Power from a Pipe

Doesn't the city of Portland pay for the electricity to pump that water. Here's where the "free energy" comes from:

https://www.portlandgeneral.com/our_company/energy_strategy/power_generation/how_we_generate_energy.aspx

Exactly... initiatives like this should be entitled "Energy Recovery" or "Energy Consumption Offsets".

I remember reading about a person that put flapper wheels in the vertical runs of sewer pipes in apartment buildings. As the waste water fell, it would spin the wheels which were connected to small generators that would feed a storage bank. Although it is taking a source of kinetic energy and converting it to electricity, and a great idea I might add... it still isn't free.

Edit: But in defense of the article, it doesn't state 'free' but rather 'clean'.

Well, in fairness to the authors, these are installed where there are sections of pipe where the water falls and is not pumped. Of course at some point, water had to be pumped up to the point where it falls (like you said, energy recovery) unless of course the water source is at a higher elevation in which case we just have a stealth hydroelectric dam.

This came up a while ago and in that thread it appeared that Portland is supplied from a dam lake high in the mountains so we do have Sir Robins stealth hydro. I thought at the time that a proper hydro somewhere at the bottom of the hill would be far more efficient and generate more power but I do like the concept of this device of just when yiu need to replace piping drop one of these in

As noted below the pay back well it doesn't!

http://cr4.globalspec.com/thread/101889

The idea needs work its only applicable if your fresh water system is free powered.

Would 'lucid' being in their name imply they are dreaming and they know it?

From the article, where the writers must be smoking something in their pipe and they think they are lucid,

"Portland's project cost about $1.7 million, which was paid for by private investors. It's expected to produce $2 million worth of energy over 20 years."

Those are some seriously stupid investors. You give me $1.7 million in cash today, and I will happily pay you $2 million dollars over the next twenty years. I get to keep anything extra I make.

Psssst: I would break even if the growth rate was about 1.6%

http://www.annuitycalc.org (Nice handy tool.)

This doesn't include the original infrastructure which will (mostly) still exist at the end of the 20 years weighted of course against its asset depreciation and any maintenance costs or parts replacement over the 20 years.

Still doesn't look very promising economically at all, I would have thought a gravity fed turbine system would potentially produce more power, but if the turbine is only up to energy production speed a fraction of the time (flow to low bro), well there you go, so same problem as wind turbines placed in less than ideal areas.

A 'shit hitting the fan' joke was also in the works for this post but I didn't have the energy.

Holy $hit! If stupidity could fly, those people would be SR-71s.

If water is taken directly from water fall it would be economical(no power loss) but is it suitable for drinking. If it is drinking treated water from city mains there will be pressure drop(head loss)when passing through the turbine. If it is storm water it is fine. If it is waste water or sewage water do you need to protect impellers from clogging?.

I'd go with power from trees any time!

Drink water does not burn well!

Unless there is leaky fracking near your clean water supply.

If that makes it in the pipeline then its the problem from the water company.

And you would not need any stupid turbine if you have a free house delivery of fuel!

I nominate Water & Wastewater Systems as one of the dumbest organizations that GlobalSpec ever sponsored, if they believe that a closed system can produce more energy than is introduced into it.

The energy to pump the water isn't sent down from Heaven. It's produced by a motor.

That motor does not run on prayers or divine intervention. Somewhere, there's an energy source for that motor. Wanna bet it's oil? Oil is black, not green.

In some water systems the energy does come from gravity via the rain water cycle. Due to the geology of New York State the New York City water system is 95% gravity fed from reservoirs at a much higher level 50 to 100 miles away.

The website of LucidEnergy is honest: it is the exessive energy in gravity fed piping systems that can be captured. Nothing more novel than a water mill.

I have a comparable issue.

My home entrance of water is, depending the time of day, between 6 and 10 bar (0.6 -1 MPa)

this is to much for normal household equipment so I have installed a pressure regulator to have a stable 3.5 bar.

This reduction transforms energy from pressure to heat.

Is there a device that can transform this energy into electricity?

A turbine does this but has the nasty habit to be very flow dependant, no flow = no pressure reduction.

Anybody an idea on how to solve this for household applications?

Gwen

Yes but no

There may be devices but you accurately nail the problem - they only work when water is flowing. The liquid has to flow past a device to generate power. Where does this water then go? I expect you get charged for it in Belgium as they do in the UK - not sure how it works in Korea but I am sure its part of the bills i pay for my apartment but I dont have a water meter so maybe I could leave the water flowing, generate my own power no its just silly and wasteful of clean water

Just a nasty envelope calc suggest that even at the biggest pressure drop the hydraulic energy is 0.6kW for a 1l/s (16USGPM) flow (which would be quite fast for a domestic supply) so you might get 0.2kW when you had the water going flat out but that is so rare in a house - even a house full of teenagers wont have the shower for more than hour; washing machines only use water for a small portion of the cycle.etc

The lucid devices go in piping that is 1100mm in diameter, that run continuously and even then dont generate a huge amount of power. Add to the problems of generating erratic supply at suitable grid quality and this is just not worth the effort.

Even a green audit would say that the energy required to make the bits far outweighs the energy that could ever be generated so you should not do it.

Simon,

Your analysis is correct: the amount of energy in water is low.

The recuperation device should be cheap.

That is why I dropped the question in the group: someone an idea?

We could work it out, analyse the viability and eventually make it through a Kickstarter.

Gotta have flow to get power. Power = flow x pressure drop, just like electricity, amps x volts.

OK, that is new to most of us

how to get the energy out in the form of mechanic movement or electricity?

So that the efficiency is high (a simple paddle wheel will do but still requires a pressure regulator in line to have a functional result.

Work is force x displacement, or pressure x area (pipe cross section) x displacement. So Work = pressure x volume. Power = Work/time = pressure x volume/time.

Example:

If your pressure is 60 psi and volume flow is 12 cu in /sec, the power would be 60 ft lb /sec = 60 x 1.355817948 J/ft lb = 81.349076897 Watts

We have shown that there is almost negligible power available in your domestic system. Why then would you waste what little energy there is in a pressure regulator.

This is not a sensible application of technology. The amount of power generated is 10's of watts. As an exercise why not time how long you have flowing water in your house.

If the potential power generation exceeds 1kWhr I will be shocked.

Even if you had a perfect generator using Rixters figures of 81J you would need to be running the power gen for 3 hours to boil a kettle (5 mins at 3kW)

As I said above this system only makes sense in continuously flowing LARGE pipes.

"Unlike conventional hydropower systems that also tap the power of moving water, the LucidEnergy technology doesn't adversely impact marine life or generate large amounts of greenhouse gas, ThinkProgress reports."

Pardon me for being confused here, but what sort of conventional hydropower system generates greenhouse gasses? I thought Hydropower was converting the kinetic energy in the water into usable-to-humans energy. Sometimes keeping the energy kinetic as in waterwheel-powered mills (Old-school tech, but it still works, and they often look lovely on a riverbank or near a waterfall), sometimes converting it into electrical energy, as in hydroelectric plants?

ThinkProgress needs better copy editors, they're letting 'weasel word' phrases get out into published articles. Those phrases may invoke the 'Jedi mind trick' and sway lesser minds, but to a mind trained in Critical Thinking (as most Engineers should be) those phrases stick out as a flaw in the writer's style, and cause the writer's credibility to be questioned.

Just did a little research on ThinkProgress.

It's an outlet for the Center for American Progress 'Think Tank' (That's what they used to call PACs before the terms PAC and superPAC became common, right?) with public and annonymous donors funding it.

named donors include Walmart, CitiGroup and the United Arab Emirites. And the Center for American Progress is supposed to be taking a Liberal (left-wing) stance on issues? Walmart HATES liberal stances, those stances require them to do things such as treat Walmart employees as 'people,' not 'disposable comodities.'

I missed that comment the first time around but as we always say here Google is your friend and I found that

There is an issue with methane emissions for some time with hydro projects. But as always it depends. When a valley is flooded the submerged vegetation rots anaerobically forming methane. Methane has 21 times the climate impact of CO2.

So it depends how you flood the valley - it would suggest that harvesting all the wood is crucial etc. There is a time frame for this and about 3 - 5 yrs after is the worst. Its worst in tropical areas. They really don't know how bad it can be but apparently some Brazilian facilities might not save much on climate impact at all

Another parameter is the steepness of the reservoir. As water levels rise and fall a shallow lake exposes more land to grow stuff that is then submerged etc

Somewhere like Portland if the lake is more than 10 yrs old it behaves like a natural lake.

So the greenhouse gas is not 'produced' by the hydro plant, it's 'produced' by the design of the water source.

The article is still 'weasel wording' to make it seem as if some hydro PLANT designs produce greenhouse gasses, making their system 'better' when it is 'parity' at BEST, and most likely less efficient. A dedicated hydro plant can extract almost all the 'head pressure' from its source, since the output is a river or lake, where Gravity will continue the job of moving the water downstream. Using the flow from a water main means you need to leave enough head pressure to run the utilities 'downpipe' which may be trying to push the water 'uphill' to reach a 2nd or 3rd story bathroom.

From the stuff I read the issue with the hydro plant is that the release of methane occurs on the slipways etc of the hydro plant which is why they get fingered. But I agree with your analysis

A proper well maintained hydro is a good low greenhouse generator and generates a large amount of power. I am sure Portland would be better off with a large scale hydro at the bottom of the hill but I m a big stuff person

Other than vegetation can methane or similar gas/odour be produced by rotten vegetation,fish poo,dead fish,sediment at bottom or non-flowing stationary water in dams?.

There is no water in dams. Dams are dry on the inside.

Should be dry on the inside

But almost never are, completely.

Rule of thumb when visiting a hydro plant or dam. If the tour guide seems unconcerned by the alarm/siren/flashing light, then it's not a safety issue. If he/she seems to be anxious to get somewhere, try to beat him/her to the destination.