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New Purification System Uses Energy from Solar Panels to Decontaminate Water

At Texas A&M University, scientists have developed a green, inexpensive solution that can help meet the water and electricity requirements of underserved communities.

Underserved communities are often isolated from centralized power and water treatment plants, making them largely dependent on infrastructure development for access to basic amenities. Image Credit: Getty Images.

The new autonomous water-energy nanogrid includes a solar-energy-based purification system for decontaminating water. According to the researchers, the system is mathematically tuned to make optimal use of solar energy so that water filtration is not hampered by the fluctuations of solar energy during the day.

To serve areas that are remote and isolated, the infrastructural cost of laying down new water pipes or setting up an electricity grid is enormous and can take a very long time. To overcome these hurdles, we presented a cost-effective solution that uses solar energy to both purify water and generate electricity for basic household use.

Le Xie, Professor, Department, Electrical and Computer Engineering, Texas A&M University

The new technology has been explained in a paper published in the Applied Energy journal.

The colonias in the United States are one of the several rural, poor communities living along the Texas-Mexico border, where access to essential resources is not readily available.

The colonias are remote, and thus their residents, mainly including migrant workers, are separated from significant utility and water treatment facilities. Thus, they have restricted access to safe drinking water and electricity. Methods such as boiling water can be insufficient and costly.

Boiling water is one of the most expensive ways of decontamination because it takes a lot of energy to heat water. Also, although boiling gets rid of biological contaminants, it does not remove many chemical contaminants. We needed a solution that could address both these problems at the same time.

Shankar Chellam, Professor, Zachry Department of Civil and Environmental Engineering, Texas A&M University

An efficient method for water decontamination is to bypass it via purification systems. Such machines feature pumps that push water via a filter.

But the pumps need electricity, which is again insufficient in the colonias. Hence, the team sought a solution that would assist with both the power and water needs of the colonia residents.

Firstly, to reduce the reliance on centralized water and power sources, Xie, Chellam, and their group proposed an energy-water nanogrid, which is an autonomous, truck-mountable filtration system with pumps that can work on solar-generated electricity.

Then, they created a cost-reduction mathematical scheme, known as scenario-based optimization framework, which reduced the entire cost for the autonomous setup by choosing the kind of filter, the number, and size of solar panels as well as the size of the solar battery.

This model showed that if nanofiltration, a kind of purification method, was employed, solar energy harnessed just at the time of peak availability was adequate to run pumps and purify water.

Simply put, the water nanofiltration system was not much affected by the daily variations in solar energy and could purify sufficient water to fulfill the weekly water requirements of the community.

Thus, any surplus solar power not utilized for filtration could be used either for storage in the battery pack or for other small basic household requirements, such as charging cell phone batteries.

The team observed that even though the nanofiltration system is more costly and advanced compared to other filtration techniques, its entire merit is that it can successfully desalinate and eliminate chemicals, such as arsenic, present in local groundwater.

According to the researchers, nanofiltration is a desirable technique for desalination as well as water purification for other remote regions where the contaminants in the water are not known earlier.

We have for the first time used a very rigorous mathematical approach to interlink water purification and energy provision. This lays out a quantitative framework that can be used in not just the colonias but in any scenario based on local conditions.

Shankar Chellam, Professor, Zachry Department of Civil and Environmental Engineering, Texas A&M University

The other contributors to the study are M. Sadegh Modarresi from Burns & McDonnell in Houston, Bilal Abada from the civil and environmental engineering department, and S. Sivaranjani from the electrical and computer engineering department.

This study was financially supported in part by the Texas A&M Engineering Experiment Station, the Texas A&M Energy Institute, and the National Science Foundation.

Journal Reference:

Modarresi, M. S., et al. (2020) Planning of survivable nano-grids through jointly optimized water and electricity: The case of Colonias at the Texas-Mexico border. Applied Energy.


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