Two questions I have:
1. How much of the fuel's energy is released as heat? They have a heat recapture device, but that's only used to preheat air/fuel, and not used to generate electricity. Is the energy in the heat simply discarded?
2. Can this be made to work without the process of burning? i.e. can it function purely from heat? If it can, it might be able to replace steam turbines in, for example, nuclear plants or CSP plants. That could be hugely beneficial.
I suppose for aviation at least this is no less efficient than a gas turbine or a piston, and it's certainly a good deal quieter, has fewer moving parts, and requires less precision engineering than a jet engine. This feels tailor-made for attritable low->medium performance aviation, aka loitering munitions and drones. Strip away the "green" talk, and you're left with something that can burn just about anything (including hydrocarbons like avgas) without the complexity of a turbine.
maybe so. i don't know about attritable for the first applications though. may long range or duration oversight. a large % of the cost is these specialty cells which have not been scaled up to mass production. in the denominator is the intensity of light we can produce, which is based on how high a temperature we can drive, there's a very nonlinear brightness vs temperature. but at 100 suns or so we can get near to $1/W on the cells at startup scale
1. It's hard to capture all the waste heat. If you could run this indoors (but vent outdoors if the fuel is anything other than H2, naturally) then you could use some of the waste heat to heat a building.
2. There are thermovoltaic generators, but they're limited by the need to cool one side of the material. These are typically used in deep space probes that use Pu 240 to power them. To my knowledge thermovoltaic generation is not scalable or practical on Earth at this time.
People use the thermoelectric effect for various "energy harvesting" applications, see
https://www.tegmart.com/wood-stove-thermoelectric-generators...
It's an area where you hear about progress from time to time because the technology could improve if people find materials that have a better ratio of electrical conductivity/thermal conductivity.
1. The countercurrent heat exchanger achieves exactly that: exhaust gases are cooled while the inflowing fuel mixture is heated up.
2. Thermophotovoltaics in general can operate with any heat source, though this device is clearly optimized for combustion. However, the efficiency is far too low to compete in the large-scale power generation segment. This is almost certainly aimed at light aviation, heavy drones, military applications, etc., where there are not a lot of alternatives that combine small size, high power density and good efficiency.