Rainwater harvesting systems can deliver collected rainwater to fixtures in homes at comparable water pressures and competitive water quality as municipal systems, when properly designed. However, moving and pressurizing water is very energy intensive, and must be accounted for in off-grid houses. For this project, I am working with Dr. Upshaw to analyze residential water usage data and create a model to calculate the solar array and energy storage sizing required to treat (via UV light) and deliver harvested rainwater to a typical residence at a desired water pressure. We are comparing power and energy storage requirements for an “On Demand” system with a “Pressurized Store” system that would treat the required daily volume during the day using solar energy and store this amount in a large pressurized tank for use at night. This exercise means to compare the relative merits of storing the energy in its end-use form (water pressure) vs. electrochemical from a cost, size, and energy perspectives.
Using the data from a study conducted by the Water Research Foundation in 2016, we were able to analyze water usage of 762 homes throughout the US. Using Python packages Pandas and Bokeh, we were able to analyze average water consumption per hour and visualize water consumption by event (toilet, shower, faucet, etc.), region in the US, and time of year. With this analysis, we created a Power Calculator that uses average volume and flow rate per hour from the data set and converts this into energy required to treat and deliver the water at a desired pressure to fixtures in the home. We then compared the power required to treat and deliver “On Demand” versus a “Pressurized Store” system.
“On Demand” and “Pressurized Store” System Power Calculators and Water Hourly Consumption Visualization coming soon!
*This research will be featured in the Environmental & Water Resources Institute (EWRI) Congress Meeting in June 2018 and will be published in the Conference Proceedings.