How Can Sustainable Urban Neighborhood be Made Affordable

A Stanford University study might help lawmakers spend billions of dollars in new federal infrastructure funds more wisely across the United States.

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A Unique Framework

The research, which was published in Frontiers in Sustainable Cities on March 31, gives a first-of-its-kind framework for determining the most efficient building mix for an urban region and systems for wastewater treatment, cooling, heating, and electricity.

Compared to typical systems that service wider regions, the strategy optimizes hourly demand and supply of electricity and water with integrated neighborhood-based power and water plants, considerably lowering costs and pollution. As a result, cities may become more walkable, habitable, and inexpensive.

"Rather than building blindly, we can use this framework to look at the long term, forecast development effects, and put numbers behind plans," said study lead author Pouya Rezazadeh Kalehbasti, who was a graduate student in civil and environmental engineering at Stanford at the time of the research.

Urban Energy Consumption

According to UN estimates, urban areas account for more than two-thirds of worldwide energy consumption and carbon dioxide emissions. Global warming and growing populations are putting a strain on their water supplies. Coordination of the design of electricity, water, and wastewater treatment systems is one option. Unlike typical huge, centralized facilities with separate functions, this local, integrated architecture can enable several efficiencies, such as redirecting excess electricity or heat from a power system to operate a wastewater system or utilizing wastewater to cool a power-producing system.

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Integrated Utility Sources

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Integrated power and water plants can be as small as two or three low-rise buildings, very efficient, and capable of turning wastewater into drinkable water thanks to sophisticated technology. They have no scents, can run on sustainable energy sources like solar energy, and produce minimal or no emissions. Depending on the size and population of the buildings, each plant may supply between 100 and 1,000 residents. In the United States, China, and other nations, including Europe and Canada, more than 4,000 integrated power and water systems currently exist. After implementing some strategy versions, private businesses and colleges, such as Stanford, have realized considerable energy savings.

The researchers studied two scenarios over 20 years of simulated operation to optimize the method. The first scenario had a combined building mix and energy system and a traditional central wastewater treatment facility powered by the grid. The second scenario incorporated modern wastewater treatment technologies into the building and energy architecture, such as forward osmosis-reverse and forward osmosis-membrane distillation.

Compared to typical segregated systems, completely integrating power and water systems with building mixes resulted in a 75 percent reduction in social, environmental, and economic impact from carbon emissions and a 20 percent reduction in lifetime equipment costs. The declines were primarily due to the reuse of waste heat and electricity in wastewater treatment and the use of a low- to zero-emission local energy system rather than the regional electric grid to power the wastewater treatment system.

Innovative Method

The method described in this paper should provide urban planners and infrastructure designers with various ideal neighborhood design combinations. They might then link the design of integrated power and water facilities with zoning laws, such as setting industrial construction limitations, to create more ecologically and economically sustainable urban communities.

It's thrilling to see how we may identify new, significant avenues toward global carbon reduction by combining current infrastructure with new urban technologies and maximizing their performance in tandem, said research co-author Michael Lepech, a civil and environmental engineering professor.

Looking to Improve

The researchers anticipate that an enhanced version of the framework may one day be used by urban planners to create various other systems, such as rubbish collection and traffic control. The framework might integrate additional efficiencies as technology advances, such as using power plant heat to dry wastewater biosolids, lowering disposal demands, and producing a source of renewable biofuels.