The gear pictured above is the first experimental wheel for the turbine, made from a recycled 3D printer plastic spool, PVC board (to decrease the rod size on which the gear will spin), threaded rod, and nuts. This particular gear will be one of two gears moving the rope pump to deliver water from the lower to the upper reservoir. The threaded rod will catch the washer disks fixed to the rope and guide them back into the PVC pipe to deliver more water to the upper reservoir. Given that one of these gears will have to be underwater, there will undoubtedly be considerable resistance, although we are not quite sure yet if the effect will be too great against the torque put out by the spinning turbine.
(Note: If you're interested in learning more about how a rope pump functions, check out my previous post on rope pumps)
During our second water generator test, a smaller-voltage-output generator was used (5V), which enabled the generator to begin spinning independently by the movement of the water. This is a lot more practical for a system where autonomous processes are essential to maximize energy efficiency and minimize maintenance. The graph, pictured above, shows that the voltage output from the generator varies nearly directly with the level of the water tank over the span of a few minutes. After 6.5 minutes, the water reservoir ran out and voltage dropped sharply to zero, indicating a minimum voltage output for the generator.
Now that we have confirmed that the water generator functions with a 5-gallon water reservoir, the next step in the research process is to integrate this generator into the rest of the turbine-driven rope pump for full autonomous electricity production. As a quick review, the rope pump (featured in a previous post), driven by the spinning of the wind turbine, will deliver water to the upper reservoir of the water generator which will return it to the lower reservoir by passing through a small generator. The resultant product is electricity that will power a small lightbulb (the current utility chosen to prove the viability of a hydraulic wind turbine).
In an effort to evaluate the potential of the generator on the turbine to power an electrical device such as a lightbulb, we graphed the voltage output over a span ten minutes. The generator produces electricity as water spins an impulse turbine (known as a pelton wheel).
From the data, we concluded that the voltage varies directly with the pressure. As the pressure decreased in the 5 gallon water tank, the voltage decreased at an average linear rate of -0.2080 volts per minute. The maximum voltage output with less than 5 gallons of water running through the system was 4.529 volts and the minimum was 2.811, at which point the voltage rapidly decreased to zero. It's possible that the turbine cannot generate any voltage below 2.811. The generator, however, can likely output more voltage with a larger volume of water.
Note: the voltage appears negative on the graph because the alligator clips running into the data collection software were switched.
We have officially begun building the wind turbine. We locally sourced pine for the structure of the turbine, bringing the lumber cost to virtually nothing. We have used a cardboard sonotube (intended for cement pouring) as the blades fixed to two bearings mounted on plywood nailed to the pine structure. What we are not sure of yet is whether the structural support provided by the pine will inhibit the rotation speed of the sonotube. The turbine is currently about six feet tall. I plan on posting more photographs and sketches after the initial test of the blades.
The design and construction process for this project will occur in two phases: The first is the wind turbine itself and the second is the water pump. In an effort to stay true to the low-or-no-cost goal of this device, our team arrived at the conclusion that a rope pump would be the cheapest solution that, at the same time, maximizes pump efficiency. This design has existed for more than 1000 years, dating back to the original Chinese version, known as a chain pump.
Here’s how it works: a rope with pistons mounted at specific intervals is wound around two wheels. The pistons are made from rubber, foam, or plastic pieces that fit snugly in the pump pipe. As the pulley wheel spins (which will be driven by the turbine), the rope is pulled through the pump pipe, effectively lifting the water. At the top, the lifted water exits the horizontal outlet pipe into a basin. A valve at the bottom of the basin can then be opened and feed over a secondary turbine/wheel that generates electricity. The water then returns to the bottom basin where it can once again be pulled up by the rope pump. Above, I’ve attached an image of the rope pump concept and I hope to update this post with our newly designed model soon.
We have researched various turbine types with a special focus on the vertical-axis wind turbine (VAWT). Its orientation is transverse to the wind, meaning that it can spin regardless of wind direction. This is especially useful in areas below the treeline where wind speeds constantly fluctuate and change direction. The mechanics of a VAWT are simpler than a traditional horizontal-axis wind turbine (HAWT), as every component can be mounted on a single vertical rod or pole without the need for a nacelle (the electrical box at the top of a standard HAWT). With the advent of the power conversion components at the base of the turbine, maintenance of the energy source is both cheaper and less physically demanding. The GIF below does a nice job of illustrating HAWTs and VAWTs.
With one of our main goals being to construct a low-cost turbine, we have sought out the simplest solutions for the turbine blades. In the image above, the turbine on the left is called a Savonius turbine. Our design is similar, but uses two blades instead of three, hence the name: a two-scoop savonius turbine.
My name is Mattheus, and along with my team of fellow researchers, we are designing and building a low-cost, low-tech wind turbine to pump and store water to generate electricity. Inspired by an internship working with a research student at the UMass Amherst Wind Energy Center this past summer, I want to apply what I learned there to a new situation that can effectively generate on-demand electricity from a renewable energy source. Feel free to check out the project I helped with here.
We have already begun designing and planning a model of our own system that uses water (either from the ocean/lake/river or from an enclosed system) as a mechanical storage medium that can be released at will to generate on-demand electricity. In the coming weeks, I look forward to sharing more about our sketches, designing process, and overall progress with our research.