Engineers point the way to more affordable, sustainable urban
neighborhoods

Date:
April 5, 2022
Source:
Stanford University
Summary:
Analysis presents a first-of-its-kind framework to design the most
efficient mix of urban buildings along with integrated systems to
supply power and water services. The approach could significantly
reduce costs and pollution compared to traditional systems.



FULL STORY ==========================================================================
A Stanford University analysis could help policymakers across the
U.S. spend billions of dollars in new federal infrastructure funding
more wisely. The study, published March 31 in Frontiers in Sustainable
Cities, presents a first- of-its-kind framework to design the most
efficient building mix for an urban district along with systems that
supply wastewater treatment, cooling, heating and electricity. The
approach optimizes hourly demand and supply of power and water with
integrated neighborhood-based power and water plants, significantly
reducing costs and pollution compared to traditional systems that serve
larger areas. This, in turn, could lead to more walkable, livable and affordable cities.


========================================================================== "Instead of building blindly, we can use this framework to look at the
longer- term, forecast development effects and put numbers behind plans,"
said study lead author Pouya Rezazadeh Kalehbasti, a graduate student in
civil and environmental engineering at Stanford's School of Engineering
at the time of the research.

Cities as problem and solution Urban areas account for more than
two-thirds of global energy consumption and carbon dioxide emissions,
according to UN estimates. Their water sources are increasingly
stressed by global warming and burgeoning populations. A solution lies
in coordinating the design of systems that supply power, water and
wastewater treatment. Unlike traditionally large, centralized plants
with segregated functions, this local, integrated arrangement can make it possible to achieve a variety of efficiencies, such as directing unused electricity or heat from a power system to running a wastewater system
or using wastewater to cool a power generating system.

Using advanced technologies, integrated power and water plants can be relatively compact -- about the size of two or three low-rise buildings
- - highly efficient and capable of recycling wastewater into potable
water. They emit no odors, can run on renewable power sources, such
as solar energy, and emit low or no emissions. Each plant can serve
between 100 and 1,000 buildings, depending on the buildings' sizes and
resident populations. More than 4,000 integrated power and water systems already exist in the U.S., China and other countries, especially Europe
and Canada. Private corporations and universities, such as Stanford,
have seen significant energy efficiency gains after adopting some form
of the approach.

Optimizing systems With an eye toward optimizing the approach,
the researchers modeled two scenarios over 20 years of simulated
operation. The first scenario was a building mix and energy system
designed together along a conventional central wastewater treatment plant powered by the grid. The second scenario integrated advanced wastewater treatment systems -- forward osmosis-reverse osmosis and forward osmosis-membrane distillation -- into the building and energy design.

The analysis found that fully integrating power and water systems with
building mixes resulted in a 75% reduction in social, environmental and economic damage from carbon emissions, and a 20% reduction in lifecycle equipment costs compared to traditional segregated systems. The reductions
were due primarily to the reuse of wasted heat and electricity in treating wastewater, and powering the wastewater treatment system with a low- to zero-emission local energy system, rather than the regional electric grid.

The approach proposed in this study is expected to inform urban planners
and infrastructure designers of a range of optimal configurations for
designing a neighborhood. This way, they could coordinate design of
integrated power and water plants with zoning rules, such as imposing
limits on industrial buildings, to lead to more environmentally and economically sustainable urban neighborhoods.

"It is exciting to see that by integrating existing infrastructure with
new urban technologies, and optimizing their performance in unison, we
can discover new, substantial pathways toward global carbon reduction,"
said study co-author Michael Lepech, a professor of civil & environmental engineering.

The researchers hope that urban planners will someday use an expanded
version of the framework to design a range of other systems, including
garbage removal and traffic control. As technologies advance, the
framework could also incorporate new efficiencies, such as using power
plant heat to dry wastewater biosolids, thereby reducing disposal needs
and creating a source of renewable biofuels.


========================================================================== Story Source: Materials provided by Stanford_University. Original written
by Rob Jordan.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Pouya Rezazadeh Kalehbasti, Michael D. Lepech, Craig S. Criddle.

Integrated Design and Optimization of Water-Energy Nexus: Combining
Wastewater Treatment and Energy System. Frontiers in Sustainable
Cities, 2022; 4 DOI: 10.3389/frsc.2022.856996 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220405143544.htm

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