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Scott L. Davis

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Recent posts by Scott L. Davis

As you are wondering, equipment in the stream itself is likely to be washed away during high water event. Thus diversion is necessary. The water needs to be cleaned of debris that could damage or clog the turbine, anyhow, with some kind of screening mechanism.

People have been taking water out of streams for irrigation and other purposes since forever, and have worked out many ingenious methods of fluming and directing water hither and yon. Miners divert water lots, as well. You have to know that if you divert water into a ditch, it will eventually fill up with gravel and mud, which means that you should make it possible to clean out the ditch every so often. Depending upon the volume, people have used removable boards to dam ditches, removing them and letting the water carry away the debris for cleaning. Some streams require little cleaning, some require lots.

Not all streams can be developed for hydro potential in a cost effective manner, so each case has many unique elements. Energy Systems and Design has a nice, 10 foot turbine that's worth investigating. There is a turbine called "Powerpal" that uses 5 feet of head and could also work at your site, it sounds like.

In many ways, low head turbines require less by way of civil works than higher pressure systems, and if you have the water flow, may indeed be the best alternative even if more head is available. Practicality is all about cost effectiveness, and so one answer doesn't fit all situations by any means...

Cheers,

Scotty

10 years ago
Just in reply to Jay:

Some people would rather eat a bug than have a battery, but others like having some power stored up so that lights don't go out when the valve gets turned off. No accounting for taste, I guess.

Pumped storage of water is possible (I do have a case study in the Serious Microhydro anthology) but it's really expensive and doesn't produce a lot of power for the amount of power you put into it.

It sounds to me that your site has lots of potential, even without wind or solar. Cliffs are hard to plumb, but probably you could drop a 2 inch pipe down it successfully. Secure it well, for water is heavy.

A battery inverter subsystem makes much from little. By storing up energy till its needed, and by providing large peak currents, the battery inverter subsystem imitates the most common pattern of use. The average amount of power used can be pretty small, a couple of hundred watts, compared to the maximum requirements.

I could offer more specific advice about your situation with more data, but really, you have lots of potential without wind generators or pumped storage. There are many similar case studies in Serious Microhydro that sound like your site...

Cheers,

Scotty
11 years ago
More on how to use these books (pardon the premature submission)

Serious Microhydro: Water Power Solutions from the Experts is an anthology of articles, mostly from Home Power Magazine, that include over 70 microhydro systems. Every site is unique, especially with microhydro, and so no one site is "typical". Thus, having a collection of sites from which to choose is the best way to proceed. There is a chart in the beginning that compares the characteristics of all the case studies, arranged by head. After you find out just how much head your potential site might have, then you can find an article about a system with similar characteristics. There's a range of heads from 22 inches to 746 feet, and flow rates from 5-10 gallons per minute up to thousands of gallons per minute. Most likely, you'll find something like your site there.

There's an article, reprinted from Microhydro: Clean Power from Water, that shows a person (for scale) and various flows of water. To estimate your water flow, compare it to these photos. More water than that? You've got lots!

There are articles about the general context of energy. You need to have a realistic notion of your needs in order to get a right sized system. For example, there's a case study from California of a household photovoltaic system that doesn't cover the whole roof of the house, but still runs both house and electric car. Enough energy falls on your roof (never mind a powerful microhydro system) to power your house and car. That's important news for people to know. Now I hear that there's a bakery in Esquimalt BC that does the same, so its not just for California.

There's also an opportunity to think about the future, with articles on net metering and a proposal for microfinance for microhydro.

Cheers,

Scotty

11 years ago
It does sound like you have multiple challenges. It all depends upon how much you need the power. Off grid, power is very valuable indeed. You might break down and use an under shot waterwheel on an arm so that it can be lifted out of the stream as required, but the flooding issue sounds pretty ferocious.

11 years ago
There are several odd things about the listing for this turbine. Of course, paying the same price as a small car for a 250 watt turbine is absurd.

I don't really know what using a turbine "along" a stream means, either.

Also, 250 watts is plenty of power for a house. There are lots of examples of houses and businesses running on 250 watts or less, using a battery inverter subsystem, in the Serious Microhydro anthology. There's a photo in Microhydro: Clean Power from Water, that shows a big pile of energy efficient lights. The caption reads "Even a small turbine will run lots of energy efficient bulbs".

And so on. The reason I wrote these two books is that there's a lot of foolishness out there and really what you need is true information, gathered from years of first hand experience.

Cheers,

Scotty
11 years ago
I think your flow rate is too low to be practical. A nozzle to deliver 1 gpm is pretty small. leading to inefficiencies because the wheel would be too big for the jet of water to hit properly. In the Serious Microhydro anthology, the lowest flow rates are about 5-10 gallons per minute.

Here's how to calculate the power you'd get from a given head and flow.

flow in gpm times head in feet divided by 14 (10 for larger more efficient systems). Note that the head in this formula is the net head, which includes deducting the frictional losses in the pipe from the gross head.

So if you have 1 gpm at 35 feet of head, you'd only expect a couple or three watts, even if you could find a really tiny turbine. People in the Serious Microhydro anthology find that even a dozen watts is useful in an offgrid setting. 50 to 100 watts delivers a lot of energy, and a 200-300 watt system will deliver a high standard of living. That's off grid. If you already have electricity, hundreds or thousands of watts needs to be generated to make a system pay at a reasonable rate.

Anyway, this will give a good rough estimate of the power output at a given site. I do go into the technie gore details of how to get a pretty good idea of your potential output in Microhydro: Clean Power from Water.

There's a good discussion in the microhydropower buyers' guide, which I helped to create.

Here's the link:


http://canmetenergy.nrcan.gc.ca/renewables/publications/2427

Cheers,

Scotty

11 years ago
More details about this site:

It looks as if there is lots of water.

Many times, you design a system around the available turbines and this seems a good idea here. There are many low head turbines available, such as the Powerpal turbines at powerpal.com and Energy Systems and Design at microhydropower.com. You do seem to have enough water that five or ten feet of head should deliver all the power needed. Serious Microhydro: Water Power Solutions from the Experts, features case studies systems with heads down to 22 inches, and many in the 5-10 foot range.

Every site has advantages and disadvantages. This site seems very flat, with only a drop of a foot or so per hundred feet of run. Many times it is more practical to consider ease of construction over maximizing power output. In an off grid situation, a system that is twice as big might easily cost twice as much, but may not deliver twice as much service. So, using only part of the head available might allow you to site the intake at a convenient spot.

It's all too easy to have the part of the system that gets the water to the turbine, whether its a ditch, flume or pipe, to cost way more and be way more trouble than the turbine. Reducing these costs is an advantage of the low head turbine, if there is plenty of water available.

Getting the water out of the stream and into a pipe or ditch may be the major challenge here. Intakes are discussed in my books and in the Microhydropower Buyer's Guide, but you can also look around and see what other people have done in your area. People have been getting water out of streams and rivers since forever and there are many clever designs out there. Some might be nearby...

Cheers,

Scotty
11 years ago
Pardon any double postings...but to answer your final question first, no, storage tanks and ponds will not improve the pressure situation. Using larger pipes can reduce pressure loss, but really all the pressure you get is from the difference in height between the intake and the turbine, minus pressure losses.

Many of the things you need to know are contained in the Microhydropower Buyer's Guide, which I helped to create. Here's the link:

http://canmetenergy.nrcan.gc.ca/renewables/publications/2427


Secondly, the flow rate should be verified, at least roughly. If you have a few hundred gallons per minute available, then thirty feet of head, with the right turbine, pipe. and battery/inverter subsystem (or not) could easily provide a high standard of living to an off grid home.

If you already have power from a utility, the economics may seem poor.

So anyway, try confirming the flow rate available.

Cheers,

Scotty
11 years ago
There are many people who collect rainwater for drinking water. I live on an island, and while we seem to have lots of water, smaller islands nearby are always short of water. There is a long history of collecting rainwater to drink.

Of course, lots of people collect rainwater for shampooing the hair, because it is soft, and when collected properly, clean.

Not all roof materials are suitable to collect drinking water. My favourite roofing anyway is metal roofing.

To keep cisterns clean, the first rainfall in a long time is allowed to rinse off the roof and discarded. Only when the rainwater is running clear will a valve be opened to lead to the water tank or cistern. It's all worked out...

Modern islanders use food grade tanks and pressure tanks to provide "nearly normal" service.

Cheers,

Scotty
11 years ago
In my book, Microhydro: Clean Power from Water (available from New Society Publishers at newsociety.com), I list the kinds of water sources that are more likely to be developed as microhydro sites. "Streams, creeks, springs, brooks" are small and easily controlled. Many systems use so little water that even a modest stream is plenty.

Rivers, not so much, in that they present lots of problems with flood waters and debris.

In the anthology, Serious Microhydro: Water Power Solutions from the Experts", I reprinted my favourite method of estimating water flow, which is to compare the flow of your stream with some photos I have taken over the years of the outflows of microhydro systems. The volume of these outflows is quite accurately determined by the nozzle size, and so these pictures show me in a quite precisely known volume of water. Even 500 US gallons per minute is a little stream you can step across easily, that barely goes over the toes of my gumboots, a few inches deep at most.

That said, one of our ingenious neighbours made an undershot waterwheel out of a wheel move sprinkler part. It was mightily geared up to run a truck alternator. It gave a few amps. Efficient lighting makes a few amps go a long ways.

These kind of systems work because in an off grid environment, the benefits you get from your electrical system show diminishing returns. After you have lighted the place up and charged up your phones and laptops and whatnot from a few dozen watts, it takes quite a bit more power to run electric refrigerators and freezers, like a few hundred watts. It's amazing how much can be done with so little when power is saved up in batteries and put through a modern inverter. The battery inverter subsystem makes much from little, indeed!

Anyways, I do know the Snake River and my gut feeling would be that there are probably better opportunities than that. It's not that there are potential watts there, its just that getting them out and dealing with big changes in water level will be difficult (which also means expensive).

You might need to examine just how much more power would be worth. Maybe gains can be made from more efficient appliances or design that would be the equivalent of more power.

Every site has many unique elements that need to work together to make a successful site. Wind power is quite effective at the right site. Maybe just more solar panels or a general system upgrade would meet your needs.

Really, that's what its all about is meeting needs, not generating a certain number of watts..


Cheers,

Scotty
11 years ago