Ann: Taking a quick look on the Internet, it appears that many states (possibly as many as 40?) have buyback programs, but it's not clear if that energy buyback is mandated.
"How many hoops did they have to jump through to get permits for zoning, excavation, disruption of "wetlands", don't step on this beetle, utility easements, etc. These are the real cahllenges to a project of this type. The technical part is simple!"
That's a really interesting point, Larry. Right now, at least in California, if I have a solar power system that produces more electricity than I need, PG&E will but it back from me. (I won't go into how long it took to get that accomplished!). But I'm not aware of any similar setup for sellback to a utility of hydroelectric-generated electricity, here or in other states.
California is a horrific state to do anything in. Regulations and tree-huggers pretty much wipe out anything that is likely to step on a bug or threaten a fish by touching the water. I put in 5 KW of tracking solar and went through "heck" to get the approvals, because I wanted some storage batteries for power outages, rather than the simple grid-tie Netmetering. New wind and seismic regulations make a lot of projects more expensive and difficult. Water pretty much does not belong to us, and my well on my property may become regulated by the State, as they want to find out usage and to require a Certified water technician to be in charge of the well. I plan to study and then take the test for the Certification. So many of the people I work with are abandoning the state when they retire, and a lot of businesses are fleeing. I plan to stay because I live out in the middle of nowhere, so not right under the nose of every meddling regulator, even though I would not knowing do anything damaging to the environment. Regulators are often people with no degrees, telling those of us with engineering degrees that we don't know what we are doing, or simply say NO to our requests to use some resource. I work for the Government and am so disgusted by what is going on that my retirement in 11 months will be a tremendous relief.
Actually applications like this may not subtract from utility profits. The ideal utility model may be a model where it owns no generation (high capital cost, enviromental issues, ....) and where it merely makes money buying, transporting, and selling.
True, this is awful close to the Enron model.
Therefore they may not be opposed to this and they may have government incentives (financial or political) to be helpful. This is green renewable energy. Even if the amount is very small, to be able to tell the enviormentalists all they are doing in renewable energy can be big.
I'm in California, too, and I second your mention that the utilities would not appreciate anything that detracts from their profits.
My main question, though, had to do with municipal and state regulations. We only own the land down to the creek, not the creek itself. It passes by our property and many others' as well.
Otherwise, I'd love to build a system something like this, even if it were just to charge batteries. It would be fun and at least a stab in the direction of self-sufficiency.
If you have a creek with fairly constant flow and you want to do it as a hobby to charge batteries or the like, a fairly simple undershot wheel (essentially paddles that turn a wheel with a horizontal axle), belts or gears to speed up the output and an alternator would work. Narrow up the creek to speed up water flow a bit and you have it. Building a dam with all the permitting, fish ladders, environmental concerns could take a lifetime. Making a waterwheel and watching it turn just because you could is reason enough to do it, even if it doesn't do more than charge a battery.
Frequency appears to be controlled by the AC motors. I'm no electrical engineer, but its sounds like they are fairly simply connected to the grid. If there were no water flow, they would drive the turbine...basically the same concept as dead-heading a pump. If you put a clutch on the turbine, they would run at no load, 3600 RPM or whatever.
If instead you engage the clutch and use the turbine to supply torque TO the motors, you should get power out. The RPM of the motor will not change because it is based on the frequency of the grid power. Conversely, if you starve the turbine with too little flow, the system will probably CONSUME energy as the motors will continue to drive the turbine at 3600 rpm (assuming 1:1 drive, etc.).
So, to start this system from an OFF state, you would probably have to go through the following.
1. initiate flow to get turbine turning at some rpm close to final drive ratio, based on motor RPM and pulley diameters, etc.
2. close contactors on motors. If rpm was determined properly, the motors should see basically a no-load start and immediately sync with grid frequency.
3. Increase flow to supply torque to the motors, thereby generating electricity.
The system is probably incapable of operating independently of the grid because it NEEDS that 60 Hz power to control the RPM of the turbine and motors. I'm surprised his local utility allows them to operate like this. Around here there are much more stringent requirements, and rightly so. After all, back-feeding the grid in the event of a power failure is a serious issue.
We generate single phase power, since 3 phase is not available in this rural location. The largest single phase induction motor we could find was only 15 hp; this is the reason we have three (15 hp = 11 KW, and we were expecting to generate 33 KW.)
Yes, I wrote this article for "User Solutions" in AutomationDirect's magazine: Automation Notebook.
This "2 Gal/minute...2 feet drop" was added by an editor. I agree this is not realistic. Several gallons per minute might be feasible for a high-head (100+ feet), pelton wheel installation, and a 2 foot drop might make sense for a small river, but I actually think our installation is about as small as you can justify unless it is just a hobby.
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