anyone heard of this

[SteveGabbard]

Anybody seen this?

http://www.mysaline.com/profiles/blogs/ ... ed-of-high" onclick="window.open(this.href);return false;

[RandyJ]

wonder what they consider a "green" generator?

[fryingsquirrel]

I think he's talking about whats called Micro Hydro, where a small dam is installed on a creek. Then the diverted water is used to turn an AC generator. Then (I think) the power is rectified to DC for storage in batteries till it's used, when it is run through a transformer back to AC. These systems can be beneficial, but the impact from installing them is not small. Anywhere there is a dam, there is impact. Also the batteries have to be manufactured somehow, and last time I checked, making batteries involved a little more than magic pixie dust and wishful thinking. Keep in mind that these will be large batteries, and quite a few of them. That said, I'd probably still spring for it, 'cause then I'd be STICKING IT TO THE MAN!!!
I'll wager Cowper knows quite a bit about this (and STICKING IT TO THE MAN!!!)
Jon Ellwood

[DeBo]

The idea is called co-generation and is usually done with wind or solar which is really green and really a great idea, batteries and all , as there is no environmental impact.

This, on the other hand, just blows my mind! Who in their right mind would ever consider destroying a stream ecosystem a green idea? :roll:

[ARzach]

Who in their right mind would ever consider destroying a stream ecosystem a green idea? :roll:

Canada, more specifically British Columbia's leaders... Interesting video on similar projects.

http://www.therangelife.com/" onclick="window.open(this.href);return false;

You'll have to look to the right under their videos and click on "49 Megawatts". Nice little documentary outlining what can happen once these types of projects progress. The video is not just about the large dam on the Ashlu if you watch it through to the end. The situation in BC breaks my heart, and to see this come to my home-state would be even more so. Check it out.

--Zach

[Cowper]

Maybe later I'll go find some example numbers, but here's my take:

1) Batteries would probably come into play for "stand alone" systems that were not on the grid; for these micro systems tied into the grid, no batteries would be needed. When you were making more than you could use, it would be sent to the grid for others to use.

2) Not sure why this is posted on a Saline county blog - to me, it is quite possibly just "spam". I say that because to get any amount of power that someone else would be willing to finance like this is talking about, you'd have to have "enough" of two things - flow in CFS, and head, that is, enough "drop" for the falling water to provide meaningful quantities of energy. Backyard streams in Arkansas just don't flow that much flow except following local rains; back yard streams in Saline county wouldn't have enough drop even when they were flowing good. Nobody is going to pay to install a generator that runs only a few days per month at best, and if there is only a few feet of drop, it wouldn't be worth it even if it ran 24/7.

I need to do some googling to bring myself up to date on what is out there, but the formulas for how much power is available in a given amount of falling water will not have changed - that's just the laws of physics, and those darn things stay pretty much the same.

[SteveGabbard]

I agree that it looks like spam, but when I read it I started thinking about the possibility of these on the Cadron, etc... Not a pretty thought.

[Fish]

Be VERY skeptical of micro-hydro claims. While working for a company that did analysis on such systems, I found that all of them we looked at were significantly less efficient than claimed. To generate electricity efficiently and in sufficient quantity to have significant "excess," you'd have to have a VERY large backyard stream indeed. Remember, it's the average flow, not the few times a year maximum flows, that matter. And any paddler in AR can tell you that high flows don't last long and drop super fast. The average flow is WAY lower than the floods. Also you need usable gradient, and that's hard to find. You'll also need a VERY big yard for the lake the dam will create (or maybe all of your neighbors want a cut of this great deal?).

That link is most likely a scam to rip off people who don't know better. Or it's a legitimate offer from someone who doesn't know any better themselves.

If you want to do the math yourself, the max potential power in kilowatts for any dam is:

P = M * g * h / 1000

where M is the mass flow rate in kg/s (M = cfs * 28.32), g is 9.8 m/s^2, and h is the height of the dam in meters. Plugging in all the numbers we know, you get:

P = 0.2775 * cfs * h

So if your "backyard stream" averages 100 cfs and you can make a lake that backs the water up to a height of 3 meters (about 10 feet), you're looking at about 82 kW. Wow, that's great, right?! Except, where can you find a stream that AVERAGES 100 cfs in Arkansas? Maybe something the size of the Piney or Mulberry would. But not anything you can dam up without serious government approval. So AT BEST you'd have a stream that averages 1/10 of that, so maybe 8.2 kW, enough for a very efficient home.

And that's the potential power - the most you'd get in a completely perfect world. Real turbine systems often operate at efficiencies of 60% to 85% - not bad, but do-it-yourself micro-hydro tends to be on the low side, so now maybe you have 5 kW from your dam. But that's only if you harness all of the energy from ALL of the water. That won't happen. When your stream floods, your little lake will often overflow and much of the water that goes into that average flow will spill over and be lost (you have to size your generator for the more typical flows, not the max). So that means quite a few less watts. And that 3 meter height is the max height of water in your lake. Part of the year, your lake will be draining down and you won't get that much...

So now that expensive lake project in your back yard with that pretty much ideal stream (10 cfs average and 10 feet of drop for your lake is amazingly good for property in Arkansas) is now maybe 3 or 4 kW at best. For sure nobody will be paying for this project to get the "extra" power you generate. It would even take you decades to recover your initial investment with the little bit of power you save in your home!

If it worked, more people would be doing it. Only the government does hydropower around here, and even they screw it up - the generators at the dam on the Arkansas R. in Little Rock have lots of flow but not much drop. I'd bet that project may not pay for itself in my lifetime. (I've always wondered about this, so if anyone knows what the payback period is expected to be, let me know).

- Fish

[Fish]

I think he's talking about whats called Micro Hydro, where a small dam is installed on a creek. Then the diverted water is used to turn an AC generator. Then (I think) the power is rectified to DC for storage in batteries till it's used, when it is run through a transformer back to AC.

This kind of system is way less efficient / productive than a conventional dam and turbine. First we don't have good / cheap enough batteries yet. Second, turbines don't work very well if you vary the flow - you'll likely only have productive flow a small portion of the year. Solve those two technological problems and this kind of micro-hydro will take a leap forward, though probably still not enough of one to make co-generation a good idea. Of course, the battery problem will also help wind, solar, etc., so it's a sure fire winner. :)

I even saw an ad once for power generator you hook onto your sink faucet. Free energy, since you still can use the sink, granted with a bit less overall pressure. Of course, the power barely lights one small bulb, but for $250 you could charge your cell phones for free! :)

- Fish

[fryingsquirrel]

Hey Fish, you know those apartments where they pay the water bill for you...
STICKING IT TO THE MAN

Seriously, this offer smells suspiciously of bovine fecal matter. Hydro power options that have my attention now are tidal based systems like this http://www.biopowersystems.com" onclick="window.open(this.href);return false;
And here's a micro-hydro that works http://bluelivingideas.com/topics/water ... gy-system/" onclick="window.open(this.href);return false;
He even mentions in the article how it fluctuates with water flow. The one thing he says is that it's not dependent on weather, but last time I checked, rain was weather. Still a good article. That's about all I know.
Jon Ellwood

[Fish]

I've seen systems before like the one that guy is using. If he's generating 2KWh steady and spent about $11K, then his payback period, not counting any maintenance costs, is between about 6 and 12 years, depending on how much he would be paying for electiricity from the grid (cost varies from around 6 to 20 cents per kWh). That's based on average usage of 900 kWh per month. So that's not bad. But maintenance costs are not zero and he's clearly got a great water source (not weather dependent) and plenty of head to generate pressure. Again, that's an ideal situation that not many people will have. Very few in AR will have it.

If you're buying land and you plan to buy for micro-hyrdro and you build your house initially to use the power efficiently, it can be done. Small scale renewable power is well within our grasp today - a mix of solar, wind, water, and some clever geothermal and you can go off the grid in style. However, the up front costs are significant, so plan for a payback period of 10 years and you likely won't be disappointed.

- Fish