car exhaust (Arthito/Shutterstock.com)

CO2 emissions data cities can actually use

Researchers at Boston University have built a tool to help cities better estimate their greenhouse gas emissions. Called the Anthropogenic Carbon Emissions System, or ACES, the technology maps carbon dioxide emissions in the Northeast part of the country with a resolution of 1 km.

“When you look at the data products on greenhouse gas emissions that exist, they’re generally very aggregated to the national level, and it makes it harder for cities and states to use the data for local purposes because there’s a mismatch in the scale of reporting that’s done,” said Conor Gately, a postdoctoral associate at the university who helped build ACES.

He and Lucy Hutyra, a BU associate professor who helped develop the tool, wanted to build data projects that were closer to the spatial scale that cities and states need and that would allow for data to be compared across locations. Although many cities inventory greenhouse gases on their own, Gately and Hutyra wanted to build something that would standardize how the data is tracked and studied.

ACES includes data from city and country records, household fuel estimates, Environmental Protection Agency databases and traffic sensors, along with emissions data from roads, residential and commercial buildings, power plants, airports, marine ports and railroads. It also takes into account the amount of gasoline, diesel, home heating oil, coal and natural gas used in the region.

“It’s essentially a big data assimilation-type program,” Gately said. “Some of it is automated, some of it comes directly from [application programming interfaces] to government websites and some of it needs to be manually cleaned and reformed and reshaped and made into a harmonized format to go into the main output format.”

Gately wrote a set of software tools to help with that reformatting and reduce the time it takes to grind through the time and location data, which is stored in the cloud in an archive hosted at Oak Ridge National Laboratory. ACES goes through nine categories of potential emissions sources and finds the free and publicly available data that's most highly resolved, often from the EPA. The tool seeks out the low-level raw data and uses the activity levels to model the amount of CO2 from each emission source at the finest spatial scale available. It then standardizes the data into a uniform grid with a 1-by-1-kilometer boxes across the domain of interest, Gately said. It estimates the emissions from each of the sources for every hour in each box.

Downloaded more than 700 times so far, the dataset provides estimates of annual and hourly CO2 emissions from the combustion of fossil fuels for 13 Northeastern states. ACES estimated emissions for nine sources for the year 2011. Hourly estimates for 2013 and 2014 were derived from that by holding the total emissions constant while accounting for seasonal and daily changes in weather, fuel consumption and traffic patterns, according to the project's description at Oak Ridge.

The current version of ACES covers only the Northeast, but Gately said he expects a nationwide version to be available this spring, and it will go from 2011 to the present.

Feedback from urban government officials informed the new version, Gately said. “A lot of the people we talked to in urban government [have] the desire to release the data not in this gridded format, which is more suited for atmospheric models,” he said. Instead, they wanted data “aggregated to various different spatial aggregations like census blocks or block groups or tracts because those are the shapes in space that cities tend to operate on.”

Leah Bamberger, director of sustainability for Providence, R.I., said that ACES helped the city track direct emissions from heating -- a statistic the city had to report to the Global Covenant of Mayors for Climate and Energy, a group that requires an emissions inventory from cities that sign up. Providence joined in 2015.

The organization provides a greenhouse gas accounting tool that is “very helpful in walking you through the data that you need and how to actually do the calculations and get your inventory,” Bamberger said. "But what it doesn’t do is provide you the data.  You have to go mine the data yourself.”

That can be difficult, especially for transportation data, she said. “We are all struggling with getting that data, so to have a centralized place where you can download for a geographical area based on boundaries of your cities, that’s huge.”

About the Author

Stephanie Kanowitz is a freelance writer based in northern Virginia.

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