Hydrogen News, page-81

Paul Martin's view on the news from Hysata:

"Let's do some math in relation to the claim.

Let's forget about the 41.4 kWh/kg claim as it's just a claim- at first glance a ridiculous one, because even if the CELL were 100% efficient, the input to the RECTIFIER would be more than 41.4 kWh/kg...that's without water treatment or a feed pump. The claim is definitely overstated, but bear with me for a moment!

Let's instead use 40 kWh/kg, because the thermodynamic limit (100% efficiency) is 39.4 kWh/kg, the HHV of a kg of H2. That number is close enough to 40, and 40 makes the math easier.

40 kWh/kg x $0.05/kWh is already $2/kg. Made using an electrolyzer which you found in the street, free of charge, which cost you nothing to install or operate.

$2/kg is already almost $15/million BTU of HHV.

Natural gas over the past 10 yrs, wholesale, was $3.50/million BTU in the US (Henry Hub average price). It fluctuates, but yeah, it's that cheap.

Electrolyzers are current devices, which means surface area devices. You don't get surface area for free. You can get high efficiencies at very low current density, but the electrolyzer isn't cheaper as a result, it's more expensive because it has more electrode area. There's no way around it. The two are related by the most basic electrochemistry.

Even at a dreamland price of $2/kg for green hydrogen, it's still a very expensive fuel.

Remember that the LHV is only 33.3 kWh/kg. That 6.1 kWh/kg worth of heat of condensation of the product water? If you want work again, not low grade comfort heat, it's gone for good. Thermodynamics ensures that.

Feed that to storage and a fuelcell or engine or turbine and you've STILL lost more than half the energy you fed.

The point is this: you can't fix what's wrong with hydrogen by making electrolysis more efficient. It might help, but ONLY if you find a way to defy physics and make it both more efficient AND cheaper at the same time"