It appears to be the same mechanism as neutronic high-energy fusion. An energetic neutron gets kicked out, which collides with some material in the cell (probably the erbium lattice), and generates heat. Which then needs to be hooked up to a water boiler to create steam, which powers a turbine, etc.
I'm much more hopeful for someone creating a Dense Plasma Focus device with aneutronic hydrogen-boron (pB11) fuel because the reaction energy can be directly captured as electricity, instead of having to capture hot neutrons to boil water.
The increase in entropy on that temperature conversion alone is absurdly wasteful.
When you get a very low entropy source and your first step on using it consist on increasing the entropy 1000000000 times, you lose a lot of flexibility and efficiency.