| Micro Hydroelectric Systems |
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Oregon Hydro Working Group
How Much Power Is Available From a Stream?
Regulation of Hydro Projects
Finding Turbines
Selling Power
Financing
Hydro Advisors
Organizations and Publishers
Publications
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| How Much Power Is Available? |
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Flow and Head
The first step in assessing the feasibility of any hydroelectric system is to determine the amount of power that you can obtain from the stream at the site. The power available at any instant is primarily a product of the flow volume and "head." Flow volume is typically measured in cubic feet per second (cfs) or gallons per minute (gpm). Higher flow means more available power.
Head is a measure of the pressure of falling water, and is a function of the vertical distance that water drops and the characteristics of the channel, or pipe, through which it flows. Higher head means more available power. The higher the head the better, because less water is needed to produce a given amount of power. If less water is needed, then smaller, more efficient, and less costly turbines and piping can be used.
Hydroelectric sites are broadly categorized as low or high head sites. "Low head" typically refers to a change in elevation of less than 10 feet (3 meters). A vertical drop of less than 2 feet (0.61 meters) will probably make a hydroelectric system unfeasible. A high flow rate can compensate for low head, but a larger and more costly turbine will be necessary. It may be difficult to find a turbine that will operate efficiently under very low head and low flow.
Determining Head
When determining head, you must consider both gross or "static" head, and net or "dynamic" head. Gross head is the vertical distance between the top of the penstock (the piping that conveys water, under pressure, to the turbine) and the point where the water discharges from the turbine. Net head is gross head minus the pressure or head losses due to friction and turbulence in the penstock. These head losses depend on the type, diameter, and length of the penstock piping, and the number of bends or elbows. You can use gross head to approximate power availability and determine general feasibility, but you must use net head to calculate the actual power available.
Determining Flow
Environmental and climatic factors, as well as human activities in the watershed, determine the amount and characteristics of stream flow on a day-to-day and seasonal basis. A storage reservoir can control flow, but unless a dam already exists, building one can greatly increase cost and legal complications.
You may be able to obtain stream flow data from the local offices of the U.S. Geological Survey, the U.S. Army Corps of Engineers, the U.S. Department of Agriculture, the county engineer, or local water supply or flood control authorities. If you cannot obtain existing flow data for your stream, you will need to do a site survey. Generally, unless you are considering a storage reservoir, you should use the lowest average flow of the year as the basis of the system design. Alternatively, you can use the average flow during the period of highest expected electricity demand. This may or may not coincide with lowest flows.
There may be legal restrictions on the amount of water that you can divert from a stream at certain times of the year. In such a case, you will have to use this amount of available flow as the basis of design. There are a variety of techniques for measuring stream flow. For more information on these methods, consult the references below or your local library for books that cover hydroelectric systems, surveying, or civil engineering.
You may be able to correlate your survey data with long-term precipitation data for your area, or flow data from nearby rivers, to get an estimate of long-term, seasonal low, high, and average flows for your stream. Remember that no matter what the volume of the flow is at any one time, you may be able to legally divert only a certain amount or percentage of the flow. Also, try to determine if there any plans for development or changes in land use upstream from your site. Activities such as logging can greatly alter stream flows.
Determining Power
Once you have the flow and head figures, you can roughly estimate the potential power available, in kilowatts (kW), with the following formula:
Gross Head x Flow x System Efficiency (in decimal equivalent) x C = Power (kW)
C is a constant (the value is different in English and metric units).
Examples:
- 20 feet x 2 cfs x 0.55 x 0.085 = 1.9 kW or: 6 meters x 0.05 cms x 0.55 x 9.81 = 1.62 kW
- 50 feet x 0.8 cfs x 0.55 x 0.085 = 1.9 kW or: 15 meters x 0.02 cms x 0.55 x 9.81 = 1.62 kW
Note that in the two examples, much less flow is needed at a higher head to produce the same amount of power. Turbine and generator efficiencies depend on make and operating conditions (head and flow). Generally, low head, low speed water wheels are less efficient than high head, high speed turbines.
The overall efficiency of a system will range between 40 percent and 70 percent. A well-designed system will achieve an average efficiency of 55 percent.
Turbine manufacturers should be able to provide a close estimate of potential power output for their turbine, given the head and flow conditions at your site. There will also be line losses in any power lines used to transmit the electricity from the generator to the site of use.
Conversion Factors
Here are some of the conversion factors you may need to assess your site’s feasibility:
1 cubic foot (cf) = 7.48 gallons
1 cubic foot per second (cfs) = 448.8 gallons per minute (gpm)
1 inch = 2.54 centimeters
1 foot = .3048 meters
1 meter = 3.28 feet
1 cf = .028 cubic meters (cm)
1 cm = 35.3 cf
1 gallon = 3.785 liters
1 cf = 28.31 liters
1 cfs = 1,698.7 liters per minute
1 cubic meter per second (cm/s) = 15,842 gpm
1 pound per square inch (psi) of pressure = 2.31 feet (head) of water
1 pound (lb) = .454 kilograms (kg)
1 kg = 2.205 lbs
1 kilowatt (kW) = 1.34 horsepower (hp)
1 hp = 746 Watts.
Other Considerations
Many other factors will determine whether developing the site is practical. Penstock routing and placement is important. You will need to inspect and clean the penstock intake regularly. Freezing weather, livestock, and vandals can damage exposed piping, but burying it may not be practical or cost-effective. The piping must have adequate support to keep it from breaking apart or moving under the weight and pressure of the water. The turbine/generator should be above the stream’s flood stage. A power line from the generator could be expensive.
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| Regulation of Hydro Projects |
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Access to water and the use, control and diversion of water flows is subject to federal and state regulation. Other regulations apply to any physical alteration of a stream channel or bank that may effect water quality or wildlife habitat. This is true regardless of whether or not the stream is on private property. If your project will have minimal physical impact, and you are not planning to sell power to a utility, there is a good chance that the legal process will not be too complex.
There are many local, state, and federal regulations that govern, or will effect, the construction and operation of a hydroelectric power plant. The larger the system, the more complicated, drawn out, and expensive the permitting and approval process will be. Penalties for not having the permits or necessary approvals can be severe. You will not escape the consequences by pleading ignorance. Although the legal process may seem burdensome, the intention of the laws is to protect all users of the resource, including the plant, fish, and animal communities that utilize the water.
When planning a hydroelectric system, your first point of contact should be the county engineer. He or she will be the most informed about what restrictions govern the development and/or control of water resources in your area.
The two primary federal agencies that you will need to deal with are the Federal Energy Regulatory Commission (FERC) and the U.S. Army Corps of Engineers. Try contacting the nearest office to you to see if they will assist you; both may be listed in the U.S. government section of your phone book.
FERC is responsible for licensing all non-federal government hydroelectric projects under its jurisdiction. A hydroelectric project is within the jurisdiction of FERC if any of the following conditions apply: the project is on a navigable waterway; the project will affect interstate commerce (i.e., if the system is to be connected to a regional electric transmission grid); the project uses federal land; or the project will use surplus water or waterpower from a federal dam. You will need to consult with FERC in order to determine whether or not your project falls under FERC’s jurisdiction. If it does, then you will need to apply for a license or exemption from FERC. The FERC application process will require contacting and consulting other federal, state and local government agencies, and providing evidence that you have done so.
If your project involves a discharge of dredge or fill material into a watercourse or wetland, you may also need a permit from the Army Corps of Engineers. Your local district office of the Corps should help determine if you will need a permit.
You will also need to determine whether, and to what extent, you can divert water from the stream channel, and what restrictions apply to construction and operation of the system.
In Oregon, the Water Resources Department regulates water rights. You may need a separate water right to produce power, even if you already have a water right for any other use.
You should consult with the Oregon Department of Fish and Wildlife in determining the ultimate design and operation of your system.
The Oregon Division of State Lands regulates the permits needed for removal or fill of wetland areas.
Other federal government agencies that may require permits include: the U.S. Fish and Wildlife Service; the Federal Aviation Administration (if a power line will be constructed near an airport); and the U.S. Forest Service or Bureau of Land Management, if the project will use land administered by these agencies.
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| Finding Turbines |
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Only a few companies make micro hydroelectric turbines. Most available turbines are high head turbines. Low head, low flow turbines may be difficult to find, and may have to be custom-made. It is possible to fabricate low to moderately efficient water wheels and turbines in a well-equipped metal workshop. You may be able to find and refurbish old but operable turbines at abandoned hydro/mill sites. Commercially available turbines and generators are usually sold as a package. Do-it-yourself systems require careful matching of a generator with the turbine horsepower and speed.
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| Selling Power |
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The Public Utility Regulatory Policies Act (PURPA) of 1978 requires electric utilities to purchase power from independent power producers if certain conditions are met. You will need to contact your local utility and/or public utility commission to determine what these technical and operating requirements are, and the price that the utility will pay you for the electricity you generate. You may also need a license from FERC. The utility will require that you ensure the system. The interconnect requirements and insurance premiums may cost more than what you earn from selling the power.
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| Financing |
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Feasibility
The process of accurately determining economic feasibility can be complex. One very simple method is to add up all the estimated costs of developing the site and for operating and maintaining the system over the expected life of the turbine. Divide this amount by the system capacity (in watts), giving you cost/watt. You can compare this to the cost/watt cost of power from some other source.
If you are considering selling hydroelectricity to a utility, you should calculate a levelized, life-cycle cost per kilowatt-hour (kWh) using standard discounting techniques, and compare that with the kWh price that the utility will pay you for the electricity. The cost per kWh is determined by dividing total life-cycle costs by the estimated amount of energy, in kWh, the system will produce over its operating life. For more information on project economic analysis, consult your local library or bookstore for books on microeconomics, project feasibility assessment, agricultural economics, or life-cycle cost analysis.
Oregon Financial Incentives
Business Energy Tax Credits
Tax credits are available to businesses that invest in hydroelectric systems under 25 megawatts of capacity in Oregon. Any Oregon business may qualify for this credit that is up to 35 percent of the project cost.
Energy Loan Program
Low-interest, fixed rate, long-term loans are available to businesses and others that develop any size hydroelectric project in Oregon.
Case Study
Crown Hill Farm
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| Hydro Advisors |
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The following list is provided to assist you with your project. We provide the list for your convenience. The Oregon Department of Energy does not make any warranty, expressed or implied, concerning these hydro advisors.
Those interested being listed as a hydro advisor should contact Hal Simms at the Oregon Department of Energy (503) 378-4314.
Mary Grainey
Oregon Water Resources Department
Information on hydropower licensing and relicensing
Phone: (503) 986-0833
E-mail: Mary.S.Grainey@state.or.us
Craig Kohanek
Oregon Water Resources Department
Information on hydropower licensing and relicensing
Phone: (503) 986-0823
E-mail: Ron.C.KOHANEK@state.or.us
Greg Wheeler
Oregon State University
Phone: (541) 737-2515.
Carel Verlinden
Cornell Pump Company
P.O. Box 6334
Portland, OR 97228-6334
Phone: (503) 653-0330 x-331
Jim Fuller P.E.
Fuller Morris Engineering
Corvallis, OR
Phone: (541) 745-54.35
Tom Johnson P.E.
H. Enwood Energy Services
Sacramento California
Phone: (916) 569-0985
Cliff Malm
Malm Engineering
Seattle, WA
Phone: (206) 270-0450
Bob Lee P.E.
Noregon, Engineering
Phone: (503) 292-3901 or (503) 780-2153
Stan Hayes
Harza Engineering
Bellevue, WA
Phone: (425) 602-4000
Jay LeStrange
Eugene Water and Electric Board
Phone: (541) 484-2411
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| Organizations and Publishers |
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Federal Energy Regulatory Commission (FERC)
Public Reference Section, 941 North Capitol Street, NE, Washington, DC 20426
Phone: (202) 208-1371
Web site: http://www.ferc.gov/industries/hydropower.asp#skipnavsub
Contact for information on FERC hydropower licensing and exemption documents.
Solar Energy International (SEI)
P.O. Box 715, Carbondale, CO 81623
Phone: (970) 963-8855
Fax: (970) 963-8866
Email: sei@solarenergy.org
Web site: www.solarenergy.org
SEI offers workshops on micro-hydro system design and installation.
Stylus Publishing, Inc.
P.O. Box 605, Herndon, VA 20172-0605
Phone: (800) 232-0223 or (703) 661-1581
Fax: (703) 661-1501
Email:styluspub@aol.com
Web site: www.styluspub.com.
Stylus is the U.S. distributor for publications of Intermediate Technology Publications, London, England.
Volunteers in Technical Assistance (VITA)
1600 Wilson Boulevard, Suite 710, Arlington, VA 22209
Phone: (703) 276-1800
Web site: www.vita.org
VITA sells seven inexpensive publications on hydropower systems, including design guides for low-cost turbines and water wheels.
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| Publications |
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The references below provide additional information.
- Protected waterways in Oregon (NWPPC, Wild & Scenic Rivers Act)
- Oregon Revised Statues Chapter 543 (Hydroelectric Projects) and Oregon Administrative Rules Chapter 690, Division 50 (Appropriation and Use of Water for Hydroelectric Power Projects) and Division 51 (Appropriation and Use of Water for Hydroelectric Power and Standards for Hydroelectric Applications).
- Microhydropower Systems: A Buyers Guide, Natural Resources Canada (2004).
- Home Power (magazine), P.O. Box 520, Ashland, OR 97520. Phone: (800) 707-6585. Email: hp@homepower.org; World Wide Web: www.homepower.com . Published bi-monthly. Contact for ordering back issues and subscription information. Selected articles:
- "From Water to Wire: Building a Microhydro System," P. Talbot, (No. 76) pp. 8-22, April/May 2000.
- "Homemade Hydro Homestead," B. Schultz, (No. 37) Oct/Nov 1993, pp. 34-36
- "Hydro Basics," J. Crowley, (No. 42) Aug/Sep 1984, pp. 34-36.
- "Hydro Siting,"P. Cunningham, (No. 8) Dec/Jan 1989, pp. 17-19.
- "Induction Motors for Small-Scale Hydro," B. Haveland, (No. 71), Jun/Jul 1999, pp. 36-44.
- "A Microhydro Learning Experience," L. Woofenden etal., (No. 76) pp. 64-71, April/May 2000.
- "Micro Hydro Power in the Nineties," P. Cunningham and B. Atkinson, (No.44) Dec 94/Jan 95, pp. 24-29.
- "Rules for Surviving Micro Hydro Power," T. Kinzel and S. Kingsley, (No. 47) Jun/Jul 1995, pp. 16-21.
- "Self-Cleaning Hydro (intake) Screens," P. Geddes, (No. 71, Jun/Jul 1991, pp. 64-67.
- "Ultra-Low Head Hydro," C. MacLeod, (No. 23) Jun/Jul 1991, pp. 6-10.
- "Water Power in the Andes," R. Davis, (No. 71) Jun/Jul 1999, pp. 50-54
- How To Build and Operate Your Own Small Hydroelectric Plant, J. Butler, TAB Books, 1982. Out of print. Check local library and inter-library loan system. This book contains a detailed description of a small-hydro system in Vermont and useful information on building a hydro system.
- Microhydropower Handbook, E & G Idaho, Inc., U.S. Department of Energy, 1983, (2 Vols.). Available from:
National Technical Information Service,
5285 Port Royal Road, Springfield, VA 22161;
Phone: (800) 553-6847; Email: orders@fedworld.ntis.gov;
Vol 1, 428 pp., $71.50, Order No. DE83006697;
Vol. 2, 408 pp., $71.50, Order No. DE83006698.
This handbook contains detailed information on system design, construction, operation, economics, and legal and environmental issues.
- Micro-Hydro Design Manual: A Guide to Small-Scale Water Power Schemes, A. Harvey, et al., Intermediate Technology Development Group, London, 1993. Available from Stylus Publishing (see Organizations). 288 pp., $55.00 plus shipping and handling. ISBN 185339-103-4.
This manual covers design, operation and maintenance, commissioning, electrical power, induction generators, electronic controllers, management, and energy surveys.
- Micro-Hydro Pelton Turbine Manual, J.Thake, Intermediate Technology Development Group, London, 1999. Out of print. 320 pp. ISBN 185339-460-2. This book provides information on how to manufacture Pelton turbines .
- Micro Hydro Power Sourcebook, A. Inversin, National Rural Electric Cooperative Association (NRECA), 1986.
Available from NRECA International Foundation, IPD9-202,
4301 Wilson Boulevard, Arlington, VA 22203-1860;
Phone: (703) 907-5500.
Cost: $22.00 plus $4.00 shipping and handling.
This manual thoroughly describes all aspects of micro-hydro system design and installation in a developing country context, but contains information applicable anywhere.
- Motors as Generators for Micro-Hydro Power, N. Smith, Intermediate Technology Development Group, London, 1994. Available from Stylus Publishing (see Organizations). 84 pp., $12.00 plus shipping and handling,
ISBN 185339-286-3. This is a guide to the use of induction motors for electricity generation.
- Pumps as Turbines: A User’s Guide, A. Williams, Intermediate Technology Development Group, London, 1995. Available from Stylus Publishing (see Organizations below). 84 pp., $12.00 plus shipping and handling, ISBN 185339-285-5. This is a practical book for using standard water pumps as water turbines.
- Solar Living Sourcebook, J. Schaeffer, ed., Chelsea Green Publishing Company, 1996. Available from:
Real Goods Trading Corporation, 200 Clara Street, Ukiah, CA 95482; Phone: (800) 762-7325; Email: realgood@realgoods.com;
World Wide Web: www.realgoods.com 712 pp., $30.00.
This book contains a section on hydro systems, and lists micro turbines available by mail order from Real Goods.
- Water Current Turbines: A Field Workers Guide, P. Garman, Intermediate Technology Development Group, 1986. Available from Stylus Publishing (see Organizations). 100 pp., $25.00 plus shipping and handling, ISBN 094668-827-3. This guide describes experience with the current turbine.
Would you like to keep up with what the Oregon Hydro Working Group is doing? Join the Oregon Hydro Working Group mailing listserv.
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