greengnu

well no storage can be 100% efficient but you are correct that thermal storage is very efficient if you want a thermal gradient to leverage for heating (cooling as well)

I am assuming you mean Pumped-storage hydroelectricity when you say PHES and no it also falls under F=ma, but when using the terrain is able to increase the amount of mass to a more industrial useful scale. The larger the scale the smaller the losses. Hence most economical when one has mountains for the storage of the water. (metal/plastic tanks on elevated platforms tend to be much less efficient and more expensive).

I guess it depends on what you mean by rare long duration events but yes one can imagine a situation where the burning of hydrogen is justified on an energy needs basis.

Depends on what you mean by a huge problem.

If you are referring to energy loses due to the large distances and the electrical resistance of the wires carrying that power; you'll discover those loses are directed related to current and that you can trade current for voltage and trade voltage for current; so we can avoid losses by upping the voltage.

If you are referring to the fact that the Earth's crust is moving, we can have geologists do some work; estimate the distances spaces where we will be running our wires and put in sufficient slack to cover the time period until the next maintenance window.

If you are referring to weather event induced disruptions in the grid (wind/tornadoes/etc taking out power lines) then you build alternate paths to route around damage.

If you are referring to solar storms and coronal mass ejections, then you need standards in your equipment to deal with out of spec distribution lines.

All of which are technical problems and easy to solve.

If you are referring to the bureaucratic hellscape that is international coordination and cooperation, then yes that is the only huge problem preventing such a solution, despite its numerous global economic and environmental advantages.

harmonization of grid standards is more than just frequency (it is mostly policy paperwork and the replacement of non-compliant equipment or the installation of conversion equipment) but you are correct high voltage DC is used for long distance power transmission. There are also details such as who is responsible for paying for what, where things are to be connected and various other bureaucratic details.

storage is only a problem if the global distribution grid is not created. The sun is always shining somewhere, especially if you realize we can leverage space to extend our collection.

cranes are just stupid energy storage (the F=ma bit basically makes this a non-starter) . Water in pumped storage only works out in huge scale (where you have mountains to provide a massive storage pool).

compressed air storage misses the point, use just a little more energy and you can use that energy to thermally separate CO2 from air. (This is a productive use of energy but bad efficiency for storage)

hydrogen production from water is a productive use if we want to remove hydrocarbons from some chemical processes but it is not an efficient battery.

Thermal storage of energy is very inefficient and not a good idea unless you are willing to waste a good deal of available energy.

And flywheels are not even mentioned and very wrong information about Tesla power walls.

The big companies are ignoring the sector and just plan on buying the most profitable startups that look promising.

So ignore the fortune 1000 entirely and invest in smaller companies that are hiring engineers in chemistry if your goal is to invest effectively in battery technology.

But you are missing the advances in metallurgy (superconducting metals are making great strides), mechanical engineering (flywheel technology is taking advantage of new micro-controlled magnetic bearings) and physics.

Well a superconducting loop (even with liquid nitrogen costs/inefficiencies) would enable a global grid with quite minimal energy loses and reduce the amount of energy storage needed to sustain a stable grid even in the face of failures and disruptions.

The big problem tends to do with harmonization of energy grid standards.

well as you can buy solar panels at $0.50/W so a 10W panel can be obtained for $5 and a raspberry pi4 only uses 2.7W while idle and 6.4W when under full load.

Efficient is sexy

Sounds like they didn't consider appealing to UK government to get subsidized liquid CO2 and use the produced hydrogen to synthetically create hydrocarbons (which are much easier/cheaper to store) and win political points doing so.

The breeder part is the production of U-233 (which is then fissioned and used to provide the neutrons for converting Th-232 into U-233 (with a chemical separation and decay storage step in between)) which although has a tight neutron economy is viable.

Working reactors for such designs were funded by the US airforce and they did operate as expected.

If you wish to argue that one will need U-235 as a startup fuel or that there are technical problems in large scale energy production it is not yet able to address, I would definitely agree on that; the technology needs more research before we depend upon it and that Uranium light water reactors are likely to be the running standard until such time and needed investment occurs. But we have enough U-235 in nuclear waste stockpiles to fuel our civilization for a thousand years to work out the details.

you don't need U-235 for nuclear power. In fact a Liquid Thorium-Fluoride thermal breeder reactor would be a more industrially useful nuclear design and Th-232 is available to power our civilization for a billion years (assuming no growth in energy consumption)

You are right in regards to very rural bus routes not being viable for electric buses but inside suburbs, cities and rural regions where the electric grid is already connected and in place, it is very cost effective to convert to pure electric.

But for rural bus routes away from a connected electrical grid, hydrogen is not a solution either as it is only 30% efficient (assuming only ideal conditions) and would be better served by liquid hydrocarbons. (I see no reason to deprive developing communities from the most efficient options)

I am in no way suggesting one would need to leave their family but one needs to understand up until the invention of the airplane, such relocation had to mean saying good bye and corresponding via mail or very rare train rides to visit with the whole family.

Green hydrogen outside of chemical processes (where it is actually useful) is a myth designed to keep the automotive industry alive past its expiration date.

The function of green hydrogen as an energy storage medium is better serviced by more custom chemistries as we are taking external energy to produce it (literally it would be the same as us taking CO2 + H2O + energy to produce gasoline [which we could do at the cost of $3.75/gal (if one ignores the CO2 collection costs)] using the Fischer-Tropsch process)

So skip the dream and accept the reality that if we are needing stored energy for transportation, it is more efficient to store it as liquid hydrocarbons. But if we need to store for transient demands, batteries and flywheels are better solutions.