Hello guys,
I don't have any experience w/ microhydro and I know most of you don't either, but many of you are experts w/ electricity so you can answer my question! I'll give some background first, especially for any newcomers.
I'm in the planning stages of my microhydro project. As most of you know, I live off-grid in the mountains of Southern Oregon. We have about 3 kw of solar panels, 16 x L16 batteries in 48 VDC setup @ 700+ amp-hours. The 6/1 Listeroid running WMO at ~2000 watts maximum charge capability is my backup. Through winter we've had to run it about 2 hours/day (?) average.
There is a fairly substantial creek, Powell Creek, that cuts through the middle of our land, but I don't have water rights. A dairy down in the valley has water rights dating back almost 100 years. I've tried a few times to get non-consumptive use rights, but the county watermaster, BLM (Bureau of Land Management), ODFW (Oregon Dept Fish & Wildlife), etc. are not interested. Powell Creek runs year-round, but the paved BLM access road is right next to it. That BLM access road is not just for access to our land -- it continues up into the mountains as a gravel road and is a secondary fire escape road for our area. Locals drive on it to check on their pot-grows up in the mountains, 4x4'ers, ATV'ers, hunters, etc. all drive on it. I don't have control over it, even though it runs through my land. The BLM and watermaster check the creek regularly so they'd see a pipe and I'd have to put a transmission line under the paved road -- therefore, using Powell Creek for a microhydro site is out of the question.
I have another option though: there are numerous seasonal tributaries to Powell Creek and there's one that is mostly on my property. We call it Bear Creek (because of the bear we saw up there a few times). Bear Creek is fairly steep and seasonal, so there are no fish in it. I'm figuring on bootlegging a small microhydroelectric system on it. Permits around here are quite a pain, and what I'm going to do won't affect the flow in Powell Creek and I'll be putting the water back in before the creek enters the neighbor's land, so no one will be the wiser. (Besides, he has a fairly substantial cannabis operation -- look for several in the map picture.) Right now it's running probably 100's of gal/minute. (Look at the video link.) When it's rainy, wintery, cloudy is when we need the extra power, so this will be perfect. My penstock would be about 1500-1600 feet long through 2" polyethylene pipe. I picked polyethylene over PVC because of it's flexibility and freeze tolerance. Also, burying it is out-of-the-question.
The general equation for microhydro average power output, assuming about 50% overall efficiency and including voltage loss of transmission lines, is:
Vertical Head (ft) x flow (gal/minute) / 10 = watts
Guesstimating for my proposed site:
Shoulder seasons: 250 ft x 15 gal/min / 10 = 375 watts
Higher water: 250 ft x 30 gal/min / 10 = 750 watts
These are *very* rough estimates. I got the vertical head and pipeline length estimates by hiking the area and looking at the elevation data from Google Earth.
On the map picture, the red line is the penstock near Bear Creek. It would terminate near the 5000 gal water holding tanks. From the water tanks to the well house is about 400'. From the well house to the power house (where the batteries and Listeroid are) is about 800'. So, about 1200' total for transmission line from hydro turbine to the powerhouse. It was a very expensive cable pull to bring power from the powerhouse to the well house, and on to the water tanks. IIRC, it was #4 cable, 2 hots, 1 neutral, and a ground. (Cost about $7k for cable and labor!) It's all buried in 2" conduit. It would be difficult to get more cable into that conduit.
The well house mainly just needs 240 V AC for the well pump, and the water tanks don't need much power except for the microwave link for internet.
The main question for this group is: can I cannibalize the neutral and ground wires for microhydro power transmission? I would disconnect the neutral and ground wires at their ends, and pound in new ground stakes at the well house and the water tanks. The well pump would then be on the 2 hots coming up from the powerhouse and the new ground. For CFL lights in the well house, I would use a smallish 2:1 transformer. One of its output leads would be 120 V hot, and the other would be neutral, bonded to the new ground. (Acts as an isolation transformer with floating ground, anyway.) Same idea for the microwave antenna up by the water tanks, except up there the transformer can be very small because it only draws 20 (?) watts. Then I could use those nice big ground and neutral wires for transmission of 120 V AC or DC power from the hydroturbine back to the powerhouse. Would save a lot of money. Should still be safe, correct? Everything would still grounded and isolated via transformers, but I'd have multiple grounds in the system. Bad? Thanks for any input.
The other option is to use small (i.e 12 gauge wire) in a new conduit, transformed up to 480 V AC at the turbine, and back down-transform at the powerhouse.
Either way, it's going into a MPPT Midnight Solar Classic charge controller. Don't know what the dump load will be yet.
Marcus
Video of Bear Creek (watch my Australian Shepherd almost slide down the falls.)
In this picture you can see the dwelling and powerhouse in the middle, well house on the far right (just the white speck of roof), and the canyon where Bear Creek is behind it.
(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=6359&g2_serialNumber=2)
Map picture:
(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=6681&g2_serialNumber=1)
Cables I'm referring to on the line between well and water tanks. The extra blue wires in the 2" conduit are the water level sense wire loop for turning the well pump on/off. The 1" conduit contains the CAT5 cable for internet/VOIP phone.
(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=6679&g2_serialNumber=1)
Hey Marcus,
Electical is not my specialty but even I know that here competing grounds is a code no no. I run into the same problem; everything is up to code spec and inspected but now I want to add all sorts of cool stuff that will never see an underwriter's lab. Are you allowed direct burial cable in your area? No conduit just a depth of 18" or more like this: http://electrical.about.com/od/typesofelectricalwire/a/directburialcab.html . Thant's one hell of a run whichever way you go.
Best regards, David
Hi David,
Thanks for the reply.
Yes, we can do direct burial. It's more the size of wire and length required and labor to do that that I'm trying to avoid. With or without conduit, trenching 1200 ft is a lot of work.
Yes, I realize it wouldn't be completely code compliant. But I think it should be safe the way I'm proposing. In the course of internet research, I've seen multiple grounds on alternative power projects, especially on long distance transmission. I've even seen people advocating no grounds on some projects. There won't be any inspections on this. The house is brand new, code compliant, and inspected. The barn that I'm building this summer falls under agriculture permit, so it doesn't have to go through building permit process either, and everything electrical in it will be totally code compliant. I don't plan on having any inspectors anywhere near the area in the near future.
Marcus
I'll 2nd that that on messing with the neutral and ground wires. BUT lets talk about how your pump house is wired. Perhaps there might be a way to back feed your power in to that circuit. So tell us, or give us a schematic there.
Looking at your the debris in your stream a hydro-screen will probably be necessary on the intake to the pentstock. Do you subscribe to Home Power Mag? They often have good hydro articles.
But the first thing to do is choose your intake area, make a small dam and measure the flow with a weir. http://www.engineeringtoolbox.com/weirs-flow-rate-d_592.html (http://www.engineeringtoolbox.com/weirs-flow-rate-d_592.html) Then you know what you've really got there for your resource.
While the poly pipe may seem like a good idea, the fittings are huge flow restrictors because they fit inside the pipe. Also the black poly will break down in the sun much more quickly in the sun. Freeze will be a non issue if there is flow in the pipe or there are no dips in the pipe to collect water.
I'm working on the schematic right now. It should be ready sometime in the next few hours.
Yes, the intake will have a coanda type filter. Planning on taking water out of the creek w/ a culvert pipe with a small dam, then over the coanda screen. See hydroscreen.com. Not sure where to get the screen though because it looks like those guys are wholesalers.
Just bought the polyethylene pipe today. 300 ft rolls of 2" diam x 5. I could cancel the order probably still. You would pick PVC? It breaks down in the sun too. Bell ends on PVC are easy to work with.
Thanks for the reply.
Marcus
OK folks. Here's a schematic. Now I think I've found a solution. Since the hydro turbine has DC output, the negative cable is bonded eventually to ground anyway, so I can use the same cable for negative of the hydro turbine and ground. (Still "code OK".) And, I know that the 2 hots of the 240 from the inverters can be transformed to 120 w/ one output lead as hot and the other as neutral, correct? But can the well pump function correctly w/o neutral from the panel at the powerhouse? So disregard the separate grounds as drawn on this schematic and tell me what you think.
(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=6685&g2_serialNumber=2)
Here's a better schematic. Now I'm just taking the neutral and converting it for use as (+) cable for DC from the hydro turbine, and not having 120 V AC unless from a transformer.
(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=6688&g2_serialNumber=2)
My first thought from your video is that its a perfect spot for an overshot waterwheel ,but thats just me ;D
A dumb question from a foreigner : with so much water sloshing around and such a good roof for gathering rain water , why do you need a well and pump ?
cheers
Keith
Hi MarcusB
I have one of those seasonal "creeks" bisecting my back yard. Unfortunately only ~10 foot drop in the ~600 feet.
Stick with your poly pipe for the freeze resistance, impact durability and proven 30+ year life. These can and are melt jointed commonly in industry and construction. Check the Internet for how.
But only 2" diameter in 1200 feet I think the flow resistance will kill your power. Be sure and use a calculator for this factor.
Regards
Steve Unruh
@KeithO: that amount of water sloshing around only happens in winter & spring. In summer it's dry here. That creek will be dried up sometime in June. Harvesting enough water off the roof to last through summer w/ irrigation would take a gigantic holding tank or pond. The pond would need all kinds of permits and I don't have any space for it on a hillside. The holding tank would cost $$$$$$$.
@SteveU.: Volume makes up for head height. If your creek is flowing fast enough, you could potential have a site. Yes, I know about the melt joining of poly pipe. But where do I get the machine? More research necessary. I just bought 2" diam poly pipe in 300' rolls. Even if there is a joint every 300', it can't be worse than a PVC joint every 20'. Plus, I could always go back and melt join the joints later. This thing isn't going to be buried. According to calcs, the 2" pipe should be about 90% efficient, which is in the ballpark. Here's a very good calculator: http://www.powerspout.com/advanced-calculator
Hi Marcus,
I can confirm that even at my elevation (5600 feet) exposed black irrigation tubing lasts for over 20 years without failing from UV exposure.
Re: Your electrical plan. I think it's unwise to use the safety ground for the microwave line, pump safety ground and the 120VDC current carrying ground. You are likely to get enough DC bias on end of the line to cause problems, especially for the microwave link at the far end. The DC noise from the microhydro generator head would also be a concern for the microwave link safety ground.
Instead, I would liberate that wire (existing safety ground for pump and micrwave link) for the DC ground use only.
The well pump head is grounded and in the water typically, and non-grounded pumps were used for 100 years until the last 20. For the safest setup, the well pump could be on a ground fault interrupting breaker. This completely eliminates the need for the safety ground to carry sufficient current to clear a fault, at the expense of some parasite load and nuisance tripping during lightning storms. For myself, I would just provide an earth ground for pump controller, etc, connected to the pump head ground wire (a 4 wire submersible pump cable I assume) and check the resistance of the pump hot wires to that ground annually. If it gets below 5 Megaohms, I'd think about replacing the pump, as the insulation is starting to fail. I have configured many pumps in this manner for people who need to reduce ground current magnetic fields at their rural homesites, since with Wye power, the neutral is not transformer isolated, and a good earth connection like a well diverts current into the aquifer, causing net current problems at the site, and elevated magnetic fields.
For the micrwave link, I would use a small step down toroidal transformer to generate 120VAC from the 240VAC, use an appropriately small fuse, and ground the secondary side to earth ground as in the delta distribution system. In your case you would ground one leg of the secondary to create a neutral and a safety ground. I've used this arrangement with a non-grounded floating secondary for several satellite dish setups for 20 years with not problem. In my case, it was so that I could used a balanced power filter without creating ground current problems. Filters with lots of capacitance to ground will cause excessive ground current unless they are balanced, either 240V or 120V with floating or +-60VAC. When the filter has balanced inputs, the AC current to ground through the matching capacitance per leg is self canceling.
It's fun to see 120VDC listed on someone else's schematics besides mine. :)
Best Wishes,
Bruce
Hi Bruce,
Exactly the input I needed! Thank you very much!
So basically you would go back to the 1st wiring schematic I posted, w/ a separate ground wire at the well casing and another up at the internet hardware. The pump is a 3 wire pump, w/ 2 hots and ground (I think). I set the pump myself, but I don't remember exactly. I'll go up and look after work today.
Marcus
Hi Marcus,
Wow, I missed this thread until now. Your overall hydro plan sounds good. I didn't check your penstock head loss and you had best double check that... As long as your flow rate is relatively small and you are mainly using the site head (i.e., pressure from elevation) to generate the power, you should be OK. Yes, 120 VDC is nice to work with. Bruce is dead on correct. You may want to read this:
http://en.wikipedia.org/wiki/Single-wire_earth_return
Bob B.
Marcus, Yes, your 2nd schematic, with the ground wire used only for the 120VDC ground is what I'd use.
BobB-
What I'm proposing is in no way a single wire system, there will be no current flowing through the earth. That is not something that the homeowner should do.
I believe the single wire systems are bad news from a health perspective (human or livestock). They inject ALL of the return current through the earth and aquifer. This is even worse than Wye systems, which do not use transformer isolation due to their "ground tie" connecting the distribution neutral to each transformer secondary center tap. Wye systems have about 25% of the total return current to the power plant (as measured on the main cooling pond pipe) flowing in parallel to the neutral wire and through the earth and aquifer. (This according to a power engineering text.) The Wye system grounding practice is an unfortunate outgrowth of Edison's DC distribution system, which of course could not use transformer isolation.
In my opinion, Delta distribution (every transformer set up to provide isolation) is vastly superior from a human and livestock health perspective. There is no current flowing through the earth for Delta systems because of the transformer isolation/grounding practice. Earthing a transformer at a single point on the secondary side only causes no current flow through the earth. Residential areas with Delta secondary power distribution typically have background magnetic fields below 0.006 milligaus, even with overhead (air insulated) wires (which are another anachronistic mistake). This is less than 1/100th of the typical Wye residential power line frequency magnetic field levels.
We all evolved with the earth's Schuman resonance (biological frequency magnetic fields in the very low microgauss to 100 nanogauss range caused by ringing of the earth from lightning strikes around the world). Without these fields, in just 2 generations, all fish were born blind. By injecting large amounts of mixed frequency AC current through the earth, my theory is that we interfere with the Schuman resonance and create a health stressor for ourselves and livestock. The problem is totally fixable, even in Wye systems, by just changing to the single point grounding practice that has been well known in electrical engineering for much over 50 years. There are such hybrid Wye systems in CA, called "uni-grounded Wye".
End rant. Sorry!
Bruce
Hi Bruce,
I wasn't suggesting that you were proposing a single wire system. I was just suggesting that Marcus might want to consider a single wire system at the distances he will be running wire. It has reportedly been accomplished safely in many places if done properly. There is apparently a huge savings in wire cost and it could be good approach if done properly. However, I don't have any first-hand experience with single wire. BTW, I found your rant to be very interesting and certainly something to consider.
Marcus, Wild Blue now has 12Mbps download satellite service for $49/mo. It is 4 times faster than DSL and works for streaming Netflix and VOIP.
Bob B.
Thank you to both of you. I enjoyed the reading. You've really just confirmed that I'm not crazy in thinking I can get away without pulling more cable. I'm also on the tractorbynet forum and posted the same question: no comparison. (I don't think they understood the part about transformers or getting 120 V from 240 V, etc.) Anyway, a microhydro consultant is coming up to my place on Wednesday. (He's the one who wired my whole off-grid system.) I'm trying to decide whether to go w/ his custom built components or something like Powerspout.
Sailawayrb: this from Wild Blue's website: "WildBlue satellite Internet service is not recommended for real-time applications like VoIP (Internet telephone service), interactive gaming and stock trading, or VPN access." And the highest download speed that I found published on their site was 1.5 mbit (Pro plan). Are you thinking for you at your Rogue River house or for me? BTW, we drove through Evans Valley on the way to Shady Cove about 1 week ago. I know you weren't there and I couldn't remember the address anyway, but it's really pretty along that creek.
Marcus
Wild Blue also has a monthly data limit that would make Netflix streaming movies not practical. I think their limit is the same as my 3G Verizon service. At 5GB/month I was lucky to have enough data left over for a couple movies a month. Now I only use the snail mail Netflix service.
I had the Wild Blue pro plan for a few years. It works and you can do VoIP with it but the delay can be real annoying. We just got wireless radio service and it's as good as 3mbit DSL, actually better because it's 3mbit up and down.
I for got about hot welding the poly tube, that would be a good alternative. I've got a bunch of 3/4" poly around here that's just crumbling, but I don't know how old it is. Max working press on the 2" is 145 psi on the poly vs 166 on the sch 40 PVC so those are about equivalent there.
You guys are talking about the OLD Wild Blue satellite which indeed truly sucked. The new ViaSat has only been in orbit for a couple weeks. I can stream about 10 hours of movies per week for every week in the month without hitting the cap. VOIP works just as perfectly as my Comcast cable internet and web surfing is about twice as fast as Comcast. Here's the current Wild Blue info:
http://www.waypath.com/wildblue-new-satellite.php
Marcus, my friend at work got it last week and bench marked it, and I'm getting it at the OR property the first week of April. Gayle will be flying down to meet installer as I'm tied up at work. I'm flying to Salem 13 April to take the infamous OR Certified Water Rights Examiner engineering exam.
OK, I ran your hydro numbers. For 250 feet of static head, 30 GPM flow rate and 400 feet of penstock, and assuming 50% total system efficiency, you are looking at about 540 Watts or 389 KWH/month. Your head losses will be about 50 feet and the minimum recommended PVC diameter is 1.4 inches. Here's the website calculator I used:
http://www.nooutage.com/hydroele.htm
Question? 250 feet of head means about 108 PSI of static pressure at the turbine. If the flow were to stop suddenly, you could easily experience surge pressures anywhere from a couple to several times that. Will your penstock pipe handle that? Might want to incorporate a relief valve or a fail-safe weak link in your penstock design. Anyhow, maybe something worthwhile to discuss with the consultant.
Bob B.
I was wondering about a relief valve akin to the TPR valves on a water heater. Cheap, simple and spring loaded, adjustable, standard 3/4" threads, brass, etc.
Also, thanks for the link to the nooutage.com site. I had been trying to remember the nooutage site name for the past few days!
Marcus
Hi Marcus,
I'm thinking for the relief valve to work in protecting your penstock pipe, it would have to open very fast and be of a sufficient diameter so as to dump enough water to keep the water hammer pressure wave from exceeding your penstock pipe pressure rating. As long as you never shutoff the water flow quickly, you may be OK. Just keep in mind that you will have a 2" diameter times 400' column of water which will weigh about 544 lbs which will be moving at about 3 Ft/Sec when your flow rate is 30 GPM. This is a fair amount of energy and this also illustrates how a hydro ram pump can pump water uphill about 10 times higher in elevation than the head you feed it without needing any additional power by using this water hammer pressure energy as it's only source of power.
Bob B.
When you turn off a hydro penstock you are never supposed to shut it off too fast because of that very reason. That's why I was thinking of a TPR valve, but I haven't seen any diagrams showing any pressure relief valves in the books I've read. I'll ask the hydro guy tomorrow. Did you have anything specific in mind, Bob?
Interesting water hammer story. A firefighter was shutting down a hydrant way to fast and the water hammered the pipes so bad they ripped through the surface of the street! Didn't see it myself, but the account was related by someone who did. Yikes that is some power.
Not to hijack this thread but, I was a wild blue customer for a long time. Right about the time the new sat went into orbit, the quality on my service went way, way down hill with 2-3 second ping times and .016 through put compared to the normal 1.5. On contacting their tech support the tec said he could not tell me how loaded the sat was (liar) and that I could pay for a tec to come check my equipment. After a bit of cajoling he finally agreed to send the tec for free since I was a good customer for so long, he also offered to put me on the waiting list for the new sat for only $149. When the tec contacted me he said every one was having the same problem and that he would come, but that most of the systems he worked on got slower. When I mentioned that I thought they had oversold the old system to encourage people to move to the new system he laughed and said he thought so too. Glad to be done with my association with Wild Blue.
Tom, unless you were on Wild Blue within the last couple of weeks, you did not experience the new ViaSat satellite with Ka band and 12Mbps download performance. While I have never personally experienced the OLD Wild Blue satellite (because I read all the negative reviews in advance), I have little doubt that it is/was very bad indeed. My friend's NEW Wild Blue ViaSat satellite has been benchmarking a steady 18.5Mbps down and 2.5Mbps up with about 650 mS latency and Skype rates it between average and good. I will be thrilled to get this performance where I my second home is located given that the ONLY other internet option is a 56Kbs phone modem that has never benchmarked above 22Kbs. :o
Marcus, I have not given your pressure relief problem much thought other than to warn you about it. A cheap solution might be to put a tee on your penstock pipe close to the turbine with a cap/disk that would not fail at some pressure higher than your 108 PSI static pressure but will fail at a pressure below the pressure rating of your penstock pipe. If anything pops into my head, I'll certainly let you know.
Bob B.
Bob, I never claimed to experience the new system, just the old system and unethical business practices. I see the latency has not improved despite their advertising hype that it would. On a good day, which was most of the time on the old system I'd get 650ms and 1.5mbit. With that you will still get a significant delay on VoIP calls and remote desktops. You might want to check for a wireless service in your area before you sign a 2 year contract. I did and now I have better service with 35ms latency, no FAP limits and saved $30 per month.
Quote from: sailawayrb on March 20, 2012, 03:42:23 PM
Marcus, I have not given your pressure relief problem much thought other than to warn you about it. A cheap solution might be to put a tee on your penstock pipe close to the turbine with a cap/disk that would not fail at some pressure higher than your 108 PSI static pressure but will fail at a pressure below the pressure rating of your penstock pipe. If anything pops into my head, I'll certainly let you know.
Bob B.
How about a stand pipe with the proper amount of weight capping it to relieve preassure at a safe level.. Like a preassure cooker uses..... It would be reusable also.....
Tom, satellite latency can NEVER improve. The majority of this latency is the delay for the signal having to travel at speed of light the 24K miles distance to the satellite and then back to earth. To the best of my knowledge, Wild Blue has not claimed to have improved this latency beyond what is possible by physics.
What Wild Blue has accomplished is improved the download speed beyond what DSL and cable internet can currently provide. I tested my Ooma VOIP device (which BTW doesn't have any monthly subscription fee other than having to pay $2.79/month state tax fees) on the new Wild Blue ViaSat satellite and it works as well if not better than my Comcast cable internet provider. Same story for streaming media via my Roku. Where this latency could and likely still is problem is with gaming applications. Fortunately, I never fell prey to that addiction...
Believe me, if I could get 3G or 4G or any wireless service at my remote "escape the world" location, that's exactly what I would do. However, both Sprint and Verizon have told me it will never happen because my valley is closed to future new development and there will never be enough customers to justify what it would cost them to provide wireless coverage. I even offered to allow them to put a tower on my property for free. :'(
However, the new Wild Blue ViaSat satellite will allow the wife and I to work remotely from our place, eliminate the current $35/month landline phone for free VOIP, eliminate the current $15/month 56K modem internet provider, and enable us stream media for no additional cost from our existing Netflix account. So for essentially the same cost of what I am paying now, this will be a HUGE improvement! :)
Bob B.
XYZER, that sounds like a great solution. One could size the cap area and the weight to meet the requirement. I think the BIG hydro electric boys use stand pipes in their penstocks, but I'll need to research exactly why and the engineering behind it.
Bob B.
Sure, sounds pretty simple. Or is it?
I'd need to grease up a cap (make it watertight and able to slide off easily) and apply the appropriate weight. For a 2" pipe, the area is 3.1415 sq inches. (pi * r^2) So, I'd have to balance 314 lbs on top of a vertically oriented capped 2" pipe to counteract 100 psi. ;D ;D ;D
The trouble with all wireless systems, including satellite, Wifi, Wimax, 3G, etc., is that while initially the performance is great, once the they fully subscribe, the performance goes to hell. My Verizon 3G service is noticeable slower than a year ago, and at busy call times, it can be a dog. Same thing with my old Hughes satellite service, and the old Wild Blue service (which was initially very good compared to Hughes/Direcway). The local Wifi service got so bad that if you called to sign up they would tell you they were over subscribed and having lots of complaints. Still like everyone else with a remote home and no chance of even a landline phone, wireless is all I can do.
Fiber to the home is where we need to go, the binge on digital microwave wireless is technically unsustainable, and biologically insane. Yep, I'm one of those crackpots.
Quote from: mbryner on March 20, 2012, 05:54:44 PM
Sure, sounds pretty simple. Or is it?
I'd need to grease up a cap (make it watertight and able to slide off easily) and apply the appropriate weight. For a 2" pipe, the area is 3.1415 sq inches. (pi * r^2) So, I'd have to balance 314 lbs on top of a vertically oriented capped 2" pipe to counteract 100 psi. ;D ;D ;D
Unless you tee off to 1" standpipe...then you would only need 78.5 lbs... ;D
Seems like something that would just fail open (and that could be cheaply replaced) might be the simplest solution. Like tee off to a closed section of threaded plastic pipe that would rupture at the desired pressure (perhaps use lathe to cut a groove to the required wall thickness). You could also drill a very small hole in the cap to bleed the air (so the rupture occurs very fast without the delay of having to first compress a pocket of air) and this very small hole would not waste any significant energy/water.
Unless something unusual occurs, you should never encounter this failure...similar situation for having circuit breakers and fuses...
If you try something like this, be sure to use pressurized water (and NOT air) to determine/test the actual rupture pressure point to avoid injury!
Bob B.
re water hammer.
I'm looking at a 4" siphon pipe to use in my pond, with a 50' drop, to a turbine. Since it would run from pond storage, and could drain it down between rainstorms (a 4" leak is a big deal on a 2 acre foot pond), I was thinking of an electric butterfly valve, takes about 30 seconds to close, would slow the water down, and enable me to easily conserve water on sunny days between storms.
Hi Mike,
The empirical water hammer pressure spike equation is P = 0.07VL/T where:
P is pressure in PSI
V is maximum velocity of water in pipe in FPS
L is length of pipe in feet
T is valve closure time in seconds
It is left to the astute student to calculate V knowing the pipe diameter and flow rate... With a 30 second closure time, you will not induce any significant water hammer pressure spike.
The theoretical water hammer pressure spike equation is more interesting in that the wave frequency is also a function of the pipe length since the pressure wave travels at the water speed of sound. Both these equations can be found in the hydro ram pump Excel spreadsheet I posted.
Bob B.
For extensive calcs and description of water hammer as it relates to penstock design see:
http://www.microhydropower.net/download/layman2.pdf
Specifically page 41-42.
(Don't know why the link has "layman" in it, because this book is anything but a layman's book unless it means you are going to fall asleep reading it.)
Quote from: mbryner on March 20, 2012, 09:36:18 PM
For extensive calcs and description of water hammer as it relates to penstock design see:
http://www.microhydropower.net/download/layman2.pdf
Specifically page 41-42.
(Don't know why the link has "layman" in it, because this book is anything but a layman's book unless it means you are going to fall asleep reading it.)
Sweet link, thanks
That's a good resource for info and I have used it in the past too. Looking forward to hearing what your consultant recommends. :)
Bob B.
Well, after meeting w/ Jerry O (from apmhydro.com) I'm reassured that my plans will work well. Max flow of 45 gpm through 2" poly pipe. He's going to wait until I install the penstock so we know the exact head height before he completes the turbine (custom stator). We're planning for about 170 V DC (rectified 3 phase), using the first wiring schematic I posted. I've ordered 1500' of 2' polyethylene in 300' rolls. It's utility grade -- $0.84/ft, not cheap, but only rated to 80 psi. The higher grade is rated to 100 psi. That psi rating is marginal for my use, so I'll probably use PVC for the lower 50' of head. He did say that some installs do include a pressure release valve. I'll give an update when I get the pipe and can snake it down the hill and check the pressure.
Marcus
Cool Marcus...this is getting very exciting!
Agreed, rectified 3-phase is good approach and assume you get it via some PMG.
Hey, if you have 250 feet of head and are planning on using 80 PSI rated PE tube for the upper penstock, you can only handle the first 186 feet of head with this tube and you will need something else for the last 64 feet of head...and you may want to have some design margin like not letting the PE tube see more than 60 PSI (which means the PE tube only handles the first 140 feet of head and something else handles the last 110 feet of head). Or maybe go with 100 PSI tube and design so as to not let PE tube see more than 80 PSI and use 187/64 approach?
Did you check the PE tube price at Grover in Medford? Seems like I got my 2" PE, which was used for my hydro ram pump, for much less.
Bob B.
Bob,
Those prices are from Grover (Grants Pass & Medford would have the same price). I'm going to decrease the head to about 200', and I'll transition to 100' psi pipe for the lower section, and probably PVC for the bottom. Yes, it is from a custom PMG head (APM hydro builds pretty efficient, solid PMG gen heads from what I've seen in their shop). It's still raining here, so I can't even drive the tractor up the hill to start building a diversion point, yet.
Marcus
Sounds like an awesome project Marcus. I had similar plans here, but since living off-grid for 4 years now we really don't need the extra power. Also my water source looked good in '05 when we had loads of rain. This year there has been almost no runoff.
One source for cheap pent-stock pipe are well drillers. I've got a friend who is a registered water system operator that has given me 700' of 3" iron pipe and another 700' of 2 1/2" pvc. Seems if a pump has issues and needs to be pulled, they don't always want to reuse the pipe. The pvc pipe is interesting in that it has threaded couplings. Never seen that before.
Another option if you want to stay all poly is to use water service line which is a heavier wall rated for around 160 psi.
Good deal Marcus, Grover had best prices on local PE when I purchased last summer. I also really like the stuff they have on-hand in general and the knowledgeable service they always provide. If I ever get my hydro electric power plant approved, I will need to check with APM about PMG. I already designed what I want for PMG, but it might be better to buy all things considered if they do things right and are local too. My penstock will be 18" diameter but only 40 feet long...
It was snowing here last night and just the normal Seattle rain now.
Bob B.
Thanks for the tip about well-drillers. Hadn't thought of that! :)
Quote from: Tom on March 22, 2012, 01:15:51 PM
The pvc pipe is interesting in that it has threaded couplings. Never seen that before.
Schedule 80 for hanging all that weight I suppose......plus you don't have to cut it as you pull it.
The well drillers have switched to schedule 100 PVC for new installs here with the deeper wells. They continue to use standard pipe wrenches on the PVC, and they were getting a lot of perpendicular hairline cracks in the schedule 80 pipe, near the fittings...du oh. These micro cracks don't show and don't leak until the pressure is high enough. They have been very annoying for customers (me).
The schedule 100 has an even heavier wall- perhaps that might suit, somewhere.
The pipe I have says Sched 120 on it, but the wall thickness looks less that sched 40. I got a bunch of nice brass check valves with both sets of pipe too. Don't know what I'll do with them though.
You're right, Tom, I was having a senior moment. Thanks. I should have written schedule 120, not 100. Here's the specs:
http://www.harvel.com/downloads/spec-pvc-pipe-sch-120.pdf
http://www.harvel.com/downloads/spec-pvc-pipe-sch-80.pdf
Schedule 120:
2" is 470 psi max. wall thickness is 0.25"
Schedule 80:
2" is 400 psi max, wall thickness is 0.218"
I didn't know there was heavier than the 80......I worked on one of my wells that had the 80 and had to thread a piece....a bitch with a sharp set of dies!
Pipe came in today but I'm at work. 300 ft rolls don't fit in the back of a Toyota P/U. Store is 25 min from my house and they don't deliver. I'll have to 2 rolls on the lumber rack at a time and drive back and forth a few times. I'll start rolling out pipe on Sunday. Woohoo!
Hi Marcus,
Right, 300' of 2" is quite bulky. A roll doesn't fit inside a Honda CRV either, but a roll or two are light enough to stack on the roof rack and tie down...but not as many as you have!
You probably already know this, but figured worth mentioning anyhow... It is best to just unroll this stuff and let it get well heated by the sun before trying to fully straighten it out and place it. This stuff tends to remember the roll and it can be quite stiff and difficult to work with until it gets well heated and relaxes. You also have to be very careful not to kink it when unrolling too, although I don't think that will be a problem with your 2"...more of a problem with 1" and less. If you do kink it, the kink will often come out if you allow it to get heated...again it tends to have a memory.
Probably the optimal time to do this would be June/July when you have higher temps and more sun, however, you might not have flowing water then and your goal is to determine the exact head available my measuring the static water pressure and dividing by 0.43 PSI/Ft, correct? I think you should still manage OK now if you don't work too fast and you don't try to overly force it.
What was the consultant's recommendations relative to anchoring the pipe? Perhaps you are just burying it in a trench?
Bob B.
Yep, Bob, I'm trying to get the static head measured so the microhydro guy can build the turbine w/ the correct stator.
He just uses stakes or trees to keep the pipe from sliding down the hill when full of water and vibrating. He recommended stainless steel bolt-around clamps around the pipe to anchor to, instead of a regular hose clamp which will rust in short order.
Here are pics from today:
(http://www.docbryner.com/misc/microhydro/IMAG0482.jpg)
(http://www.docbryner.com/misc/microhydro/IMAG0483.jpg)
Hi Marcus,
Looks like a very pretty spot to work new project and you can admire your other projects too! Watch out for that poison oak. :o
As a minimum, I think you may want to securely anchor the inlet point, places where the pipe bends, and the turbine point. Yes, SS is the right way to do it. When I did my hydro ram pump penstock last summer, I embedded short lengths of SS chain into the reinforced concrete anchor points. This allows inserting SS pipe clamps into the chain link. The benefit of doing this is that you can replace the clamps if necessary and you can also use different size clamps as required. I also used a small section of split 2" pipe to protect the pipe from any clamp abrasion. I attached a couple photos that illustrates how I did this.
Bob B.
Very nice. I like how you wrapped a piece of 2" pipe around the pipe to prevent abrasion at the pipe clamp.
Yeah, given all the back-breaking work to hand dig the holes and fill them with reinforced concrete, I really didn't want to experience any rust in my lifetime... The other thing that I did was to tack weld some rebar across the bottom portion of SS chain. In addition to ensuring that the chain will never come out of the concrete, the rebar acts as an active sacrificial galvanic anode to provide some cathodic protection to the SS chain and clamps.
Bob B.
Hey Marcus, what's taking you so long getting this project operational. I want to see some photos of the turbine soon!
Actually, I just wanted to let you know that Gayle got the new Wild Blue internet installed at the property today. It is as good as expected...absolutely no problem streaming movies or using VOIP.
Bob B.
Good to know. If Applegate Broadband goes under, I'll have other options.
Hey, watch those snide remarks! :) I'm working on it in all my spare time. So far, I've pulled 600 ft of 2" poly through the woods, in the rain, in a steep canyon filled w/ poison oak. I have poison oak all over my arms. :( I also put together 200' of 2" PVC for the last section, and it has a TPR valve, pressure gauge, and ball valve at the end. I only have 2-3 more rolls of 300' of poly to pull! I'd actually be further along, but family came up to visit 2 days ago, and I've been on-call at the hospital, + regular work days. Today we're going down to my parents for a few days for Easter. Sometime next week the pipes will be joined and I'll be able to report a static head pressure. Yeaahh.
Well, I warned you about that poison oak! I am very allergic to it myself..and I am sure it will kill me someday too! I guess every time one gets exposed the reaction gets worse...in other words, you do NOT build up a tolerance to it...had an expensive doc tell me that... The body also seems to remember where it was previously exposed and subsequent exposure causes previously exposed areas to erupt again. Very nasty stuff indeed!
Hey, if you email Gayle, she will give you her temp VOIP phone number and you can try it out. Plan is to port the landline number to VOIP, but takes a couple weeks to accomplish. Gayle is happily working from her virtual office with Evans Creek view right now.
Best wishes for happy Easter with your familiy!
Bob B.
What VOIP company are you using?
Hi D34,
Not a VOIP provider company, just VOIP equipment from Ooma. You can buy it at Costco for about $160. Essentially unlimited US long distance and there is no monthly subscription fee. You do have to pay about $3 month for the local/state phone fees. Been using first one in our suburban house for about 3 years and now finally using the second one. It essentially replaces the phone company...all of the phones in your house become VOIP.
Bob B.
mbryner,
This stuff has saved my butt (literally) many times. works with all the types.
http://www.duluthtrading.com/store/product/poison-ivy-treatments-32-oz-bottle-of-tecnu-oak-n-ivy-cleanse-TECNU32.aspx?kw=Poison Ivy&processor=content
Love your house,
Terry
Ah, yes, Tecnu. An old friend around here. But, Wow!, that's a great price for 32 oz bottle. Thanks for the link.
Sounds like great progress considering your work schedule, Marcus. I hope the remainder of the pipe laying goes smoothly, with less poison oak. On the bright side, you probably don't have to watch your step for Cholla (cactus), rattlesnakes, and scorpions. ;D
Quote from: d34 on April 05, 2012, 01:27:17 PM
What VOIP company are you using?
Hope y'all don't mind an off topic reply to an off topic question.
You weren't asking me but I thought I'd chime in anyway.
I have used Vitelity Communications (http://www.vitelity.com/) for years, $1.49/month for telephone number and $0.012/minute. It is a bring your own hardware service.
I also have a VoIP iNum number with VoIP.ms (http://voip.ms/), but I never use it. Their rates are $1.49/month for telephone number and $0.0105/minute. It is a bring your own hardware service.
Bruce, we don't have cactus or scorpions (I don't think...), but we sure do have rattlesnakes, mountain lion and bear. In fact, I had a 10 minute Mexican stare down with a rattlesnake last summer in the crawl space under my shed while plumbing my irrigation system. It was about 120 deg F in the sun so the snake wasn't very motivated to move out from the shade. He was only about 3 feet away from my face when he started rattling and I noticed him. I was in a pretty tight and confined spot and decided it would be best not to move at all. Eventually the snake settled down and slowly left the scene. Nevertheless, poison oak is still the worst fate of all!
Bob B.
That's a scary rattlesnake story. Nothing's worse that a surprise in a crawlspace. Glad you lived to tell the tale, Bob B.
I had a visitor in my shop last summer, I damn near stepped on him. Lucky for me it was just after dawn and he was not up to speed yet. I got past him before he could strike.
I had no idea rattlers were up there in western Oregon. They must have a huge range.
Great story, Bob! Everyone needs a good rattlesnake story. I have several stories, including killing 5 rattlers near our new house over the past several years. Yes, plenty of rattlers in Oregon. Yes, we also have scorpions here, but I can remember seeing only one.
http://scorpionforum.darkbb.com/t39-uroctonus-mordax-nortwest-forest-scorpion
http://www.arachnoboards.com/ab/showthread.php?14511-Oregon-Scorpions
I use Broadvoice for VOIP. We haven't had regular telephone in years. Broadvoice included 20 countries in it's $25/month and they sent hardware. We call Europe (specifically Switzerland) so that was important for me.
Getting poison oak is a yearly occurrence for me. Nothing new! :(
Glad you enjoyed my snake story. Wow, didn't know we had scorpions! We have poisonous spiders too:
http://oregon.gov/ODA/PLANT/IPPM/spiders.shtml
Broadvoice sounds like a great choice for international calling. We have been very happy with Ooma for national calling...no $/minute charge at all. We also like the caller ID, voice mail, and call forwarding capability that is also free.
Bob B.
I use an OBI 110 and google voice. 49.00 for the box. USA is free calls.
http://obihai.com/
Wow! I didn't realize the range of the 'rattler. We have black (or very dark) ones here and Copperheads. For spiders we get Black Widows and the Brown Recluse. The scorpions here are about an inch to an inch and a half and light brown. Not to mention the Red wasp, Black wasp,
Yellowjackets (mean little boogers) Baldfaced hornets and Japanese hornets!
Fellow has to keep a good look out.
Ron.
When I was building the house, working under the deck is about a 3' crawl space. I'm sitting there working on some plumbing and move a piece of tar paper from the siding and there is a cute little rattle snake right there striking distance from me. Fortunately it was morning and cold so it died.
Quoteit was morning and cold so it died.
I love how you wrote that. ;D
I feel like we are long lost brothers Marcus, we have done so many of the same things! My hydro is working pretty good right now, 3.8A at 49V. Spring project is to run another 400ft or so of 3" PVC through the steep canyon, luckily we are too high elevation wise to have much poison oak. You tend to do things more "right" than I do though! I'm wondering if I can make my own coanda screen, my screen intake is always clogging up and $300 is steep for a piece of sheet metal with some holes in it.
-Jedon
Harris Hydro Pelton Wheel, Metro CS 6/1, Lister SR2, Onan 10K etc
@Jedon: More like $500. And I thought that was a lot of money, too, for a Coanda screen until it came in the mail a week ago. It was a bit different than I expected. Much thicker and welded. The screen itself is not sheet metal at all, but the sides are. Still much heavier than I thought it would be. I have 2 sisters but no brothers, so maybe you are my long lost brother!
So here's an update: I am so happy w/ this project, so far. I dug a small pond/puddle at the diversion and installed the screen last week. The pipe has a couple high spots where the terrain was difficult. It took a while to flush out all the air, but when all is said and done -- 80+ PSI static head!!! Running at 10-15 gpm the net head doesn't change from 80 psi. That's 190 ft vertical. (Google Earth said 215 ft.- just shows it is only relatively accurate.) Today, I modified the wiring to the well and internet as per the diagrams I posted earlier in this thread. I cannibalized the neutral and ground wires going up from the house since the well casing had a good ground on it. (That ground was bonded to the house ground before.) The well pump didn't have a neutral; just 2 hots and ground. For other small loads, like internet and relays I just used 240 V from the 2 hots or used a isolation transformer. Works great just like theory said it should! Funny, when I looked closely at the IT equipment, it's built for 120/240, so all I had to do for that portion was change the neutral wire to Hot2 and disconnect neutral and ground, then turn the breaker back on. I labeled all receptacles that are not standard voltage, so no one plugs anything else in. The turbine will hopefully be installed Wednesday. Fingers crossed for 300+ watts...
Marcus
Here are some pictures of the diversion and screen:
(http://www.docbryner.com/misc/microhydro/hydro1.jpg)
(http://www.docbryner.com/misc/microhydro/hydro2.jpg)
(http://www.docbryner.com/misc/microhydro/hydro3.jpg)
(http://www.docbryner.com/misc/microhydro/hydro4.jpg)
(http://www.docbryner.com/misc/microhydro/hydro5.jpg)
That's an awesome amount of pressure at 10-15 gpm. Congrats, Marcus. The inaccuracy of inexpensive pressure gauges might account for some of your head discrepancy.
Securing your pipe run through the woods with that much vertical must have been something! I hope you'll meet your 300 W goal!
Best Wishes,
Bruce M