Hydropower: The Final Experiment

So here we are. This is the final installment on my group’s final experiment. A semester’s worth of experimenting and lab performance has culminated into this one final test: to see if we are capable of successfully creating our own experiment. I have to admit, it was not always easy. There were good times and there were bad times, but they all were the best of times. Anyways, I digress. For those of you arriving late to this post I’ll review everything for you! Prepare yourself, for this is the final rundown.

The Technology of Hydropower

Hydropower. Can you picture it? I’m sure you can because it’s been around for a while. Only recently, however, given the rising demand for green electricity, has hydropower been advancing and becoming a more prominent source of energy. To give you a bit of background, these are the words of my teammate Nicholas O’Keefe:

“Hydropower is one of the largest sources of clean, renewable energy found on earth today.  Harnessing the mass amounts of potential energy contained in the world’s water supply to create electricity has become a viable alternative energy source. Today, hydropower accounts for 9% of the total electricity supply in the United States, and about 73% of the nation’s renewable energy.  The advantages of hydroelectricity include zero pollution and the substantial availability of water on earth.  The different kinds of hydropower plants include diversion, pumped storage, and impoundment; each of which uses a turbine to generate electricity.”

Our experiment focuses on the turbine, the method in which the kinetic energy of the water is transformed into mechanical energy, which can be used as electricity. It’s a simple yet efficient and green method for harnessing the natural energies of the water in rivers and lakes. To the right is a simple diagram outlining the basic structure of a hydropower facility.

Just to get an idea about the importance of this technology, hydropower is currently the largest, most reliable, and inexpensive source for renewable, clean energy in the U.S. as of now. In September of 2011, the Department of Energy stated that it was funding 16 Research and Development Projects in 11 states across the country in an effort to advance hydropower. They stated that $17 million was to be released between 2012-2015. They claimed this funding is meant to develop hydro-technologies in an effort to produce more efficient, inexpensive, and environmentally friendly hydropower systems. This government funding of research and development, with the eventual goal of application if everything goes well, furthers the government’s ambition to reach the nation’s goal of having 80% of all electricity in the country be generated by a renewable source by the year 2035. If you ask me, people are pretty serious about this technology and it has promise enough to invest large amounts of funding into its development. It’s for this reason that our experiment is important. Hydropower is becoming more and more significant in this country as a prominent source of energy. We should understand this technology. My team’s experiment sought out to educate another group on how hydropower functions, and it did so in a simple, yet effective, way.

The Experiment

So now that you know the basics of the technology and it’s application, it’s time to put that knowledge to the test! Here is a version of our experiment:

Yes, it’s really that simple. But that’s the beauty of it! Hydropower is a simple and straightforward technology and understanding it is as simple as building your own waterwheel. So that’s what we did! Below is a description of how the experiment works, taken and revised from my first post on this experiment:

It starts by creating a waterwheel using an ordinary tin pan. We actually used two and stapled them together (after testing it ourselves we found that the tin needed to be stronger to resist the weight of the falling water). The students then cut and fold the tin to create panels so that it will catch the water when it falls. The waterwheel is then placed on a dowel over a bucket. The wheel is taped tight to the dowel so that when the water hits it the wheel won’t shake and the dowel is loosely fitted on the bucket so that it can rotate, but it’s unable to fall out. On the other end of the dowel there is a string attached, onto which a small weight is tied (the weight is decided upon my the students, with a minimum of two different weights being used). The objective of this experiment is to lift the weight using only the energy provided by the water source, which is a pitcher of water being poured into a funnel (there are three different funnel sizes, all of which are used for each weight). The falling water from the funnel, which has kinetic energy, hits the waterwheel and rotates it, which in turn rotates the dowel. Now we have mechanical energy. The string, which is attached to the dowel, begins to wind itself, carrying the weight upwards as it shortens. The mechanical energy preforms the work needed to lift the weight, all of which happens because of the falling water rotating the wheel.

For the experiment my team created this worksheet, as previously posted:

As the worksheet explains, the objective of this experiment is to test the different perimeters of hydropower. The varying sizes of the funnel (one releasing a small amount of water, a second releasing a moderate amount of water, and the third releasing a large amount of water) are measured and compared for their effectiveness, along with at least two different weights that the wheel has to lift. Each trial is timeed and recorded in the chart provided so they can compare their results. Finally, the grand question is what all this means in terms of hydropower.

The Performance of the Experiment

As mentioned earlier, our initial test run did not go as easily as we hoped. The tin wheel was too thin to withstand the weight of the falling water. For this reason we improvised for the actual experiment, stapling two tin plated together for additional strength. This ended up working perfectly. The students cut the wheel according to our directions and it proved to be a much more stable design than a single tin plate. As for the rest of the experiment’s construction, we provided them with our already constructed bucket and dowel set up. We did this in order to save time and hassle, after all the experiment is not about enginuity and craftsmanship, but about the waterwheel and the data. As their teachers we didn’t have to explain too much, the worksheet we gave them having adequately described the experiment. They knew what they needed to do and they set out right away in doing it! Having constructed their double-plated wheel, they attached it to the dowel and taped it secure. They were now ready to pour the water and collect data.

We discovered in the initial experiment that pouring the water was a fine art, so to speak. Having poured the water myself, I experienced how difficult it was to get the water to fall on the appropriate place on the wheel. It proved no different for our students. With their reinforced waterwheel they didn’t experience any troubles due to a flimsy design, but there was a learning curve to how they should pour the pitcher into the funnel and where to aim the falling water from the funnel on the wheel. It took a few test runs for them, but they were able to get the hang of it and produce results. Besides those two issues, however, the rest of the experiment performed perfectly, producing the results we anticipated and allowing everyone to have a good time while doing it!

The Experiment’s Results

Our team of students decided to run the experiment with two different weights (mostly due to time restrictions). For the first weight they used 70 grams of weight on the end of the string. The first and smallest funnel was used first, the yellow funnel, and they recorded a time of 11 seconds for the weight to reach the top of its determined distance (the distance from the floor to the dowel). Next they used the blue funnel, which allowed a moderate flow of water to fall through it. This time the weight took 7.9 seconds. Finally, the red funnel, the largest of the three, was used to record a time of 5 seconds. They determined that the larger the water flow allowed, the faster the waterwheel turned, resulting in the weight being lifted quicker.

To further test their analysis, the students recorded a second set of data using a weight of 90 grams. For this weight the yellow funnel yielded a time of 16 seconds, the blue funnel yielded a time of 12.8 seconds, and the red funnel yielded a time of 9.7 seconds. They determined that this new set of data corresponded to their first set, confirming that the more water flow allowed the faster the weight was lifted. In addition to this confirmation, they discovered that the additional weight, while following the trend of the first results, took more time to rise. They further concluded that while water flow increase results in a quicker time, weight increase results in a decrease in time. The results: the more water flow the more energy generated, but the greater the weight the more work that needs to be done, meaning a greater water flow is needed to keep efficiency.

But what does all of this mean for the greater question of hydropower that our experiment asks? Well without getting too technical in an effort to keep the simplicity of this experiment in tact, what this experiment teaches about hydropower is that the more powerful a water source, such as a river or a waterfall, the greater potential it has in generating more energy due to the fact that it can rotate stiffer turbines while remaining efficient. This conclusion makes sense when you think about it. The more water moving the more hydropower generated. Simple, yet promising in its potential for real world application.

The Experince of it All

Overall, I would say this experiment went very well. It was education for both my team and our students, and it was fun at the same time. We discovered that a great deal of planning, as well as trial and error, goes into creating an experiment, and looking back we have a greater appreciation for the projects we have done over the course of the semester. It’s not easy leading an experiment where anything can happen, and even the best planned experiments can go wrong. In the end though it was a positive experience, and I think we all were able to take something away from it.

Sources

http://energy.gov/articles/16-rd-projects-across-11-states-advance-hydropower-us