EcoModder Forum Pee power!

Register Now
 Remember

 11-13-2012, 07:50 PM #1 (permalink) Moderate your Moderation.   Join Date: Nov 2008 Location: Troy, Pa. Posts: 8,919 Pasta - '96 Volkswagen Passat TDi 90 day: 45.22 mpg (US) Thanks: 1,369 Thanked 430 Times in 353 Posts Pee power! Teenage Girls from Africa Invent a Urine-Powered GeneratorEndAllDisease.com This has been floating around FB lately, and I caught "the bug", so I did the math based on what was being presented. I was as loose as possible with the figures, hoping to give it /any/ chance of being real, but provided I covered all necessary points, it ends up being break-even in a completely perfect environment, if not a net loss of energy. Anyone care to correct or add something? Here's my comment on the page and on FB regarding it: Has anyone actually done the math on this? There isn't enough hydrogen in the water present in 1 liter (volume) of urine to actually make 6kw/h of electricity. Unless they're talking about running at nearly zero load for 6 hours, or we're missing some very large part of the story, there's literally nothing about this that can work. It takes energy to separate the hydrogen from the urine, which comes from where? Hydrogen (raw) is 51,500 BTU/lb. Electricity, given a 100% transfer efficiency, requires 3,413 BTU per kW/h. In a liter of urine, which for a healthy person, should weigh no more than 8.5 lb/gal, there is about 2.25lb of weight total. Of that, even if it were pure H20, would at best, and not accounting for losses, produce only 420 grams (just under a pound) of H2. The energy required to maintain electrolysis for a gallon of water = 168,164 BTU. So, 44488 BTU for 1 liter of water. Assuming the processes were still 100% efficient at this point (which is not only an exaggeration, but currently impossible), you would be left with 51,500 - 44488 = 7102 BTU of energy to feed the generator to produce electricity, and that's BEFORE losses. So you've basically got 2kW/h of AVAILABLE fuel before accounting for any losses in the entire separation/energy transfer process. Believe me, the losses would eat that up in a heart beat. __________________ "¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"
 Today Popular topics Other popular topics in this forum... View the most popular topics in this subforum by views or by posts
 11-13-2012, 08:01 PM #2 (permalink) EV convert     Join Date: Jul 2011 Location: NewMexico (USA) Posts: 9,706 Sub - '84 Chevy Diesel Suburban C10 SUV 90 day: 19.5 mpg (US) camaro - '85 Chevy Camaro Z28 Riot - '03 Kia Rio POS Team Hyundai 90 day: 30.21 mpg (US) Bug - '01 VW Beetle GLSturbo 90 day: 26.43 mpg (US) Sub2500 - '86 GMC Suburban C2500 90 day: 11.95 mpg (US) Snow flake - '11 Nissan Leaf SL SUV 90 day: 141.63 mpg (US) Thanks: 231 Thanked 3,169 Times in 2,486 Posts I saw something kind of like that on discovery channel where in Indina people were taking apart dead alkaline batteries and sticking the electrodes in cow poop, they got enough power out of 6 or 8 poo cells to charge a cell phone battery. __________________ 1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost. 1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end. 2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.

Join Date: Nov 2008
Location: Troy, Pa.
Posts: 8,919

Pasta - '96 Volkswagen Passat TDi
90 day: 45.22 mpg (US)
Thanks: 1,369
Thanked 430 Times in 353 Posts
Quote:
 Originally Posted by oil pan 4 I saw something kind of like that on discovery channel where in Indina people were taking apart dead alkaline batteries and sticking the electrodes in cow poop, they got enough power out of 6 or 8 poo cells to charge a cell phone battery.
Did you read the article? They're attempting to electrolyze human urine into "brown's gas" (not really, but close enough) to burn in a generator.

They're suggesting it will provide "6 hours of electricity" (their words), which one can only assume means 6kW/h, from one liter of urine.
__________________
"¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"

 11-13-2012, 08:22 PM #4 (permalink) (:     Join Date: Jan 2008 Location: up north Posts: 12,761 Blue - '93 Ford Tempo Last 3: 27.29 mpg (US) F150 - '94 Ford F150 XLT 4x4 90 day: 18.5 mpg (US) Sport Coupe - '92 Ford Tempo GL Last 3: 69.62 mpg (US) ShWing! - '82 honda gold wing Interstate 90 day: 33.65 mpg (US) Moon Unit - '98 Mercury Sable LX Wagon 90 day: 21.24 mpg (US) Thanks: 1,585 Thanked 3,548 Times in 2,215 Posts Here, I was looking at that too: http://ecomodder.com/forum/showthrea...tml#post339605 __________________
 The Following User Says Thank You to Frank Lee For This Useful Post: Christ (11-13-2012)
 11-13-2012, 08:35 PM #5 (permalink) Moderate your Moderation.   Join Date: Nov 2008 Location: Troy, Pa. Posts: 8,919 Pasta - '96 Volkswagen Passat TDi 90 day: 45.22 mpg (US) Thanks: 1,369 Thanked 430 Times in 353 Posts Yeah, basically what that article is saying is exactly what I was thinking. It's valid for a waste-stream, but to actually power anything, they're violating the in/out principles. __________________ "¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"
 11-13-2012, 08:39 PM #6 (permalink) (:     Join Date: Jan 2008 Location: up north Posts: 12,761 Blue - '93 Ford Tempo Last 3: 27.29 mpg (US) F150 - '94 Ford F150 XLT 4x4 90 day: 18.5 mpg (US) Sport Coupe - '92 Ford Tempo GL Last 3: 69.62 mpg (US) ShWing! - '82 honda gold wing Interstate 90 day: 33.65 mpg (US) Moon Unit - '98 Mercury Sable LX Wagon 90 day: 21.24 mpg (US) Thanks: 1,585 Thanked 3,548 Times in 2,215 Posts You got it! __________________
EcoModding Lurcher

Join Date: Dec 2010
Location: Los Angeles
Posts: 324
Thanks: 147
Thanked 102 Times in 74 Posts
Quote:
 Originally Posted by Christ Did you read the article? They're attempting to electrolyze human urine into "brown's gas" (not really, but close enough) to burn in a generator. They're suggesting it will provide "6 hours of electricity" (their words), which one can only assume means 6kW/h, from one liter of urine.
I think the 6 hours is just idling the generator. But you should read the link in the article "cracks the urea" You'll need to redo your math.

There they say that the energy to electrolyze urea is about 1/3 of that required for water. Of course a liter of urine only contains a few grams of urea.
-mort

Join Date: Nov 2008
Location: Troy, Pa.
Posts: 8,919

Pasta - '96 Volkswagen Passat TDi
90 day: 45.22 mpg (US)
Thanks: 1,369
Thanked 430 Times in 353 Posts
Quote:
 Originally Posted by mort I think the 6 hours is just idling the generator. But you should read the link in the article "cracks the urea" You'll need to redo your math. There they say that the energy to electrolyze urea is about 1/3 of that required for water. Of course a liter of urine only contains a few grams of urea. -mort
Like I said, I was being REALLY LAX on the numbers in hopes that it could SOMEHOW work.

Urine is like 97 percent water by volume. Ergo, water would be the best candidate to remove the maximum volume of hydrogen per unit energy invested from that particular medium.

Actually leaving the urea in the water lessens the electrolytic load necessary to separate the hydrogen from the oxygen, but it's still completely unrealistic.
__________________
"¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"

EcoModding Lurcher

Join Date: Dec 2010
Location: Los Angeles
Posts: 324
Thanks: 147
Thanked 102 Times in 74 Posts
Quote:
 Originally Posted by Christ water would be the best candidate to remove the maximum volume of hydrogen per unit energy invested from that particular medium..
No, really, read the link. The urea electrolyzes at a much lower voltage than water. The water doesn't participate in the energy equation in this case.
-m

Join Date: Nov 2008
Location: Troy, Pa.
Posts: 8,919

Pasta - '96 Volkswagen Passat TDi
90 day: 45.22 mpg (US)
Thanks: 1,369
Thanked 430 Times in 353 Posts
Quote:
 Originally Posted by mort No, really, read the link. The urea electrolyzes at a much lower voltage than water. The water doesn't participate in the energy equation in this case. -m
I'm aware. Like I said, I was trying to give them the absolute best chance of success. The amount of urea salts in urine wouldn't be able to produce the amount of hydrogen necessary to do what they were claiming, so I went the other way with it.

__________________
"¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"