NEW STUDY: Role of Cross-Sector Strategies in City Efforts to Reduce GHG Emissions, Improve Health

Based on “bottom-up” emissions data from 637 cities in China–the most comprehensive data set of its kind–a new study published in the journal Nature Climate Change  by SRN researchers models the role of cross-sector strategies in city efforts to reduce GHG emissions.

The study specifically considers the aggregate GHG emissions impacts and local health impacts that could be generated if cities deployed strategies of cross-sector industrial symbiosis to capture and re-use “waste heat” and other other byproducts of industrial activity located in or near cities. The study has key implications for:

• 1) quantifying what cities can and cannot do to contribute to national aggregate CO2 mitigation efforts
• 2) quantifying what city-level CO2 mitigation efforts mean for local health benefits
• 3) understanding the potential impact of circular economy policies and urban design strategies that encourage cross-sector reuse of “waste heat” and other industrial byproducts

The remainder of this post is excerpted from an article posted on the Humphrey School of Public Affairs news page. See the original article here. 

Concerns over global climate change and local air pollution have led many cities around the world to get creative in their efforts to reduce the use of fossil fuels. They’re going beyond conventional single-sector strategies such as energy-efficient buildings and power plants to look at innovative ways to capture waste heat from industries and businesses—from cement plants, to pulp and paper mills to grocery stores—and pipe it to homes and buildings up to 30 kilometers away.

Some cities are also reusing waste materials from industries in urban construction as a substitute for cement and other construction materials, helping reduce the demand for these materials.

Scientists use the terms “cross-sector strategies” and “circular economy strategies” to describe such novel approaches to urban infrastructure planning, which have several goals: to reduce material and energy use; to reduce reliance on fossil fuels; to improve air quality; and to improve the health of residents in urban areas, while simultaneously creating value from resources that were previously wasted.

New research by Professor Anu Ramaswami of the Humphrey School of Public Affairs at the University of Minnesota, published Monday in the latest online edition of Nature Climate Change, is the first to demonstrate just how successful these strategies would be, if widely adopted.

“Cities are the critical centers of change when it comes to taking action on greenhouse gases,” said Ramaswami, who led this study that looked at all 637 cities in China at the same time. “Our research shows there’s great potential for cities to reduce energy demand and carbon emissions by adopting cross-sector strategies, such as reusing industrial byproducts like waste energy, on a mass scale. And that means a better quality of life for residents. It’s a win-win.”

Professor Anu RamaswamiThe study finds that if all cities in China adopt these strategies, they would reduce greenhouse gas emissions by up to 36 percent—and at the same time, protect up to 57,000 people from dying prematurely due to poor air quality. Researchers base these findings on models that examine potential carbon reductions and the expected health improvements.

The study also found that the benefits varied from city to city, depending on the locale.

For example, two cities can take similar actions and reduce emissions or energy use by the same proportion, and see very different health and environmental outcomes, due to differences in how air pollution flows into and out of their cities from the surrounding areas.

Ramaswami noted that most research on greenhouse gas emissions up to this point has focused on what national-level policies can do, typically impacting individual sectors of the economy such as power generation, transportation, or energy-efficient building construction. This is the first of its kind to measure the impact of holistic urban planning in cities that encourages compact city development, eco-industrial parks, waste-to-value projects and district energy systems. Cities can readily adopt these practices, Ramaswami said, but they rarely get credit for them in terms of reducing greenhouse gases.

Since her study is the first to collect information at the city level, it’s a starting point for analyzing the science behind what cities can and cannot do to help reduce greenhouse gases on a nationwide basis, and what those steps mean for the local communities.

“The insights we gained from this study will inform how we design sustainable urban areas in China and elsewhere around the world in the future,” said Ramaswami. “That’s important because we expect to see another 2.5 billion people living in cities by 2050, with most of that population growth in Asia and Africa.”

Read the complete findings.

The study was conducted in collaboration with researchers at the Georgia Institute of Technology, Yale University, Tsinghua University, and Shanghai University.

The collaborations were enabled by a Partnership for International Research and Education (PIRE) grant from the National Science Foundation (NSF). The PIRE project concentrates on reducing greenhouse gas emissions from cities, while addressing broader sustainability goals such as economic development, water scarcity, environmental pollution, and public health. Several of the study authors are current affiliates with the Sustainable Healthy Cities Network, supported by an NSF sustainability research network grant.

Ramaswami is the Charles M. Denny, Jr., Chair of Science, Technology, and Environmental Policy (STEP) at the Humphrey School of Public Affairs. The STEP program integrates science with public policy, community action, and multi-sector governance.

Study of Wastewater Treatment and Reuse in Urban Ag Receives Press in India

The Indian Express newspaper (link below) reports on a study in Hyderabad, India that identifies the linkages between urban agricultural practices, sewage treatment and reuse, carbon emissions and health. Network member Anu Ramaswami (University of Minnesota), Leslie MiIler-Robbie (University of Colorado, Denver) and Priyanie Amerasinghe (International Water Management Institute) collaborated on this study, recently published in the journal Environmental Research Letters (Link to article). The study finds that sewage treatment along with water reuse in urban agriculture can offer benefits to carbon mitigation and public health, although the public health benefits are less than expected due to farming practices and prior history of sewage-related soil pollution in the region.

Climate change: Untreated sewage major contributor in The New Indian Express

The carbon emission benefits of sewage treatment are large since untreated sewage discharged to rivers converts to methane which is a potent greenhouse gas. Untreated sewage and household waste, along with emissions from burning of petrol and diesel in cars, and coal to provide electricity are among the major contributors to greenhouse gas emissions in cities.