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Thread: harvesting waste heat from my water heater

  1. #31
    General Engineering Contractor ballvalve's Avatar
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    Ge didnt put the plant on a beach in a KNOWN tsunami and earthquake hot zone. And the Japanese put the poison on the roof to save buying some non-existent or expensive real estate.

    If GE had any part in the infrastructure design, which as you know the Japanese are too proud to allow, it at least would not have put the gensets in a hole or in front of the plant. It was the spent fuel that should have been in the sealed hole, and the gen sets on the roof.

    And these are the engineers that we all bow down in front of a Subaru for?

    In any case all of our present power gen systems will loook like wooden sewer pipe in a museum in 40 years.

    What will bring particular laughs is a gasoline engine that could heat a Walmart, pushing one old frail lady to the Winn-Dixie, in 6,000# of Iron.

    So they built Solyndra without taking a tube to Wisconsin in the winter? Sounds like Fukastupidity.

    I dont care how your panels shed snow when you have a week of fog and clouds. Which is why our deserts may soon look like down town New York.

    The French, being so goofy in most things except food, managed to build out most all of their fossil fuel with nuclear. Why does it work for them?
    Last edited by ballvalve; 10-24-2011 at 11:27 AM.

  2. #32
    In the trades Dana's Avatar
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    where to begin...

    The French nuke system was paid for with a huge subsidy pushed on the backs of the French taxpayer, and contrary to popular opinion in some quarters doesn't really work very well for them at all. During sustained high air conditioning load conditions they run out of cooling capacity and have to either get a waiver to allow them cook all the fish in the rivers, or import power from Spain & Italy (if they have any spare capacity to trade) at peak-prices. In order to avoid falling short for the AM demand ramp they have to run them all night in power-dumping mode. Fortunately for them they can usually sell off-peak power to Spain & Italy (usually at a financial loss) otherwise something like half the power would have to be sent out the cooling systems. While the net balance of megawatt hours traded to their neighbors is in France's favor, the balance of cash value of those megawatts traded is not. They sell at loss during off-peak just to keep revenue for those plants they need to keep going all night non-zero, and buy only peak-power back.

    The French system was pitched to the taxpayer back in the 1970s and early 1980s as a means of reducing oil imports, despite the fact that oil was never a big player on electricity production in France, and their transportation sector was then and is now largely fossil-fired. Wherever French nuclear designs have been exported, the contract price is high, and even then no project to date has come in on-budget. They've gotten away with it in France, but it's not exactly a model of efficient or economic grid operation, rather it's a model of a government picking a winner and sticking by it even when proven to be a loser. Were it not for the huge capital investment already put up they'd be better off decommissioning 30-50% of them off and doing something more flexible. France more than any other country needs electric cars and smart-chargers, just to have a load for buffer their copious excess off-peak and baseload power of their overbuilt nuke fleet, but it will still be more expensive electricity than PV circa 2020.

    And GE surely did TOO put the plant on the beach in Japan, who are you kidding? If GE engineers had issues with where & how the customer wanted to configure and site the equipment, it didn't stop them from commissioning the plant, eh? Nukes aren't packed up in a box and dropped on the pier with a "some assembly required" instruction packet. If site plans were not consistent with GE's best-practices guides, they didn't let it get in the way of the sale. Japanese law may leave them largely off the hook, but it's a stretch to say that any egregious oversights were solely on the part of the Japanese operators.

    And SFAIK no automotive engineers from Subaru were involved in the design or siting of the Fukushima plant.)

    I have no idea as to whether Solyndra had snow-country field testing of their designs or not, but since they're not insulated evacuated tubes I'd be surprised if they had a long snow-melt situation the way some thermal-tube panels can. As long as their tubes were mounted on racks taller than the anticipated snow depths the sides of the tubes would shed snow pretty readily, and the solar gain would then raise the temp of the glass to clear the rest. I was never convinced that they could build their panels sufficiently cheaply that their cheap racking system would make them viable, but they had a lot of people convinced that it could work when silicon flat panels were over $6 per peak-watt. At $3 peak-watt and falling there's simply no way. There is definitely an industry shake-out in progress as growth in PV soars at the lower price point. On my daily commute (in a snowier climate than WI) I pass something like a dozen small scale solar installations, both PV and thermal- snow burial is not a problem- the only system than hangs onto snow for more than 24 hours after the sun returns is the evacuated tube thermal system on the roof of the Aka Bistro in Lincoln MA. In 3 days it's usually clear, even if the temps stay sub-20F.

    All generating power needs backup, including (especially?) nukes, which need to be periodically shut down for days or weeks on end for maintenance or refueling. With solar the regional output is predictable with the weather, and the degree of grid-hardening something that can be calculated. The wintertime and nighttime reduction in output in cold places can be nicely offset by the relatively increases in output of micro-cogenerators as part of the grid-mix even without smart-grids. But to achieve a very high level requires smarter systems to be sure. Over wider regions wind power functions remarkably well as base generators, and the average wind power output is predictable days in advance by weather. Unlike large centralized power systems, taking small scale local generation offline for repair has no impact on the grid operation as a whole- fixing a 1-5kwh home-scale cogenerator does not need to be scheduled with the grid operator any more than testing a 5 ton air conditioning compressor does.

    Oversized desert development of solar power are hampered by grid infrastructure costs and loss of efficiency of PV at high temps. It's cheaper & more efficient to use solar-thermal boilers as the heat source for more conventional turbines in the desert than PV, but if you need to build a huge transmission line to hook it up the point becomes moot. Maybe Las Vegas and Phoenix could get a substantial amount of power that way, but the costs of the infrastructure for shipping that power to LA & Orange county are ridiculous, especially compared to how cheap it is to do on-site PV nearer those loads. And smartening up the local grids to better balance capacity to load and going aggressively after efficiency are still far more cost effective than any new source generation. The efficiency well is deep & cheap- too cheap to be able to rationalize building a whole new fleet of nukes.

  3. #33
    Retired Defense Industry Engineer jadnashua's Avatar
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    FWIW, regarding Niagra Falls, at night, they keep enough water going over them to keep the tourists happy. There are some really significant tunnels that run the water to a reservoir that have the capacity to actually stop the flow at the falls. They run out of the reservoir for the most part during the day for power generation, and adjust how fast it is refilled, based on the available flow and system load.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  4. #34

  5. #35
    General Engineering Contractor ballvalve's Avatar
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    When Chinese submarines start a Blitzkrieg, the French will be very happy to have their expensive power.

    And they have some nice mountains in France, no reason not to pump water uphill at night.

    As to infrastructure from Utah to LA, I understand LA gets a huge amount of its power from coal plants in Arizona and Utah, and even Hoover dam. Those towers you drive under on the way to vegas from LA make your hair stand on end, and could stop a pacemaker. I know that power is not going east.

    Tehachapi has problems getting its wind power 'out', but the hideous mess of wind turbines around Palm Springs ties into the existing import grid.

    Japan keeps a tight lid on its designs and locations, by cultural nuance, so I hardly believe that GE did anything without a gaggle of japanese engineers modifying and approving it. Looks like they NEEDED a review by a Subaru engineer, or perhaps a good mechanic or fisherman to tell them their plan was patently absurd.

    Fuel rods on a ROOF on a beachfront property perfectly known for a future monster earthquake? Now thats a useful class action suit. Gensets that my mother could figure were in a ridiculous location?

    We are not much better brainwise with a perfect billion dollar hole in Nevada sitting empty. Perhaps we could at least move the national archives there along with the backrooms of the Smithsonian.
    Last edited by ballvalve; 10-26-2011 at 11:19 AM.

  6. #36
    In the trades Dana's Avatar
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    I'm sure there are places to site large PV or solar-thermal turbine generation along existing transmission lines. But there's very little reason to do so with PV- there isn't really much economy of scale, and the transmission losses over the long-haul lines and multiple transformers between generator & load cut into any increase in solar output from the same panels by siting them in AZ or UT instead of on rooftops in L.A. or Orange County next to the loads. With remote generation & large transmission lines the grid is less stable, more susceptible to disruption compared to a widely distributed model to. It's a model that only makes sense if there ARE great economies of scale.

    Somehow foggy-dew northern latitude Germany is making huge headway on making distributed PV a nice slice o' pie. It was at quite a cost intially, but still cost-competitive with nukes, if not untaxed coal. At current PV pricing and German feed-in tariff it's a no-brainer investment for anybody with an unshaded roof or yard. Unlike nuclear projects, it's dead-easy to get private capital to finance PV these days.

    When the Chinese subs start a blitzkrieg we're all screwed (even the French, eh? ;-) )

    If the transmission lines to Spain & Italy are cut, the French are screwed, since they would have to throttle back to something like 1/4 capacity on the nukes overnight, and they don't just wake up when the alarm clock rings- they'd be short daytime capacity. If they had stopped at only 1/4 of their power from nukes they would have been fine, but circa 1980 projections of the total grid load circa Y2K proved to be wildly overstated. Prediction of future demand is a huge risk factor when building decade-long giga-projects, but once they break ground it's nearly impossible to halt the project in the face of newer-better projections, due to all sorts of political ramifications (unions, unemployment payout, contractual obligations to the builders etc.) Only a major financial crash like the WPPS fiasco seems to be able to stop a nuke once the project begins, regardless of how outlandish the cost overruns are. In the French case the construction was entirely a government run project- none of the administrations (of any party or coalition) had the political gravitas to be able to pull the plug on any of them after the initial sales-job, but it was pretty obvious by the '90s that things were out of hand.

    If pumping water uphill were economic in France, they'd be doing it already rather than taking the financial hit from power dumping and selling off-peak at a loss to their neighbors. It's theoretically possible, sure, but I suspect there are better grid investments that they could be making (and I suspect they already ARE.) Their ability to export their nukes within Europe and build 'em on-budget has proved to be an international fiasco.

  7. #37
    General Engineering Contractor ballvalve's Avatar
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    They can sell to Germany that is closing all its nuclear decades prior to reasonable re-evaluation.

    Or Germany can sell its soul to the devil Russia and use its gas until they get in a bad mood and shut it off.

    Huge controversy in California about applications for MEGA PV farms in BLM - public lands areas, Which is about 1/3 of the state..

    They are out collecting desert tortoises just now for relocation on a monster PV farm.

    Unless China goes to about .9 births per couple, you can expect the lemmings to come over the cliff at some country. Best we keep our thermo-nuclear arsenal polished up.

    I did tons of copper roofs at $1.65 a pound, now I get $3.85 for my SCRAP. Welcome to India, Asia and China with satellite TV.

  8. #38
    In the trades Dana's Avatar
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    They can only sell to Germany if they're buying, but maybe. The majority of new-generation capacity in Germany is renewables. Germany has quite a bit of untapped coal seam gas, if things turn dicey in the east.

    Mega PV farms make no real economic sense, since the economies of scale of megasystems don't give it a cost advantage over 100KW locally sited (and no much over 10KW rooftop installations). It's no surprise that building monster systems on public lands is controversial.

    Yes, "the rise of the rest" does indeed impact resource economics of the already-developed world. Raw materials costs will continue to rise along with the standard of living in the developing world. When it's no longer economic, copper roofs and pipes will become rarer than they already are, but the developed world will still have roofs & pipes. Copper wire may be a more critical issue, since there are few good substitutes.

    The annual net annual emigration rate of China is between -0.25 and -0.5 persons per 1000 per year. That is controlled by their own national policies- they make it difficult to leave. If things get out of hand internally they can easily increase that by an order of magnitude or more, which is perhaps a bigger risk to the west than wars over resources. At the moment it's tough for them because a large fraction of the emigre's are the educated (particularly the foreign-educated), and the wealthy, representing a brain and cash drain for the nation as a whole. They work hard at attracting those on the fence, and even those already out of the country back in, with some modicum of success. (Most of large Chinese PV companies have of former ex-pats at the helm and in the engineering & management.)

    FWIW: I have a nephew who married a Chinese national who was working on her PhD in the US (and continues to live & work here after earning the degree.) Before they married he went with her to meet the 'rents and get their approval, but getting her back out of the country became a real project of it's own taking several weeks. China had invested a lot in her education, and someone clearly did NOT approve of her marriage & emigration plan. But as China become richer, attracting more foreign investors, these policies are likely to change.

  9. #39
    General Engineering Contractor ballvalve's Avatar
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    But the Chinese are masters at sending their kids to our universities, to harvest a century of our knowledge without controls, and happily wave them off to China to build the new missile and spacecraft.

    The Chinese recenly stole some incredible code for our wind machines that will set us back decades in any advantage. Wall street journal - all the rest of the news is about sports on TV.

    We have taken freedom to a new level of self destruction. And I assure you a gaggle of Soviet scientists at 500$ an hour are working the centrifuges for the next piece of global warming between Israel and Iran.

    Soviet engineers in Russia get paid in Vodka.

  10. #40
    In the trades Dana's Avatar
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    Theft of intellectual property (as happened recently & blatantly with American Superconductor's special-sauce on wind turbine components) is a problem with more than just Chinese competitors, but it's a relatively new concept for their legal system, and it's (slowly) changing. Evergreen Solar just headed to China with their ribbon-growth silicon crystal technology, which is going to be ever more difficult for them to protect, I'm sure. It's a problem for both China and the rest of the developed world.

    Educating the foreign-born has been more of a benefit to the US than a problem. The US economy has managed to skim a big slice of the best & brightest that way (and I'm not just talking about my nephew's wife), reaping the advantage of some of the best-educated people in the world, and mostly paid-for by their home countries/families. Without European-educated ex-pats we'd have taken decades longer to develop nuclear technology and rockets, there simply wouldn't have been a space program anything like the 1960s. It's not all invented here, and it's not all "stolen" from here.

  11. #41
    General Engineering Contractor ballvalve's Avatar
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    Looks like Evergreen should have gotten Solyndras 5 mil in order to stay here.

    Lets watch Dr. Strangelove and be reminded of our German ex-pats contribution to the rocket race after the war.

    And thank Hitler for driving so many Genius Jews here before the war.

  12. #42
    DIY Senior Member Runs with bison's Avatar
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    Didn't see any serious replies since the end of page 1, but I would have three concerns:
    1. Condensation in the flue--if it works you will get a lot of this. This is generally not a good thing since the condensate has to go somewhere and it is moderately corrosive with all that CO2 dissolved in it (carbonic acid--although I'm accustomed to dealing with extremely corrosive HCl condensation in high dollar chemical recovery furnaces.) A condensing system typically has stainless parts to account for the carbonic acid.
    2. Potential for draft problems. Depends on how efficient the system is in removing heat and the overall dynamics of the home/outdoor temps/HVAC. Cooler air equals less draw (lower differential pressure to draw flue gas out.) I've never had combustion draft problems in any home--except in fireplaces with short chimneys.
    3. Cost vs. benefit. For my home and already efficient uses, a drain water heat recovery system is marginal at today's gas rates (I'm still curious enough that I'll probably install one some day since I've worked on similar equipment industrially.) Without doing a detailed heat transfer and mechanical design I anticipate a flue gas recovery system is going to be even lower efficiency and require a lot more copper/stainless for the same duty...even though I have ~20 feet of vertical stack to play with. Gas side heat transfer coefficients with natural draft are typically very poor even with partial condensation (the higher percentage non-condensibles are a killer IIRC) so it takes a fair bit of area to accomplish much. And that gets pricey with copper or stainless.

    Note: a key consideration for me in a drainwater heat recovery system was pressure drop on the supply water side--this can be substantial for the area required. To do this efficiently can require parallel flow paths such as dual or quad coils.

    It is more efficient to design a proper exchanger in the tank (a condensing unit with induced draft) with proper material and layout than to do an economizer on the flue gas. But condensing in the tank is also pricey. So while I would gladly take a condensing unit offered to me for free, a drainwater heat recovery system appears to be better bang for the buck with today's pricing if I must pay for it myself.

  13. #43
    Master Plumber master plumber mark's Avatar
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    Default here is a better idea

    you guys are a hoot....... that coil idea has been out
    for a long time but has nver taken off because there is
    not enough energy worth re-capturing......

    just put a water heater blanket on the heater and be happy....


    here is another great idea ....

    if you really want to save all the energy
    you can, why not just take the chimmney off the water heater
    and let all the heat just flow into the home....
    just think of all the energy you would save doing this......

    you could also do this with your dryer vent...
    ..
    if you start to get a headache, step outside

  14. #44
    In the trades Dana's Avatar
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    Sadly, people DO vent the HW heaters & dryers to the interior. While in some areas venting an ELECTRIC dryer to the interior can save a modest amount of energy with low risk to indoor air quality, it would create a mold hazard in much of North America. Venting of any gas-burner (even your kitchen range) into conditioned space adds moisture, suspended particulates, and some even nastier stuff.

    Going with power-drafted rather than atmospheric drafted hot water & space heating equipment prevents backdrafting, and lowers the air-infiltration cutting heating/cooling losses for the house independently of the equipment's own efficiency ratings. Any open flue depressurized the house- where the air gets in is usually random. It's generally better from both indoor air-quality and energy use points of view to build the house as air-tight as possible, and control the ventilation rather than just hoping the "natural" air exchanges of the air leaks & stack drives are providing the right amount of ventilation to the right spaces.

  15. #45
    Master Plumber master plumber mark's Avatar
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    Quote Originally Posted by Dana View Post
    Sadly, people DO vent the HW heaters & dryers to the interior. While in some areas venting an ELECTRIC dryer to the interior can save a modest amount of energy with low risk to indoor air quality, it would create a mold hazard in much of North America. Venting of any gas-burner (even your kitchen range) into conditioned space adds moisture, suspended particulates, and some even nastier stuff.

    Going with power-drafted rather than atmospheric drafted hot water & space heating equipment prevents backdrafting, and lowers the air-infiltration cutting heating/cooling losses for the house independently of the equipment's own efficiency ratings. Any open flue depressurized the house- where the air gets in is usually random. It's generally better from both indoor air-quality and energy use points of view to build the house as air-tight as possible, and control the ventilation rather than just hoping the "natural" air exchanges of the air leaks & stack drives are providing the right amount of ventilation to the right spaces.
    People are dumb as rocks.... it is funny that we go out all the time
    and repair FVIR water heaters with lint caked up around them for this
    exact same reason.... the dryer is venting into the laundry room.....

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