Hydro Design Parameters

I was just curious what some hydro design parameters are that people are using? I thought maybe a thread regarding design multipliers might help other people on here come up with great hydro set-ups.

For instance, at work, out transmitters are not working right, so it shows a very low cubic feet per second flow. I use the multiplier of 1 cubic foot per second equates to .0029 megawatts to derive the correct amount. Therefore, 14.93 megawatts is consuming around 4850 cubic feet per second.

Converting that down for a microhydro system, a 500 watt system would consume about 1 cubic foot every six seconds, or 1 cubic foot of consumption per minute for a 2900 watt system. Having that information, a person can size their piping accordingly.

Are you planning a system?

John C Daley wrote:Are you planning a system?

Yes and no. I am starting to put together a plan for a hydro system at a new house I bought on a river, but it will be a hydrokinetic turbine and thus will not need water turbined through it, just under it.

I also do not have a huge demand for electricity now that I am an empty-nester, but living in Maine have a huge demand for heat. I would like to harness the power of the river to heat up water, hoping a modest sized hydro set up could at least provide enough heat for domestic hot water.

(1cfs = 7.5 gallon per second = 449gpm)
Net Power = 1/10 x Head x Flow
500W = 1/10 x 10ft x 500gpm
500W = 1/10 x 5ft x 1,000gpm
500W = 1/10 x 1ft x 5,000gpm
500W = 1/10 x 0.33ft x 15,000gpm

https://www.smart-hydro.de/renewable-energy-systems/hydrokinetic-turbines-river-canal/
(1 cubic meter per second = 35.3cfs = 15,850gpm)
1m diameter turbine * 1m/s water speed = 0.7858m3/s = 12,449gpm
1m diameter turbine * 1.3m/s water speed = 1m3/s = 15,850gpm = 500W

My rule of thumb would be to use the usual formula of:
Net Power = 1/10 * Head * Flow,  but set the head to 0.33ft for insteam/hydrokinetic

Another rule of thumb would be:
Reduce the advertised output by 10, so 5,000W is really 500W
Rivers usually have a speed of 0meters/second to 3.1meters/second (0miles/hour to 7miles/hour).
So the advertised 5,000W is only for max speed of 3.1meters/second, but a more realistic output and river speed is 500W at 1.3meters/second

We also have to be mindful that we aren't doing the flow for the entire river, but only the portion that the turbine is intercepting.
If the stream is 30ft wide with a total flow of 900cfs, but your turbine is only 3ft wide or 1/10th, the flow that your turbine is getting is only 1/10 of 900cfs aka 90cfs

Steve Zoma wrote:1 cubic foot .... for a 2900 watt system

I wouldn't call "1 cubic foot" yout total flow just your rate thingy

Net Power = 1/10 x Head x Flow,  (1cfs=449gpm)
2,900W = 1/10 x 1ft x (449gpm * n)
2,900W = 44.9 x n
2,900/44.9 = n
64.6 = n
64 = 8 x 8

I wonder if your turbines has a diameter of 8ft or most likely 9ft (3meters)?  If so your flow isn't really just 1cfs, but really 1cfs for every square foot that the turbine covers.
Total Flow = Area x Flow Rate = (8ft x 8ft) x 1cfs = 64 x 1cfs = 64cfs (technically the turbine is a circle and not a square)
Net Power = 1/10 x Head x Flow,  (1cfs=449gpm)
2,900W = 1/10 x Head x (64cfs*449gpm)
2,900W = 1/10 x Head x 27,000gpm
2,900W = 2,7000 x Head (is about 1/10 the diameter aka 1.1ft)

Sadly due to the exponential growth vs linear growth of wind turbine and the similar hydro-kinetics turbine, it doesn't really scale down from MW to KW easily.  

Uhmmmm?
Net Power = 1/10 x           Head       x       Flow
Net Power = 1/10 x (Diameter/10) x (Diameter x Diameter x Rate)
Net Power = 1/100 x Diameter^3 x Rate
Net Power = 1/100 x 8^3 x 1cfs,  (the diameter is most likely 9ft or 3meter, so my numbers are a bit low)
Net Power = 1/100 x 512ft^3 x 449gpm
Net Power = 1/100 x 229,900
Net Power = 2,299W

So for a 3ft system
Net Power = 1/10 x           Head       x       Flow
Net Power = 1/10 x (Diameter/10) x (Diameter x Diameter x Rate)
Net Power = 1/100 x Diameter^3 x Rate
500W = 1/100 x 3.3ft^3 x Rate
500W = 1/100 x 30ft^3 x Rate
500W = 1/3 x Rate
1500gpm or about 3.3cfs = Rate
Total Flow = Diameter x Diameter x Rate
Total Flow = 3.3 * 3.3 * 1500gpm
Total Flow = 15,000gpm

I am not sure.

I know 1 cubic foot per second equates to .0029 megawatts is an industry standard multiplier, but I am not sure how it was devised. Every dam is different of course, but wicket gate percentage to blade pitch angle is calculated on some kind of curve that is tied in with PLC controls to make it all seamless. Like at start-up, wicket gate position is at 17% with a blade angle of 30 degrees, but at full rpm (116 rpm) at full production it will be 100% wicket gate percentage, and 91.7 degree blade pitch angle. The variable blade pitch is what makes the Kaplan versus Francis turbines more efficient, and reduces cavitation to almost nothing since everything is not tied into wicket gate percentages alone. Unfortunately, Kaplan Turbines cannot be the reversible type however to make pumped storage feasible. Yep, there is no free lunch with runner designs.

As for diameter, our penstocks are variable in diameter to get the venturi effect on the other side of the runner, but there are two, at 20 feet in diameter. Flows over what can be turbined are controlled by flood gates of course.  Naturally, and always, 6% of whatever is turbined goes out the upstream fish escape passage by federal law.

Unfortunately, the river I have a house on is apart from the river in which I work, and there are no reported flows on that river. The closest I got was 17,000 cubic feet per second for spring flows on the dam two miles upstream of my house. Below my house by 5 miles there is another dam that gets 20,000 cubic per second in the spring, I know the dam operators there even though they work for a different company,  and they say they could easily turbine more water flow if they had more capacity. They are only a 4.5 megawatt dam, so you can do the math and deduce what they typically turbine for cubic feet per second.

We do have a company that is experimenting with FERC on hydrokinetic turbines on grid-scale, but while they are kind of cheating, but even then, they are NOT disclosing how many megs they expect to put out. That tells me they don't expect to put out much power.

https://waterdata.usgs.gov/monitoring-location/01034500/#parameterCode=00060&period=P365D&compare=true
Summer:
Depth of 2ft
Flow = 5,000cfs (~2,500,000gpm)
(the yearly average is about 2X the flow and depth , and spring 3X)
Width = ??

What type of Hydrokinetic turbine could someone directly put in a 2ft deep stream?
Would you recommend that said person get a canal/penstock/etc, to setup a more controlled enviromend.

The biggest question is where can I get buy a hydrokinetic turbine, that delivers 500W-5,000W for say $2,000-$5,000.

S Bengi wrote:https://waterdata.usgs.gov/monitoring-location/01034500/#parameterCode=00060&period=P365D&compare=true
Summer:
Depth of 2ft
Flow = 5,000cfs (~2,500,000gpm)
(the yearly average is about 2X the flow and depth , and spring 3X)
Width = ??

What type of Hydrokinetic turbine could someone directly put in a 2ft deep stream?
Would you recommend that said person get a canal/penstock/etc, to setup a more controlled enviromend.

The biggest question is where can I get buy a hydrokinetic turbine, that delivers 500W-5,000W for say $2,000-$5,000.

I don't know anything about the Penobscot River. It is not the river I am stationed on, nor is it the river where my new house is at. I do know there is a decent sized dam at West Enfield though, so I know it is way deeper than two feet. I suspect if they have a flow monitoring station there, it is probably at the tailrace of the dam where the operators would want the lowest depth so that the height differential is greatest to get the most power out of the dam's generators. It would also be the best place to get flow readings.

The hydrokinetic test project for grid power is on the Penobscot River, but it is located in Millinocket Maine, well upstream from West Enfield.

As for a hydrokinetic turbine able to get 5 KW for $2,000?

That is easy; you build it yourself.

When you build something yourself, there is just the cost of materials involved. You don't have labor, research and development costs, promotional costs, nor any overhead. Reducing it down to just your building costs allows you to get the most KW's per dollar spent. There is no free lunch however, when you cut out all the middlemen, you MUST also do THE WORK that the middleman do. With engineering, you run the risk of making research and design errors.