I don't know that 30% is possible within the current stated capabilities of the E-Cat (hence my point about the current stated maximum usage temperature). But there are plenty of different working fluids (from SO2 to ammonia to freons) that are quite capable of converting even low grade heat (<100 C) into electricity by a liquid-to-vapor expansion cycle driving either a piston or turbine engine/genset.
Conversion efficiencies will be lousy, but we already live with that with our cars and trucks.
I posted a link to a home/small business sized genset series (10KW to 100KW) based on such a cycle on one of these threads (and no, I'm not going to chase down the link again).
Look up OTEC (Ocean Thermal Energy Conversion) for an example of one proposed LARGE scale usage of such.
I didn’t ask you for a list of lower efficiency and well-known methods of electricity generation—I asked you to explain how Rossi was going to convert 30% of his heat to electricity.
I will take your non-answer as an admission on your part that it’s not possible with current tech.