Fuel Cell Boilers - Thoughts?

michaels

Does anyone have any experience?  Currently the ship seems to have sailed on getting them at an economical price as the FIT was withdrawn and then presumably since Brexit we are no longer eligible for the PACE grants?  But if they were included in the green recovery deal I would definitely be interested, not sure what the DNO would say about adding this to PV and V2G...
https://www.viessmann.co.uk/products/combined-heat-and-power/fuel-cell

Ignoring the economics do they make green sense or is GSHP (vertical loop) a better option?

Martyn1981

Hiya. Purely my thoughts, that I've probably posted before somewhere, but I like the idea, especially if combined with PV, small ASHP (air con) and storage.
My thought/idea was that storage would help if you have too much PV generation, and also when you have too much fuel cell generation (because you are heating your house), so that doubles up the economies of storage, be it stationary batts or BEV charging, or best still V2H/V2G. Also, when heating the house and producing 'too much' leccy, you could also run the A/C units to boost the heating COP from that leccy.
Of course, whether this makes economic sense, or if there is a better environmental solution, like GSHP, I don't know. Simply pointing out how a combination of tools would seem to work together very well, especially if you could 'green up' your gas supply in some way through your energy supply deal, or if in the future the gas becomes less FF and more bio-methane.

ABrass

michaels said:

Does anyone have any experience?  Currently the ship seems to have sailed on getting them at an economical price as the FIT was withdrawn and then presumably since Brexit we are no longer eligible for the PACE grants?  But if they were included in the green recovery deal I would definitely be interested, not sure what the DNO would say about adding this to PV and V2G...
https://www.viessmann.co.uk/products/combined-heat-and-power/fuel-cell

Ignoring the economics do they make green sense or is GSHP (vertical loop) a better option?

I'd be shocked if they made any sense financially. The linked one would be able to use natural gas for heating at least, but hydrogen is expensive and difficult to get hold of.

In terms of greenness I'd say GSHP is  better. It means youre dropping the carbon footprint immediately from about 200g/kWh to 50 ish compared to gas. At the moment blue Hydrogen has a larger carbon footprint than natural gas based on a quick search.

Give it five years and there may be industrial scale green hydrogen production facilities so it might become a green solution, but GSHPs are there now.

michaels

My understanding was the boiler linked (effectively) chucks natural gas into the fuel cell rather than requiring a source of hydrogen and a bit like the old mechanical CHP boilers uses the waste heat from generating electricity as domestic heat - thus you basically get the same heat output from the gas as with a standard boiler but also get perhaps 25% as much energy again back as electricity.  Compare this to generating the electricity in a gas power station: the efficiency will be lower but the heat rather than all being waste will all be used for DHW and or space heating.

Exclude the boiler cost and you have say 4kwh of gas at 2.5p per kwh generating 1kwh of electricity, value anything between approx. zero if you export at a bad moment to 25p if you are on a time of day Octopus style tariff and the power is generated when you need it or you can time shift it via battery storage.  On top of this you also still get the value of the gas heat output, assuming similar efficiency to a standard gas boiler this is worth the 10p you paid for the gas.  We burn 32k kwh of gas per year so if we assume the leccy is worth 10p per kwh this would give us £800 worth of electricity if all the gas were 'fuel celled' instead of burned.
In reality not all the gas would be turned to heat via the fuel cell as the output is too low so perhaps only 400-600 of annual savings, ovr the 10 year warranty lifetime of the boiler that would be say 5k.  Suppose we need a new boiler anyway that would be about 1500 so if the boiler were about 6.5k it would make cost sense, at 16k not so much....
In terms of Green credentials basically it would be saving however much electricity was generated x 3 kwh of gas being burned in a power station at 33% efficiency (perhaps, not sure if we can compare to the marginal grid or the grid average).  Not sure what happens to the carbon in the fuel used in the fuel cell and whether it releases just as much co2 as burning it.

Pile_o_stone

I was looking at one that used natural gas. I think the power output was a constant 18kwh electricity generation and 30.8kwh heat generation per day (so 750 per hour electicity and 1.1kwh heat) for the largest chp in the domestic range. The electricity was fine as you could either store the excess in a battery or export it to the grid (providing your FIT paid enough to cover the cost of the gas it took to generate the electricity). The issue I had was what to do with the heat in the summer months. We currently have solar connected to a large water tank and what that reaches max (which is quite quickly on a sunny day), it then dumps the excess power to the grid. With the fuel cell, if you can't dump the heat then I assume the unit will switch off for safety so you lose the electricity generation. You could turn off the fuel cell during the summer, but that means the ROI on the fuel cell gets longer. 

The heat output from the fuel cell was more comparable to a heat pump than a central heating boiler, so they have the same recommendations where they should be fitted in a well insulated house with UFH or oversized radiators.

It still might have worked for us as we have large stone house that leaks heat, so we could have run the central heating to remove some heat from the fuelcell. However, I was told by a gas engineer pal that they're a complex piece of kit and need a lot of expensive maintenance to keep going and that put me off. Unlike solar which had a relatively large up-front cost but then zero maintenance or outlay (so far), the fuel pump has an expensive outlay and annual maintenance, coupled with the possibility of not being able to run it 24/7 in summer.

Here's on of the CHP fuel cells I was looking at: https://www.viessmann.co.uk/products/combined-heat-and-power/fuel-cell/vitovalor#anchor-product-data

michaels

That is the one I was looking at.  The daily fuel cell output wouldn't even support our dhw needs and we are currently on a v2g trial getting 26p per unit of electric export (of course can use the car battery for storage but try not to as we are much better off exporting at 26p/unit and then buying the power we need at 13p/unit).

In theory if it were supported, with PV, CHP and storage we could go off grid and our annual gas usage would generate enough electricity to meet our needs.  Problem is we would probably need the car plugged in all the time so has enough amps to boil the kettle etc.  Interesting idea huh?

Pile_o_stone

michaels said:

That is the one I was looking at.  The daily fuel cell output wouldn't even support our dhw needs and we are currently on a v2g trial getting 26p per unit of electric export (of course can use the car battery for storage but try not to as we are much better off exporting at 26p/unit and then buying the power we need at 13p/unit).

In theory if it were supported, with PV, CHP and storage we could go off grid and our annual gas usage would generate enough electricity to meet our needs.  Problem is we would probably need the car plugged in all the time so has enough amps to boil the kettle etc.  Interesting idea huh?

Very interesting, and it's an idea I've had in the past but I didn't see it working for us. Sounds like it might work for you with a few simple lifestyle changes. I was also concerned about high energy use items like kettles and looked at those qooker style hot taps that have a vacuum cylinder for storing hot water to take away that 3kw requirement. I think irons and hoovers were the other high current items in the house but you can buy non-iron clothes and hoovers are getting more efficient these days.

You're left with just the maintenance costs. It'd be good if you could find figures from the manufacturer to see how often the unit needs to be serviced and the typical costs of the service, plus details on what parts need regular replacing.

joefizz

Not quite the same but over the last few weeks been looking at videos on youtube of home hydrogen and compression production (yeah I know, accident waiting to happen). I have most if not all of the equipment supplies already so might be my next 'project' when I get home.
Its pretty much rained at home constantly for the last month so theres an excess of water but not much excess electricity but would be ideal form of time shifting excess energy in summer, to put excess into small scale hydrogen engine, compress and store for winter.
Theres a hydrogen conference back home next week but I'll be out of internet contact again next week so wont be dialling in which is a shame.

I installed a 2nd oil tank last week as Im expecting oil prices to perhaps dip then just ramp up from now and with the 2nd tank that should be 4-5 years worth of winter heating/hot water for me. That should bring me roughly to the end of my oil boilers lifetime and from the figures Ive seen bring it into the timeframe of hydrogen only boilers (not fuel cell). Dont think they will be money saving though but then again in that time frame I dont think fossil fuels will be either!

michaels

I read a bit on home energy storage via compressed air - might be worth starting with that before the explosive gases!

Hexane

Pile_o_stone said:
and hoovers are getting more efficient these days.

Indeed. The vacuum cleaner used by my cleaning company (or at least, the one they used today while I happened to be looking at my myenergi app) draws 400W to 500W in use.

joefizz

michaels said:

I read a bit on home energy storage via compressed air - might be worth starting with that before the explosive gases!

Was party to a lot of developments in that area so not allowed to work on it myself ;-)
Besides which Im from the Falls, what could possibly go wrong ;-)