Equity and modeling in sustainability science: Examples and opportunities throughout the process.

Equity is core to sustainability, but current interventions to enhance sustainability often fall short in adequately addressing this linkage. Models are important tools for informing action, and their development and use present opportunities to center equity in process and outcomes. This Perspective highlights progress in integrating equity into systems modeling in sustainability science, as well as key challenges, tensions, and future directions.

The state of macro-energy systems research: Common critiques, current progress, and research priorities.

The growing field of macro-energy systems (MES) brings together the interdisciplinary community of researchers studying the equitable and low-carbon future of humanity's energy systems. As MES matures as a community of scholars, a coherent consensus about the key challenges and future directions of the field can be lacking. This paper is a response to this need.

Combined Heat and Power May Conflict with Decarbonization Goals-Air Emissions of Natural Gas Combined Cycle Power versus Combined Heat and Power Systems for Commercial Buildings.

This study compares the environmental impacts of a centralized natural gas combined cycle (NGCC) and a distributed natural gas-fired combined heat and power (CHP) energy system in the United States. We develop an energy-balance model in which each energy system supplies the electric, heating, and cooling demands of 16 commercial building types in 16 climate zones of the United States. We assume a best-case scenario where all the CHP's heat and power are allocated toward building demands to ensure robust results.

Water Use in the United States Energy System: A National Assessment and Unit Process Inventory of Water Consumption and Withdrawals.

The United States (US) energy system is a large water user, but the nature of that use is poorly understood. To support resource comanagement and fill this noted gap in the literature, this work presents detailed estimates for US-based water consumption and withdrawals for the US energy system as of 2014, including both intensity values and the first known estimate of total water consumption and withdrawal by the US energy system. We address 126 unit processes, many of which are new additions to the literature, differentiated among 17 fuel cycles, five life cycle stages, three water source categories, and four levels of water quality.

Response to "Discourse over a contested technology on Twitter: A case study of hydraulic fracturing"-Word choice as political speech.

Hopke and Simis ( Public Understanding of Science, online 4 October 2015) find that #fracking, the most popular of five shale-related hashtags analyzed from a 2013 period, is associated with pro-shale attitudes only 13% of the time and note that the dominant voice of the activist community, coupled with a lack of engagement from industry, is unexpected. This comment offers additional perspective on the sentiment- and actor-skewed result by noting that the term "fracking" is highly political, specifically because the spelling "frack" versus "frac" is associated with activism. Furthermore, in public speech, the industry tends to deemphasize the hydraulic fracturing process in favor of the product, consistent with the findings that #natgas is a relatively pro-industry hashtag.