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Concrete is a primary material in infrastructure projects and is a significant contributor to global climate emissions. However, there is a lack of readily available cement and ready-mix concrete inventory data for evaluating the environmental performance of the industries. This study describes the development of cradle-to-gate inventories for U.S. ready-mix concrete and gate-to-gate inventories for portland cement production technologies. These life-cycle inventories provide baselines for the environmental releases associated with concrete that is used for major infrastructure projects. The inventories are incorporated into the publicly available Greenhouse gases, Regulated Emissions, and Energy use in Technologies (GREET) model. The life-cycle inventories are created using facility-level environmental release data from U.S. datasets normalized to activity levels which are based on production capacity and utilization data provided by Portland Cement Association (PCA) and the U.S. Geological Survey Minerals Yearbook. Unit processes for limestone quarrying, sand and gravel quarrying, and wet-mix concrete batch plants are developed on the basis of national total point-source environmental releases and production statistics, coupled with corresponding flows associated with off-road fuel consumption and other non-point-source emissions. Midpoint impact assessment results are normalized to provide insight into their relative significance in the context of U.S. total impacts. These findings show that advanced calcination technologies help reduce greenhouse gas emissions, but the full set of releases also highlights the significance of metal releases and particulate-matter emissions generated by non-combustion-related activity. [Display omitted] • Independent, detailed, and transparent life-cycle inventories are developed for U.S. average concrete. • Estimated CO 2 emissions are higher than those reported to the U.S. EPA's Greenhouse Gas Reporting Program. • The inventories update previous results and can support LCA of concrete products and benchmarking for process improvements. • Continued transition toward advanced kiln technologies has reduced combustion related impacts of cement production. • Inventories are made publicly-available in GREET and through the LCA Commons. [ABSTRACT FROM AUTHOR]

Steam cracking is an energy-intensive process used to convert natural gas liquids, naphtha, and gas oil into ethylene and propylene, as well as other chemicals. It is the primary source of ethylene, one of the most important building blocks for the chemical and plastics industry. Steam cracking also co-produces hydrogen which is typically combusted with the tail gas onsite for process heat, but alternatively could be separated and sold as a by-product. This study provides a detailed life cycle inventory for the United States steam cracking industry based on publicly-available, facility-specific information; provides industry average results; and assesses variability across facilities, feedstocks, and technologies. This life cycle inventory provides the baseline needed for comparison of plastic alternatives designed to improve recyclability and reduce the environmental effects of plastics. Likewise, the environmental profile of by-product hydrogen from steam crackers is important for assessing its potential benefit in decarbonizing transportation and/or industry, considering the energy use for separation and compression, as well as the make-up fuel requirements. We present the cradle-to-gate results for all steam cracking products and find the life cycle GHG emissions for average U.S. ethylene and propylene are 1.13 kg CO 2 e per kilogram using a mass allocation, 1.05 kg CO 2 e for facilities that combust their hydrogen, and 1.30 kg CO 2 e for facilities that separate by-product hydrogen for use. With natural gas production and ethylene demand continuing at high levels in the United States, decarbonizing steam cracking would be an important step toward mitigating emissions from the chemical industry. Similarly, the benefit of using by-product hydrogen to decarbonize other processes is dependent on the relative benefit of the hydrogen application compared with the alternative energy source used for steam cracking process heat. Results are also reported for criteria air pollutant emissions, energy use, water use, and a series of life cycle impact potentials. [ABSTRACT FROM AUTHOR]