New heating system

[Deleted User]

macman said:

Heat pumps are not really a solution in existing houses, as the rads will all need replacing with larger ones due to the lower output from heat pumps.

Plus INSULATE; INSULATE and INSULATE. Sadly, not all properties are suitable to become semi Passivhaus’. There is an irony here in that if all houses were insulated to a very high standard there would be a massive drop in the need for fossil fuel heating without bothering with heat pumps.

If experts are to be believed,  hydrogen use for home heating will not become widespread. 

Reed_Richards

Whilst what @[Deleted User] says is true, there is a sort of myth that heat pumps will not work unless you have a well-insulated house.  This is rubbish, no more sensible than saying a gas boiler will not work unless you have a well-insulated house.  What you cannot get with a poorly-insulated house is a Government subsidy for your heat pump (such as the Renewable Heat Incentive).  Very sensibly, you are required to meet minimum standards of insulation (as determined by your EPC) in order to qualify for the subsidy.  So you do need to insulate, if not quite INSULATE; INSULATE and INSULATE.        

ic

Cadent just spent two months replacing the gas mains and supply pipes to all houses in my road (it was originally supposed to take three weeks - and they were busy six days a week, sometimes past midnight).  God knows what that cost, and they're moving street by street in the area - there's no way an investment of that size in the network is being made if its to be decommissioned in five years time (in fact when they knocked on, they said such the work won't be required again for another 80 years).  Your cold caller can be safely ignored.

FreeBear

Reed_Richards said:  do we have enough extra fresh water to make all the hydrogen that would be needed? 

There is more than enough sea water that can be used to generate hydrogen once the problem of accelerated corrosion of the electrodes is solved.

Reed_Richards

FreeBear said:

Reed_Richards said:  do we have enough extra fresh water to make all the hydrogen that would be needed? 

There is more than enough sea water that can be used to generate hydrogen once the problem of accelerated corrosion of the electrodes is solved.

So that's a "No" then.  We seem to be relying on solving a lot of technical problems to get to a zero carbon future.  Doubtless many problems will be solved but surely not all of them.

QrizB

Alternatively ...

Reed_Richards said:  do we have enough extra fresh water to make all the hydrogen that would be needed?

My household uses 300 litres (300kg) of tapwater a day, 3000kg in ten days.

3000kg of tapwater, if converted into hydrogen and oxygen, contains 330kg of hydrogen.

Burning 1kg of hydrogen produces 140MJ of energy, so burning 330kg of hydrogen would produce 46200MJ, equal to 12800kWh.

12800kWh is roughly equal to my current annual natural gas consumption for CH and DHW.

So the additional water required is equal to ten days worth of domestic usage.

Reed_Richards

QrizB said:

So the additional water required is equal to ten days worth of domestic usage.

Or roughly 3% extra water usage if you are typical.  Perhaps in future when there is a drought your gas supply will get cut off?  Or we'll discover that smart gas meters have a rationing function they haven't told us about?

Currently electrolysis of water to make hydrogen is about 80% efficient in its use of electricity and perhaps you can achieve 90% efficiency when you burn it again so around 70% overall.  Or you can use a heat pump at around 300% efficiency.  Converting to hydrogen requires a lot of extra infrastructure to make the hydrogen and lots of extra electricity generating capacity.  Converting to heat pumps requires new infrastructure (radiators) in each household and 7/30 of the extra generating capacity that hydrogen electrolysis needs.  I wonder which works out cheaper?  Are people thinking about hydrogen-fuelled power stations so you can make and store hydrogen in summer then burn it in winter to meet demand?      

QrizB

Reed_Richards said:

QrizB said:

So the additional water required is equal to ten days worth of domestic usage.

Or roughly 3% extra water usage if you are typical.  Perhaps in future when there is a drought your gas supply will get cut off?  Or we'll discover that smart gas meters have a rationing function they haven't told us about?

I wonder which works out cheaper?  Are people thinking about hydrogen-fuelled power stations so you can make and store hydrogen in summer then burn it in winter to meet demand?      

I generally use more gas in the winter, when it's wet and cold, and less in the summer, when it's warm and dry (these past few dayes excepted).

Yes, you can store hydrogen which is one of the things promoted by its advocates. In my example, 330kg of liquid hydrogen takes up roughly 4.5 cubic metres. Storing the equivalent energy in lithium batteries would take roughly 35 cubic metres.

coffeehound

Reed_Richards said:
Are people thinking about hydrogen-fuelled power stations so you can make and store hydrogen in summer then burn it in winter to meet demand?      

 There's a company in S. Yorks manufacturing equipment to produce H2 using spare electricity generation capacity for energy storage and grid balancing

https://www.itm-power.com/markets/power-to-gas-energy-storage

It looks like we can already add 20% H2 to the gas grid in the UK