Abstract

Drinking Water Conservation: Designing Passive Self-Tessellating Unit as Efficient & Effective Reservoir Cover

Emmanuel Eppinger; Advisor: Graig Marx

Background: Recent drought in California and around the world has placed water at a premium. As a result, municipalities have needed to conserve their limited drinking water in their reservoirs. In places with a Mediterranean climate, like California, municipalities are attempting to prevent the evaporation of this water. Taking Los Angeles as an example, one of their numerous reservoirs loses 330 million gallons of water annually to evaporation.

Engineering Goals: Reservoir covering allows municipalities to reduce the amount of water lost to evaporation significantly. However, these covers can be expensive, costing upwards of 300 million dollars, far more than most municipalities are willing or able to spend. To help alleviate the cost burden that municipalities face, we sought to develop a cost effective covering system that would reduce the evaporation.

Method: We iteratively designed a shape for a small unit that would float on the reservoir surface and block sunlight. It was designed to self-tesselate as the units would passively self-align themselves to nearly cover the reservoir’s entire surface. We then looked for methods for mass production as several millions of these units would be needed to effectively cover a reservoir. We then tested plastics that would not degrade when exposed to sunlight and water for an extended period of time in order to determine which plastic would be most durable in a reservoir. The amount of evaporation reduced was then measured.

Results: A fourteen-faced shape with a hexagonal base and top, connected with twelve parallelograms (See .stl file here: goo.gl/6tlJyj), self-tessellates, allowing large numbers of these units to effectively cover an entire reservoir.

Conclusion: The self-tessellating shape would effectively cover almost an entire reservoir. Its shape would allow for a more cost efficient covering of reservoirs. The cost of these units to cover an entire reservoir is a fraction of the cost of the current reservoir covers.

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