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Rocket Thrusters Used To Treat Sewage 73

Zothecula writes "Rocket engines are generally not thought of as being environmentally-friendly, but thanks to a newly-developed process, we may someday see them neutralizing the emissions from wastewater treatment plants. The same process would also see those plants generating their own power, thus meaning they would be both energy-neutral and emissions-free. Developed by two engineers at Stanford University, the system starts with the formation of nitrous oxide (N2O) and methane gas — something that treatment plants traditionally try to avoid."
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Rocket Thrusters Used To Treat Sewage

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  • by Monkeedude1212 ( 1560403 ) on Tuesday August 17, 2010 @01:17PM (#33277824) Journal

    Is it like... Rocket science?

  • On a hot day the Lowell, MA water treatment facility can me smelled for a good mile plus in every direction, strongly. And there's a low-incoming housing complex right next to it. How those poor people can live there is a mystery. Although I guess I just answered that. Ok, so not a mystery.

    At any rate, it would be a great candidate for this sort of technology. And I wonder how this tech could be applied to space travel and such self-contained environments or poor areas such as submarines, underwater fa

    • Re: (Score:2, Funny)

      by Kepesk ( 1093871 )
      And if rockets can be used to solve this stinky problem, what can't they do?

      Can't get into the pickle jar? Rockets!

      Neighbor's cat keeps leaving presents in your yard? Rockets!

      Excessive cell phone charges on your bill? Lasers! Then rockets!
      • Yes, I'm sure they will prefer the roar of a bunch of rocket engines 24/7 over the smell of sewage.

        • Can't be any worse than the roar of a few Cisco Catalysts and a few dozen servers, can it? Which would you prefer? You can turn up your TV or put on headphones, it's a little less comfy to walk around with nose plugs all the time. ;)

      • These scenarios sound like they should all end in... profit!

    • by Wyatt Earp ( 1029 ) on Tuesday August 17, 2010 @01:28PM (#33278004)

      Because after a few minutes you just won't smell it anymore.

      I've worked in a sewage treatment plant doing process pipe design. You don't smell it after about 5-10 minutes.

      • Re: (Score:2, Funny)

        by danbert8 ( 1024253 )

        Yes, luckily H2S numbs your sense of smell first... (note this is sarcasm, while H2S is the "rotten egg" smelling chemical, it can kill you pretty quick)

      • by hitmark ( 640295 )

        got to love how the brain takes away unpleasant, but not directly harmful, experiences.

    • How do you associate incoming with rockets?

  • Ah! I remember reading about the same idea in Stephen Baxter's "Manifold: Time" - http://en.wikipedia.org/wiki/Manifold:_Time [wikipedia.org]

    It has not ended well there :)

  • by vlm ( 69642 ) on Tuesday August 17, 2010 @01:20PM (#33277888)

    Why all the complication of a rocket engine (aerodynamic flow, high thrust to weight ratio, ignition problems, injector stability/howling issues, injector clogging issues, high pressure fuel pumps) when they could just pipe it into a nice boring fluidized bed?

    Sounds more like a stunt, to "get kids interested in science", than a solid technical engineering decision.

    • by kg8484 ( 1755554 ) on Tuesday August 17, 2010 @01:58PM (#33278422)

      Probably because they approached the problem from the other direction (e.g. not looking for something to do with all that N2O, but looking for a source of the gas).

      Brian Cantwell, a professor of aeronautics and astronautics at Stanford, has created clean-burning rocket thrusters that run on N2O. "We wondered whether nitrous oxide could be exploited as an emissions-free source of energy," Cantwell said. "Since the product of the decomposition reaction is simply oxygen-enriched air, energy is generated with zero production of greenhouse gas. But first we needed to find a cheap, plentiful source of nitrous oxide."

      That source, of course, would be the wastewater treatment plants.

      Seems like Cantwell developed the N2O rocket first and then looked for where to get fuel. He got in touch with Craig Criddle, "a professor of civil and environmental engineering and senior fellow at the Woods Institute for the Environment at Stanford," and this idea was born.

      • by vlm ( 69642 )

        (e.g. not looking for something to do with all that N2O, but looking for a source of the gas).

        The problem is that rocket fuel grade N2O (few particulates to clog the injectors, few corrosives, low water content, low contaminant content such as CO2, N2, etc) is frankly pretty cheap, about twice the cost of cow milk per volume.

        Even if N2O from sewage is magically "free" (don't they need enclosed tanks instead of open top tanks?), the filtration and purification plant is going to make it more expensive than the industrial product.

        So its all just a stunt.

        Finally I laughed at the whole concept of it bein

        • In ancient religions like Hindi and Taoism, they believe that there is a source of energy to all life, accessed spiritually by the body and by breathing. Your body blocks most of it, because you need very little to live; and by certain exercises, you can access much more of it.

          Do you honestly think that your body uses every ounce of energy it can get? If there's an infinite life force to access, your body doesn't need to access it at maximum burn. Similarly, with so many plants and bacteria and animal

          • by blair1q ( 305137 )

            In ancient religions like Hindi and Taoism, they believe that there is a source of energy to all life, accessed spiritually by the body and by breathing.

            They got the breathing part right, but you have to wonder how they missed the role food plays in it.

            Or maybe they couldn't care less about reality and were trying to find out who's gullible and who isn't.

            • They got quite a bit of the framework right. When you exhale, your breath is still usually pretty oxygen-rich. 21% oxygen going in, 4-5% less coming out. So yes, your body has access to a large amount of life-giving oxygen with each breath, and only uses a fraction of it (20-25% of the available stock in this case).

              They also believed that all life requires balance. Overdosing on oxygen, water, vitamin C, and the like seems silly; but you can do it. Hell, you can overdose on exercise. Gluttony and ano

          • "but why, when running just fine on that small bit of energy, would our bodies evolve to process carbon-rich complex fatty acids into methane and N2O and then slow-burn it metabolically? Especially when we can always acquire a hundred times more food than we need?!"

            Life has NEVER been able to acquire a hundred times more food than we need, except for the last few seconds of history. Life evolved to metabolize anything it could find, because food was ALWAYS scarce.

            Life doesn't decide to hide away exce
            • Life has NEVER been able to acquire a hundred times more food than we need, except for the last few seconds of history. Life evolved to metabolize anything it could find, because food was ALWAYS scarce.

              Right, that's why when I bring down a deer I eat it all in an hour and go looking for more. The big issue here used to be refrigeration; and the balance was that we get 75 pounds of meat so we get 75 cavemen together and SOMEBODY finds a deer and we ALL get 1 pound of meat. It's not hard to get 2 or 3 deer in a day (well okay, it's not hard like it's not hard to hit 4 or 5 home runs in a day... you can't do it, but someone whose only food source is what they kill damn well can).

              Or maybe large predators

    • Because they're changing the chemical environment to cause a lot more methane and N2O production. Then they burn the methane; but they don't have a way to deal with the N2O, so they use a different type of combustion system (a rocket booster) to burn that and emit oxygen and nitrogen gas (2N2 + O2). Normally, they add excess oxygen to the waste to produce N2; but the bacteria that fixate methane then get less fuel, and make less methane. So this process allows them to produce more fuel from human waste w
      • by vlm ( 69642 )

        but they don't have a way to deal with the N2O, so they use a different type of combustion system (a rocket booster) to burn that and emit oxygen and nitrogen gas (2N2 + O2)

        Still doesn't answer my question of why a rocket?

        Chemical oxidation is chemical oxidation no matter if you react it in a catalytic chamber, a boring old flame, a fluidized bed, or a rocket engine. They picked a rocket, which seems like a pretty stupid idea.

        A rocket engine : Has a high thrust to weight ratio so it flies further but is an unholy PITA to design, Operates at high pressure AND temperature so you need exotic materials (either one separately is way simpler than both simultaneously), rockets have

        • Rate of burn, burn characteristics, temperature, ability to direct output through a turbine (you wouldn't just pipe this into a chamber and ignite it...). Rocket engines consume fuel very quickly, and give a high amount of thrust. They're also the most energy efficient jet engine design as a group.
        • Have you seen any nitrous oxide engines being produced..? The only engines I'm aware that use NO2 are the ones that inject it along with gasoline (i.e. rice burners, drag racers, etc.).

          My assumption is that they want a rocket to increase consumption of the NO2, which a rocket would burn considerably faster than a simple internal combustion engine. An NO2 ICE still needs to be designed, which will cost money. And a rocket would burn much hotter, allowing for faster use of energy. You could use this to
  • Aww, shit (Score:3, Funny)

    by bl8n8r ( 649187 ) on Tuesday August 17, 2010 @01:30PM (#33278028)

    The shit will hit the fan with this in numerous ways:
    * Most likely raise shit with the EPA
    * Environmentalists will shit when they see the carbon produced in the process
    * Oil companies will continue not giving a shit about fossil fuel consumption

    • Re: (Score:2, Informative)

      by 21mhz ( 443080 )

      * Environmentalists will shit when they see the carbon produced in the process

      These must be quite ignorant environmentalists. The carbon in biomass is fixed for short time periods, so burning it is still carbon-neutral.

    • Environmentalists will shit when they see the carbon produced in the process
      Where exactly do you see the carbon in the chemical N2O? It decomposes into nitrogen and oxygen, or as we Earthlings refer to it, "air"!
    • Re: (Score:2, Informative)

      N2O doesn't contain any carbon. And as for the methane, when you burn it it gives off water and carbon dioxide. But the vast majority of the combustion reaction creates water. It's far better than releasing methane into the atmosphere without burning it. If environmentalists flip out over this, then fine... just release the methane into the atmosphere and see how happy they are. It's a much worse greenhouse gas than CO2.

      Besides, these "self-powered" plants will cut down on energy consumption and ve
  • I'm confused that the article thinks that this is a new concept. Many wastewater treatment plants already make use of the methane gas for on-site power generation. For example, East Bay MUD [ebmud.com] in California generates 90% of its power requirements at the primary treatment plant.
    • Re: (Score:3, Insightful)

      by nedlohs ( 1335013 )

      Why not read the article and see which part is new.

    • by bluefoxlucid ( 723572 ) on Tuesday August 17, 2010 @02:02PM (#33278488) Homepage Journal
      Yes, but this process produces more methane along with nitrous oxide fuel. It then adds a method to reduce N2O to N2 and O2, producing more power in the process. In this way, the primary treatment plant produces 110% of its power requirements without increasing emissions simply by adding a piece of equipment the size of a basketball and removing a waste aeration system.
      • by locallyunscene ( 1000523 ) on Tuesday August 17, 2010 @03:09PM (#33279452)
        Also, they mention that usually waste water plants try and limit NO2 and methane production by pumping air into the waste water.
        The benefits of this approach:
        1.) It reduces power needs substantially by removing the requirement to pump air.
        2.) It removes more nitrogen from the water in the process.(Hooray for not killing our oceans!)
        3.) The thruster can be as small as a basketball and handle all of the gas generated.

        You really should just read TFA; it's short, informative, and to the point.
    • by AB3A ( 192265 )

      Agreed. Anaerobic digestion usually results in lots of methane.

      I do not understand the rocket part. It could be burned to heat a boiler or in a four cycle engine. Why screw around with a rocket? It's not as if the thrust is needed for something.

      • If I read it right, the rocket is just a convenient way to burn the N2O to get rid of it, in the simplest and cheapest way possible. They happened to have this handy rocket engine design and those can be very simple if their controls are well designed.

        Getting useful heat out of the N2O is a handy side-effect. (Run a small steam cogeneration system with it if you feel ambitious. Or use it where you need a bit of extra heat.) But the main gain is the enormous extra production of methane, which can already

  • by drooling-dog ( 189103 ) on Tuesday August 17, 2010 @01:38PM (#33278134)

    I just had my main sewer line rooted a couple of weeks ago. If I had known I could use one of my spare rocket thrusters for that, I might have saved a bundle of money...

  • FTFA- "the system starts with the formation of nitrous oxide (N2O) and methane gas"

    We now have a scientific reason why we laugh at fart jokes.
  • Nuclear weapons, while also not generally thought of as environmentally friendly, are remarkably effective at vaporizing large volumes of human waste.
  • Developed by two engineers at Stanford University, the system starts with the formation of nitrous oxide (N2O)

    Any solution that starts with laughing gas is bound to be a success. And if not, nobody gives a rat's ass anyway. And it will be definitely a hoot and a half for all involved.

    Reporter: "Does the sewage plant still stink?"

    Resident: "Yeah, but I really don't give a damn anymore."

    This could be the beginning of a new age for nuclear energy, if the plants started spewing out nitrous oxide.

    Reporter: "Aren't you concerned that the nuclear power plant next door could be the next Chernobyl?"

    Resident: "Yes, I

  • From the article:

    Usually, air is pumped into wastewater sludge to boost its oxygen content. This promotes aerobic bacteria that convert the sludge’s sugars and other organic materials into harmless nitrogen gas.


    I presume at least one of those aerobic bacteria has a philosopher's stone in his pocket? Converting sugar, which is a carbohydrate, into harmless nitrogen gas, requires more than mere chemistry.

    Struck me there were a couple of similar chemical faux pas(ii? -- how does one do pluralization on such imports?) in the article, making one wonder whether some parts of it can be believed...

    • by JSBiff ( 87824 ) on Tuesday August 17, 2010 @03:16PM (#33279546) Journal

      Urine is the body's way of disposing of excess nitrogen: Urea (one of the components of Urine) has the chemical formula: (NH_2)_2CO.

      Thus, there's plenty of nitrogen in the 'other organic materials' in waste water. Not every hydrocarbon is exclusively hydrogen and carbon - other elements can be present too.

      • Not every hydrocarbon is exclusively hydrogen and carbon - other elements can be present too.

        Well, sure, if you are inventing your own language. Otherwise, "hydrocarbon" refers to compounds that contain only the elements hydrogen and carbon.

        Compounds that include hydrogen, carbon, and other things are not hydrocarbons. (Note that naming conventions may confuse some people on this, as, e.g., compounds containing chlorine, flourine, hydrogen, and carbon are called "chloroflourohydrocarbons", but are not a sub

        • by JSBiff ( 87824 )

          Fine, I screwed up on that statement. Rest of the comment is still valid. Urine in waste water is definitely a source of nitrogen, and is an organic compound.

      • I was aware of the presence of nitrogen in organic compounds (but not, I think, in sugar?).

        l may have misunderstood the intent of the original sentence, and simply reacted to the sentence itself. I suspect the intent was to suggest that N2 was created rather than NO2, but "organic matter is converted into harmless nitrogen gas" is not the same as "the nitrogen in organic matter is converted into harmless nitrogen gas" in my usage of the language -- I was, actually, expecting to see CO2 and water in the li

        • by JSBiff ( 87824 )

          Ok, this is how I read the sentence: "This promotes aerobic bacteria that convert the sludge's sugars and other organic materials into harmless nitrogen gas."

          So, I see that as meaning (sugars + "other organic materials" [Urine and maybe other waste products]) is reacted together/metabolized by the bacteria, producing "harmless nitrogen gas" (as well as other byproducts [I guess that would be your implied 'and whatever'] which the writer doesn't mention because he's not interested in them).

  • by BJ_Covert_Action ( 1499847 ) on Tuesday August 17, 2010 @02:51PM (#33279178) Homepage Journal
    Well I RTFA and there are some parts of the process that seem lacking. Essentially, a few rocket engineers said they could take the output gas from waste water plants (NO2) and use it to fire and burn a rocket engine. The emissions from the rocket engine would be oxygen enriched air. The power from the rocket engine is supposed to be used to generate electricity for the plant to allow it to continue processing waste water and producing rocket fuel, thus completing a fully self-contained power cycle and allowing the waste water plant to be self-sufficient.

    What's left out, however, is how the rocket engines are supposed to be used to generate electricity. Rocket engines are optimized to produce thrust. While liquid engines have turbine machinery in them, this engine would be burning gas with it's own oxidizer in the fuel (NO2). Without the separate fuel and oxidizer plumbing, I am not sure how much pump/turbine machinery would be in the design of the rocket engine. That said, I don't know what kind of spinning motion would be used to generate the electricity for the waste water plant. It would be nice to see some details on how the engine design will be used to actually produce electricity. Don't get me wrong, rocket motors are great sources of energy, but they very rarely, if ever, are used to drive electricity into a circuit. So I am curious if they are simply planning to use the nozzle flame to heat water for a steam turbine, or if they have an internal turbine that is driven by the NO2 (preburn) to drive a magnet surrounded by copper, or if they intend to stick a turbine in the thrust column of the engine (expensive materials).

    It's an interesting idea, but some technical details would be nice. Typically rockets attempt to minimize spinning components and, thus, are not nearly as good electricity produces as other types of engines that have spinning components as a fundamental part of their design (ICEs, Diesels, etc.).
    • \ facepalm

      Self-edit after rereading, s/NO2/N20/g in my post above.
    • The article doesn't really explain how they use the methane. Are they burning it in the 'rocket engine' along with the N2O (using the N20 as both a source of energy, and a source of oxygen for combustion of the methane?

      Is this in any way particularly different than the numerous existing natural gas electric power generation plants around the world?

      Don't get me wrong, this seems like a good idea - use the waste water as a source of energy to run the treatment plant, but, the use of a 'rocket engine' (e.g. ga

    • They could used something similar to a huge turbochager ( which is basically two turbines connected by a shaft) but instead of having the a second turbine compressing air, you could have the shaft connected to an electric motor to generate electricity.

      I am not saying this is the best or most efficient way ( it clearly is not ) but this was just as a possible answer to your question.
    • Re: (Score:3, Interesting)

      by LWATCDR ( 28044 )

      Simple they are not really going to use it as a rocket motor.
      My guess that is more PR than anything.
      Think of it as more of a wielding torch. IE it is going to be a burner.
      You but a big tank of water over it and make steam.
      steam that turns a turbine.
      Or you could use it with a Stirling engine but they cost more than a simple steam turbine.

      • Yeah, the more I read it the more I think you are right. There is nothing "rocket" about the science I would bet. Essentially, I would wager that all they are going to do is burn the N20 like in any other combustible engine and the only "rocket science" that will go into the process will be figuring out proper mixture ratios and flow rates...
        • by LWATCDR ( 28044 )

          Well a rocket is really nothing more than a really big burner with a nozzle. So yes I see this as nothing but a big steam kettle.
          The other option would be a gas turbine but then you would almost need to have some kind of EGR to make it work. If you add in NO2 to the a standard gas turbine I would think that it would tend push the temps very high and cause NOx creation issues. Using an oxidizer in a gas turbine at sea level would seem to just be a problem in the making.
          Unless the CH4 happens to be mixed with

    • Windmills, so it can be even more green
    • by Raptoer ( 984438 )

      It's a lot easier to think of it as a gas powered turbine that doesn't use atmospheric oxygen for combustion. It also seems like they're somehow reacting the N2O itself, instead of using it as an oxidizer for another fuel.

  • Nitrous Oxide is no laughing matter!
  • I preferred the Futurama [imdb.com] application of rockets to the garbage problem.
  • This was entirely not the article I expect, damn.

If I had only known, I would have been a locksmith. -- Albert Einstein