So, stores 3x as much but yields at most 1.5x as much as a 10 kWh Powerwall. And it’s limited to 5 kW output. Maybe you could use a Powerwall battery as a buffer to handle higher power levels. I wonder if you can pipe the hydrogen to your Mirai? This makes it clear why Elon Musk has characterized Fuel Cell cars as “a really dumb idea”, or similar words.
Peter Forte
Efficiency is the key factor. With coming improvements in fuel cell and electrolyzer technology, this would be the perfect complement to an intermittent green power source. As long as the cost is not excessively more than that of alternative storage solutions it's a must! Remember that saving the planet is not restricted to drastically reducing carbon output, but also includes moving to a more sustainable lifestyle.
Peter, I believe your take is spot on. When considering “green energy” solutions, one really has to look at a big picture scenario. Hydrogen, as a supplement to a hybrid energy system, is a great idea. When looking at virtually all energy capture/production systems (on large and small scales), the amount of research done and progress made increases enormously each year. When one considers solar as a “mature” technology, even that has made substantial gains in efficiency over the past five years.

I can see a future home using a combination of solar and wind, with some places able to access geothermal, as well as others to generate electricity for homes and communities. Storage, too, will likely take more than one form. Costs will continue to decrease, technologies will continue to proliferate, and the future looks promising. The biggest hurdle to overcome at the moment is the traditional energy sector trying to hamstring progress instead of investing heavily in it.
It's the (in)efficiency that ruins it for me. I could live with the fire risk and the lack of toxic chemicals is a big plus. But 50% (dubiously claimed)?! I don't have a battery system yet, partly because there's this web site (newatlas!) that promises great new battery tech any day now. Also, thanks to Loz for the warning about the video.
Doug Bursnall
Assume it would be fairly easy to add a bigger tank, at which point you could use the fuel for cooking and heating, removing natural gas from your home but retaining choice in appliance.
The efficiency of the fuel cell's side can reach 95% IF the waste heat generated by the fuel cells is used for heating water or heating the house.
You use 3 times the energy, 120KWh to store 40KW, so using the same sunlight and more batteries this is hopeless.
Hydrogen is miles more explosive than LNG - any "natural" gas. The blast is faster and the impact can be directed, say straight up, very unlike here, where the house/building where it is installed will be wiped out.
Replace the fuel cell with a contraption that can generate at least 80% of the energy and we have something (The Mazda Wankel motor can do this - but this is not invented in the USA).
But hydrogen can be move and sold. They have a novel unit to produce hydrogen, and in the summer, the solar cells produce electricity that cannot be used except for heating swimming pools. They can produce the hydrogen that can be solde, and used to charge BEV fast. Hydrogen produced this way can be traded on Wall Street. You can safely invest in it - and we have tanks that are "safe". Because free hydrogen explodes in a huge bang.
We deliver standard battery packs of 100KWh and most cars need more than 40KWh, more usual is 70KWh. This determines the range the car can drive without being charged. 400KWh is for boats - leisure crafts and eventually planes depending on weight.
Hydrogen should be considered for charging the BEV, but drop the "fuel cells" - but a 40KW charger on a hydrogen generator can charge 1000KWh in 25 hours - and big boats with a 400bhp motor also need to be charged. They can pay per KW, and they are used to pay for the diesel.
George Cernigliaro
What's great is that all of this technology is coming along WITHOUT the elite political pressures of Globalism and government interference. This technology will likely find a sizable niche, as will the other non-fossil fuel technologies. What will likely drive success is REAL low carbon footprint manufacturing, unit cost, and safe operation. Once again, free market initiatives will lead the way.