Small-Scale Hydroelectric Plant Promises Profit
Micro hydroelectric power is making a comeback in electricity generation for homes, farms and small businesses. This trend is fueled by a number of factors including favorable regulation, rising energy prices and advances in automation—and do-it-yourselfers all over the world are diving in.
If there’s access to a stream, the only requirements to generate electricity are a 2 ft. drop in water level and two gallons of flow per minute. A hydroelectric system isn’t overly complicated, it isn’t difficult to operate and maintain, it has longevity and it’s often more cost-effective than any other form of renewable power.
Some experts say a successful micro hydroelectric plant will pay for itself in 15 years. At Red Bank Hydro in West Columbia, South Carolina, we implemented our own micro hydro system, Figure 1, and we expect to see a complete return on the investment after only eight years. After that, it will be money in the bank.
Although we’d never built such a system before, we were able to do so by using low- cost components and free technical support, both supplied by AutomationDirect (www.automationdirect.com).
Building a Hydroelectric Plant
In 1980 my father Arno Froese began investigating the potential for generating hydro-electricity on the property he had just purchased. The land is situated near the dam of a 64-acre communal lake, allowing access to the 10 ft height differential between the lake and the tail water on the other side of the dam.
My dad measured the amount of water flowing over the spillway and determined that an average of 40 cubic feet of water per second flowed through the pond, making it a marginally feasible hydroelectric project. However, this dream remained dormant until 2004 when my brother Simon discovered our dad’s research and decided to move forward.
On March 4, 2004, Simon began excavation for this project. For two years, the project was a challenging and sometimes disappointing excavation site, as it was necessary to dig 17 feet below lake level for the foundation while groundwater and mud continuously seeped into the hole. By the end of 2006, the underwater portions of the plant had been built, a four-foot aluminum pipe through the back of the dam was in place, the dam was restored, and the temporary cofferdam was removed.
On December 2, 2006, a refurbished 50 horsepower Francis turbine was purchased and installed. The turbine was tested and it was determined that the optimal speed would be 150 rpm. The next step was sizing the electrical generation equipment and designing the automation system.
This is the point where I became involved in the project. I have only a bit of experience in troubleshooting industrial electronics, mainly printing equipment, and I work as a computer programmer. I had never designed an industrial control system from scratch. Thankfully, I found an AutomationDirect catalog and recognized that they had the components I needed at a reasonable price, along with much needed free technical support.
Designing the Automation System
The hydroelectric system is powered by water draining from the lake that flows through a turbine which, in turn, drives three generators via a belt and pulley system (Figure 2). The generators are actually three Baldor Electric model L1177T 15hp single-phase induction motors.
When an induction motor is driven at greater than normal speed, it generates electricity. Output from the three motors was tied into the local electric grid via the same transformer that formerly only provided power to the property. The utility’s meter now turns backwards when the plant is supplying more power than consumed by the home and office.
We realized that as a grid-tied induction-based generation system, the generator/motors would freewheel if the excitation current from the grid was lost. The grid acts somewhat like a battery that is being charged, providing a degree of needed resistance to the generators.