microwave c/h boiler

[Seeker]

another idea to replace gas boilers:
https://www.theguardian.com/environment/2021/mar/16/first-microwave-powered-home-boiler-could-help-cut-emissions

[johnnyrod]

Seems like a lot of trouble when you could just use a heating element to heat the water directly, and I wonder how consistent the recovery of waste heat is - easy to say, hard to do in reality. You need the same amount of output power (i.e. power taken up by the water) regardless of how it gets in there. I guess a house already has pipes but if you wanted electric heating then surely you'd just fit electric heaters which are a lot more controllable than rads, and again you are heating directly. For any of this we need to ignore how the leccy is made and its cost.

[SV650rules]

The grid is gonna need rebuilding at massive cost, everyone is putting extra loads on it, car charging, heating, and even heatpumps need significant amounts of energy to run. Added to that is the fact that renewables are unreliable in their outputs and often go walkabout for many days at a time, sometimes whole weeks, often during coldest periods, and solar is pretty useless in UK winter anyway.

[keith_d]

I can't see how microwave heating would be any more efficient than using a simple resistance heater. As Johnny has already highlighted, it takes the same amount of energy to heat water however it is delivered. The best we can do is try to use that energy as efficiently as possible.

[Bibio]

why cant they just use induction sleeve heating elements. like a cooker hob but in a tube.


there is farrrrr too much can we instead of should we going on.

[johnnyrod]

Probably because there are grants available to investigate new ways

[keith_d]

why cant they just use induction sleeve heating elements. like a cooker hob but in a tube.


Induction heating is used in stoves because it allows us to heat a pan without direct contact with a heating element. It is significantly less than 100% efficient, but makes for easy to clean cooker tops.

A resistive element completely immersed in the water will convert very nearly 100% of the electrical energy supplied into hot water (a small amount of heat will be lost through the supporting structure and the walls of the enclosure). That's pretty hard to beat.

Keith.