Sangmin Shin is assistant professor in the School of Civil, Environmental and Infrastructure Engineering, Southern Illinois University Carbondale.

According to Shin, the world’s water infrastructure is run reasonably well considering all the possible variations in availability, need, economics and technology. Unfortunately, they aren’t up to the task of all the uncertainty and major disturbances that are rapidly becoming more prevalent, including devastating floods, droughts, population growth and disruptions to related systems that immediately impact water systems, such as food and energy.

To summarize: “Water systems have been expanded and extended, but current water infrastructure systems are not ready to provide reliable water services under extreme and unexpected failure events,” he explains.

Decentralize the System

Although centralized water systems (e.g., government municipalities, large utilities, etc.) provide many benefits—including scale, storage and centralized management—Shin believes extreme events require a more-decentralized system to prevent a catastrophic breakdown.

To work out the details of how this should work, he and his students at Southern Illinois University Carbondale won a grant from the National Science Foundation to develop a physical, lab-scale microgrid system to test all the various ways water can be kept flowing under difficult conditions.

“Initially, we planned to develop a single, best and optimal microgrid model,” notes Shin. “But we realized there’s a need to classify more different and various types of water microgrids, like branch or radial types, considering the real-world system applications. Considering all the different circumstances in the real world, we’re trying to make various types of water microgrids.”

Microgrid Explained

A water microgrid is a hybrid centralized and decentralized system, according to Shin. Beyond a traditional centralized water-supply system, it also considers local water sources such as harvested rainwater, treated wastewater, desalinated water or groundwater.

“Water can be supplied from the centralized water system and the local water sources, and their portions in the water supply will change depending on the energy efficiency or system efficiency or operational cost or failure conditions,” he says.

“Like a hub, if there is a big storage tank filled with water supplied by the centralized water system, then the water in the storage tank also can be supplied to each subnetwork,” adds Shin. “The subnetworks are interconnected through the centralized water system and also have their own local water sources.”

The benefit of a microgrid is apparent during a failure in any of the networks, as the failed subnetwork can be isolated from the others and not propagated across the overall system. Interconnected subnetworks also can help minimize the damage or losses in water service by supplying their available water to other subnetworks.

“This is well aligned with the resilience concept, minimizing the damage or losses from some failure event and facilitating rapid recovery to the previous state,” adds Shin.

Everything Is Related

Shin emphasizes that water systems are tightly integrated and dependent on most, if not all, of the world’s other important resources and systems.

“Water sectors are interconnected with other sectors such as transportation, energy and food, and the interconnections are increasing,” he notes. “There is an urgent need to upgrade the existing systems to cope with extreme and uncertain disruptive events.”

Shin admits that the basis of his water research project stems from energy microgrids, which face similar problems: sustainability, resilience to extreme events (such as power outages) and concerns about carbon emissions. He notes that renewable energy sources often are used to broaden centralized power grids.

To better integrate these related systems, Shin suggests two strategies: a “smart system” that can combine water, energy, transportation and other integrated sectors; and community participation, which he believes can act like human sensors.

Building a Real Model

Shin and his students have been researching and building digital models, but a key part of the research project is to move from theoretical and digital to a real, working lab-scale water microgrid built with tanks, tubes, pumps and other elements of a large-scale water-distribution system. Multiple pumps will feed water into the network, and valves will isolate the subnetworks and control the flow depending on demands.

“We also install sensors for pressure and flow measurement, because we need to analyze the hydraulic performance of the water microgrid,” he notes. “The lab-scale physical model will be a real, physical model of the water microgrid—not a simulation model.”