Heating Homes from Sewage

[MR10]

I found this article both interesting and fascinating

https://www.theguardian.com/environment/2023/nov/08/how-the-dutch-went-down-the-toilet-looking-for-heat-sewage

[joe90]

Makes a lot of sense, using existing warm water and heat pumps.

[SteamyTea]

Interesting idea, but not new.

 

Let us say that a house discharges 500 litres of water at a mean temperature of 20°C every day.

Cooling that water to 17° with a heat pump will yield:

 

4.2 [kJ/kg.K] x 500 [kg] x 3 [K] =  6,300 kJ or 1.75 kWh

 

Enough for a shower.

[MR10]

Read somewhere that Mogden Works discharged 20.6 billion litres of raw sewage between 2019 and May this year. It must be possible to work out roughly how much kJ can be harnessed and potentially put back in homes. 

Would this be considered 'renewable' I wonder?

[SteamyTea]

4.2 x (20.6 x 1,000,000,000) x 3 = 259,560,000,000 kJ (72,100,576.8 kWh or 72 GWh)

 

National Grid is currently reporting 35 GW of electricity is going though the grid.

So two hours of electrical generation.

[joe90]

If that was generated at the treatment plant you need a hot water distribution system, shame it could not generate electricity (if only to run itself).

[SteamyTea]

13 minutes ago, joe90 said:

shame it could not generate electricity (if only to run itself).

Sewage is already used to produce electricity.

That would be the main competitor thermal energy, and as you rightly say, redistribution would be the biggest issue.  Wires are cheap and easy, I wish the 'distributed urban heat network' advocates would realise this.  Would save a lot of time and wasted resources.