Microhydro planning, 1200 ft transmission cable

[mbryner]

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

[BruceM]

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.

[Tom Reed]

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.

[sailawayrb]

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.

[mbryner]

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

[sailawayrb]

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.

[mbryner]

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?

[Tom Reed]

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.

[sailawayrb]

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. 

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.

[Tom Reed]

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. 

[XYZER]

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.....

[sailawayrb]

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.

[sailawayrb]

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.

[mbryner]

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.    

[BruceM]

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.