ODE TO A LITTLE STREAM – Off Grid Power, Part 2: MICRO-HYDRO
MICRO HYDRO – a site specific ecological alternative to fossil fuel generators.
On Earth Day (a few posts back) I posted about our off-grid energy system and how it’s evolved since early 1980’s. Included were details of solar and wind power, with a promise to to expand on the micro hydro aspect of our electrical production.
I fore-warn you – this post is lengthy and quite comprehensive – lots of photos though. Here is part Two.
In mid 2009 we began our most recent energy system upgrade which involved months of planning, engineering and building new infrastructure. By February 2010 we had a new water powered turbine and a bigger solar array, up and running.
The little stream pictured below, now provides more than half of all our electricity. A good part of the success is because we conserve energy and use it efficiently.
Here’s the stream again – on it’s last tumble before it feeds into the lake.
In our temperate rainforest along the the Pacific Coast of Vancouver Island snow melt from the mountains doesn’t last long – even less so, with reduced snow pack due to climate change. Hence, the stream becomes a mere trickle in the summer months and the water powered turbine becomes in-operational.
During the other 8 to 9 months of the year the normal flow of the stream is nominally impacted by utilizing the hydro power system. Part of the reason for this is because water for the turbine is taken from a nearby tributary. Here, the intake also has a special stainless steel screen designed to protect all riparian life as well as to keep debris out of the penstock.
Although the lake is excellent habitat for trout, they are unable to migrate more than 100 feet up the stream because of its numerous waterfalls. Also, salmon are unable to migrate into the lake past Bear Falls.
All these factors ensure the micro hydro system has a small ecological impact.
The Installation of the Micro Hydro System:
Conceptualized Micro Hydro Plan from 1996
Before installation, summer 2009: After installation:
These two photos were taken in nearly identical locations looking down the stream. In the left photo I’m standing where the concrete wier (or dam) is to be built. The wier is shown in the foreground of the right photo. It diverts water out of the stream via a wooden flume and then into a 3” pipe (or penstock). The water flows through the pipe to run the turbine much further down the stream.
Sectional Plan (as built in 2009):
Looking up to the the site (before development).
In the first stage of the project I used a chain saw, ropes and come-along to carefully cut and manoeuvre a large log (top left) that had originally fallen across the stream. Shored up with rocks, the log later became the base for the wooden flume.
A buried blue intake barrel is under the plywood on the right. The black pipe exits the barrel.
This photo shows the finished concrete wier that feeds water into the flume…
Here is some of the concrete formwork for the wier during construction, midsummer 2009. The two black pipes temporarily diverted the water flow of the stream. Note the reinforcing steel embedded in the stream bed and the metal chase that will later hold the wooden flume.
These photos show the concrete wier, the wooden flume and intake screen built in place:
To reiterate – the blue barrel is located below the wooden intake structure on the left.
Here’s the whole intake infrastructure operational. Notice that a large volume of water from the flume goes back into the stream. Only a small amount is required to run the turbine – about 60 gallons per minute to create full output of 1 kilowatt.
For the project could be properly designed, my wife Francis and I first measured the vertical drop from the proposed intake (above) to the proposed turbine site.
This diagram shows how we did this:
We also had to measure the flow of the water, over a period of time. We timed how long it took to fill this 5 gallon bucket.
Peter Talbot of homepower.ca. is a solar specialist and a leading expert in micro hydro based out of Vancouver, British Columbia. Consulting via email we planned and collaborated on the system, and he later supplied and installed the electrical components. His website includes the technical aspects of our new power system.
With compliments to Peter, I’ve included his written summary, along with a few of my added notations.
Combination Solar, Micro Hydro and Wind Home Power System
– by Peter Talbot (with Bruce Witzel)
- Turbine: Bronze Turgo runner with four nozzles
- Generator: Induction motor, 2 HP at 240 volts
- Operating Head: 175 feet gross
- Rated flow: 110 gallons per minute
- Output: up to 40 amps at 28 volts nominal, or 1120 watts
- Inverter: Magnum pure sine wave, 4.0 kW, 24 volts
- Solar PV (photo-voltaic): 1000 watts
- Wind Generator: 300 watts (now defunct, due to an extreme weather event)
This project was an extensive upgrade to an existing system that had been in operation for over ten years. However, the 300 watt solar array and 300 watt wind turbine was too small to supply sufficient battery charging for much of the year.
As is often the case with solar only systems, a gas generator was frequently used to top up the old battery bank.
The generator is housed in a re-purposed dog house and now rarely used.
We did a complete rebuild and added 700 watts of PV with an MPPT tracking regulator and a 1 kw hydro turbine.
In addition, new batteries, a new 24 volt inverter, controls and breakers were added. As is usually the case, it is necessary to convert over to 24 volts when DC power levels get to the 1 kW range.
The system includes the 1 kW solar because the stream dries up in the summer.
This project was in three stages –
We added 700 watts of new PV in the form of four 175 watt BP modules on a custom designed rack that would holt both the old and new modules. This was all fed to an Outback maximum power point tracking regulator.
We installed am entire micro hydro system, capable of producing up to 35 amps at 28 volts for about 1 KW.
The intake filter and flume feeds the 1000 foot long, 3 inch polyethylene penstock.
The penstock drops down about 170 vertical feet creates 72 psi of pressure at the turbine site. Here is the original pressure test at turbine site.
The outtake pipe built under the turbine shed returns water back to the stream.
Peter Talbot – building turbine nozzles
Installed water turbine – operational
The old batteries were replaced with a new set of 500 amp hour, 2 volt cells.
The new battery bank, with the lid not installed – the white pipe vents Hydrogen gas.
In addition, a new 4000 watt sine wave inverter and all necessary switching, regulation and protection completed the upgrade.
The 12 volt system can also be charged from the new inverter using an existing old Todd 50 amp charger.
The existing 12 volt wind turbine and two of the old PV modules were left connected to the existing 12 volt battery. This is used for LED and other 12 volt lighting and small electronics.
“The lovely home is equipped with all the modern electrical gadgets.”
Conclusion & Current Status of the System:
Over 38 years the system cost has added up to about $40,000, an average annual cost of $1050 per year.
Today we were running the stream engine at 12 amps or about 250 watts, which brought us 6 kilowatt-hours of electricity over the past 24 hours. The solar panels brought in an additional 2 kilowatt hours, for a total of 8 kw-hrs.
in this photo we have a heavy load on – maybe the electric oven?
The fridge is running, we did 2 loads of laundry and a bit of cooking, I used the skill saw today, and now we have lights, computer, fan, etc. As Peter says – all the modern gadgets.
The battery is 72% full, and its charging at 1.2 amps or 30 watts. All in all – a good day, of off- grid living.
Cheers ~ Bruce