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Power to the People
In February 1987 we had the opportunity to plan and install a small DC hydroelectric generator on a rural dairy Co-Operative in Nicaragua. The ranch had belonged to a Minister in the Somosa Regime. After the Revolution, the land was distributed to the workers who had formerly lived under conditions resembling serfdom. The Co-Operative has a total of 34 families, 9 of which presently live on site. Our objective was to provide enough user friendly electricity for lights and improvements for present and future families.
Eight houses are spaced about 75 feet apart in 2 rows of 4 each. The 9th house is over 1/4 mile away and was the original hacienda. It also serves as a gathering place for meals and fiestas. A creek runs within 500 feet of the nearest house and a 3,000 feet long nearly level flume passes between them. The flume was built to feed the swimming pool. It now also provides agricultural water for the dairy operations.
In November, 1986 I was contacted by some friends who were planning the "Power to the People" project and needed information and hardware. The project was sponsored by Technica, a Berkeley, California based technical assistance organization. They expedited all the complexities of getting to and from Nicaragua. Always one to travel, I joined. Kate, a project organizer, had been at the site previously on a house construction project. From her memory, we had enough site data to build the turbine and collect other necessary parts.
A prime design consideration was to make the system be locally serviceable. This precluded the use of some of the fancier electronic equipment that is so useful to us in the U.S.A. The exception to this was the Enermax charge controller. We had to control battery overcharge and these units are nearly indestructible.
Because of the U.S. embargo, Delco alternators, which we usually use, are very scarce. Japan trades extensively with Nicaragua and the 40 amp Toyota alternator has the proper characteristics. We committed to 12 Volt operation because of the universally available automotive light bulbs, radios, batteries, etc. We chose edison base, 12 Volt, 25 Watt lightbulbs because of their reliability, but took along adaptors to convert to automotive type bayonet base bulbs, just in case.
On February 3rd, four days before I was to board the plane to Managua, I got a frantic message from Kate and Bill. They had driven down thru Mexico and Central America the month before. They had discovered that pipe availability was a problem and we probably couldn't get the 100' of head that we had planned on; perhaps as little as 20! A quick conversion back to a rewound Delco alternator produced a system that would operate from 10' of head up and could use 1 to 4 nozzles.
My plane tickets gave me two weeks in Nicaragua. We had to plan, scavenge parts, transport everything 100 miles, install, troubleshoot and get back to Managua in that very short period of time. Upon touching down in Managua, I was met by Bill, Kate, and Ben Linder, the first American to die at the hand of the Contras.
20' pipe lengths on an 11' truck. Photo by Don Harris
We spent the next 2 days in and around Managua rounding up pipe and hiring a truck to haul the 3,000 feet of 4 inch PVC we managed to obtain. On the 3rd day we headed North to Esteli and the project site.
The original plan was to run a pipe parallel to about 1500 feet of the old flume and then pick up as much head as possible in the creek bed. We set out surveying and found that with our 3,000 feet of pipe we could get almost 100 feet of drop, our original estimate. But we also noted the rugged, almost vertical canyon walls in the gorge and the fact that we had only 9 days left to get it all done. We had the full time help of 2 local people and the whole community at crucial times.
Chris, an American working in Central America, and Ben arrived about this time and an alternative plan emerged: If the flume delivered far more water than the needs of the ranch, we could divert some of the water some of the time thru a 300 foot long pipe back into the creek. This would be much quicker (and thus more likely to be finished) and would save 2,700 feet of very precious pipe for other use. The flume had a diversion gate at about the right place. With a little brick work and some screen as a filter it could be used. Chris and Ben consulted the ranch elders and determined that they could afford 12 hours a day operation in the dry season. We quickly surveyed and found we had 78 feet of head. WE HAD A SYSTEM!
The practical (50% efficient) potential from 300 feet of 4 inch pipe and 78 feet gross head is about 2,100 watts. This would be using 450 GPM at 54 feet net head. Our unit using 4 nozzles can use up to 160 GPM and could, with the right alternator and at the right voltage, produce 800 watts. Our commitment to 12 Volt operation and our use of the ultra-low head alternator limited us to 8 Amps. This latter limit is due to the small diameter, long wire in the special stator winding.
We had to go 500 feet from the turbine to the batteries and up to 250 feet from the batteries to the houses, a long way for 12 Volt transmission.
We had 3,000 feet of 12-2 Romex wire which translates into 9,000 feet of #12 wire including using the ground wire as a
8 houses with central
conductor. We battery shed did get 200 feet of #10 single strand wire in town, but it is scarce and it seemed almost antisocial to use too much.
After playing with the numbers, the best choice seemed to be 1 run of Romex to each house, 2 conductors + and one -This is about .7 Ohm resistance in the worst case. The 25 Watt lights we used are 6 Ohms, so wire losses are a little over 10%. Though not ideal this was acceptable. The practical result is slightly dimmer lights that will probably last longer because they are running at 12.5 volts. The 2-100 Amp-hour gel cell batteries are held at 13.8 volts by the Enermax regulator.
The remaining wire provides 4 runs of Romex from the turbine to the batteries; 6 conductors +, 6 -. This is about .26 Ohms. With 8 Amps output the alternator runs at 16 Volts to deliver 13.8 Volts to the batteries, about 14% line loss. Again not ideal, but acceptable in this case. Any significant increase in power will require raising the system voltage.
The pipe runs almost level for 240 feet, gaining maybe 20 feet head then plunges almost vertically for 60 feet into the creek gorge. A very steep switch back trail goes part way down the canyon, but the last 20 feet are so steep we had to build a ladder to even see if there was a spot to mount the turbine. The wood was milled on site, freehand with a chainsaw. I wish the wood I buy at the lumber yard were all as straight. Fortunately, there was a convenient little flat at a spot about 20 feet above the creek. No one remembered seeing the water that high in the wet season. We had to tie the pipe to trees to support the weight of the long vertical section and build a sturdy shed roof over the unit because our working resulted in a continual avalanche on the site. Indeed, someone often
8 houses with central
watched as others worked to warn that boulders were on the way!
Kate worked on building the light and switch wiring for the houses. She surveyed each family for their choice of light placement. Because of the mild climate, most people live more outside than in the house. Someone came up with the ingenious idea of knocking out a high wall board, allowing light both inside and out, and everyone followed.
As our Romex was not direct burial rated, we encased it by dragging it thru 1 inch plastic pipe for protection before burial. This was a most strenuous operation, especially the 4 wire section from the turbine to the batteries.
Each house was individually fused on the + side at the battery end and a protective box was built around the storage/distribution complex. Not only did this protect the children from the hardware, but also the hardware from the pigs, which will aggressively explore anything they can get at.
Finally, one day before we had to leave, the moment came, we turned the valve and the turbine gurgled and belched its way up to 8 Amps in a few minutes. We were on line! Later that day we connected the houses with periodically and possibly a nozzle unplugged. Time will tell. Some Final Thoughts
One late night about a week into the project we were awakened by 2 earth shaking explosions. The next day we found that the Contras had blown the main power lines 15 miles from where we slept. These were no firecrackers. Much of Northern Nicaragua was down. When we left for Managua a week later, the only evidence of electricity I saw was at our project. A striking impression was that of hundreds of people hauling drinking water on their backs for miles. The city's water treatment plant is electrically operated. Two facts were evident: 1) the real burden of terrorism is born by the common people, and 2) those of us that produce our own power are free indeed in times of civil strife.
PVC glue smells the same in Nicaragua as here... nary a glitch and the neighborhood lit up!
We had forgotten the 9th, more distant house until the last week. Bill located a battery in town and we set up a shuttle system to the charging station. The following month, Dave Katz of Alternative Energy Engineering went down with solar panels and — but that's another story.
The final statistics are 125 watts at the turbine using 21 GPM and 77 feet net head. This rather low 40% efficiency is due to high losses in the special wound, low head stator. 110 watts are getting to the batteries after wire losses. The system operating 12 hours will produce 1.3 KWH a day, enough to allow each house 6 hours of light. This far exceeds the perceived needs of the families.
The last day at the ranch was a festive occasion in celebration of the project. We left for Managua with warm feelings and happy memories of this time with our Nicaraguan friends.
What It Cost
If translated into USA terms, the total hardware cost of the system was $2,850. It breaks down something like this:
The cost per house is $316 including delivered power, house wiring and one set of spare light bulbs and fuses.
Maintenance costs should be primarily battery replacement every 5-7 years, plus occasional light, fuse, and alternator part repairs. The leaves need to be cleaned off the screen
Ben Linder was at the site for two days in the early part of the project. We sat one night and talked about the World. He shared a profound understanding of the situation in Central America. He wanted so much to heal the wounds. We made plans to apply water power to grinding corn and coffee. Ben brought lights and happiness to the people and they loved him. Not only did he electrify several villages, but he helped bring the Children's Circus to Nicaragua. He was the best kind of Ambassador America could possibly have. He is missed there as well as here.
Contributors to the Project
Alternative Energy Engineering, Box 39HP, Redway, CA 95560, 707-923-2277
Earth Lab, 358 S Main St, Willits, CA 95490, 707-459-6272 Harris Hydroelectric, 632 Swanton Rd, Davenport, CA 95017, 408-425-7652
Integral Energy Systems, 105 Argall Way, Nevada City, CA 95959, 916-265-8441
AND COUNTLESS GROUPS AND INDIVIDUALS who helped in one way or another.
Celebrating of Day 12.
Many people have access to some form of running water and are wondering just how much power, if any, can be produced from it. Almost any house site has solar electric potential (photovoltaic). Many sites also have some wind power available. But water power depends on more than the presence of water alone. A lake or well has no power potential. The water must be FLOWING. It also must flow from a high point to a low one and go through an elevation change of at least three or four feet to produce useable power. This is called the head or pressure, usually measured in feet or pounds per square inch (PSI). The flow is measured in gallons per minute (GPM) or for those blessed with larger flows, cubic feet per second (CFS).
At most sites, what is called run of river is the best mode of operation. This means that power is produced at a constant rate according to the amount of water available. Usually the power is generated as electricity and stored in batteries and can be tied to an existing PV or other system. The power can take other forms: shaft power for a saw, pump, grinder, etc.
Both head and flow are necessary to produce power. Even a few gallons per minute can be useful if there is sufficient head. Since power = Head x Flow, the more you have of either, the more power is available. A simple rule of thumb to estimate your power is Head (in feet) x Flow (in gpm) /10 = Power (in Watts). This will give you a rough idea of the power available at the average site and reflects an overall efficiency of 53%. This is a typical output for a well designed system. For example: if your head is 100 feet and the flow is 10 gpm, then 100 x10/10 = 100 watts. Keep in mind this is power that is produced 24 hours a day. It is equivalent to a PV system of 400-500 watts -if the sun shines every day. Of course, the water may not run year round either. So it is apparent how a combined system can supply your power needs on a continuous basis.
Determining Head & Flow
Let's start with the head since that is easier than the flow and will give you confidence to continue. The best method to determine the head is also the easiest and can be used at any site. It is also very accurate. It involves using a length of hose or pipe in the neighborhood of 1/2" diameter. You can start anywhere along the brook and proceed upstream or down. First submerge the upstream end in the water and weigh it down with a rock or something similar. With the top end fixed in place underwater you move the rest of the pipe downstream. When you have reached the end, it is now time to start the water flow through the pipe. This may require you to suck on the end. Once flow is established and all air bubbles are removed, slowly raise the pipe upward until the flow ceases. When this point has been reached, use a tape measure to measure the distance from the end of the pipe to the surface of the water. This reading is the head for the stretch of brook. The pipe then becomes a convenient measure of horizontal run if you use a standard length like 100
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Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.