This burns fuel at very high temperature, and I wonder how they plan to deal with NOx production. They could attempt to burn the fuel in pure-ish oxygen (with an oxygen concentrator?), but that would increase the complexity of the design and compromise the "quiet" part.
oxygen works and might be worth it for a stationary application like a powerplant for an AI data center. but NOx breaks down exothermically. so our approach if you hold the flame at >1300 C for less than a second or so you can destroy most of the NOx. This doesn't happen in a Diesel because the pulse stays that hot for only a short time, locking in the NOX that is produced. this is a matter of sizing the heat exchanger / flow rates correctly. we have to validate all this though. good question
