Purpose: Lettuce and other vegetables are predominately produced with open-field methods in agriculturally optimal locations and transported long distances to markets; alternative methods can produce vegetables in the regions where they will be consumed. This study aims to comprehensively assess the environmental impacts of lettuce cultivation methods: ranging from uncontrolled open-field farming to lightly controlled high-hoop greenhouse cultivation, to fully controlled hydroponics with artificial lighting and climate control systems. The overarching purpose is to illuminate the impact of cultivation methods on vegetable production, including the effects of transport, and to support efforts to reduce impacts across production methods. Methods: We constructed a life cycle inventory for cultivating lettuce, including energy, water, nutrients, pesticides, carbon dioxide, nitrous oxide, nitrogen oxides, ammonia, and particulates. The system boundary is cradle-to-gate, including the production and utilization of electricity, fertilizers, irrigation water, and the utilization of pesticides. We included the energy use of production and post-harvest transportation at a continental and regional scale to market. Excluded from the system boundary are the retail sale of the lettuce, residential or commercial preservation, preparation, consumption, and end-of-life. We assessed the impacts using ReCiPe 2016 impact assessment methods (hierarchist perspective (H)) which includes both midpoint and endpoint evaluation. We investigated regional and long-distance lettuce production with the US state of Georgia representing the regional state and California and Arizona serving as examples of long-distance states for lettuce cultivation to the US East Coast (e.g., Georgia) region. Results and discussion: Lettuce produced through controlled environment hydroponic farming has relatively high energy consumption, primarily due to the use of artificial lighting. In contrast, open-field farming and low-energy greenhouse farming have higher impacts across other environmental categories, due to higher use of fertilizer, pesticides, land, and irrigation water. Using detailed data on fertilizer, pesticide, and water consumption, we show that open-field production has higher impacts in every midpoint category other than climate impact. Endpoint analysis suggests that the climate impacts of controlled environment hydroponic agriculture have greater impacts on human health and ecosystems than all of the other impacts of both open-field and greenhouse production. Conclusion: To match conventional agriculture, energy consumption and greenhouse gas emissions of controlled environment hydroponic agriculture must be substantially reduced. This could be achieved with use of low carbon electricity combined with use of natural light. Graphical

The U.S. Department of Energy's Office of Scientific and Technical Information

Energy scarcity and subsequent global fuel market shocks have become a significant concern for the United States. Process heating in industry accounts for over half of all industrial energy usage and is almost entirely (>95%) supplied by natural gas, coal, and byproduct fuels. Many existing alternatives, technologies, and strategies can reduce dependency on this fossil fuel usage to promote energy security and competitiveness. It is expected that adoption of alternatives is limited by capital investment. A working group exploratory exercise was performed to evaluate the current barriers to alternative process heat technology adoption for the manufacturing sector. Although the working group’s findings emphasize electro-technologies due to their emergence as the central topic of discussion, we have contextualized these results by providing a fair and consistent comparison against several alternative thermal technology options. The most reported issue was the lack of financial incentives, with the second key issue for engineers and manufacturing sector decision-makers being the lack of awareness or understanding of available alternatives. This paper aims to provide an analysis of the levelized cost of heating for a variety of alternatives as part of addressing concerns from the emergent patterns reported in the exploratory exercise, as well as provide guidance on barriers to further adoption. Levelized cost of heating analysis considered the capital investment, operations and maintenance, lifespan, and fuel stream costs of various systems delivering heat to the product or process as a generalized cost per megawatt-hour delivered. The analysis indicates that biomass burners, industrial open-loop heat pumps, and central-receiver heliostat fields are at cost parity under average 2024 United States natural gas and electricity prices against well-optimized natural gas burners, though further cost reductions are necessary for consistent adoption.