This interesting case study spotlights the old rule that most great engineering efforts are 80% perspiration (actually, I think it's 90%) and 20% technical smarts. This project simply wouldn't have happened without all that digging, building, and dirt moving.
Design News asked for people to moderate and presumably add comments to their web site. You had to make a certain number of posts to remain in the system and to receive a stipend or whatever it was called. I get the feeling that this thread is more about maintaining a posting record than making real comments about an idea that is impractical in almost every state.
The idea may or may not be impractical, but the comments are entusiastic. Those who comment on the Design News site are passionate about their views. I think that's very clear in this thread as well as the other comment threads.
Great idea. Getting tied into the grid seems to be an important factor here. Saves the whole problem of storage. The perspiration will probably pay for itself in time, since the foundation is the least likely part of this power plant to fail over time.
I agree, Rob, this sure eliminates the storage problem. And it's heartening to read that the minimum for generating hydroelectric power is only a two-foot drop and two gallons per minute. That's a lot less than I would have guessed.
I've often wondered if we could generate power from the creek in back of our house. At least part of the year, it fulfills those minimum requirements.
If renewables are going to make a significant impact, a certain percentage of the power and a certain percentage of the storage will have to happen on the micro level. This is a great effort and it's a perfect example of what can happen at that micro level.
I agree that there needs to be support and commitment at the micro level. The challenging economic climate of the last few years has definitely fanned the flames of the local movement and a do-it-yourself mentality. Perhaps that will translate into more people attempting projects as ambitious as this one.
@letsthink: I agree with you that the numbers don't add up. If 40 cubic feet per second of water (18,000 gallons per minute) falling 10 feet generates 20 kW, then 2 gallons per minute falling 2 feet should generate about 1/90,000 as much power, or 0.2 W. Maybe you could make a LED light up with this.
I read the article as saying that technically you CAN generate electricity with as little as 2 gpm and only 2 feet of head. This doesn't necessarily mean it is economically attractive, or even that much of a benefit. I gather that in this application they have 10 feet of head and run close to 320 gpm, when generating 20KW. It sounds like the lake does not always have enough flow to permit continuous generation at this rate. The use of three 15 HP motors is to adequately load the 50 HP turbine.
This was an interesting article. I have been very interested in low rise lakes for storing wind or solar photovoltaic energy. When you have wind or sun, you can drive pumps to pump up to a reservoir/lake/tank from a lower lake or river. Then you can generate hydroelectric power when you need it, or when the peak load gives the best payback to feed the grid. The "potential energy" of gravity on water may be more cost effective than batteries.
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.
What wasn't clear to me is if they generated single phase or three phase power. Why the three motors? 15hp is about equal to 20kW, so any one motor could have been a generator. Can anyone fill in the blanks here?
Also, I'm curious what prompted the report--it does read suspiciously like an Automation Direct ad....
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.
Froese, thanks for taking the time to respond to my question. You have done something I wish to do, although my application would be a pelton wheel system since I have fairly low flow but a 900 foot head.
It looks like you took the time to research the highest efficiency in belt power transmission- are all your drives toothed belting? The video is not clear--the main drive from the turbine looked like it might be a multiple v-belt setup but the motor drives certainly looked like toothed belt drives. Do the toothed belt drives on the motors allow for automatic synchronization of all three motors with each other? Did you have to play with the shaft orientation on each motor to get all three sinewaves from the motors to coincide?
Congratulations on your efforts! You can be justifiably proud of your accomplishment. And I probably will investigate Automation Direct as well!
The main belt (from the turbine shaft to the secondary shaft) is toothed, but the belts to each individual motor/generator are ordinary v-belts. We have found that the slippage allows them to synchronize. On rare occasion, when starting starting a generator after other(s) have been running for sometime, it can be 180 degrees out and cause the breaker to trip, but most of the time they seem to sync up by themselves in a fraction of a second.
...try again with the watts to horsies...as one horse is 746 watts...so a 15 horse motor would be around 10 KW....
Article says 3 of the 15 horse motors...so yes...about 20KW...if all goes well.
Then, to get the buy-back...I'm assuming the generator must be exactly 60 Hz...?
I've worked at a couple small (30-40) Mega-watt Bio-Mass plants...the on-line syncro is extremely important...and...I'd assume this set-up here in the article has at least a transfer switch of some kind...? That is one of the first things any hydro or PV set-up requires. Otherwise I would think you could end up with utility power running your motors and pumping the water backwards...but then, I could be wrong....
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!
"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!"
"It is easier to ask forgiveness than permission." Seriously, the environmental impact is minimal since the lake has been there for 100+ years, and there was already a spillway here. Regarding utility interconnection and net metering, our state (South Carolina) does not have rules and regulations for this yet and our local electrical co-op was actually quite helpful and generous in this regard. I'm quite certain that if we had to fulfill all the environmental, engineering, seismic, etc. regulations California has, this project would have been a "no go."
Froese beware. The term "environmental impact" in the 21st century is NOT related to a technical assessment or common sense. "Environmental impact" is a legal and political term that is based on a maze of disjointed, over bearing, and convoluted laws, regulations, and policies writen by some clueless folks, supposedly with good intensions. The majority of the enforcers are egotistical morons who have a basic policy of 'deny/reject all applications unless unless forced to approve them".
To be clear-
1. We need to protect and care for our planet.
2. Some of the 'enforcers' are very competent and diligent.
3. We need a single set of intelligently integrated [and understandable] laws and regulations with a workable enforcement mechanism.
My favorite 'bonehead policy' relates to petroleum- [oops-way off topic]
Choice A-extract it from the earth in the US using the best companies, under the best supervision, using the best workers, creating the most domestic jobs, with the least chance of environmental damage.
Choice B-the current hypocritical, 'head in the sand' policy of exporting US dollars to pay countries who are not 'environment friendly' to extract petroleum, sometimes using marginally competent workers who 'do not spill much'. Petroleum is then placed into a leaky tanker that travels 1000s of miles to unload it in the US.
Still trying to understand the ROI if I do have a creek without that nice dam the guys had to work with. Thanks to my beavers ... I've got some 3 foot drops (some of the year) and good volume (but not 40 cubic feet per second). I also have an issue that the creek is a good distance from the house and/or grid. Would love to see more detail from the perspective of implementation.
If you are interested in small hydroelectric installations, spend some time on the internet and following some of the other links provided by the other post'ers (is that a word??).
I did a short analyisis on a similar system for my brother who has a trout farm down south - he has a fair amount of water flowing (the details are buried away someplace on this computer) and he thought that maybe he could make some money from that by selling (or at least 'replacing') electrical power. Unfortunately, from the information I could find, the ROI was clearly NOT in his favor even for a mainly DYI system.
The author's system is impressive - very impressive. But I doubt if it makes economic sense IMHO.
This is a great DIY project, but it probably doesn't scale well to similar sized commercial applications. I'm thinking mainly because of labor costs involved. It sounds like the two brothers did most of the work, with no costs associated with their time. Labor costs alone can be a very significant cost in projects like this. Many applications may also require the design services of professional engineers (structrual, electrical and mechanical), another significant cost.
Incentives (and hardware requirements) vary from utility to utility, also. Sounds like these guys got the best of both worlds...simple grid-tie in requirements and very attractive buy-back rates for surplus power. In some areas its exactly opposite. Very expensive equipment required for grid connection and buy back rates less than what you typically pay as a consumer.
And even a 100W generating system may require the same level of automation and control of this 20kW system. This means that there is really no way for the 2 gpm / 2 ft. drop system to have ANY payback if you want to make it grid-connected. But, if all you want is a stand alone system to charge up your cordless drill, you're off the races. A simple water wheel and a DC motor will get you up and running without even needing a dam.
I don't mean to be a pessemist, but there are real technical and regulatory barriers to this kind of thing. The real success story in this applciation is the amount of time and effort (the perspiration) that these two guys put into the job. Kudos to them.
When I was wondering whether the creek in back of our house would support a system like this, even a very small one, I was also wondering about potential difficulties with local and state zoning requirements.
Anybody have any ideas? I know that in our area I found out we're a protected salmon run, so that tosses that idea out the window.
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.
Indeed. I did a quick check. First, I assume the typo of minutes vs. seconds. 2 gallons per sec is about 16 pounds per sec over a 2 ft drop is 32 pound-ft/sec is about 43 watts at near 100% efficiency.
The basic premis is all wrong. You can't do a whole lot with 40W but it might be better than nothing in some circumstances.
My 20 year old analysys of low-head hyrdo didn't come up with a service period that equalled or exceeded the payback. Power companies are notably fickle about allowing any frequency other than 60HZ, so generating AC, converting to DC, then back to 220VAC/60.00HZ was a significant expense. Older turbine water wheels had adjustable 'vanes' that kept speed constant independant of load but their accuracy was unacceptable; most newer wheels use a 'throttle' plate to control input flow which greatly reduces the efficiency of the set-up, though if flow can be held constant, speed can be controlled varying the field to control load. Finding and rehabing a hundred year old bronze 20-50HP turbine was the best economic solution, though these are few and far between. In Maine, fish are more important than electricity, so we're tearing down 100 year old hydro dams in hopes there is a 100 year old salmon who may want to come home to spawn. Several of my fellow hyrdo co-conspirators genrate DC and use that to run resistive heat, controlling indoor temperature by opening or closing windows. Assuming you own a dam which will supply minimum flow, can find an old turbine wheel, can cludge-up the necessary controlls to meet the grid requirements, can meet the environmental concerns, can do most of the labor yourself, you still have to be aware that the government in all its wisdom will change the rules and remove the requirement that the power company must pay you at their 'cogeneration' rate, rather than some other contrived rate. Like electric cars, the analysis of the economics for hydro power is more emotional than economic. I congratulate the writer on an apparent successful installatioin, other than the typo of water flow, the research looks good, though I don't see how he controlls frequency to meet the grid requirements.
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.
I caught that they dug a 17-Ft hole, and combined with the 10 Ft drop they mentioned, there could be a roughly 25-Ft head of water with the turbine down at the bottom of the hole. About 12 PSI. Also, induction motors, run as motors, turn at a slip frequency a bit slower than the 60 Hz driving them. BUT, when you run them for a bit as a motor and they achieve near synchro speed, 1750 RPM or so, then try to spin the shaft faster than that, you will push power into the grid as a generator once you try to turn it faster than 1800 RPM. The grid is bigger than the motor, so the grid prevents the motor from going as a generator faster than the 60 Hz grid frequency, but power will flow into the grid as you push harder. This was a Motors Lab exercise we did at the University of Idaho back in the 70s. Of course, if the grid drops, the motor will run overspeed because the hydro turbine wants to spin it faster than 1800 RPM, so the need for shutdown controls. This project is a LOT of work, but very nice. Here in California, the utility companies might not accept a home-grown control system for Netmetering or grid-tie operation. I have always wanted to do a hydro generator system, but here in the Mojave Desert, we have no water....
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.
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.
Jim, I agree. That's mind-boggling. But here in California, for decades PG&E fought solar power in homes tooth and nail. A once-famous local columnist, Herb Caen, once famously said "PG&E wants to put a switch on the sun." When PG&E finally had to give in, it then fought buy-back for many more years.
What part of free is so tough to get? I think it's actually about control, not about free.
I also read the article in the Automation Direct publication. and I found it fairly interesting. I can certainly imagine that there would be a whole lot of government people wanting to have control over exactly how it was done.
The method of using standard induction motors driven a bit faster than synchronous speed was quite interesting. I can understand needing to have some belts that could slip, as a means of allowing the motors to synchronise with the mains power, because otherwise it would not work. It is also probably the cheapest approach, although it may not be the most efficient. My choice would be to drive three phase alternators and then convert the power to the correct frequency using a switching cycloconverter. That is more costly, however. The advantages are that one single device could be controlled to deliver the desired amount of power, and the generator would not need to have the drive speed controlled so precisely. Besides that, I like alternators more.
One interesting thought is that one of the older mecanical meters could be driven backward quite simply, but the newer generation of smartmeters could easily be programmed to not run in reverse. In addition, It is certain that the power company could pull all kinds of tricks with the smartmeter programming.
One last comment is that it would be interesting to see a detailed description of both the mechanical and the electrical design of the system.
My admiration for all the hard work and ingenuity!
Here in Michigan (and in most states I would think) the DNR would be all over this. Also FERC (Federal Energy Regulatory Commission) claims jurisdiction and requires that a hydro have a license even with the tiniest stream generated electricity if it is grid interconnected. These two entities would easily double the cost of the project even at this small scale. I would like to know how you avoided these burdens.
A lot of people have trouble conceptualizing the induction aspect of a motor/generator. An induction machine delivers the nameplate rated hp as a motor at the nameplate rated amount of slip below synchronous rpm and, in turn, will generate the rated equivalent electricity as a generator at the same amount of slip above synchronous rpm. An electric motor is not "synchronized" at start up - that is just the condition under which it delivers maximum torque because it is at maximum slip. The line sets the voltage, frequency and phase relation. The induction machine simply uses those properties to operate without need for complex controls, regulation and phasing.
Thank you, renuengineer for that explanation of how induction generation works; I couldn't have done it better!
Re: FERC, they don't involve themselves with individual installations this small. In South Carolina, our department of Health and Environmental Control does regulate dams & reservoirs, but our lake had already been in existence for over 100 years. The utility company was satisfied with some cursory drawings and assurance that we were entirely induction-based. The only official inspection was that of the county building department.
I applaud this project from a technical and ingenuity standpoint.
However, I tend to agree with the pessimism on the regulatory stuff. Here in NY, the environmental hurdles as well as the federal & state energy commisions/authorities and utilities would make it nearly impossible. The thousands you would have to spend on attorneys, permits, fees, and political contributions to make it happen legally could buy you electric power from the utility for a hundred years or better. I think in this state the only thing attempting such a project would get you is legal trouble and the related fines and attorney fees.
If I can get 20Kw from 2 gallons a minute falling from 2 feet, I can easily pump it back up again with little ornamental pool pump, which uses less than 250 watts, so I will have 20250 Watts to sell back to the utility.
I dont even need a stream !
The story was talking about 40 cu ft per second, dropping 10 feet, which is 18,000 gallons per minute, or equivalent to 90,000 gallons per minute dropping 2 feet as opposed to the 2 gallons in the opening paragraph.
You are absolutely correct. There's little more than .001 hp available from water @ 2 GPM dropping 2 feet. If this was able to produce 20 Kw we'd have ourselves a nice perpetual motion machine! I think that the heading of the article is misleading. The article itself is worthy.
I have yet to connect our Micro Hydro to the grid. Except for a few hours of testing, when I discovered what 'absolute value' metering meant, we have been running autonomously since commissioning 2006. I used pumps as turbines and 3 phase motors as single phase generators to cut costs. I don't think I gave up any efficiency at all since I'm getting a bit more than my initial calculations indicated. NY just passed the net-metering law for under 25kW hydro, so we'll be hooking up soon.
Syncing induction generators of a few tens of KW to each other or the power-line is not a problem as long as they are within a few RPM or Hz of each other.
This is a very good work! I wonder if this is affordable for developing countries like Mexico or Latin America where there is good potential for micro hydroelectric generation, how expensive is the system and where can I purchase one? Thanks
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