101:. The penstock builds up pressure from the water that has traveled downwards. In mountainous areas, access to the route of the penstock may provide considerable challenges. If the water source and turbine are far apart, the construction of the penstock may be the largest part of the costs of construction. At the turbine, a controlling valve is installed to regulate the flow and the speed of the turbine. The turbine converts the flow and pressure of the water to mechanical energy; the water emerging from the turbine returns to the natural watercourse along a tailrace channel. The turbine turns a
134:
head must be considered. Gross head approximates power accessibility through the vertical distance measurement alone whereas net head subtracts pressure lost due to friction in piping from the gross head. "Flow" is the actual quantity of water falling from a site and is usually measured in gallons per minute, cubic feet per second, or liters per second. Low flow/high head installations in steep terrain have significant pipe costs. A long penstock starts with low pressure pipe at the top and progressively higher pressure pipe closer to the turbine in order to reduce pipe costs.
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288:, the simplicity and low relative cost of micro hydro systems open up new opportunities for some isolated communities in need of electricity. With only a small stream needed, remote areas can access lighting and communications for homes, medical clinics, schools, and other facilities. Microhydro can even run a certain level of machinery supporting small businesses. Regions along the
90:
diverted from the natural stream, river, or perhaps a waterfall. An intake structure such as a catch box is required to screen out floating debris and fish, using a screen or array of bars to keep out large objects. In temperate climates, this structure must resist ice as well. The intake may have a gate to allow the system to be dewatered for inspection and maintenance.
138:
feet, the theoretical maximum power output is 5.65 kW. The system is prevented from 100% efficiency (from obtaining all 5.65 kW) due to the real world, such as: turbine efficiency, friction in pipe, and conversion from potential to kinetic energy. Turbine efficiency is generally between 50-80%, and pipe friction is accounted for using the
224:, a pressurized self-cleaning crossflow waterwheel, is often preferred for low-head micro hydro systems. Though less efficient, its simpler structure is less expensive than other low-head turbines of the same capacity. Since the water flows in, then out of it, it cleans itself and is less prone to jam with debris.
260: : advanced hydraulic water wheels and hydraulic wheel-part reaction turbine can have hydraulic efficiencies of 67% and 85% respectively. Overshot water wheel maximum efficiency (hydraulic efficiency) is 85%. Undershot water wheels can operate with very low head, but also have efficiencies below 30%.
275:
Microhydro systems are very flexible and can be deployed in a number of different environments. They are dependent on how much water flow the source (creek, river, stream) has and the velocity of the flow of water. Energy can be stored in battery banks at sites that are far from a facility or used in
89:
Construction details of a microhydro plant are site-specific. Sometimes an existing mill-pond or other artificial reservoir is available and can be adapted for power production. In general, microhydro systems are made up of a number of components. The most important include the intake where water is
346:
Microhydro systems are limited mainly by the characteristics of the site. The most direct limitation comes from small sources with the minuscule flow. Likewise, flow can fluctuate seasonally in some areas. Lastly, though perhaps the foremost disadvantage is the distance from the power source to the
171:
always operates at the grid frequency irrespective of its rotation speed; all that is necessary is to ensure that it is driven by the turbine faster than the synchronous speed so that it generates power rather than consuming it. Other types of generator can use a speed control systems for frequency
150:
Typically, an automatic controller operates the turbine inlet valve to maintain constant speed (and frequency) when the load changes on the generator. In a system connected to a grid with multiple sources, the turbine control ensures that power always flows out from the generator to the system. The
137:
The available power, in kilowatts, from such a system can be calculated by the equation P=Q*H/k, where Q is the flow rate in gallons per minute, H is the static head, and k is a constant of 5,310 gal*ft/min*kW. For instance, for a system with a flow of 500 gallons per minute and a static head of 60
133:
is the pressure measurement of water falling in a pipe expressed as a function of the vertical distance the water falls. This change in elevation is usually measured in feet or meters. A drop of at least 2 feet is required or the system may not be feasible. When quantifying head, both gross and net
212:
turbines are used. Very low head installations of only a few meters may use propeller-type turbines in a pit, or water wheels and
Archimedes screws. Small micro hydro installations may successfully use industrial centrifugal pumps, run in reverse as prime movers; while the efficiency may not be as
292:
mountains and in Sri Lanka and China already have similar, active programs. One seemingly unexpected use of such systems in some areas is to keep young community members from moving into more urban regions in order to spur economic growth. Also, as the possibility of financial incentives for less
179:
which produces output at grid frequency. Power electronics now allow the use of permanent magnet alternators that produce wild AC to be stabilised. This approach allows low speed / low head water turbines to be competitive; they can run at the best speed for extraction of energy, and the power
276:
addition to a system that is directly connected so that in times of high demand there is additional reserve energy available. These systems can be designed to minimize community and environmental impact regularly caused by large dams or other mass hydroelectric generation sites.
199:
can be used in micro hydro installations, selection depending on the head of water, the volume of flow, and such factors as availability of local maintenance and transport of equipment to the site. For hilly regions where a waterfall of 50 meters or more may be available, a
300:
Micro-hydro installations can also provide multiple uses. For instance, micro-hydro projects in rural Asia have incorporated agro-processing facilities such as rice mills – alongside standard electrification – into the project design.
266: : part of the river flow at a weir or natural water fall is diverted into a round basin with a central bottom exit that creates a vortex. A simple rotor (and connected generator) is moved by the kinetic energy. Efficiencies of 83% down to 64% at 1/3 part flow.
338:" system meaning that water diverted from the stream or river is redirected back into the same watercourse. Adding to the potential economic benefits of microhydro is efficiency, reliability, and cost effectiveness.
48:
is offered. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without the purchase of fuel. Micro hydro systems complement
254: : Is a high flow, low head, propeller-type turbine. An alternative to the traditional kaplan turbine is a large diameter, slow turning, permanent magnet, sloped open flow VLH turbine with efficiencies of 90%.
163:
may be automatically connected to the generator to dissipate energy not required by the load; while this wastes energy, it may be required if it's not possible to control the water flow through the turbine.
128:
of electricity. This can be enough to power a home or small business facility. This production range is calculated in terms of "head" and "flow". The higher each of these are, the more power available.
216:
In low-head installations, maintenance and mechanism costs can be relatively high. A low-head system moves larger amounts of water, and is more likely to encounter surface debris. For this reason a
109:; this might be directly connected to the power system of a single building in very small installations, or may be connected to a community distribution system for several homes or buildings.
798:
93:
The intake is then brought through a canal and then forebay. The forebay is used for sediment holding. At the bottom of the system the water is tunneled through a pipeline (
53:
because in many areas water flow, and thus available hydro power, is highest in the winter when solar energy is at a minimum. Micro hydro is frequently accomplished with a
322:
Microhydro power is generated through a process that utilizes the natural flow of water. This power is most commonly converted into electricity. With no direct
44:. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks, particularly where
175:
With the availability of modern power electronics it is often easier to operate the generator at an arbitrary frequency and feed its output through an
1056:
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resulting from this conversion process, there are little to no harmful effects on the environment, if planned well, thus supplying power from a
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pool, at the top of a waterfall, with several hundred feet of pipe leading to a small generator housing. In low head sites, generally
486:
650:
457:
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site in need of energy. This distributional issue as well as the others are key when considering using a micro-hydro system.
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Quaranta and Muller (2017). "Sagebien and
Zuppinger water wheels for very low head hydropower applications".
597:
544:
519:
925:
139:
955:
1175:
756:
Quaranta and
Revelli (2015). "Output power and power losses estimation for an overshot water wheel".
685:. Final Technical Report, The US Department of Energy, August 1998, The Department of Energy's (DOE)
187:), a few kilowatts or smaller, may generate direct current and charge batteries for peak use times.
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958:(project financed by the European Commission, involves Italy, Croatia, Norway, Greece and Austria)
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high as a purpose-built runner, the relatively low cost makes the projects economically feasible.
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The cost of a micro hydro plant can be between 1,000 and 5000 U.S. dollars per kW installed
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245:: the Gorlov helical turbine free stream or constrained flow with or without a dam,
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use an
Archimedes' screw which is another debris-tolerant design. Efficiency 85%.
205:
106:
956:
SMART - Strategies to promote small scale hydro electricity production in Europe
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Microhydro systems are typically set up in areas capable of producing up to 100
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Usually, microhydro installations do not have a dam and reservoir, like large
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processes grows, the future of microhydro systems may become more appealing.
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159:. In some systems, if the useful load on the generator is not high enough, a
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651:"Module 3e: Comparison of Pipe Flow Equations and Head Losses in Fittings"
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using the natural flow of water. Installations below 5 kW are called
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frequency is controlled by the electronics instead of the generator.
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have, relying on a minimal flow of water to be available year-round.
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620:"Preparing Your Land for Hydroelectric Power - Renewable Energy"
61:, low flow water supply. The installation is often just a small
686:
231:(Reverse Archimedes' screw): two low-head schemes in England,
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950:
289:
687:
Information Bridge: DOE Scientific and
Technical Information
16:
Hydroelectric power generation of 5 to 100 kW of electricity
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874:. The Ashden Awards for Sustainable Energy. Archived from
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that typically produces from 5 kW to 100 kW of
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509:
458:
RENEWABLE ENERGY TECHNOLOGIES: COST ANALYSIS <:SERIES
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Example of a new
Scottish Highland micro hydro system
683:
Development of the helical reaction hydraulic turbine
598:"Determining a Potential Microhydropower Site's Flow"
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1057:List of conventional hydroelectric power stations
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660:. University of Alabama College of Engineering
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155:generated needs to match the local standard
847:. Research Institute for Sustainable Energy
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487:"Micro Hydro in the fight against poverty"
97:) to the powerhouse building containing a
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648:
559:
493:. TVE/ITDG. November 2004. Archived from
204:can be used. For low head installations,
80:
20:
980:, Idaho National Engineering Laboratory
733:. MJ2 Technologies. n.d. Archived from
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829:: CS1 maint: archived copy as title (
1007:
968:European Small Hydropower Association
649:Pitt, Robert; Clark, Shirley (n.d.).
465:International Renewable Energy Agency
837:
642:
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334:manner. Microhydro is considered a "
264:Gravitation water vortex power plant
926:"Micro Hydro Power - Pros and Cons"
719:
13:
479:
14:
1192:
1082:Run-of-the-river hydroelectricity
984:Ashden Awards hydro power winners
944:
928:. Alternative Energy News Network
1090:
964:, Dorado Vista ranch application
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25:Micro hydro in northwest Vietnam
1062:Pumped-storage hydroelectricity
791:
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520:"How a Microhydro System Works"
280:Potential for rural development
248:Francis and propeller turbines.
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994:Home built micro hydro project
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438:Gravitation water vortex power
1:
572:"Micro Hydroelectric Systems"
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120:Head and flow characteristics
105:, which is then connected to
770:10.1016/j.renene.2015.05.018
574:. Oregon DOE. Archived from
313:Advantages and disadvantages
7:
350:
10:
1197:
973:Micro Hydro Association UK
951:Portal on microhydro power
183:Very small installations (
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1088:
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545:"Microhydropower Systems"
85:Typical microhydro setup.
1171:Power station technology
146:Regulation and operation
962:Micro Hydro information
467:. June 2012. p. 11
365:Renewable energy portal
304:
140:Hazen–Williams equation
1181:Distributed generation
1166:Appropriate technology
1125:Gorlov helical turbine
270:
86:
51:solar PV power systems
26:
978:Hydropower Prospector
84:
24:
403:up to 10,000 kW
114:hydroelectric plants
811:on 26 December 2017
624:motherearthnews.com
578:on 29 November 2010
169:induction generator
153:alternating current
34:hydroelectric power
1140:Cross-flow turbine
878:on 1 November 2010
785:Hydraulic Research
737:on 16 January 2017
727:"Hydrovision 2015"
423:Sustainable energy
87:
71:Archimedes' screws
27:
1153:
1152:
898:"Microhydropower"
628:Mother Earth News
286:rural development
222:Ossberger turbine
195:Several types of
157:utility frequency
151:frequency of the
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1176:Hydroelectricity
1101:Hydroelectricity
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799:"Archived copy"
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630:. February 1986
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409:up to 5 kW
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1130:Pelton wheel
1071:
930:. Retrieved
905:. Retrieved
892:
880:. Retrieved
876:the original
849:. Retrieved
845:"Microhydro"
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813:. Retrieved
806:the original
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739:. Retrieved
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576:the original
549:. Retrieved
524:. Retrieved
499:. Retrieved
495:the original
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469:. Retrieved
452:
433:Vortex power
428:Water wheels
393:Water portal
345:
336:run-of-river
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233:Settle Hydro
220:also called
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202:Pelton wheel
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77:Construction
67:water wheels
55:pelton wheel
46:net metering
29:
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1145:Water wheel
1072:Micro hydro
1067:Small hydro
932:24 November
907:20 November
882:20 November
815:25 December
764:: 979–987.
679:Gorlov A.M.
604:28 November
551:28 November
526:28 November
413:Hydro power
401:Small hydro
332:sustainable
258:Water wheel
237:Torrs Hydro
38:electricity
30:Micro hydro
1160:Categories
1077:Pico hydro
1045:generation
1035:Hydropower
903:. U.S. DOE
851:9 December
741:14 January
664:14 January
658:eng.ua.edu
634:14 January
600:. U.S. DOE
582:1 December
547:. U.S. DOE
522:. U.S. DOE
501:14 January
471:14 January
463:(Report).
444:References
407:Pico hydro
318:Advantages
185:pico hydro
172:matching.
73:are used.
42:pico hydro
1103:equipment
328:renewable
324:emissions
161:load bank
126:kilowatts
103:generator
57:for high
825:cite web
351:See also
177:inverter
95:penstock
711:29 June
491:tve.org
206:Francis
99:turbine
243:Gorlov
63:dammed
901:(PDF)
809:(PDF)
802:(PDF)
654:(PDF)
461:(PDF)
290:Andes
934:2010
909:2010
884:2010
853:2010
831:link
817:2017
743:2017
713:2009
666:2017
636:2017
606:2010
584:2010
553:2010
528:2010
503:2017
473:2017
305:Cost
235:and
69:and
59:head
1052:Dam
766:doi
271:Use
208:or
167:An
1162::
917:^
861:^
827:}}
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