https://en.wikipedia.org/wiki/Liquid...cal_properties
https://en.wikipedia.org/wiki/Liquid...gen#Properties

No I am not violating these laws. It costs energy to make synfuel as energy to be used plus the losses in the process has to be input. And I think that over the longer term (decades) I think it will be economically feasible to use renewable energy for powering this process. The sources are mainly water and CO2, so actually one is recycling CO2. Mankind will be forced to do this for survival on this planet.

Referring to the same online chemistry textbook I see however, your statement applies to mass. By volume however, compressed H2 gas is only 5.6MJ per liter while Jet-A is 37.4. Again, by volume, Jet-A1 is the most dense fuel.
H2 gas is very bloated in volume, so that requires monstruously large aircraft. LNG is even a better option, but far more flammable, so the sky is filled with flying bombs, just like H2 powered planes. Remember the Hindenburg airship in 1937 ?

On the environmental cost, I agree. On the economic and/or energy cost, I suspect it will cost more than 100% of energy produced. The question is if the solar or whatever renewable energy can be put to better use.

But in a 100% renewable only economy of the 2050s there is no choice for the energy source. That might result in far higher energy prices.

And, as said (unless a miraculous battery or hydrogen storage technology emerges), jet fuel has the best energy density, so there is no choice for another propulsion source.

And an economy without aviation is also impossible (unless for shorter distances < 500km which might be replaced by high speed train or Hyperloop).

I didn't say that they were. You said (correctly) that a nuclear reactor would be a great safety hazard. Well, stuffing a commercial airline to the brim with batteries is a great safety hazard too.

Look what happens to this (tiny) lithium battery

Then try imagining what happens if we don't have a few Wh (e.g the iPhone 5 battery has 5 Wh (14,000 mAh @ 3.8V) but a couple of GWh. (1 GWh = 1,000 MWh = 1,000,000 KWh =1,000,000,000 Wh)

At least the resulting contamination from a large lithium battery fire int likely to be anywhere near as toxic and devastating as radioactive material contamination.

I wouldn't want to be anywhere near either of the two catastrophic events though.

That's for sure, but that doesn't make Lithium batteries safer.

Indeed. But of course, a crashed plane with lithium batteries aboard isn't going to spread radioactive waste either.

Nothing different than a crashing planeload of Jet-A1.
Assume an aircraft loaded with 180 tons of fuel, that makes (180000 kg *43.7 MJ/kg) / 3.6 kWh/MJ = 2185000 kWh is indeed 2GWh.
The damage is not different from exploding Li-ion with the same capacity.

How about directed energy beams?
Instead of aircraft being burdened with carrying their energy source onboard, planes fly along prescribed routes populated with ground-based energy beam stations that continually shoot the planes with directed energy beams (insert magical process here) providing thrust and onboard power.
Similar to current-day VORTAC stations and published airways.

Are you writing this from Earth-616?

This! I get that batteries and synthetic jet-a and similar are going to be the next step. But surely we should also be thinking about inventing the next technology that will completely revolutionize traveling, in the same way that the internal combustion engine did to enable the car, or the jet engine did for planes?

If we are going to dream, let's dream big! Even heavier-than-air flight was once thought to be a magic process, now thousands of aircraft take to the sky each day.

Bring on the energy beams I say!

If the plane crash, he doesn't matter what happens: Both the passengers and the people on the ground will almost certainly perish. The batteries would however be a constant danger. A faulty battery cell could have horrible consequences.

Given how highly reactive lithium is, I wouldn't wanna sit on thousands of batteries, that are needed to generate the couple of GW/h needed for a flight. Filling up a plane with lithium batteries (which are considered to be so dangerous, that they may no longer travel as air freight on board of passenger aircrafts), seems to me to be equally idiotic than filling up an airship with hydrogen.

Add to that multiple other issues:

• Charging the batteries is going to take considerably more time. More time on the ground = Less money for airlines
• Maintenance of the batteries
• Lithium isn't in infinite quantities available
• Insufficent energy density
• Complexity of the system: You'll need to cool the batteries on the ground (e.g. LAS, DXB, SYD where temperatures are that friendly to batteries) and to heat batteries while airborne and on the ground in colder countries.

The same with fossil fuel.
But you are right: Li batteries are not an option at all.
The energy beams sound very science fiction to me. But maybe somday in the 2080s it might be feasible....?
Then a 'magic' battery technology which does not have the big disadvantages of Li batteries is more probable.
In the 1970s we also never thought that within 50 years an electric car was possible.

Which is way, the technology has to be further tested and developed in ground transportation.

There were electric cars as early as 1896. But yes, nobody thought in the 70s, that we would see EVs that could rival many sports and supercars. Even in the 90s and the early 00s, when I thought about EVs, I thought about Milk floats. The Swiss towns Sass Fee and Zermatt have prohibited the usage of traditional engines have been using Milk floats as vehicles as early as 1951.