Models for Decarbonization in the Chemical Industry.

Various technologies and strategies have been proposed to decarbonize the chemical industry. Assessing the decarbonization, environmental, and economic implications of these technologies and strategies is critical to identifying pathways to a more sustainable industrial future. This study reviews recent advancements and integration of systems analysis models, including process analysis, material flow analysis, life cycle assessment, techno-economic analysis, and machine learning. These models are categorized based on analytical methods and application scales (i.e., micro-, meso-, and macroscale) for promising decarbonization technologies (e.g., carbon capture, storage, and utilization, biomass feedstock, and electrification) and circular economy strategies. Incorporating forward-looking, data-driven approaches into existing models allows for optimizing complex industrial systems and assessing future impacts. Although advances in industrial ecology-, economic-, and planetary boundary-based modeling support a more holistic systems-level assessment, more effects are needed to consider impacts on ecosystems. Effective applications of these advanced, integrated models require cross-disciplinary collaborations across chemical engineering, industrial ecology, and economics. Expected final online publication date for the Annual Review of Chemical and Biomolecular Engineering , Volume 15 is June 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Multidimensional well-being of US households at a fine spatial scale using fused household surveys.

Social science often relies on surveys of households and individuals. Dozens of such surveys are regularly administered by the U.S. government. However, they field independent, unconnected samples with specialized questions, limiting research questions to those that can be answered by a single survey. The presented data comprise the fusion onto the American Community Survey (ACS) microdata of select donor variables from the Residential Energy Consumption Survey (RECS) of 2015, the National Household Travel Survey (NHTS) of 2017, the American Housing Survey (AHS) of 2019, and the Consumer Expenditure Survey - Interview (CEI) for the years 2015-2019. This results in an integrated microdataset of household attributes and well-being dimensions that can be analyzed to address research questions in ways that are not currently possible. The underlying statistical techniques, designed under the fusionACS project, are included in an open-source R package, fusionModel, that provides generic tools for the creation, analysis, and validation of fused microdata.

Growth and inequality trade-offs to eradicate absolute poverty.

The relationship between growth, inequality and poverty remains elusive, despite considerable scholarship. To what extent can governments rely on growth to eradicate poverty without reducing inequality? We derive a closed-form relationship between a minimum income threshold, changes in the Gini index of income inequality and average national income required to meet this target, independent of the form of income distribution. We develop a generalized form of redistribution and validate it against historical changes in inequality. We use this formulation to illustrate feasible growth-redistribution strategies to raise entire populations above the International Poverty Line ($1.90/day) by 2030, the Sustainable Development Goal 1, in two selective countries: India and Rwanda. We show that meeting this target would require unprecedented rates of both growth and inequality reduction in Rwanda. India could not eradicate acute poverty by 2030 with growth alone, but it could with only a modest reduction in inequality.

Climate resilience of dry season cereals in India.

India is the world's second largest producer of wheat, with more than 40% increase in production since 2000. Increasing temperatures raise concerns about wheat's sensitivity to heat. Traditionally-grown sorghum is an alternative rabi (winter season) cereal, but area under sorghum production has declined more than 20% since 2000. We examine sensitivity of wheat and sorghum yields to historical temperature and compare water requirements in districts where both cereals are cultivated. Wheat yields are sensitive to increases in maximum daily temperature in multiple stages of the growing season, while sorghum does not display the same sensitivity. Crop water requirements (mm) are 1.4 times greater for wheat than sorghum, mainly due to extension of its growing season into summer. However, water footprints (m3 per ton) are approximately 15% less for wheat due to its higher yields. Sensitivity to future climate projections, without changes in management, suggests 5% decline in wheat yields and 12% increase in water footprints by 2040, compared with 4% increase in water footprint for sorghum. On balance, sorghum provides a climate-resilient alternative to wheat for expansion in rabi cereals. However, yields need to increase to make sorghum competitive for farmer profits and efficient use of land to provide nutrients.

Review of Urban Building Types and Their Energy Use and Carbon Emissions in Life-Cycle Analyses from Low- and Middle-Income Countries.

Urbanization, slum redevelopment, and population growth will lead to unprecedented levels of residential building construction in "low- and middle-income" (LMI) countries in the coming decades. However, less than 50% of previous residential building life-cycle assessment (LCA) reviews included LMI countries. Moreover, all reviews that included LMI countries only considered formal (cement-concrete) buildings, while more than 800 million people in these countries lived in informal settlements. We analyze LCA literature and define three building types based on durability: formal, semiformal, and informal. These exhaustively represent residential buildings in LMI countries. For each type, we define dominant archetypes from across the world, based on construction materials. To address the data deficiency and lack of transparency in LCA studies, we develop a reproducibility metric for building LCAs. We find that the countries with the most reproducible studies are India, Sri Lanka, Turkey, Mexico, and Brazil. Only 7 out of 54 African countries have reproducible studies focused on either the embodied or use phase. Maintenance, refurbishment, and end-of-life phases are included in hardly any studies in the LMI LCA literature. Lastly, we highlight the necessity for studying current, traditional buildings to provide a benchmark for future studies focusing on energy and material efficiency strategies.

Response to comment on "Fairness considerations in global mitigation investments".

We welcome the analysis of Semieniuk et al. (1) as an additional sensitivity to illustrate a more extreme distribution of regional contributions to climate mitigation investments that supports our main conclusion regarding the North-South divide in mitigation investment capabilities. In response to Semieniuk et al. we would like to first point out that, in defining the required global mitigation investments for the 2020 to 2030 period, our study relies on the estimates in the sixth assessment report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) WGIII (2). These are based on diverse sources and underlying models that to varying degrees reflect regional differences in technology costs and consider both purchasing power parity (PPP) and market exchange rates (MERs). We use these IPCC estimates as a starting point and focus entirely on the question of how much of the needed regional investments, given different fairness considerations, should be financed from sources within a region.

Fairness considerations in global mitigation investments.

Current mitigation finance flows are inadequate and unfair.

Improved Copper Circularity as a Result of Increased Material Efficiency in the U.S. Housing Stock.

Material efficiency (ME) can support rapid climate change mitigation and circular economy. Here, we comprehensively assess the circularity of ME strategies for copper use in the U.S. housing services (including residential buildings and major household appliances) by integrating use-phase material and energy demand. Although the ME strategies of more intensive floor space use and extended lifetime of appliances and buildings reduce the primary copper demand, employing these strategies increases the commonly neglected use-phase share of total copper requirements during the century from 23-28 to 22-42%. Use-phase copper requirements for home improvements have remained larger than the demand gap (copper demand minus scrap availability) for much of the century, limiting copper circularity in the U.S. housing services. Further, use-phase energy consumption can negate the benefits of ME strategies. For instance, the lifetime extension of lower-efficiency refrigerators increases the copper use and net environmental impact by increased electricity use despite reductions from less production. This suggests a need for more attention to the use phase when assessing circularity, especially for products that are material and energy intensive during use. To avoid burden shifting, policymakers should consider the entire life cycle of products supporting services when pursuing circular economy goals.

Durable Goods Drive Two-Thirds of Global Households' Final Energy Footprints.

Sustainability endorses high quality, long-lasting goods. Durable goods, however, often require substantial amounts of energy during their production and use-phase and indirectly through complementary products and services. We quantify the global household's final energy footprints (EFs) of durable goods and the complementary goods needed to operate, service and maintain durables. We calculate the EFs of 200 goods across 44 individual countries and 5 world regions for the period of 1995-2011. In 2011, we find 68% of the total global household's EF (218 EJ) is durable-related broken down as follows: 10% is due to the production of durables per se, 7% is embodied in goods complementary to durables (consumables and services) and 51% is operational energy. At the product level, the highest durable-related EFs are: transport goods (148-648 MJ/cap), housing goods (40-811 MJ/cap), electric appliances (34-181 MJ/cap), and "gas stoves and furnaces" (40-100 MJ/cap). Between 1995 and 2011, the global household EF increased by 28% (48 EJ), of which 72% was added by durable-related energy. Globally, a 10% income growth corresponded to an increase in EF by 9% in durables, 11% in complementary consumables and 13% in complementary services-with even higher elasticities in the emerging economies. The average EF of the emerging economies (35 GJ/cap) is 2.5 times lower than in advanced economies (86 GJ/cap). Efficiency gains were detected in 47 out of 49 regions, but only 16 achieved net energy reductions. The large share of durable-related EF across regions (40-88%) confirms the dominance of durables in driving EFs, but the diversity of patterns suggests that policy and social factors influence durable-dependency. Demand-side solutions targeting ownership and inter-linkages between durables and complements are key to reduce global energy demand.

A Framework for Modelling Consumption-Based Energy Demand and Emission Pathways.

Energy demand in global climate scenarios is typically derived for sectors - such as buildings, transportation, and industry - rather than from underlying services that could drive energy use in all sectors. This limits the potential to model household consumption and lifestyles as mitigation options through their impact on economy-wide energy demand. We present a framework to estimate the economy-wide energy requirements and carbon emissions associated with future household consumption, by linking Industrial Ecology tools and Integrated Assessment Models (IAM). We apply the framework to assess final energy and emission pathways for meeting three essential and energy-intensive dimensions of basic well-being in India: food, housing and mobility. We show, for example, that nutrition-enhancing dietary changes can reduce emissions by a similar amount as meeting future basic mobility in Indian cities with public transportation. The relative impact of energy demand reduction measures compared to decarbonization differs across these services, with housing having the lowest and food the highest. This framework provides complementary insights to those obtained from IAM by considering a broader set of consumption and well-being-related interventions, and illustrating trade-offs between demand and supply-side options in climate stabilization scenarios.

Assessing the sustainability of post-Green Revolution cereals in India.

Sustainable food systems aim to provide sufficient and nutritious food, while maximizing climate resilience and minimizing resource demands as well as negative environmental impacts. Historical practices, notably the Green Revolution, prioritized the single objective to maximize production over other nutritional and environmental dimensions. We quantitatively assess outcomes of alternative production decisions across multiple objectives using India's rice-dominated monsoon cereal production as an example. We perform a series of optimizations to maximize nutrient production (i.e., protein and iron), minimize greenhouse gas (GHG) emissions and resource use (i.e., water and energy), or maximize resilience to climate extremes. We find that increasing the area under coarse cereals (i.e., millets, sorghum) improves nutritional supply (on average, +1% to +5% protein and +5% to +49% iron), increases climate resilience (1% to 13% fewer calories lost during an extreme dry year), and reduces GHGs (-2% to -13%) and demand for irrigation water (-3% to -21%) and energy (-2% to -12%) while maintaining calorie production and cropped area. The extent of these benefits partly depends on the feasibility of switching cropped area from rice to coarse cereals. Based on current production practices in 2 states, supporting these cobenefits could require greater manure and draft power but similar or less labor, fertilizer, and machinery. National- and state-level strategies considering multiple objectives in decisions about cereal production can move beyond many shortcomings of the Green Revolution while reinforcing the benefits. This ability to realistically incorporate multiple dimensions into intervention planning and implementation is the crux of sustainable food production systems worldwide.

Impact of Historical Changes in Coarse Cereals Consumption in India on Micronutrient Intake and Anemia Prevalence.

BACKGROUND: Production of rice and wheat increased dramatically in India over the past decades, with reduced proportion of coarse cereals in the food supply. OBJECTIVE: We assess impacts of changes in cereal consumption in India on intake of iron and other micronutrients and whether increased consumption of coarse cereals could help alleviate anemia prevalence. METHODS: With consumption data from over 800 000 households, we calculate intake of iron and other micronutrients from 84 food items from 1983 to 2011. We use mixed-effect models to relate state-level anemia prevalence in women and children to micronutrient consumption and household characteristics. RESULTS: Coarse cereals reduced from 23% to 6% of calories from cereals in rural households (10% to 3% in urban households) between 1983 and 2011, with wide variations across states. Loss of iron from coarse cereals was only partially compensated by increased iron from other cereals and food groups, with a 21% (rural) and 11% (urban) net loss of total iron intake. Models indicate negative association between iron from cereals and anemia prevalence in women. The benefit from increased iron from coarse cereals is partially offset by the adverse effects from antinutrients. For children, anemia was negatively associated with heme-iron consumption but not with iron from cereals. CONCLUSIONS: Loss of coarse cereals in the Indian diet has substantially reduced iron intake without compensation from other food groups, particularly in states where rice rather than wheat replaced coarse cereals. Increased consumption of coarse cereals could reduce anemia prevalence in Indian women along with other interventions.

Decent Living Standards: Material Prerequisites for Human Wellbeing.

We define a set of universal, irreducible and essential set of material conditions for achieving basic human wellbeing, along with indicators and quantitative thresholds, which can be operationalized for societies based on local customs and preferences. We draw support for this decent living standard (DLS) from different accounts of basic justice, including the capability approach and basic needs. The DLS goes beyond existing multidimensional poverty indicators by comprehensively addressing living conditions and the means of social participation. The DLS offers a normative basis to develop minimum wage and reference budgets, and to assess the environmental impacts, such as climate change, of eradicating poverty.

Outlook for modern cooking energy access in Central America.

The Central American nations of Guatemala, Honduras and Nicaragua are among the poorest in the Americas. While the fraction of population dependent on solid fuels has declined in these nations over the last 25 years, the number of people using them has risen. Here, we first assess current patterns of cooking energy use in these nations. We then apply a discrete model of household cooking choices and demand to simulate future pathways of clean cooking uptake and the outlook for achieving target 7.1 of the Sustainable Development Goals (SDG), which aims to ensure universal access to affordable, reliable and modern energy services by 2030. We find that by 2030, ensuing income growth is likely to enable 90% of urban populations in these nations to switch to using modern cooking energy services. However, without supporting policies, between 40% to 50% of rural Guatemalans and Hondurans, while over two-thirds of rural Nicaraguans, are likely to find clean fuels or stoves unaffordable in 2030. A targeted subsidy on modern fuels, like liquid petroleum gas (LPG), is the most effective policy mechanism we studied that could provide such support. A 50% subsidy policy on LPG targeted to the rural and urban poor population could, by 2030, make cooking with LPG affordable to an additional 7.3 million people in these countries. We estimate that such a policy would cost about $250 million per year and would have negligible greenhouse gas emissions impacts. Such a policy could also have significant health benefits, preventing about 8,890 premature deaths annually from reduced exposure to cooking-related household pollution in 2030.