Combined heat and power - the way forward?

Here's a demonstration of a domestic fuel cell, from Ceres. These systems behave like gas boilers from the point of view of generating hot water and heating, but have the added benefit of using the wasted energy to generate electricity, at a level of up to a kilowatt or so. This has the effect of reducing carbon emissions and also reducing the consumer's electricity bill.

Ceres are in the process of getting their micro Combined Heat and Power boiler to the market place. Based on a quick trawl across the internet, there are a couple of boilers already on or close to the market which do this - the Baxi Ecogen, which is expensive (the boiler itself seems to cost around the £6000 mark) and relatively powerful (it is capable of providing 24 kW of heating for water), and the e-on Whispergen, which seems to be less expensive but also less powerful (around 12 kW of heating). I just checked our boiler - which is a combi boiler, so has to produce hot water on demand - but it's capable of an output of 30 kW. All the mCHP systems I've seen seem to work on the basis of using a hot water tank. Maybe the next boiler we get is going to require us going back in the direction of having a tank....