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Micro-Hydro Questions answered


Q: What’s the first step to identifying a good hydro site?

The two primary components of hydro-electric power are head (vertical drop) and flow.
A good site needs a combination of these two.
Higher head sites may be more cost-effective to tap, since you can use smaller pipe and less water.  Ideally, you want water tumbling down the hillside—this is one sign of a potential hydro site.
Water that is dead “flat” won’t do much for you—if there is no head, there is no power.
If you double the head, you double the power available.  
The same is true if you double the flow.
A good home-scale system might have a vertical drop in the range of 40 to 200 feet.
A steady flow from a constant stream is ideal.
Seasonal  streams that suffer wide fluctuations in flow linked to wet and dry seasons can be designed for, but require compromises in the design parameters.
Look for a good site rather than the closest site.
With high voltage transmission coupled to modern MPPT controllers and grid-connected inverters, wire cost for longer distance is often not the biggest issue. Other good attributes are a convenient and environmentally friendly intake site, easy access and permitting, and a relatively short pipe run.

Q: What types of water sources are not appropriate for micro hydro systems?

Because available power comes from head and flow, water sources with little flow or little head will not work. Flat-water rivers are difficult or impractical to capture energy from, which is why we see few if any products on the market for this type of site. A “low-head” site typically needs to dam the whole river or divert a large amount of water in a canal to create some head.
flat water no power 1Water that is not moving has no energy in it.
And of course, you need to have legal access to the water source, and the ability to tap it without undue restrictions. Very high-head sites (above 500 feet) can be costly to tap because of long pipe runs and high pressure.
Tapping a part of the available head can be a viable solution.
Also note that water sources that have very high water at some time in the year make for difficult intakes.
High water often means a lot of debris comes down the stream, which can clog or damage turbines. 
Other inappropriate sources would be using drinking or irrigation water systems just to make electricity. These sources often rely on energy to pump and pressurize the water, so they are not actually renewable energy sources.
And the intended end uses often need pressure, which a hydro system brings to zero. In addition, the volume of flow is usually not adequate to make much energy.

Q: Once you’ve identified a potential site, what measurements do you take to assess the site’s production capacity?

MEASURE WATER FLOW WITH BUCKET 1 1What are the best methods for taking these measurements?
Several measurements are needed, and there are multiple ways to obtain most of them.  Most important is to take very accurate measurements of head and flow.
This will tell you how much power is available, and the type of turbine appropriate to the site.
To measure vertical drop (head), you can use:

• Altimeters, if meter accuracy is good
• GPS units (some may have enough accuracy)
• Survey level or laser level
• Maps with good contour lines, for higher-head sites
• Google Earth (in some cases) for offsite pre-assessment
• Accurate pressure gauge (if there is an existing pipeline)

To measure  flow (this is best done multiple times throughout the year to ascertain seasonal variations):
• Bucket and stop watch to measure gallons per minute for small- to medium-flow sources and time surface velocity
• Weir with measuring notch and appropriate flow tables
• 100-foot (or longer) tape measure to determine the crosssection of stream


Q: What do you consider to be the maximum feasible distances for penstock length and transmission wire run?

A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydraulic turbines and sewerage systems.
penstockThis depends on the scale of the system, the power available, cost of alternatives, the system voltage, and the terrain, among other factors. Penstock and transmission cable lengths of more than a mile are workable in the right situations, though less than 1 km is more typical.
If you need long pipe and long cable, the site will need to be very good or the economics may not work. But if you need a long pipe and a short cable or a short pipe and a long cable, you may have a viable site. There are too many variables involved to generalize on distance limits, because so much depends upon the diameter and the material composition of the penstock that is required for the local conditions, and the voltage, distance, and size of wire.
Financial feasibility is usually the governing factor.
How much is the power worth? Note that transmitting small amounts of energy, such as an energy-efficient household
would use, can be pretty inexpensive over long distances.
Every site is unique, and careful balancing of factors is required. Ultimately, the maximum feasible distance is directly related to the depth of your checkbook and what is “worth it” to you.

Q: What are the advantages of a microhydro system compared to other renewable electricity systems (wind turbine, PV array)?

renewable energy solutions 1A microhydro system will generate continuously, if it has a constant water supply. This alone is a significant advantage over either wind or solar power because a battery bank may not be required, and a smaller battery bank will suffice if one is needed.
Also, microhydro is generally less expensive per kilowatt-hour than either wind or solar electricity. It’s working all day, every day. If you had a site where all three systems had equal potential near to the point of use, microhydro would probably be the least expensive choice per delivered watt-hour.
The hydrological cycle follows the human consumption cycle very well where summer cooling is not used. In winter, when a stream usually has more flow, households tend to use more energy; in summer, households use less energy and generally have less water. Solar electricity provides the opposite result, giving the highest yield in the summer, when you typically need less. Hydropower is there when you need it. When the sun goes down and the wind stops blowing, your hydro turbine will continue generating electricity. 

Q: What are the limitations of hydro-electric systems compared to other Renewable Energy systems?

The main limitations of hydro-electric systems are the limitations of the water supply. No water equals no power.
Few people have access to a good microhydro site—there are far fewer potential sites than solar and wind sites. And few people who live near good sites are aware of the potential of microhydro.
Hydro is for one home in 1,000 at best, so the technology has only a light dusting of installations.
These will generally be in rural environments near or in the mountains.
Even though hydropower is comparatively inexpensive and consistent, it requires special conditions that may be hard to come by.
  • you need head, which usually means a location close to mountains.
  • It takes the land area to collect the water and develop the head.
  • It requires physical spaces for an intake, penstock, and power house.
  • The permitting process can be difficult, because you will be physically altering the watershed, even if only a little

Q: How do you assess the financial viability of a system, compared to, say, energy produced by a PV system?

A little simple math will answer this question.
First, measure your head and flow and apply a formula to determine how much you can generate.
Then get price quotes for the intake, penstock, and powerhouse equipment.
Add it all up and divide by the lifetime energy you expect to produce, and you will have your cost per kilowatt-hour.
solar on roof alternative energy 1While every site has so many unique elements that generalizing is pretty risky, with an appropriate water supply, a microhydro system is usually many times less expensive than a PV system.
Maintaining a microhydro system also can be quite inexpensive.
There is just the one moving part, and bearing replacement is required only every few years.
The intake can be the only point of regular maintenance, and the system shouldn’t cost anything but labor to maintain. On the other hand, PV arrays that are mounted on fixed racks have no moving parts, or intakes, to maintain.

Q: What are common challenges encountered in installation?

Each site has its own challenges, but most are overcome by the use of common sense and some basic engineering skills.
Steep, bush terrain and rocky stream courses can make installation more difficult.
Specific challenges include:

• Intake site selection and installation
• Proper pipe selection and installation, including dealing with poor access and long distances
• Routing pipeline or power line over rough or steep terrain
• Avoiding private land, public land, or road crossings
• Air blockage in pipes laid with an uphill slant
• Proper transmission cable selection, installation, and protection
• Inaccurate measurements of head, flow, and distances
• Protection of penstock from sun, slides, and other physical damage
• Permitting and regulatory issues
• Freezing conditions (i.e., ice plugging screens and low water levels)


Great features of PowerSpout.  

The PowerSpout is the latest micro hydro generator from EcoInnovation New Zealand. It is a custom made Pelton turbine attached to a reconnected Fisher and Paykel Smart Drive generator via a robust bearing assembly, all in a weatherproof casing to create consistent renewable electricity.
  • POWER SPOUT WORKING 1 1Permanent magnet brushless alternator Smart Drive
  • Marine grade construction
  • Recycled inner packaging
  • Up to 68% Recycled materials used in manufacture
  • Renewable energy used to manufacture this product
  • Jets can be replaced in less than 5 minutes
  • Supplied with 2 jet unit with 10 spare jets
  • Supplied with 2 x 2 inch (50mm) valves- BSP or NST threads
  • No exposed rotating parts
  • No exposed wiring
  • Fully enclosed from the elements – no protection needed
  • Long life low rpm 10.5 inch (270mm) diameter generator
  • 9 inch (230mm) diameter high efficiency Pelton rotor
  • Large bearings front  6205 rear 6005
  • 1 inch (25mm) stainless shaft
  • Smart Drive generator can be adjusted onsite for max output
  • BE (Battery Enabled) Version - Charge 12,24,48 batteries
  • ME (MPPT Enabled) Version - Charge 12,24,48 batteries via MPPT Regulator
  • GE (Grid Enabled) Version - Connect to the grid without batteries
  • Educational version for colleges EE version (Education Enabled)
  • Dealer Enabled sample  DE version (Dealer Enabled)
  • Works on net heads from 3m to 100m
  • 3 years warrantee extendable, subject to service schedule
  • Up to 1.2 kW per unit (1.6 kW possible in some cases with high power version)
  • Multiple units for sites up to 16 kW at reduced prices
  • Over 6 years operation in the field
  • Designed to be safe, reliable, efficient and cost effective
  • Looks great inside and out
  • Conversion efficiencies up to 64% (50-56% typical)
  • Designed by a qualified mechanical design engineer with 15 years experience in the design of micro-hydro systems

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