Now in its 26th year, ISSST is one of the longest-running research conferences related to sustainability and the intersection of technology, policy, and behavior. We are a vibrant community of engineers, scientists, professionals, and educators, sharing cutting-edge research and forming interdisciplinary teams for future collaboration.
For previous talks, see:
E&S-1: Energy in the developing world
Time: Tuesday, 25/Jun/2019: 2:00pm - 3:30pm
Climate change impacts on Brazil’s electricity load
Sydney Prince Forrester1, Jeremiah X. Johnson2
1University of Michigan, United States of America; 2North Carolina State University, United States of America
Brazil’s growing middle class, electrification rates, and urbanization has led to a significant uptick in residential appliance adoption. Air conditioner usage, increasingly relevant to both average and system peak demand, will have strong environmental and economic impacts to the country as a whole. With nearly every Brazilian household connected to the centralized electricity grid, increasing temperatures, higher incomes, and vulnerability from reduced energy supply; residential cooling demand will have a large impact on Brazilian electricity grid reliability and whether or not the country will be able to meet both environmental and efficiency goals. Though Brazil’s air conditioner impacts have been referenced anecdotally, most detailed studies of cooling demand are focused on countries such as the U.S. This study increases temporal resolution to hourly grid impacts as well as improving spatial granularity to municipality-level climate and air conditioner adoption predictions. The paper is split into two parts with separate models. The first outlines a econometric model that utilizes census data (municipality urbanization, household density, household income) and downscaled global climate model results (humidity, temperature) to project each municipality’s household air conditioner adoption rate showing an increase of 44.6% between 2000 to 2010 in households with air conditioners, specifically in municipalities with hot climates and high average incomes. The second part aggregates adoption numbers up to five regional levels to match each region’s hourly grid data with three-hourly climate data to closely study how the air conditioner peak impacts grid requirements at various temporal levels. Though this paper is specific to Brazil, it highlights a potential future for other fast-developing countries in warm regions pertaining to energy demand, grid reliability, and environmental consequences.
FEW-1: Dynamic Systems Modeling in the Food-Energy-Water Nexus
Time: Tuesday, 25/Jun/2019: 2:00pm - 3:30pm
Potential Emissions Changes from Refrigerated Supply Chain Introduction and Mitigation Opportunities
Brent R. Heard, Shelie A. Miller
University of Michigan, United States of America
Refrigeration is a transformative technology in the food-energy-water nexus, changing the underlying logistics of food storage and transportation. This study assesses changes in the pre-retail food supply chain following the introduction of an integrated refrigerated supply chain, or “cold chain.” Drivers of emissions changes are identified, and the relative effectiveness of interventions for mitigating emissions increases is assessed.
This study models the introduction of an integrated cold chain into sub-Saharan Africa and estimates changes in pre-retail greenhouse gas (GHG) emissions if the cold chain develops similarly to North America or Europe. GHG emissions (in CO2e) required to supply food to retail are estimated for seven categories: cereals, roots and tubers, fruit, vegetables, meat, fish and seafood, and milk. The food supply chain (FSC) is modeled with four key parameters: loss rates (% of food loss at FSC stages), demand (kg type consumed per capita), agricultural emissions factors (kg CO2e/kg food), and cold chain emissions factor (kg CO2e/kg food).
Refrigeration presents an important and understudied trade-off: the ability to reduce food losses and their associated environmental impacts, but increasing energy use and creating GHG emissions. It is estimated that postharvest emissions added from cold chain operation are larger than food loss emissions avoided, by 10% in the North American scenario and 2% in the European scenario. However, the cold chain also enables changes in agricultural production and diets. Connected agricultural production changes decrease emissions, while dietary shifts facilitated by refrigeration may increase emissions. These system-wide changes brought about by the cold chain may increase the embodied emissions of food supplied to retail by 10% or decrease them by 15%, depending whether shifts towards a North American or European diet is modeled.
Motivated by these findings, we then examine potential interventions to mitigate postharvest emissions increases from cold chain introduction and operation. Preliminary results for fresh and frozen broccoli are reported here, with results for additional foods including chicken, apples, fish, and milk to be presented. Emissions discussed are for kg CO2e added after agricultural production per 1 kg food reaching retail in an integrated cold chain. For fresh broccoli, the most-effective mitigations modeled include decreasing truck transportation distance by 25% and replacing its standard R404a refrigeration unit with a more-efficient unit, both decreasing pre-retail emissions by 24%. Frozen broccoli has higher pre-retail emissions than fresh, due to more-intensive processing. A 25% decrease in electricity grid emissions-intensity for food processing provides a 5% emissions decrease for this product. For frozen broccoli, a 25% decrease in trucking distance yields a 19% decrease in pre-retail emissions. Using an R452a refrigeration unit provides a notable emissions decrease for frozen broccoli (12%) through providing increased energy efficiency and using a refrigerant with lower global warming potential, as does using the more-efficient R404a refrigeration unit (-10%). The efficiency improvement from the R452a unit only occurs at lower temperatures, with this unit only providing a 2% decrease for fresh broccoli. Additional technical interventions, changes in supply chain logistics, and the effects of potential diet shifts will be assessed.
Time: Tuesday, 25/Jun/2019: 5:30pm - 7:30pm
- A decision-tool for managing the end-of-life of commercial lighting --- Lixi Liu
- Conceptualizing Resilience in LAC and Across the Food-Energy-Water Nexus: Where are the best opportunities for adaptation? --- Calli VanderWilde
- Determining the social, environmental, technical, and physical barriers to engaging in aquaponics and sustainable agricultural systems in São Carlos, Brazil --- Alexandria Brewer
- Life Cycle Comparison of Manual & Machine Dishwashing in American Homes --- Gabriela Yvonne Porras
- Remarkable Energy Use Rebound Effect of Self-Driving Vehicles --- Morteza Taiebat, Samuel Stolper, Ming Xu
E&S-3: Power plants and electricity production
Time: Wednesday, 26/Jun/2019: 8:00am - 9:30am
The Impact of Forecast Net Load on Real Time Power System Costs
Nicole Alyssa Ryan1,2, Jeremiah X. Johnson3
1School for Environment & Sustainability, University of Michigan; 2Department of Mechanical Engineering, University of Michigan; 3Department of Civil, Construction, and Environmental Engineering, North Carolina State University
It is anticipated that for the electricity grid to remain reliable with growing generation from variable renewable resources (i.e., wind and solar), it will need to become increasingly flexible. A major driver of system inflexibility is the need for greater system ramping requirements. System ramp rates increase when there is a misalignment between peak demand and peak renewable generation. If traditional generators cannot adjust rapidly enough to changes in net load (i.e., demand minus variable renewable generation), renewable generators may be curtailed, reducing the overall carbon free electricity supplied to the grid. To better understand the management of increasing system ramp rates, one needs to understand the role of forecasting errors during times of high variability and ramping. By focusing on the net load shape, we attempt to normalize for other system characteristics and isolate relationships between forecast net load shapes and real time system impacts. Although it is already assumed that hours with high ramp rates require additional system flexibility and that higher percentages of variable renewable generation require increased reserves, there has been limited statistical analysis on these assumptions. This work examines the relationships between forecast net load characteristics (e.g., ramp rate, percent of capacity) across time and realized system characteristics on an hourly basis (e.g., generation costs, generator commitment changes) through statistical modeling, in order to quantify the significance of these relationships such that they could inform a future predictive method. This modeling informs reserve requirements by identifying times that are likely to have large inefficiencies in day-ahead generator scheduling, in addition to providing foresight into times of potential increased system cost. The analysis is completed on data from a model of the Western Interconnection Cooperating Council although the results are intended to be system agnostic.
FEW-3: Diet and Food Waste
Time: Wednesday, 26/Jun/2019: 8:00am - 9:30am
Food Choices and the Food-Energy-Water Nexus: Evaluating Energy Demand, Water Scarcity and Carbon Footprints of Self-Selected Diets in the U.S.
Martin C. Heller1, Amelia Willits-Smith2, Gregory Keoleian1, Diego Rose2
1Center for Sustainable Systems, University of Michigan, United States of America; 2Department of Global Community Health, Tulane University, United States of America
Food choice has been implicated as an important driver of the environmental impacts of food systems. Assessment of diet-level environmental impact across multiple impact categories can inform not only consumption-oriented abatement strategies, such as dietary modifications, but also identify aspects of food production systems that warrant further attention.
In previous work, we developed dataFIELD (database of Food Impacts on the Environment for Linking to Diets) based on an exhaustive review of the food life cycle assessment literature. DataFIELD contains greenhouse gas emissions (GHGE) and cumulative energy demand (CED) associated with production of 332 food commodities, and was linked to dietary recall data from the 2005-2010 National Health and Nutrition Examination Survey (NHANES), a representative survey of U.S. dietary intake. In this work, we add a spatially explicit assessment of the blue water use (surface and ground water used for irrigation) associated with food production, including a characterization of water scarcity, and link this to self-selected diets from NHANES.
Blue water consumption per ton of crop at the watershed level across the U.S. was obtained from a dataset compiled by Pfister and Bayer (DOI: 10.17632/brn4xm47jk.2). To characterize water scarcity, we used the Available Water Remaining (AWARE) method, with characterization factors also at the watershed level. Water consumption and water scarcity (consumption x characterization) per crop were aggregated to the national level using production-based weights, also available in the Pfister and Bayer dataset. Since not all food consumed in the U.S. is domestically sourced, water use and water scarcity footprints (WSF) per crop were adjusted for imports using FAO detailed trade matrix data and country-of-origin national average water consumption and AWARE factors. Water use for animal based foods were based on simplified feed rations from Peters et al. (DOI: 10.12952/journal.elementa.000116). Only water use associated with fee requirements of farmed fish and seafood were included.
At the population average, meats, dairy, beverages and fish & seafood were the top contributing food groups in the U.S. diet for both GHGE and CED. For WSF, meat was also the highest contributor, followed by fruits, beverages, dairy and vegetables. On average, diets higher in GHGE were also higher in CED and WSF. Such correlation of impacts across individual diets was the strongest between GHGE and CED (r=0.68, p < 0.01) and next strongest between GHGE and WSF (r=0.45, p < 0.01). Rankings based on GHGE demonstrated that the top 20% of U.S. diets are responsible for 46% of emissions. Impacts for the top quintile of diets when ranked on energy demand or water scarcity footprint were 43% or 42%, respectively. 7% of diets evaluated were in the 5th quintile (highest impact) of all three metrics, whereas 9% were consistently in the 1st quintile.
Consideration of the food-energy-water nexus from a diet perspective offers valuable insight into ways that consumption behaviors influence environmental impacts of production systems. Understanding such relationships between food choices and the multiple dimensions of environmental impact allows for targeting policy work to address dietary hot-spots.
E&S-5: Energy storage
Time: Wednesday, 26/Jun/2019: 2:00pm - 3:30pm
Green principles for responsible battery management and strategies to maximize battery service lifetime
Maryam Arbabzadeh, Maxwell Woody, Geoffrey Lewis, Gregory Keoleian
University of Michigan, United States of America
Vehicle electrification is expanding worldwide and has the potential to reduce greenhouse gas emissions (GHGs) from the transportation sector. Batteries are a key component of energy storage systems for electric vehicles (EVs), and their integration into EVs can lead to a wide range of possible environmental outcomes. These outcomes depend on factors such as powertrain type, electricity source, charging patterns, and end-of-life management. Given the complexities of battery systems, a framework is needed to systematically evaluate environmental impacts across battery system life cycle stages, from material extraction and production to use in the EV, through the battery’s end-of-life. We have developed a set of ten principles to provide practical guidance, metrics, and methods to accelerate environmental improvement of mobile battery applications and facilitate constructive dialogue among designers, suppliers, original equipment manufacturers, and end-of-life managers. The goal of these principles, which should be implemented as a set, is to enhance stewardship and sustainable life cycle management by guiding design, material choice, deployment (including operation and maintenance), and infrastructure planning of battery systems in mobile applications. These principles are applicable to emerging battery technologies (e.g., lithium-ion), and can also enhance the stewardship of existing (e.g., lead-acid) batteries. Case study examples are used to demonstrate the implementation of the principles and highlight the trade-offs between them.
One of the most important principles is Principle #6: Design and operate battery systems to maximize service life and limit degradation. We expand Principle #6 to provide guidance and strategies that promote battery health and lifetime extension to promote sustainable and responsible battery management. The goal is to provide practical guidance, metrics, and methods for battery designers, suppliers, EV and electronics manufacturers, users, and material recovery and recycling organizations to accelerate environmental improvements of battery systems in electronics and vehicles.
ET-3: Approaches for assessing emerging tech
Time: Wednesday, 26/Jun/2019: 4:00pm - 5:30pm
A harmonized life cycle approach to improve the environmental performance and life cycle assessment guidelines for carbon capture and utilization (CCU) based methanol production
Dwarak Ravikumar, Gregory Keoleian, Shelie Miller
University of Michigan
Methanol is a vital feedstock for the chemical and the energy industry and over 90% of the global annual production of 90 million tons is synthesized from natural gas. To decrease the reliance on natural gas as a raw material and meet climate goals, carbon capture and utilization (CCU) is increasingly favored as an environmentally sustainable pathway to synthesize methanol. In the CCU pathway, methanol is synthesized through the hydrogenation of carbon dioxide (CO2) captured from point sources (e.g. power plants). The use of renewable energy sources is proposed to reduce the environmental burdens of electrolyzing water and generate hydrogen (H2), which is necessary for the hydrogenation of CO2.
Despite the suggested improvements and claims of sustainability, there is a lack of a critical and systematic assessment of the environmental performance and trade-offs between methanol production through the conventional and CCU based pathways. Life cycle assessment (LCA) studies and a recent effort to develop LCA guidelines for CCU systems fail to harmonize data across the 4 key processes - the capture of CO2, the production of hydrogen through electrolysis, compression and transport of CO2 and H2 and the synthesis of methanol. As a result, the quantified environmental impacts may not be accurate or representative of real world conditions. For example, this research a preliminary literature review demonstrates that the energy required for compressing CO2 may be included in both the carbon capture and methanol synthesis processes, thereby overestimating the energy burdens of methanol production through CCU. Furthermore, as the production of methanol from CCU is an emerging technology, there is a significant scarcity and uncertainty in the material and energy inventory data required to conduct an LCA. The current practice of using of point values for inventory data masks the overall uncertainty in the quantified environmental impact. As a result, stakeholders cannot explore the impact of data uncertainty on the trade-offs between the alternate methanol production pathways, identify environmental hotspots and direct R&D efforts to improve the environmental performance of CCU based methanol.
To address the aforementioned limitations, this research is the first to comprehensively harmonize life cycle inventory data and model the environmental impacts of the four key processes in the CCU pathway for methanol production. We have reviewed a total of 180 studies and shortlisted 50 key parameters that impact the environmental performance and trade-offs between conventional and CCU pathways for methanol production. Through a combination of principles in thermodynamics and exploring the values reported in industry and scientific literature, this work determines the range of uncertainty in the 50 key parameters, which represents the basic uncertainty in the inventory data. In addition, we apply the pedigree matrix approach to further account for uncertainty in the geographical, technological and temporal correlation, and the completeness and quality of the inventory data. Based on a Monte-Carlo approach, we will stochastically explore the trade-offs between the conventional and CCU-based methanol pathways across 18 environmental impacts in the ReCiPe impact assessment method. Through a moment independent sensitivity analysis of uncertainty in the 50 parameters, we determine R&D priorities to address the hotspots in CCU based methanol production. Subsequently, based on the harmonized data, the improved model to quantify the environmental impact, and uncertainty assessment for the early stages of technology development, this research will propose improvements for emerging guidelines for LCA of CCU systems.
Time: Thursday, 27/Jun/2019: 8:30am - 10:00am
Green Principles for Vehicle Lightweighting: Guidance for Reducing Transportation Impact, With Examples
Geoffrey M. Lewis1, Cailin A. Buchanan1, Krutarth D. Jhaveri1, John L. Sullivan1, Jarod C. Kelly2, Sujit Das3, Alan I. Taub1, Gregory A. Keoleian1
1University of Michigan; 2Argonne National Lab; 3Oak Ridge National Lab
A large portion of life cycle transportation impacts occur during vehicle operation, and key improvement strategies include increasing powertrain efficiency, vehicle electrification and lightweighting vehicles by reducing their mass. The potential energy benefits of vehicle lightweighting is are large, given that 29.5 EJ was used in all modes of U.S. transportation in 2016 and roughly half of the energy spent in wheeled transportation and the majority of energy spent in aircraft is used to move vehicle mass. We collect and review previous work on lightweighting, identify key parameters affecting vehicle environmental performance (e.g., vehicle mode, fuel type, material type and recyclability), and propose a set of ten principles, with examples, to guide environmental improvement of vehicle systems through lightweighting. These principles, based on a life cycle perspective and taken as a set, allow a wide range of stakeholders (designers, policy-makers, and vehicle manufacturers and their material and component suppliers) to evaluate the tradeoffs inherent in these complex systems. This set of principles can be used to evaluate tradeoffs between impact categories, and help to help avoid shifting of burdens to other life cycle phases in the process of improving use phase environmental performance.
ET-5: Building a community for LCA of emerging technologies
Time: Thursday, 27/Jun/2019: 10:30am - 12:00pm
Building a community for LCA of emerging technologies
Mik Carbajales-Dale1, Joule Bergerson2, Jeremiah Johnson3, Thomas Seager4, William Morrow III5, Joe Cresko6, Marcelle McManus7, Sean McCoy2, Eric Williams8, Daniel Posen9, Heather Maclean9, Garvin Heath10, Tim Skone11, Adam Brandt12, Scott Matthews13, Shelie Miller14, Stefano Cucurachi15, Valentina Prado16, Derrick Carlson11, Michael Wang17, Arman Shehabi5, Alberta Carpenter10
1Clemson University, USA; 2University of Calgary, Canada; 3North Carolina State University, USA; 4Arizona State University, USA; 5Lawrence Berkeley National Lab, USA; 6Dept. of Energy, USA; 7University of Bath, UK; 8Rochester Institute of Technology, USA; 9University of Toronto, Canada; 10National Renewable Energy Lab, USA; 11National Energy Techology Lab, USA; 12Stanford University, USA; 13Carnegie Mellon University, USA; 14University of Michigan, USA; 15Leiden University, Netherlands; 16Earthshift, USA; 17Argonne National Lab, USA
To tackle societal grand challenges, technology developers and engineers must simultaneously maximize economic benefits while minimizing environmental risks and impacts associated with processes, products or services. The Department of Energy is increasingly relying on both techno-economic analysis (TEA) and life cycle assessment (LCA) as additional information to be submitted within proposed projects (e.g. the recent MEGABIOS and ABY2 FOAs), even for research at very early-stage development (e.g. technology readiness level, TRL, 3 or 4). Being able to use LCA within the laboratory stage (TRL2-5) could provide guidance for technology developers to greatly minimize environmental impacts. Existing LCA guidelines are well suited to evaluate products or processes that are already commercially established. However, tools appropriate for prospective assessment of early-stage technologies are not well defined and have practical and methodological difficulties.
As a group we have already held an internationally attended two-day workshop in Banff, Canada, hosted several special sessions in multiple years at ACLCA, and developed a special track at ISSST on this topic of LCA for emerging technologies. We feel that the next step is to attract more people within the community to build an international network of practitioners working in the field and attract funding in order to engage in further workshops and dialog. The core group is putting together an NSF Research Collaboration Network proposal for submission this year and is contemplating a proposal to NSF Accelerating Research through International Network-to-Network Collaborations (AccelNet) for 2020.
Engage in a dialogue around development of these proposals. Try to understand, (1) whether there is outside interest in joining our group, (2) elict feedback on our NSF RCN proposal, (3) identify what elements or topics researchers would like to engage in, and (4) plan future activities that volunteers are willing to undertake.
Attendees will be invited to join and strengthen our network of researchers interested in LCA of emerging technologies. Specifically in planning the next steps in building out this network by submitting proposals to NSF RCN and AccelNet programs.