Thousands of tractor-trailers travel across the nation’s highways every day to bring fresh produce to American consumers. Growing more food closer to consumers could significantly reduce greenhouse gas emissions from all those trucks, right?

Not necessarily, or at least not yet.

New research from Colorado State University shows that the current production and distribution supply chain is still a better option, in terms of total greenhouse gas emissions, for getting vegetables like lettuce from the field to the dinner table.

Researchers in the College of Agricultural Sciences and the Walter Scott, Jr. College of Engineering compared the cradle-to-store-shelf emissions of four different lettuce production systems to help communities understand the tradeoffs at play.

The results show that controlled environment agriculture – such as hydroponic systems – always have higher total greenhouse gas emissions than centralized production and distribution from California via trucking.

Mechanical Engineering Ph.D. student Reid Maynard served as the first author on the research, which was recently published in the Journal of Cleaner Production. He said indoor production facilities offer more control over water use and light but would still need to electrify all systems with low-carbon sources to have equivalent or lower greenhouse gas impacts than centralized production and transportation.

“Many communities are considering these types of questions in their local food production methods and are trying to balance the value of water use, energy demands and the overall impact on the climate from those activities,” he said. “Hydroponic systems offer benefits in terms of efficiency, and this research informs the ways we can adapt those technologies to improve food sustainability in the future.”

He added that other approaches like local seasonal growth and distribution through farmers markets may produce lower overall emissions but could also feature higher demands on water in different situations.