Round trip conversion efficiency of electrolytic hydrogen production

Storage is another big energy loss. It's hard to store hydrogen.

Fuel cells have been the generator of the future since they were invented in 1838.

My overall guesstimate answer to your question is about 20% and huge investment cost.

Why not use utility power and get a backup generator if you think you'll need it? Spend the money on efficiency, like insulation and good appliances.

My interest was what efficiency level you'd need to reach wrt conversion and storage to effectively arbitrage utility power production, i.e. store energy somehow overnight on off-peak rates, and then resell during peak demand.

At the present time, batteries may be the most efficient way to convert and store demand energy for short periods of time, but they're more limited in the number of charge-discharge cycles they can endure.

The problem with most "renewable" sources is that they are intermittent and there is no good way to store the energy.

Utilities would not appreciate the arbitrage thing... if it worked.

Room-temperature superconductors, or at least high-temperature cryogenic superconductors would sure help!

You could just build a big inductor and let the current go around and around and around...

If the idea was to pull power from the grid at low cost during off peak, and then pump it back into the grid to sell it back to them during on peak, I could see how that would tick the utilities off.

But that's not the only thing you can do.

Pumped water storage... wiki says 70-80%.

If batteries were cheaper I'd think utility companies would use them.

George H.

That seems like it would be the most efficient given current technology, but the downside is that not everyone has a mountain to spare.

May be of interest:

Sounds like the wrong question, actually. One-home inversion to 120VAC can be a poor economic decision, because community-sized power distribution of 120VAC is optimized for central power. Conversion of as-delivered electricity to hydrogen in homes is ... not useful You'd do the hydrogen generation/storage at a community central facility or power plant.

It's easy, either low-pressure gas (accumulator tank, bubble of gas in the top, water seal on bottom, the tank floats in a water pool), or high pressure gas, or intercalation (dissolved-in-solid) storage. All the quick-and-dirty systems are simple, but it's intercalation that scales up the best, and it is hard to describe. Acetylene storage was a harder problem. We don't care much about the difficulty, because the problem only had to be solved once; building the solution is easy.

So? Electricity was near useless from ancient Greek observations with amber and fur, to Ben Franklin's day. Would that tell you that it didn't have a future?

Ben Franklin would have agreed, though, that magnetism was clearly a dead-end technology, useful only for pointing at North.

Even if you had, some greenies would come telling that it must not be done.

That has been proposed, using conventional superconductors. A tunnel a mile or so in diameter, lots of turns in liquid helium. It might confuse migrating birds and magnetic compasses.

People, to this day, keep not using fuel cells except when cost doesn't matter, like in the ISS. Maybe submarines.

Alcohol fuel cells were supposed to power laptop computers 10 or 20 years ago. It was a stupid idea. Fuel cell cars are still too expensive by about an order of magnitude.

Yes -- what's the deal with that? I was looking forward to starting a flight with the conundrum of whether I should pour the ethanol into my laptop, or mix it with Coke and drink it.

Just the opposite. Utilities would *love* if you stored energy when it is plentiful and cheap and sold it back when it was sparse and therefore pricey. It would save them building a lot of peak power generation.

No, it wouldn't tick them off. But if it were economical to do that, they would already be doing it themselves. It is only useful if you can do it while getting something else out of it in addition. Maybe the waste heat?

You don't need a mountain. You do need *lots* of water though, which is where you run afoul of the authorities. But they may let you do it if you are large enough and also provide drinking water for a community.

Imagine a smelly, mouldy brief case full of watery alcohol.

Have you tried Ron Zacapa 23? It would be a sin, an expensive sin, to run a laptop on that. It would also be a sin to mix it with Coke. 10 Cane is better for that.

Their is a way.. Thermal storage.. I.E. Cool down your house while you have excess power prodution, make a tank full of hot water, drop temp in freezer by a few degrees, etc..

They never will.

We need a bacteria that produces hydrogen as a by product and eats silica. That's all.