Spencer Checkoway, a research assistant at the Center for Sustainable Systems (CSS) at the University of Michigan School for Environment and Sustainability (SEAS) is first author of a new study, "Carbon and energy footprinting across archetypes for U.S. maple syrup production" published by the American Chemical Society in the journal Environmental Science & Technology on October 7, 2024.

We asked Checkoway, whose research centers on the intersection of energy, life cycle analysis, mathematical modeling and complex systems, to answer five questions about the study, its findings and the main recommendations made by the authors.

The other authors of the study are SEAS Professor and CSS Co-Director Gregory Keoleian and CSS Research Specialist Geoffrey Lewis. 

Does maple syrup production in the U.S. have a significant carbon footprint, and do producers have an awareness of their footprint?

Any product that undergoes significant processing is going to have some carbon footprint, and maple syrup is no different. However, maple farmers get to tell a different story because they are the stewards of a resource that they tap into year after year. Most sweeteners made from crops are raised and cut down annually, but maple syrup is meant to be harvested in a sustainable way for the growth and health of the trees. The community is generally aware of the impacts of making syrup, and producers are curious about ways to improve the sustainability of their products as well as the health of their forests. In terms of production, there is debate about the impacts of wood-burning, and whether or not it is as bad as burning fossil fuels. In the life cycle world, they physically have the same warming impact, but the carbon emissions are on different timescales, meaning the wood-burning folks are not reintroducing carbon that had been sequestered for millions of years like those who burn fuel oil. What this means is that there is still a lot of debate surrounding carbon credits, and the question of additionality for those who harvest their own wood. For the purposes of this study we reported them as separate categories, so producers could see the breakdown of their emissions, but treated the impacts of the emissions the same.

What were the goals of this study?

The goals of the study were to quantify the energy, emissions, and solid waste impacts of specific technological decisions that farmers can make when they are setting up their maple syrup operation.

Were any of the findings surprising? 

The most surprising finding was just how much of an energy and emissions improvement reverse osmosis (RO) makes. In maple syrup production, reverse osmosis is utilized by pumping sap across fine membranes which filter out the sugar. While most reverse osmosis techniques are used to purify water, the sugary concentrate left behind when filtering is actually what gets boiled down into syrup. Most producers already know this technology saves money and time, but we didn’t know just how large an impact it would have on the carbon footprint of syrup.

The study looks at the entire life cycle model for maple syrup production—from starting sap sugar content to distribution. Was there one part of the cycle that produced the highest carbon footprint? If so, does this have implications for other agricultural products? 

The boiling process almost always has the largest impact of any production step. Other agricultural products that use high heat or pressure to distill and/or concentrate can look to improve the efficiency of heat transfer in order to lower the amount of energy needed. Electrification and the purchase of renewables to supply energy can also help lower the emissions footprint whenever possible.

What are some of the recommendations you make in the study for maple syrup producers?

The biggest recommendation we make is that if you can afford to implement an RO unit or a different type of concentrator in your production process, it will substantially reduce emissions and costs. On top of that, looking to electrify other parts of your operation, e.g., pumping, vehicles, and filtering can help improve efficiency and emissions as we put more renewables on the grid.