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1. A regional assessment of land, irrigation water, and greenhouse gas emissions from canola biodiesel feedstock production in California

   Winans, K; Yeo, B-L; George, N; Kendall, A; Kaffka, S (July 2017, Proceedings of the International Symposium on Sustainable Systems and Technologies)

   The objective of this research is to evaluate the effects of cropping choices on land, water use for irrigation, and greenhouse gas emissions after introducing canola (Brassica napus L.) cultivation for the production of 60 million gallons of biodiesel per year. Characterization of regional farm-level cropping patterns and agronomic inputs and economic data are used to model the adoption of canola in place of the diverse incumbent cropping patterns in four regions of California: Northern and Southern San Joaquin Valleys, Sacramento Valley, and Southern California, using the Bioenergy Crop Adoption Model. The life cycle assessment approach is then used to assess environmental impacts due to cultivation of canola in place of the incumbent cropping patterns in terms of: (1) land use; (2) life-cycle greenhouse gas emissions due to direct land use change (kg CO2e ac-1); (3) greenhouse gas emissions due to irrigation water (kg CO2e ac-1); and (4) life-cycle greenhouse gas emissions expressed in grams of carbon dioxide equivalent per megajoule of biodiesel. Preliminary results show the adoption price of the canola with a yield of 1.5 U.S. tons per acre is estimated to be $481 per ton of canola in 2012 dollars at which point a total of 508,400 acres appear in canola cultivation. This land area (508, 400 acres) is equivalent to approximately 89 million gallons of biodiesel from canola per year given the assumptions stated in this study. Consequentially, crops that are less profitable are replaced with canola and greenhouse gas emissions due to irrigation water are reduced while maintaining a diversified percentage of the incumbent cropping patterns, as well as canola cultivation. 

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2. Sustainability of lettuce production: A comparison of local and centralized food production

   https://doi.org/10.1016/j.jclepro.2023.139224  

   Maynard, Reid; Burkhardt, Jesse; Quinn, Jason C (November 2023, Journal of Cleaner Production)

   Communities are considering local food production in response to the pressing need to reduce food system greenhouse gas (GHG) emissions. However, local food systems can vary considerably in design and operation, including controlled environment agriculture (CEA), which refers to agricultural production that takes place within an enclosed space where environmental conditions, such as temperature, humidity, and light, are precisely controlled. Such systems require a considerable amount of energy and thus emissions; therefore, this study seeks to quantify these environmental impacts to determine how local CEA systems compare to alternative systems. For this study’s methods, we apply life cycle assessment methodology to quantify the cradle-to-storeshelf GHG emissions and water consumption of four lettuce production systems: local indoor plant factory, local greenhouse, local seasonal soil, and conventional centralized production in California with transportation. Using geographically specific inputs, the study estimates the environmental impact of the different production systems including geospatially resolved growth modeling, emissions intensity, and transportation distances. The results include the major finding that baseline CEA systems always have higher GHG emissions (2.6–7.7 kg CO2e kg−1) than centralized production (0.3–1.0 kg CO2e kg−1), though water consumption is significantly less owing to hydroponic efficiency. In contrast, local seasonal soil production generally has a lower GHG impact than centralized production, though water consumption varies by crop yield and local precipitation during growing seasons. Scenario analyses indicate CEA facilities would need to electrify all systems and utilize low-carbon electricity sources to have equivalent or lower GHG impacts than California centralized production plus transportation. We conclude that these results can inform consumers and policy makers that local seasonal production and conventional supply chains are more sustainable than local CEA production in near-term food-energy-water sustainability nexus decision making. 

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3. Selective electrochemical synthesis of urea from nitrate and CO2 via relay catalysis on hybrid catalysts

   https://doi.org/10.1038/s41929-023-01020-4  

   Luo, Yuting; Xie, Ke; Ou, Pengfei; Lavallais, Chayse; Peng, Tao; Chen, Zhu; Zhang, Zhiyuan; Wang, Ning; Li, Xiao-Yan; Grigioni, Ivan; et al (October 2023, Nature Catalysis)

   The nitrogen cycle needed for scaled agriculture relies on energy- and carbon-intensive processes and generates nitrate-containing wastewater. Here we focus on an alternative approach—the electrified co-electrolysis of nitrate and CO2 to synthesize urea. When this is applied to industrial wastewater or agricultural runoff, the approach has the potential to enable low-carbon-intensity urea production while simultaneously providing wastewater denitrification. We report a strategy that increases selectivity to urea using a hybrid catalyst: two classes of site independently stabilize the key intermediates needed in urea formation, *CO2NO2 and *COOHNH2, via a relay catalysis mechanism. A Faradaic efficiency of 75% at wastewater-level nitrate concentrations (1,000 ppm NO3− [N]) is achieved on Zn/Cu catalysts. The resultant catalysts show a urea production rate of 16 µmol h−1 cm−2. Life-cycle assessment indicates greenhouse gas emissions of 0.28 kg CO2e per kg urea for the electrochemical route, compared to 1.8 kg CO2e kg−1 for the present-day route. 

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4. Carbon Footprint Assessment on the Viability of Utilizing Brewer’s Spent Grain to Produce Biochar

   https://doi.org/10.3390/app15105525  

   Newman, Emily; Nitin, Nitin; Spang, Edward; Fox, Glen (May 2025, Applied Sciences)

   The waste generated by the brewing industry, particularly brewer’s spent grain (BSG) and wastewater, presents challenges for sustainable management practices. While BSG is traditionally utilized as cattle feed, this option is not universally accessible. This study considered the environmental impact of a novel, laboratory-based process for converting BSG into biochar that also utilizes brewing wastewater, as compared to disposing of BSG and cleaning chemical wastewater. The study employed a carbon footprint assessment approach to quantify the greenhouse gas (GHG) emissions associated with each disposal method, using one unprocessed kg of BSG as the functional unit. The results indicated that landfilling BSG generated approximately 3 kg CO2 equivalent (CO2e) per kg of unprocessed BSG, whereas biochar production reduced emissions to 1.18 kg CO2e per kg of BSG. The study concluded that diverting BSG from landfills to biochar production presents a viable strategy for minimizing environmental impacts associated with BSG disposal. However, several factors must be considered in the development of a biochar production facility, including biochar transportation. These elements may contribute more GHG emissions than landfilling if not properly designed. 

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5. Predicting the spatial variation in cost-efficiency for agricultural greenhouse gas mitigation programs in the U.S.

   https://doi.org/10.1186/s13021-024-00252-6  

   Cameron-Harp, Micah V; Hendricks, Nathan P; Potter, Nicholas A (December 2024, Carbon Balance and Management)

   Abstract BackgroundTwo major factors that determine the efficiency of programs designed to mitigate greenhouse gases by encouraging voluntary changes in U.S. agricultural land management are the effect of land use changes on producers’ profitability and the net sequestration those changes create. In this work, we investigate how the interaction of these factors produces spatial heterogeneity in the cost-efficiency of voluntary programs incentivizing tillage reduction and cover-cropping practices. We map county-level predicted rates of adoption for each practice with the greenhouse gas mitigation or carbon sequestration benefits expected from their use. Then, we use these bivariate maps to describe how the cost efficiency of agricultural mitigation efforts is likely to vary spatially in the United States. ResultsOur results suggest the combination of high adoption rates and large reductions in net emissions make reduced tillage programs most cost efficient in the Chesapeake Bay watershed or the Upper Mississippi and Lower Missouri sub-basins of the Mississippi River. For programs aiming to reduce net emissions by incentivizing cover-cropping, we expect cost-efficiency to be greatest in the areas near the main stem of the Mississippi River within its Middle and Lower sections. ConclusionsMany voluntary agricultural conservation programs offer the same incentives across the United States. Yet spatial variation in profitability and efficacy of conservation practices suggest that these uniform approaches are not cost-effective. Spatial targeting of voluntary agricultural conservation programs has the potential to increase the cost-efficiency of these programs due to regional heterogeneity in the profitability and greenhouse gas mitigation benefits of agricultural land management practices across the continental United States. We illustrate how predicted rates of adoption and greenhouse gas sequestration might be used to target regions where efforts to incentivize cover-cropping and reductions in tillage are most likely to be cost -effective. 

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