The economies of scale seem to be much larger. For example, utility scale solar seems to be about half the unit cost compared to residential and commercial solar: https://www.nrel.gov/analysis/solar-installed-system-cost.ht...
It is also difficult to store, so I suspect the hydrogen ship has sailed.
Decentralization brings an obvious benefit - if power is consumed near generation, you need less infrastructure to distribute it, thereby lowering costs. Once we start adding large numbers of EVs charging at home, our energy consumption will tilt more and more towards the home, making generation and consumption on the spot much more efficient and useful.
Another benefit of decentralization is grid resilience. Removing single points of failure by distributing them means that large scale power outages (while already infrequent) would become less frequent.
It doesn't cause metals to become brittle. Its relatively stable. It doesn't require as low temperature or as high pressure to liquidize. It also stores ~50% more hydrogen per volume, as each ammonia has 3 hydrogen, unlike elemental hydrogen with just 2.
- To be carbon-neutral, the hydrogen must come from splitting water.[1] Currently hydrogen comes from steam reforming of methane (which releases lots of carbon).[2]
- Hydrogen is a very pernicious molecule. It will slowly leak through metal and weaken it.[3]
- Hydrogen vehicles must be refueled at special fueling stations. Electric vehicles can be charged anywhere there is electricity (such as at home).
- Hydrogen fuel cell vehicles are more expensive than battery electric vehicles. Toyota sells the Mirai for $57,500 and loses money on each one.
- Storage and transportation of hydrogen is very difficult. It must either be stored in gaseous form at very high pressure, or in liquid form at 20 degrees above absolute zero. Current vehicles use high pressure tanks, which also require high pressure pumps. Many hydrogen stations can only provide 5,000psi pumps, which means you'll only get half a tank (and half of your expected range).[4]
- Hydrogen is more flammable than gasoline (it will ignite in a much wider range of mixtures with oxygen).[5] Unlike gasoline, the flame is invisible in daytime. Unlike gasoline, hydrogen is invisible and has no smell, making leaks undetectable without special equipment. If an odorant is added to the hydrogen, it will likely damage the fuel cell.
- Hydrogen is more expensive than gasoline and far more expensive than electricity. Even with subsidies, refilling a Toyota Mirai costs over $80.[4] That gives you just over 300 miles of range. My Tesla Model 3 has the same range and a full charge costs me $6 at home. Supercharging is also cheaper, at around $25.
- Batteries got cheap faster than anyone predicted (except Tesla). In 2015, a study looked at past estimates of battery prices versus observed prices. They found that analysts were consistently pessimistic about cost reductions. Correcting for this, they noted that cost per kWh, "...could reach $200 by 2020." Actual cost in 2020 was $123.[6]
Given all of these disadvantages, I don't see how hydrogen vehicles could be considered reasonable. The economics, physics, safety, and convenience simply don't work out.
1. https://en.wikipedia.org/wiki/Water_splitting
2. https://en.wikipedia.org/wiki/Steam_reforming
3. https://en.wikipedia.org/wiki/Hydrogen_embrittlement
4. https://www.cars.com/articles/fill-er-up-refueling-the-2016-...
5. https://en.wikipedia.org/wiki/Hydrogen_safety
6. https://www.weforum.org/agenda/2015/04/will-falling-battery-...
There's the physical security aspect of this, which is as you say, hard to take down when it's decentralized. However, as power generation gets more distributed, we'll naturally start seeing more (if not most) of these pieces of equipment be controlled over networks (private or public), and securing distributed infrastructure from a software standpoint is still a hard problem.
Just look at the state of IoT security today. It's quite bad, and that's not even realistically including nation state attackers in the threat model. I don't expect this to go well with a decentralized grid, at least not for a while initially.
There's not a lot of other great options today if we want to decarbonize those sectors because of the energy density required.
Hydrogen is flammable when mixed with air between 4% and 75%, and it takes a minimum energy of 0.016 millijoules to ignite. Ammonia is flammable between 15% and 28% and takes 680 millijoules to ignite. It takes much more energy to ignite ammonia and there's a much narrower range of mixtures with air where it can support combustion.
Yes the world deals with ammonia all the time. However we have special training for anyone who handles it. Even the most caution to the wind types wear full respirators and thick gloves when handling it.
When you buy ammonia at walmart what you get is 1% ammonia, 99% water. Then you are instructed to dilute it with more water 16:1, Even at that ratio it is nasty enough that those who use it have windows open.
https://www.rechargenews.com/transition/nel-to-slash-cost-of...
IoT is a raging tirefire. It's hard to even imagine how bad the security situation is.