whisper tech, page-4

The Stirling Engines inside a Whispergen are not a traditional combustion engine either - the engine itself runs at about 40% efficiency, which is pretty good! Combined with a means of recovering the waste heat to heat up water for heating the system would become more efficient.

Looks like a good technology. The Whispergen is a mechanical solution whereas BlueGen is a chemical solution.

This comment is interesting though:

"In the UK, the WhisperGen would cost about 2,000 pounds more than an traditional boiler, but Moriarty estimates households would recoup this through savings and FITs over the first four years of the boiler's 10-12 year life expectancy."

Bluegens cost a lot more than this at the moment.

The article mentions that they are shipping 100000 units to Germany and looking to sell 80000 in the UK.

This is competition to CFU, although if CFU brings prices down it will deliver a better solution. Having a mechanical object in your house will require frequent servicing and maintenance. From what I can see, Bluegen would require no more regular servicing than a normal gas boiler does.