I have been interested in building a small scale hydropower system to generate clean electricity from the creek running through my backyard. With rising electricity rates and a desire to live more sustainably, I decided to research how feasible it would be to build my own DIY hydropower system.
Assessing the Potential of My Backyard Creek
The first step was to assess whether my backyard creek could realistically be used to generate usable electricity. There were several factors I needed to evaluate:
Water Flow Rate
The amount of power able to be generated is directly related to the flow rate of the water. I measured the width and depth of the creek in several spots to calculate the cross-sectional area. I also timed how long it took for sticks and leaves to float down a measured 10-foot length of creek to estimate the surface velocity.
With some simple math, I was able to calculate the approximate flow rate in gallons per minute (GPM). The higher the flow rate, the more potential power can be produced. My creek had a flow rate of around 8-10 GPM during dry periods.
Head Height
Head refers to the vertical drop distance between the water intake point and turbine outflow point. More head equals more power potential. I used a leveling tool and tape measure to determine the head height available in my backyard was around 4-5 feet.
Site Layout
I mapped out the layout and elevation changes of the creek through my property. Having a basic site map allowed me to visualize where the water intake, penstock pipe route, turbine location, and outflow point could be situated to maximize head height.
Permits and Regulations
I researched what permits and regulations apply to small scale hydropower installations in my area. Fortunately, my system did not require any permits as long as I did not significantly alter the stream environment. However, regulations vary greatly so this is an important step.
After collecting this data, I determined my backyard creek had the potential to produce 300-600 watts of electricity - enough to charge batteries or power some lighting.
Selecting a Turbine
The heart of any hydropower system is the turbine that actually converts the mechanical power of moving water into rotational energy. The most common options for small scale hydropower are impulse and reaction turbines.
Impulse Turbine
Impulse turbines like Pelton wheels use the velocity of water from a pressurized pipe or nozzle to drive the turbine blades. This allows them to operate under a wide range of water flow rates. The simplicity of an impulse turbine made it an appealing choice.
Reaction Turbine
In contrast, reaction turbines like propeller and Archimedes screw designs fully submerge the turbine in the water flow. They are rotated by the reactive force as water is pushed past the blades. Reaction turbines tend to be most efficient with relatively low head heights around 5 feet or less.
Since I had sufficient head height, I opted for an impulse Pelton wheel turbine designed for the estimated flow rate of my creek. This gave me the best energy production potential for my specific site conditions.
Designing and Sizing System Components
Once I selected a Pelton wheel turbine, I could properly size the other system components like the penstock pipe, water intake, and tailrace.
Penstock Pipe Sizing
The penstock pipe carries water from the intake to turbine. To minimize friction losses, the penstock pipe diameter must be sized based on the desired flow rate.
I used PVC pipe and selected a diameter of 1-1/2 inches which allowed my system to operate efficiently at 8-10 GPM flow rate.
Water Intake Approach
The water intake structure diverts a portion of the creek's flow into the penstock pipe. I opted for a simple run-of-stream intake that did not require a complex dam or weir. The intake was screened to prevent debris from entering the penstock.
Tailrace Outlet
The tailrace is the outlet where water exits the turbine and re-enters the stream. It must be designed to prevent backflow of water into the turbine. My tailrace emptied into a small plunge pool below the turbine house.
Properly designing each component ensured my system would safely operate within the constraints of my specific creek environment.
Turbine Housing and Mounting
Since my Pelton wheel and generator would spin at several hundred RPM, I needed to house them in a protective structure.
I framed a simple turbine housing using 2x4 lumber and plywood sheeting. Inside this I mounted a steel mounting plate connected to a concrete foundation. The Pelton wheel assembly was then directly bolted to this mounting plate to ensure stable and vibration-free operation.
Making the housing watertight with silicone caulk prevented splashing water from reaching the generator components. I also included a top-hinged access hatch so I could easily service the turbine and generator as needed.
Connecting the Generator
The rotating shaft of the Pelton wheel turbine transmits mechanical power to spin the rotor of a generator to produce electricity.
I used a 3-phase AC synchronous generator designed for hydro applications. Because of its slower rotational speed, this type of generator can be directly coupled to the turbine without requiring a gearbox.
The generator needed to be properly wired and connected through a circuit breaker panel before feeding to my home electrical system. This ensured the micro-hydropower system safely interfused with the main utility grid.
Monitoring and Maintaining the System
Even a small scale hydropower system requires some periodic maintenance and monitoring:
- Checking for erosion around the water intake and tailrace to prevent leaks or clogs
- Ensuring proper lubrication levels in the turbine bearings
- Visually monitoring the turbine shaft alignment to check for signs of wear
- Logging power output to track performance over time
- Testing the generator wiring for faults or deterioration
I also keep the intake screen clear of leaves and debris that could reduce flow. Periodic maintenance helps my homemade system operate safely and efficiently for many years.
Real World Experience Summary
Over the course of 3 months and with an initial budget of around $2000, I designed and built a small scale hydropower system that harnesses the energy from my backyard creek.
The Pelton wheel turbine generates approximately 500 watts which I use to help offset my home electricity usage. This real world project was an interesting and rewarding way to learn about small scale renewable energy systems.
While requiring some upfront planning and effort, a DIY backyard hydropower system can serve as a fun and educational sustainability project. The free clean power from your own creek over many years makes the investment worthwhile.