Halve the panels halve the storage and electrolysis / BATTERY! house and change the mushroom farm into a playpen.
Looks more like a boondoggle good for reviving 'the economy'
Otherwise a good thing, cute.

Smart hydrogen station? Smart house? All this to justify their fuel cell car? A fuel cell car is what you build when you were not smart enough to design the Tesla.

>>>>"Storing extra power in the form of H2 would be worse than storing it in batteries. By far."

Ok, let's do some math:
1) At 35-40% round-trip efficiency for H2 from RE, electricity to electricity, the cost of 1 kWh delivered from storage would be, assuming 6-cent /kwh electricity:
[{(6 cents / 0.8) + 1.5 c electrolysis plant depreciation } /0.5 eff of FC] + 2 c depreciation of FC = 20 cents per kWh from H2 storage. The H2 will be stored in existing NG reservoirs at no additional cost. Even when stored in carbon fiber tanks at $15 per kWh for 10,000 cycles at 80% DOD, the additional cost would be only negligible at 0.2 cent per kWh.

Storing RE from electricity to purely heat, or combined heat and power, would have 75-80% round-trip efficiency, and would cost even less: (6 c / 0.8) + 1.5 c electrolysis plant depreciation = 9 cents /kWh for 100% heat, and 10 c to combined heat and power due to the 1 c depreciation cost of FC per kWh.

2) At 80% round trip efficiency for battery storage from RE, the cost of each kWh delivered from storage: (6 c / 0.8) + 18.75 c cost of battery depreciation = 26.25 cents per kWh from battery storage..
Battery depreciation is calculated assuming $300 per kWh and 2000 cycles at 80% DOD, so $300 / 1600 kWh = $0.1875. This is without taken into account the cost of borrowing of the $300 / kWh of that battery over 10-15 years. If an investment of $300 is made for 15 yrs at 4% annual interest, would result in $540 in 15 years, so $540 /1,600 kwh = $0.34 per kWh, added to this the $0.075 electricity cost, will give 41.5 cents per kWh from battery storage, vs 20 cents per kWh from hydrogen storage

So, please kindly give the data to support your contention that storing extra power in the form of H2 would be far worse?

If the cost of excess RE power is less than 6 cents per kWh, say 3 cents per kWh, then H2 storage, from electricity to electricity, would cost much less than 20 cents per kWh, now down to 12.5 c per kWh, while battery electricity would not change much, at 22.5 cents per kWh when drawn from storage.
H2 e-storage from electricity to heat would cost very little, 5.25 cents per kWh delivered as 100% heat, or 6.25 cents per kWh for combined 50% power and 50% heat.

Significant amount of energy used daily is for hot water production. A home-based FC turned on at sun-down can use the H2 produced from solar PV during the day, for both home electricity AND for water heating for bathing and dish washing and laundry later. In this usage, the round-trip efficiency of H2 is equal to the round-trip efficiency of battery, yet at much lower cost, at 1/2 to 1/3 the cost!

Natural Gas for comparison:
NG at $12 per MMBTU at the pump will cost about 4 cents per kWh thermal energy. At 25% thermal efficiency, this will cost about 16 cents per kWh delivered by the engine. Engine depreciation cost at $3,000 for 150k miles will be 6 cents per kWh delivered at the shaft, assuming 3 miles per kWh. So, NG will cost 22 cents per kWh of power at the engine shaft.
Since Japan and Germany have no NG reserve, H2 would be a sensible replacement for NG at competitive cost when the cost of solar and wind will be around 6 cents per kWh, when the H2 is used for transportation, AND when RE will cost 3 cents per kWh, when the H2 will be used for heating or Combined Heat and Power.

Gasoline for comparison:
Gasoline at $2.5 per gallon will cost about 7.4 cents per kWh thermal energy. At 25% thermal efficiency, this will cost about 30 cents per kWh as delivered by the engine. Same engine depreciation cost as above will result in 36 cents per kWh at the engine shaft.

Roger, I just want to say I appreciate your making a case for your position using an economic model.

I don't agree wjth some of your assumptions, especially like "The H2 will be stored in existing NG reservoirs at no additional cost." which is pure fantasy, but do appreciate you made an attempt to explain alternate scenarios that have a better relationship to reality.

We are seeing right now today in Southern California that storing gas in underground reservoirs does not come withiut cost, or risk.

Another thought: "Storing extra power in the form of H2 would be worse than storing it in batteries. By far."

This all depends on what's your yardstick. Roger gave us the numbers for dollars & cents - that's his yardstick. My yardstick is climate change. Which is better in GWP emissions?

More considerations.
Practicality and cost:
Example:

Remote occasional motor vehicle requirement that includes tractor or lawn equipment.

Cost of infrastructure required is battery(s) and X number solar panels.

The solar panels if undersized can be very modest at say $1000 / KW for a twenty year lifetime.
One kilowatt of panels is relatively portable.

Larger arrays would lose portability but the cost would advantage the BEV option at twice the rate for F.C. owing to the 2X relationship.
Lets be generous and assume on board DC booster can take care of matching.

Lets be generous again and also consider that we can only operate one machine at a time.
Assume that the batteries are (can be) designed as swappable so the total requirement is for the max for any single vehicle requirement.

Say over the top battery pack $20K.
No cost for batt management.===$0K
The FC pack ------------------$2K.
Total cost--------------------$22K.

The cost of the non swappable there are lets say 5 vehicles.
1 lawn tractor
2 push mower
3 motorcycle
4 car
5 sawmill.
the same 1KW energy production requirement.

For The cost of the non swappable F.C. option, we will use a near fantasy give away costing.

5 x < $4K F.C's.------$20K
2 @x $1K = $2Kpanels.--$2K
2KW batt pack----------$2K
Electrolyse @ say ----$6K
Pump and intermediate
storage say---------- $5K
Bat management---------$0K
Total--------------- $35K

The battery(s) required to support fuel cell is smaller.
Lets average and say 10% of pure bev.

There is a requirement for dedicated plumbed f.c and tank or would it be possible to have a bank of F'c's?

I don't think it would be very easy but possible to build along the lines of a gang of small portable air compressors.

But then there is H2 high pressure Q.C. coupling and high pressure gasses to consider. UNLIKELY TO MEET OH&S certification.

Both above options are imaginary but demonstrate one realistic way of looking at the problem.

Lets assume similar average weight for the two options across the fleet.
The Xtra battery weight trades against added fuel cell. But FC requires 2X extra panels, electrolysis,interim storage tank, travelling storage tank(s) means we lose portability and adds to complexity as well as cost.

eci said:

'I don't agree wjth some of your assumptions, especially like "The H2 will be stored in existing NG reservoirs at no additional cost." which is pure fantasy,'

Assertion without any documentation.
What is fantasy is the notion that by magic a lot of renewables can be used in the grid outside the tropics using only batteries for storage.

So show us the numbers for how your renewable society would work without hydrogen, instead of trolling every thread about hydrogen.

Boy, this is tireless. Batteries are really, really great, until you need to store a lot of power over long periods. You see, batteries have a fatal flaw in that department. All of their storage capacity is tied up and locked into bonds between the materials of which they are made.

It inherently limits their capacity and ensures that they will ALWAYS cost more to store a given unit of energy (if the energy is needed over a long duration) than almost any other storage solution, H2 via cavern, tank or other storage media included. One possible exception being hydride storage which suffers similar problems as batteries.

You will never be storing weeks of energy capacity with batteries because the materials alone that make the battery will cost roughly an order of magnitude more than the materials to contain a fluid fuel, H2 included. It is the square versus cubic relationship between a tank where one is concerned primarily with surface area versus batteries, hydrides etc. where we are dealing with cubic material requirements. To make matters worse, batteries tend to require materials that have higher embedded energy and higher scarcity values like lithium etc. when compared with the materials for tanks like steel, aluminum, carbon fibre etc.

In a nutshell, Davemart is correct. We will not be running an industrial society on batteries. They are simply not up to the job. Both Japan and Germany understand this. The countries that are less enthusiastic tend to have large fossil reserves (CH4 anyone)

SJC, on its face, the idea that any company is going to store H2 or any other gas in a vast underground reservoir "at no additional cost" is fantasy. You can debate that, but rebuttal to ludicrous assertions like that do not require supporting evidence.

Despite that, I did post a link to one of the most consequential environmental catastrophe's related to storing gas in underground reservoirs in California's history. Which just coincidentally happens to be current news. Hundreds of people have been moved from their home (at the expense of Southern California Gas Co.) There have been serious health consequences to the affected population. The litigation will drag on for many years.

As SCG's insurance company if gas can be stored "at no additional cost" anywhere, in any form.

Conditions are not the same in many places.

We currently have a huge surplus of clean Hydro + Wind e-energy for the next 15 years or so. Instead of spending a few $$B to build more ground and underground high voltage power lines to sell this clean energy for under $0.05/kWh to USA's North Eastern States we could.

1. Use the current surplus to supply 200+ large public H2 stations, at local industrial rate (0.028/kWh for 24/7 usage and/or under $0.01/kWh for off peak demands hours = for about 7200 hours/year) using existing e-distribution network (grid).

2. Add more Hydro + Wind energy and boast the grid on an as required basis to satisfy increased local demand.

3. This would create more local permanent jobs, reduce our 100% Oil importation, reduce our current clean e-energy surpluses, increase Quebec-Hydro profits, reduce GHG and pollution etc.

4. We could continue to sell 30+ terra-watt hours/year of clean e-energy to USA (at $0.08 to $0.10/kWh) without expending the grid.