Last week I wrote about the carbon emissions from the water system, and how those emissions increase as climate change puts pressure on water supplies. As a follow-up, here’s an interesting solution highlighted by DW’s Planet A series on Youtube. They highlight how the water system can be used to generate electricity, through in-pipe turbines.
Not something I’d heard of before, but it’s been done successfully in a number of locations. What is particularly exciting is that perfecting this technology now means it can be fitted as standard in any appropriate cities in the global south where water infrastructure is still being built.
The Earthbound Report 
This is a very deceptive article and video. The practical application of this technology is VERY limited. Basically just to places where there is EXCESS water pressure. I.e. you have to already have too much of it, for example because your reservoir is at the top of a mountain. This is not applicable to the majority of cities. Indeed in most places, if you start harvesting energy from the mains water pressure, you will simply be stealing energy from the water companies (at a very low efficiency) because they will have to pump more water to bring the water pressure back up again. Promoting this as something which is environmentally beneficial is irresponsible.
I would have expected better from you, Jeremy, in doing due diligence to ensure that this is not ‘fake news’ before publishing something like this.
Fake news is a little strong! The video mentions five cities where it’s already being done, so it’s clearly not fake.
Portland, which is the one they mention first, has in-pipe technology in a place where the water runs downhill and doesn’t need to be pumped. That’s where it’s applicable, sure. No, it’s not going to be installed everywhere, but a huge number of places have gravity-fed water systems where it may be appropriate. It can be retrofitted, but where infrastructure is being built for the first time, that’s a real opportunity to make it a low carbon system from the outset.
Am I addressing all the detail of the technology? Clearly not, in a two paragraph article recommending a video! But it’s a new idea with potential. The thing now, as with any new idea, is to work out where and when it can be applied – not to declare it a game changer too quickly, and not to dismiss it too quickly either.
Fascinating idea, but the commenters cite some issues.
The main one was that these turbines would put more resistance to flow in the system and therefor require more power to move the water.
If there is too much pressure in the system, other commenters suggested better regulation of the pumps creating the pressure. This would reduce the energy consumption of the pumps and may extend their life cycle.
If you have natural pressure from moving water to a lower elevation, this idea may have a positive impact on energy consumption.
As in most cases, reducing consumption would reduce the problem. If people used water wisely and if utilities put more money into pipe maintenance, they could reduce the amount of water they need to move which would reduce energy consumption and pressure on the water resources they draw from.
What a brilliant concept. We have a pressurized hot water tank to enable us to use our rooftop solar hot system. Regulations (and common sense) demand that the pressure in the tank be regulated, so a pressure reduction valve reduces the pressure to 3bar. So our showers have balanced pressure, the cold water is fed from after the valve, so also at 3bar. Only two taps in the house are directly connected to the mains and both these use the service valve to stop the flow so that we don’t get sprayed with water every time we turn on the tap (and also don’t use too much).
So it seems to me to be a no-brainer to fit a turbine at the house stop tap to both reduce the pressure to 3bar (or even 2.5bar would still give us decent showers) whilst generating electricity, which could then charge batteries for use around the house.
So I look forward to someone developing a WRAS approved combined turbine and fixed pressure outlet that I could fit to our water main.