Efficiency is everything. If this invention converts 1% of heat into electricity, it really isn’t a big deal (there are other conversion methods with greater efficiency). If it converts 50%, the results would be astounding. New nuclear reactor designs (no more steam turbines), hyper-efficient solar arrays, you name it.
Actually, 1% could be huge. It all depends on the temperature (quality) of the heat. If it can do 1% with a very low temperature differential, at low capital cost, it could be a real breakthrough.
But right behind is portability, economy, size/weight, and amount of power. A 40% efficient process that only produces 300 or 500 watts will help in many places for a short time, but can’t replace even a lightweight gas or diesel generator.
A “million dollar” “never-needs-refueling” marvel that can’t be used in the field or a building (like a Pu-power radioactive-fired satellite generator) isn’t practical either for a truck or remote station.
More likely, this first model will generate only a few watts. But it’s a start - future versions might have applications using the high-level heat from a gas turbine, smokestack, or steam piping.