Micro Hydro Book Summary

8/3/2019 Micro Hydro Book Summary

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MicroHydro Book summary

Given enough head and water flow a small microhydro will produce WAYmore electricity than a comparably priced PV system, and do so at night andon cloudy days.

Electricity is like water so its a great matchFlow = amps, pressure = voltage. Resistance = pipe friction

As current flows potential(voltage) is lost to resistance (voltage drop).

Water POWER is the Flow X pressure (amps + voltage)1866 Nikolas Tesla (10 years old) had a vision of harnessing Niagra Falls with

some kind of a wheel.

The pressure in a pipe is the highest when no water is flowing this is calledstatic pressure or static head. The more water flows, the more pressure is

lost (friction). Pressure loss is called head loss. The pressure that remains

is called net pressure or net head.

Typical micro hydro system:Intake Screen penstock turbine transmission lines inverter/controller(Stream, tailwater by turbine)

Extracting KW from heads under 50 ft is impractical and very expensive.

Assessing energy needs = how much is minimal, how much is enough?Basics, Essentials, Conveniences, HW, Space heat, full-service

Usage vs. CapacityCapacity is how much you need a one time (1=charge laptop, 4=electric

HW, full service)

Assessing available energy

Assessing the site:

a. how much water flow is availablewill not use whole creek.Container method:gallon container timing (gpm)this is usually OK for


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Net head will be ~ 2/3 to of the static head.

c. length/diameter/characteristics of pipe (freezing, turns,Survey needed. Vertical drops, length and turns of potential pipe. Usetransit level and poles. Or can use an altimeter, GPS. Or can use a rod andlevel (water filled hose) used by ancients.

Stream Profile

the first 100 feet drops 20 feet. The second 100 ft are not as steep anddrops 16 ft and so on.

Rule of thumb: Electricity is easier to move than water it can also gouphill! A turbine can be located way below where power is needed. Thepenstock will be the most difficult part of the system to install. Easier to uselow head and short penstock where creek is the steepest, and moving the

electricity (would use more water tho).

Calculating potential output

As water begins to flow, friction reduces available pressure. As more waterflows, more friction, less pressure. Length of pipe determines total amount of

friction and flow. Max power coming out of a penstock occurs when the flowof water causes about to 1/3 of the static to be lost. If a limited flow isavailable, a larger pipe will have lower friction. A higher output from samepipe length will result from increasing the penstock size. However the price

goes up accordingly. In many cases there is more water available than anaffordable pipe can handle. A long pipeline delivers less water to turbine

than a short pipeline.

Example: head loss in pipe.

Static head of 60ft in a run of 600 ft. of 2 poly pipe.25% (loss to friction) of 60 = 15ft of head loss33% of 60 = 20 ft of head loss

Ideal head loss15 / 6 (hundred feet of pipe) = 2.5 ft/100

20 / 6 (hundred feet of pipe) = 3.3 ft/100 (40-45 gpm)Lower head loss would produce more power.

Limiting to 20gpm from table6ft of head loss = 54 net head (60-6)

600ft of 2 poly pipe @ 60ft static head results in 54ft of net head @ 20 gpm.

MUST HAVE TABLES HERE = head loss from friction in pipe.e.g.: PVC160: 10gpm @ 1 pipe = 9.2, @2 = 0.3

40gpm @ 2 pipe = 16.6, @ 4 = 0.1100gpm @ 2 pipe = 90.3, @ 6 = 0.1

Poly pipe: 10gpm @ 1 pipe = 8.0, @ 2 0.340gpm @ 1.5pipe = 14.5, @ 3 = 0.5100gpm @ 2 pipe = 19.4, @ 3 = 2.7


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Nozzles: (from penstock pipe to turbine wheel) more water can be putthrough a given wheel by using more than one nozzle. Net pressure from

pipe must be matched to properly sized nozzle at desired flow rate. Can usedifferent sized nozzles for different season/creek flow rates.e.g. 10 psi net @ 23ft of net heat with 0.5 nozzle = 23.6gpm jet flow rate

30 psi net @ 81ft of net head with 0.5 nozzle = 40.9, with 1 nozzle=164 (table on page 49)

Turbines: High head is > 6 ft up to 600ft. Impulse turbines such as turgoor pelton are used. Low head turbines (2-10ft) use river turbine like Aquair.

Turgos are used for high water flows = shorter penstocks, can use up to four1 jets. Very rugged. Pelton is a little more efficient than Turgo used for

low flow and high head. Harris Hydro (pelton type) can generate power withas little as 2gpm, handle up to four jets. Turns at 1800rpm at only 32psi.Low head is under 10ft. Uses reaction type turbines. LH-1000 from EnergySystems and Design. Produces power >2 ft of head rated at 1000 watts at

10ft head using 1,000gpm.

AC microhydro requires high head >75ft. direct AC also requires a constantRPM to make 60 or 50 hz (uses a governor). Motors/pumps run cooler.Problem is to keep constant water flow 24/7 and avoid AC/DC conversion to

charge batteries. With new microprocessor controls AC direct is better.Low head AC turbines: Powerpal technology from Asian Phoenix Resources =where lo-cost is important. Makes AC sinewave directly. 60hz. MHG-200w/500w/1000w head=5ft.554-2060gpm, 144-720KW/mo.

Making your own turbine (reverse flow on a pump impeller) is very inefficientyoure using an induction motor as an alternator. In 3rd world countries,

cross-flow turbines are common. (spraying water at anything will make itturn).

BATTERIES: RV type are not true deep discharge, will fail quickly. Forklift

batteries (2 cell) are excellent but have higher capacity than needed. Golfcart batteries are used most commonly for microhydro since they have thesmallest capacity as true deep discharge. Since they are not worked veryhard *hydro is continuous* they last a long time. If importing (flying in) due

to lead acid, sealed gel cells or AGMs are common.

CONTOLLERS: eventually the batteries are fully charged, and the system

needs to stop charging the batteries this is where charge controller isneeded.

Example: power outputNeed to have net head first. (optimal net head is 2/3 of static head)

Continuous watts = flow (gpm) x net head (feet) / 10

KW output/month = flow (gpm) X net head (feet) / 13.8


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This if for modern turbines. If youre using an efficient automobile alternator(Ford 70A) reduce output by 40%. If using a Delco, reduce by 60%.

4 graphs on pg 13 are SUPER!

a. typical daily power consumption

b. typical daily PV outputsc. typical wind genset output

d. typical hydro outputOverlay all the graphs and you can see patterns/issues

Getting Started

Need:

1. > 2gpm of constant water flow and a lot of dropa. Or 2ft of drop and 500gpmb. Or something between these two

2. proper turbine and alternator3. powerhouse to keep turbine out of weather4. hydro resource needs to be within 1-2km where electric needed5. permission from local authorities, especially penstock runs

6. need vacuum breaker (exp tank?) at lower end of penstock (avoidscollapse in case of water shutoff/obstruction)

7. need valve/diverter to allow for turbine maintenance

PIPINGPerformance and budget dictate this: Poly (ethylene) 2 pipe is commonlyused. 4 PVC very steep and very short, can also produce a lot of power.

O+M

The upkeep of micro-hydro system is of utmost importance.

Documents

Micro Hydro Book Summary