high volume low head

[Robert Nicholson]

My parents live on an old mill pond with a flow aprox 300 gal minute the drop is about 8 ft. and the chase is about 15 feet across the top of the dam. There is a drainage pipe that might can be used some how. how can we best utilize this power. :D

[Rob Beckers]

Hi Robert,

There is something called a "low head stream engine". It's meant for 2 - 10 feet drops, with up to 1000 gal/minute in volume. Peak output is 1000W, and I'm proud to say it's made in Canada! :D You'd have to find out how much it'll produce for your head/volume.

Here's a link to the manufacturer's site (http://www.microhydropower.com/products/lh1000.htm) and to get to their main page use this link (http://www.microhydropower.com/).

This is a place selling it. (http://www.gaiam.com/retail/product/17328) It ain't cheap, then again, compared to solar or wind it's not that bad (keep in mind that water runs 24 hours a day, while solar and wind, well, don't...).

-Rob-

[Robert Nicholson]

Great link for info thanks.

In some previous post there was info you posted on voltage regulators. What I am interestested in is how to use a auto alternator to generate the Hydro Energy. My Idea was to take a squirell ? cage out of an old ac and connect a shaft to an altenator and sort of copy an auto sytem 12v going to battery bank. Also considered turning hydraulic pump and then using a hydraulic motor to spin a generator head in a dry safe environment. Possibly opperate saw mill or a chipping mill.

Is there any truth in the rumor that an alternator puts out ac current which is then converted to dc.

Any links to generator / alternator applications would be appreciated.

[Rob Beckers]

Hi Robert,

Take a look at the Otherpower site (http://www.otherpower.com/otherpower_hydro.html). They have a DIY hydro page with a few links in it that may help you find what you're looking for.

-Rob-

[Mark Parsons]

Greetings Robert,

A couple of years ago, I built a Banki type turbine prototype to harvest some energy from the creek at my cottage. It is made from 1/2" HDPE plastic sheets for end walls and 3" ABS pipe cut in half for paddles. I use one of the end walls as the primary pulley for the drive belt to an Automotive Alternator. The first photo shows a different motor where the auto alternator was installed. I played with magnets and coils but wasn't enough angular velocity to make sufficient voltage. The Alternator is actually a PM Alternator specially wound to produce 12VDC at about 60RPM. The pulley ratio provides over 10:1 speed increase. This little unit provides me with about 20W just sitting in the creek. When I get it installed under an overflow pipe, I am expecting to get over 50W. It has stood up great for 3 years of service. I have to pull out in fall and insert in spring. Under the overflow pipe, I will leave year round inside a housing to keep from freezing.

Mark

[Gary Williams]

In Houston and all along the Gulf Coast, there are thousands of bayous, creeks, and rivers draining into the Gulf of Mexico. Amazing quantities of water flow down them, especially released from flood protection dams like Addicks Dam into Langham Creek and Buffalo Bayou. As far inland as 100 miles, the land slopes towards the Gulf at a rate or head of 1 foot per mile.
Probable challenges from local flood control district officers & bureaucrats. Possible grid tie-ins at every bridge across the bayous, along every 1/2 mile or so of water. Langham Creek expands from 1 foot deep by 20 feet wide to 4 feet deep by 100 feet wide depending on the water release. Capturing energy at the dam is obvious and not yet done. I'm interested in the energy all the way downstream.
I have several ideas of capturing this incredible energy but I want to ask the group: What have you got or what can you come up with? Probably no permanent dams until a local group can build up political power (money).

[Jay Miller]

Hey Gary,
I am not sure if you have seen this site but it might offer some thoughts:

http://wildwaterpower.com :)

[Mark Parsons]

Thanks Jay for the reference.

Gary, I am the 'Canadian Fellow' shown on Dennis Buller's site referenced by Jay - wildwaterpower.com I have been collaborating with Dennis for a couple of years now. It is an astoundingly simple technology that has greatly impressed me.

You live in an ideal location to exploit this technology. You don't have any ice flows to worry about. The system is designed to be floating to automatically adjust for flooding and seasonal variation conditions. It is scalable, requires little civil works, and when designed to be closed loop does not interfere with the biology in the waterway.

There is another thread in this Hydro power forum titled 'Paddlewheel Power and Pumping' with more photos and description of the working model and technology.

Water flow kinetic energy harvesting is very new and not many concepts have been tested. There is a huge amount of kinetic water energy that can be captured with very little environmental impact if designed and applied properly.

Mark

[Gary Williams]

A couple of Houston's major bayous drain water that usually 1-2 inches deep. Lots of water. Zero head. Ideas?

[Mark Parsons]

Hi Gary,

Zero head also means zero flow. I'm sure there must be flow otherwise stagnation would be a problem.

The paddlewheel (and all other kinematic devices) harvest a percentage of the energy in the flowing water. Just like wind. Betz limitatons apply as well due to the fact you can't harvest all the energy or the fluid can't exit the device. If the average flow velocity is low then a larger swept area is required to acheive expected power output. Water has the advantage of being 800 times more dense than air. This means 800 times less swept area produces an equivalent power to wind.

The small working model that supplies my cottage with water sweeps a 5.5" deep x 60" wide area. At 36 inches per second of water velocity it provides about 30 watts of power (in the form of pressurized water). A significant percentage of this small amount of power gets lost just in the conversion methods to electricity (turbines and alternators). With a larger scale model the conversion losses would be a smaller percentage of the total.

I have modeled the system and developed a design aid spreadsheet that can provide power expectations and sizing criteria based on the site specifics. If you can provide width, depth and water flow velocity it can indicate a power expectation and size of the machine required to harvest the energy.

I thoroughly enjoyed the few times that I visited the Houston and Galveston area. I am familiar with your topology. The hurricane berm located between Houston and Galveston must be an obstacle that is either pumped over or (probably) able to be closed off during hurricane events.

Regards,
Mark

[Gary Williams]

Looking down into our local bayous, I observe water flowing at 1 meter/second. Forget paddlewheels, turbines, alternating bellows-type compression devices. Think pure rotational energy transmitted through drag. A low mass device sits high on the water, only an inch deep, rotating at the same speed as the water flow underneath. The device contacts the water along a 6 inch curve and bobbs gently as the water flows.
Now, how much power is able to be extracted from the water using a device ranging weighing from 0.5-1.5 pounds assuming the device will also rotate at a speed of 1 meter/second at its circumference?

[Mark Parsons]

Hi Gary,

Power is a simple equation for any rotating device = torque * RPM

In your example the RPM is easily determined from the circumference of the extraction device. Circumference = 2* PI * radius. RPM = velocity / circumference * adjust to minutes - just keep all units the same. i.e. meters if using meters/sec velocity. In your example of a device that has a 6" radius and exposed to 39 inches per second flow (1 m/s), = 62 RPM no load.

Torque is the key. Torque is force * length of arm. Force is paddle area * velocity of water hitting the paddle squared. The force is in Newtons if meters are used. The velocity in this equation is the differential amount the paddle slows the water velocity down. i.e. no torque is produced by spinning at water velocity, maximum torque when paddle is stationary. Only spinning slower than river velocity produces torque. Betz indicates that maximum power is transferred when paddle moves at about 1/3 of river velocity. In your example at about 20RPM.

The very small amount of power in your example of a 1.5 pound device with 6" radius wheel with 1" paddles by unknown length (assumed short due to 1.5 pound constraint) in a 39" per second flow would likely be lost in bearing friction regardless of mass let alone further losses in conversion to electrical energy.

Weight (mass) of extraction device only comes into play for inertia. The resistance to changes in velocity.

Perhaps I don't understand your concept.

Regards,
Mark

[Stewart Corman]

here is an article on how in NYC, they are extracting electrical power from the East River at 4 knots (4.6mph) flow rate from tidal action

note that the design is not that much different from a wind turbine blade, which surprises me as I would have thought a longer corkscrew shape would be better. Water isn't compressible like air, but has a lot more weight behind it
It swivels to accomodate the change in direction of water flow

http://www.renewableenergyaccess.com/rea/news/story?id=25114

[Mark Parsons]

Hi Stew,

A very interesting concept. Limited to relatively deep water applications. Requires civil works placed on the river bottom to anchor the turbine adequately.

I'm concerned about longevity and reliability by permanently submerging mechanical power transmission and high voltage making devices. In this case a salt water tidal estuary.

I look forward to see how the pilot project stands up. Hopefully, their design is robust enough to handle the conditions and provide a decent ROI. I can imagine naysayers (oil company spin doctors), claiming that fish are being killed by the slowly rotating blades, or this extraction of tidal power is slowing the earth's rotation, or some other absolute nonsense that might sound plausible enough to spread doubt, further delaying our withdrawal from fossil fuels until the last drop of obscene profits can be squeezed out. (My little rant for the day....;) )

Mark

[Greg Eckard]

Hi ;

I'm new to the forum and just read about someone looking into a low head application. Get online and search for " Gorlov". His turbine has been used in several spots for producing power from tidal flows. His turbine requires little or no head, only flow from any direction.