I visited the NASA campus in Cleveland, OH many years back and got to talking to one of the engineers who worked on this tech for the ISS. The batteries they use up there run $10k a piece, but he stressed how rock solid the chemistry and design is.<p>Nickel hydrogen has incredible endurance, but the part that really struck home with me: they measure the state of charge with a pressure gauge.
It's strange they didn't compare these batteries to lithium titanate, which is the other chemistry that can do 30,000 cycles and is something anyone can buy right now. They have extremely high charging C rates and sit somewhere between normal batteries and full capacitors in what they can do. They end up being about 50% more than LiFePo batteries in cost.
This sounds great on paper but there’s a couple of questions left hanging:<p>> We take the battery, put it in an open fire, and watch it continue to heat up. What ends up happening is that the pressure above top charge will force the hydrogen back into water. And then we have a release valve designed into the unit so at a predesigned pressure and temperature that will release, and you’ll get a steam vent.”<p>But what about the hydrogen ? doesn’t that risk getting vented out with the steam ? into the barbecue ?<p>What’s the self discharge characteristics ?
Can anyone comment on the design of the cell, specifically why it is long and thin, which would work against the square cube law. Is a large surface to volume chosen for thermal reasons?
> So far, EnerVenue has been operating a pilot production line that can manufacture 100 megawatt-hours’ worth of batteries per year—and they’ve deployed small-scale test systems. But, says Heinemann, the company already has over 7 GWh, or about 400 million dollars’ worth of purchase orders...<p>We should soon see if this is a viable business then.
I enjoyed this video about this topic: <a href="https://www.youtube.com/watch?v=2zG-ZrC4BO0&t=189s">https://www.youtube.com/watch?v=2zG-ZrC4BO0&t=189s</a>
I'm curious how they solved the hydrogen leakage/seepage problem through the walls. Even though it is designed for many (daily?) cycles and not long-term storage, it seems that H2 is in the tank anytime there's a charge ready or building. Maybe the pressures are low enough that it's insignificant even over 30k cycles?<p>Or does it just require occasional recharging with water or H2, and if so, what is the value of "occasional"?
Since it's relatively low pressure (5% of a hydrogen fuel cell), couldn't they have larger batteries for grids? The current size would be great for homes.