h a l f b a k e r y
Renovating the wheel
idea:
add, search, annotate, link, view, overview, recent, by name, best, random
meta:
news, help, about, links, report a problem
account:
Browse anonymously,
or get an account
and write.
or Create a new account.
|
|
|
Every time I flush the toilet I think of the release of potential energy and the waste of that energy, particularly at work, where I am 35 floors up.
Small Hydro plants at strategic points in sewers and especially tall buildings could add many kWh to the power generation of advanced countries.
I
cannot believe this has not been baked already, but I can't find any links. Maybe I'm looking in the wrong places?
I cannot believe it either
http://www.halfbake...a/Urinal_20Turbines
A big version of this. [angel, May 22 2001, last modified Oct 05 2004]
[1]
http://dnr.metrokc....ge/index-link01.htm
[egnor, May 22 2001, last modified Oct 21 2004]
[2]
http://www.ci.seatt...tomerguide/#ConStat
[egnor, May 22 2001, last modified Oct 21 2004]
Humanure
http://www.jenkinsp...g.com/humanure.html
No, shit, man. [hello_c, May 22 2001, last modified Oct 21 2004]
Biogas
http://www.rosewort...ogas/beginners.html
Cf. Thunderdome. [hello_c, May 22 2001, last modified Oct 21 2004]
[link]
|
| |
sounds pretty good... would save your company money on the electricity bill if they used their own employees' crap to power all those kWh being used while employees were wasting time on the internet. |
|
| |
Possile problem: cleaning the turbines - they'd get clogged up quickly I should think. (a) who'd want to do it, and (b) if you automated it, you'd have to use a lot of water to flush it out - not so environmentally friendly after all. |
|
| |
True egnor, but there's only one Columbia. There are millions of downpipes and sewers. |
|
| |
angel, I'm aware of that *piddling* little version of it, and how I got this idea. |
|
| |
Some sewer service districts in Oregon, USA, have looked at this a bit, I believe, not for pre-treatment lines so much as for the treatment plant outfall. If you have a city on a hill it could work, I think, but most sewer lines are laid at a fairly precise gradient so that the waste flows well but the pipes don't dive deep in the ground any faster than necessary--it's expensive to pump the water back up to near the surface so it can trickle downhill through the next long run of pipe. The upshot is, I think, that excess hydraulic head is engineered out of most sewer lines. Likewise, treatment plants are typically located at almost the same elevation as the receiving water, and in the couple of cases I know about there wasn't enough fall even in the discharge line to justify installation of a low-head hydro generator. |
|
| |
But it's a serious idea and one which, in various forms, has been put on the table several times over the years in my part of the world. |
|
| |
[High-rise buildings might be a different story. You might get enough head in the building's system to spin a generator. Once the wastewater enters the main sewer, though, I think probably the opportunity is lost--in order to keep waste from exfiltrating through pipe joints and cracks sewers typically avoid pressurization, so the flow from a tall building would just splat into the main and join the swirling mix.] |
|
| |
lewisgirl: Who would clean them? The city's public works department, most likely. They already have to clean lines and lift stations and storm gratings and so on. |
|
| |
lines, lift stations and storm gratings are nothing compared to what a couple of floors full of office staff can produce in a morning. And anyway, if this was a private energy resource (like having a couple of solar panels on the roof of your house), the City's public works department couldn't be called upon to clean it. It would be the in-house staff of the office block. I can see the arguments now... "the boys on the 28th floor eat more curry than our girls on the 29th - they should pay more for the poor little guy with his bog brush to shimmy down the pipe..." |
|
| |
And I'm most disappointed that my "employees on the internet too much" didn't get a rise out of UB. |
|
| |
To be honest LG, I didn't see the point. I posted the idea at 11:00pm, well outside working hours. I trust the fine distinction to be drawn there was not lost on you? |
|
| |
My Pop managed a Water District for 42 years. He was also Fire Chief for 19 of those years. He used some technology of his own design to make pre and post water treatments more efficient and eliminate unpleasant odor - even within a few feet of what should have been unpleasant odor - none. Since we share a common interest in hydropower in its various guises - let alone share the thumbwax family crest, I'll ask him next time we speak. |
|
| |
[1] King County, Washington (where I happen to live) processes a total of 240 million gallons of wastewater daily at two treatment plants. |
|
| |
Let us assume that every drop of that water falls 100 feet on its way to the outflow, and that we can harvest all of the potential energy lost by the falling wastewater. (Both of these are generous assumptions.) |
|
| |
E = mgh, so that's (900,000,000 kg) x (9.8 m/s^2) x (30 m), for a total of 73,500 kWh/day, which is an average power of 3MW. |
|
| |
[2] Seattle City Light's customers -- a subset of King County -- consumed 10,000,000,000 kWh during 1998. Dividing by (24 x 365), that's an average power consumption of over 1,000 MW. |
|
| |
So, if the system were *perfectly* efficient, a city's sewer system could supply less than 0.3% of the city's electricity. This is nothing to get too excited about. |
|
| |
Of course, that doesn't mean it's not worth doing. That analysis would require an estimate of the cost to build and maintain the generation system and how much power could actually be feasibly extracted -- more complex calculations, to be sure. |
|
| |
And the population of King County is 1,737,034 people from a total US population of 275,000,000. If we were to multiply your 3 MW of power production by 158.3 we get 475 MW generated daily, which is suddenly a significant number. (you could replace the Ross power plant in your area) |
|
| |
Though in the grand scheme of increasing energy consumption in the US, it's just a drop in the bucket, so to speak. |
|
| |
Perhaps we could divert it to fertilise cheap biomass fuel farming projects, thereby reducing the cost of that fuel. It's got to be better than pumping it out to sea for fish to eat. |
|
| |
Anything but that. Absolutely mindboggling that is even allowed. And egnor, I'm always impressed by your numbers crunching and ability to back up what you say as a result thereof. |
|
| |
Good idea, but sewage needs to be filtered first. Toliet papers are the worst pests clogging up drains! |
|
| |
Print confidential data on toilet paper, so you feel obliged to tear it into tiny pieces before you drop it into the water. |
|
| |
I wonder whether Col Oliver North had a shredder in his toilet? |
|
| |
PeterSealy: Yeah, methane is captured whenever possible--typically, sewage solids are fermented anaerobically for about a month in a heated tank; pathogens are (mostly) destroyed, organic matter is stabilized, and the anaerobes produce methane (mixed with about 30% carbon dioxide) which can be burned in turbine or piston engines to spin a generator. Landfills also capture methane produced by anaerobically decomposing garbage. There's quite a push to do this, as it is very cost-effective. |
|
| |
In many west-coast USA cities stabilized sewage sludge is used as a soil amendment on fields growing non-food crops like grass seed. A finite number of applications are allowed, usually, because the "biosolids" almost always contain small amounts of copper and/or lead which can accumulate in the soil. The sludge has a fair amount of nitrogen and phosphorus--enough to rate officially in the US as a soil amendment but not enough to be called a fertilizer. If the sludge is partially dried and then composted, pathogens can be eliminated completely and the product can be used on food crops. |
|
| |
(Everything you wanted to know about poop treatment and more...) |
|
| |
Once it's at ground level, I likewise would guess that biogas is the best way to get energy out of poop. Still, it seems a pity to waste the gravitational potential of all the garbage in skyscrapers. |
|
| |
Maybe not a hydro plant - how about a lever that gets pushed down by falling garbage (different channels for recyclables, trash, sewage; the latter fall into, say, tanks that keep them out of the clockwork). Eventually the trash is removed & the lever puts the energy somewhere useful on the rebound. Maybe we could run a paternoster with it. |
|
| |
Good idea. Let's vote on which paternoster we would like: |
|
| |
A fishing tackle device.
One of the large beads on a rosary string.
A prayer or a magic formula.
The Lord's Prayer.
A continuous chain elevator which passengers step on and off whilst it's moving.
I can't think of any other definitions, off the top of my head. The elevator idea is cool, shades of the movie "Brazil". |
|
| |
Mephista: Yes. Someones are getting serious. Threshold 1, water reclamation for specific uses, is already well established in places like Las Vegas, where reclaimed wastewater is used for non-drinking purposes (irrigation, industrial). Threshold 2, treatment of wastewater to regain drinking-water standards of cleanliness, is underway (and may be used in Israel, I'm not sure.) Most strategies involve filtration, as full-scale distillation is very energy-intensive. |
|
| |
Solids disposal has been driven by the expense of putting the material in a landfill, but has resulted in agricultural recycling of sewage sludge from most treatment plants in Oregon. (This was baked in China and Japan centuries ago, wasn't it?) |
|
| |
UnaBubba's original idea could be realized by using a large waterwheel located in the basements of skyscrapers. Unmentionable filth falling from above would plop onto the wheel, and it's size and robust construction would make clogging unimportant. Denizens of the basement--Morlocks, I think--tend the wheel and attached generator, invisible from inhabitants of the building except when they snatch a particularly plump intern to add a little protein to their diet. Only the wafting of certain odors thorugh the ventilation system betrays the presence of the Great Wheel of Krapma to those who labor above... |
|
| |
You simply have to look is the benifit worth the cost.
A huge water wheel at the bottom of tall buildings would require alot of maintenence, and a sytem would have to be devised to get the wheel to spin at a constant frequency, other wise there would be very little power generated. Water in sewers move at a very low flow rate, (except when there is a flood) but agian the problem of maintence would come up. The best place would simply be at the water purification plant. But it would have to be one of the dynamic type plants, the chemical and aggregate purification plants wouldnot be a likely place. And usually it is prefered to have a head of at least 100 ft, reaction and francis systems can operate with a head of only 5 ft but they require a very large water source and extremely high dynamic pressure.
But If someone can design a system to make all this work then I suppose it would be a good idea. |
|
| |
The reason this isn't done is the same reason tiny streams and ditches aren't dammed up. |
|
| |
There simply isn't enough energy there. |
|
| |
Oh, and also, you want the sewer lines (and ditches) to keep running. |
|
| |
We ran all of the lighting & power needs for several houses and farm buildings from two 6 ft waterwheels over the spring in the horse paddock when I was a kid. That did not include cooking, which was woodfired, nor vacuum cleaners or televisions, neither of which we possessed. |
|
| |
If we eschewed some of the power-hungry appliances with which we adorn our lives it would be relatively simple to do something similar for many people. |
|
| |
Ok, then, when are you giving up your computer? |
|
| |
I assume that this sludge is fairly acidic. Why not dunk some electrodes into the flow and extract electricity that way? A constantly recharged battery, or a kind of fuel cell. |
|
| |
I would think it more likely that household sewage will be alkaline, because of the carbonate, bicarbonate and sodium hydroxide content of cleaning products as well as the carbonates released by the breakdown of foodstuffs. Carbonates generally run at pH levels above 8 point something (high school chemistry was a long time ago). |
|
| |
Likewise, phosphates, common in many soap products, raise pH levels above 8.5, where eutrophication of affected waterways and water bodies occurs. I've seen this happen on golf courses, where fertilisers have caused fish kills in standing bodies of water. |
|
| |
Does anyone here actually know whether raw sewage is acidic or alkaline? |
|
| |
There I was innocently sitting in the cafeteria at work when suddenly a fantastic idea strikes me. Why not use the kinetic energy of a skyscraper's wastewater to generate power with a turbine? I'll be rich, I'll be famous, and better yet I'll be able to come up with a really swell fecal-related acronym to call the thing (tougher than it sounds- Subterranean Highspeed Inline Turbine was the best I could come up with). After some online searching though, my dreams were shot down. Curses, half-bakery! Like they say, there are no new ideas under the sun. Therefore we must travel to the center of the sun to discover the abundance of fantastic ideas that await! |
|
| |
Even better in stormwater drains. |
|
| |
Impeding the flow of stormwater sounds like an awesome idea. |
|
| |
Sewer water too. Maybe more so. |
|
| |
Then ye shall see no power. Power generated is the volume flow rate multiplied by the pressure drop across the turbine (multipled by the efficiency of said turbine). |
|
| |