UNIVERSITY PARK, Pa. — Cities can be paradoxes when it comes to energy and the environment. For example, in a city, people live in a dense infrastructure of housing and businesses. In this scenario, one possible positive opportunity is the reduction of transportation and the pollution and energy use that come with it. However, not everyone can live and/or work in the city, so commuters near urban areas can have higher transportation energy and air pollution footprints from driving vehicles that enter and exit the city daily.

This example is one reason cities are such complex human-created systems. Recognizing the challenge of this complexity, the Institutes of Energy and the Environment (IEE) created a new research theme: Urban Systems. The theme will address the essential and urgent needs for sustainable, healthy and affordable solutions for urban areas.

“Urban systems offer up both challenges and opportunities where we can really have an impact,” said Tom Richard, director of IEE. “The disparities in terms of environmental pollution, energy access, and climate impacts are extreme, yet cities are also crucibles of innovation that inspire the next generation of solutions.”

This is the first time IEE has focused on man-made infrastructure, according to Bruce Logan, associate director of IEE.

“Other themes have focused on the ‘natural’ environment, especially ecosystems, water and health,” Logan said. “Increasingly with the global population growing, coupled with a need to shift to renewable energy sources and reduce greenhouse gas emissions, this new emphasis on the urban infrastructure makes sense.”

Moreover, research in Urban Systems is inherently interdisciplinary, a key focus for IEE.

“The exciting part about urban research is that it is necessarily integrative,” said Erica Smithwick, associate director of IEE. “It is impossible to study complex urban systems without taking an interdisciplinary lens. For example, studying water availability, air quality, energy efficiency or food systems benefits from integration across disciplines.”

In addition to cities being complex, they are growing. The United Nations’ prediction is that by 2050, nearly 70% of the world will live in cities. With the projected world population to be nearly 10 billion people by 2050, that means nearly 7 billion people will live in cities in less than 30 years. Compare that to today’s approximately 4.5 billion people who live in cities.

With projections such as these, the world is facing multiple city-related challenges. This includes health, water and energy. And all of these challenges are connected to environmental justice.

One facet of cities that must be addressed to meet the world’s environmental needs is construction materials.

Thirteen percent of total greenhouse gas emissions comes from the manufacturing of cement and steel, much of which goes into the urbanization of areas around the world, said Logan, an Evan Pugh University Professor and Kappe Professor of Environmental Engineering in the Department of Civil and Environmental Engineering.

“There is a continued increase in cement production, particularly due to the urbanization of China,” Logan said. “Global anthropogenic CO₂ emissions in 2018 were 33.1 gigatons with cement and steel production accounting for 4.4 gigatons.”

Logan said that alternatives to traditional cement must be found for the world to stop climate change.

Shirley Clark, professor of environmental engineering at Penn State Harrisburg, said this high density of people also influences stormwater and flooding.

“Waste generation is confined to a small space, and the delivery needs of clean water and collection of sanitary wastewater is vital in large quantities,” she said. “Urban areas contain a lot of impervious surfaces, such as rooftops, sidewalks, streets and parking lots, which results in increased stormwater runoff and potentially increased flooding.”

Clark said flooding is increasing in many areas due to climate change and the change in precipitation patterns.

According to Clark, to better manage flooding, the public must be educated, and design guidance and modeling must be improved based on the ongoing research in urban stormwater systems, such as that conducted by multiple researchers at Penn State.

“We need to educate the public that temporary water in swales and rain gardens is good, that rainwater harvesting for landscape irrigation is good, and that installing these devices can help reduce flooding,” she said. “Most people think that what is needed is simply to put in a bigger pipe underground. They do not understand that this simply moves the flooding problem elsewhere.”

According to Clark, design and modeling must be updated to meet the requirements of the world’s changing storm patterns.

“Our design criteria now are static, based on worksheets, and does not incorporate current science” said Clark. “Responding to the climate crisis in relation to stormwater management will require being able to evaluate a design over multiple rainfall patterns, especially these short-duration storms that we are seeing increase currently.”

For energy use, cities require a lot of energy to be delivered to a relatively small footprint. However, some sections of cities are overlooked when it comes to updating infrastructure, according to Hannah Wiseman, an IEE cofunded faculty member and a professor for Penn State Law.

“As many cities move toward low-carbon solutions through renewable energy and energy efficiency programs, city officials and industry leaders need to more proactively target low-income areas as the first recipients of grants, rebates and other services and goods offered through these programs,” Wiseman said. “And they need to ensure that when low-carbon policies negatively affect low-income residents — if they raise electricity prices, for example — that these cost increases are offset.”

Wiseman said that she hopes urban-centric research will primarily target low-income, frontline communities who could benefit the most substantially from energy efficiency improvements, affordable rooftop solar or community solar, and other modern energy solutions.

In addition to Urban Systems, IEE has four other research themes: Climate and Ecosystem Change, Health and the Environment, Integrated Energy Systems and Water and Biogeochemical Cycles. IEE is one of Penn State's University-wide research institutes that connects and supports interdisciplinary teams of researchers to solve some of the world’s most difficult energy and environmental challenges.