Life-cycle impact assessment methods for physical energy scarcity: considerations and suggestions

Purpose Most approaches for energy use assessment in life cycle assessment do not consider the scarcity of energy resources. A few approaches consider the scarcity of fossil energy resources only. No approach considers the scarcity of both renewable and non-renewable energy resources. In this paper, considerations for including physical energy scarcity of both renewable and non-renewable energy resources in life cycle impact assessment (LCIA) are discussed. Methods We begin by discussing a number of considerations for LCIA methods for energy scarcity, such as which impacts of scarcity to consider, which energy resource types to include, which spatial resolutions to choose, and how to match with inventory data. We then suggest three LCIA methods for physical energy scarcity. As proof of concept, the use of the third LCIA method is demonstrated in a well-to-wheel assessment of eight vehicle propulsion fuels. Results and discussion We suggest that global potential physical scarcity can be operationalized using characterization factors based on the reciprocal physical availability for a set of nine commonly inventoried energy resource types. The three suggested LCIA methods for physical energy scarcity consider the following respective energy resource types: (i) only stock-type energy resources (natural gas, coal, crude oil and uranium), (ii) only flow-type energy resources (solar, wind, hydro, geothermal and the flow generated from biomass funds), and (iii) both stock- and flow-type resources by introducing a time horizon over which the stock-type resources are distributed. Characterization factors for these three methods are provided. Conclusions LCIA methods for physical energy scarcity that provide meaningful information and complement other methods are feasible and practically applicable. The characterization factors of the three suggested LCIA methods depend heavily on the aggregation level of energy resource types. Future studies may investigate how physical energy scarcity changes over time and geographical locations.

167 Impacts on Biodiversity, Environment and Society of Beef Production in the Mexican Tropics: A Life Cycle Assessment Approach

Beef production exerts strong environmental pressures and can also generate negative social effects. In this study, the impacts on biodiversity, environment and society of beef production in the Mexican tropics, were evaluated through the Life Cycle Assessment (LCA) approach. The functional unit of the study was 1 kg live weight of calf and focused on three productive systems: native silvopastoral (NSP), intensive silvopastoral (ISP) and monoculture (MC). This research was divided into four analysis steps. (1) social impacts; (2) damage to biodiversity; (3) methane emissions and 4) environmental LCA impacts. Using the Social-LCA, we evaluated 18 social indicators, grouped into five categories: human rights, working conditions, health and safety, socio-economic repercussions, and governance. The results showed similarities between the three livestock systems, which revealed a deficient social performance. For projecting the biodiversity damage of pasture land use from an LCA perspective, characterization factors (CFs) were estimated. CFs consist of dimensionless figures representing the potential for damage per unit area of pasture land (potential species loss per m2). The CFs were calculated for three levels of pasture land use intensity (minimal/NSP, light/ISP, intense/MC). Based on the characterization factors developed, the MC showed the least potential species loss. Enteric methane emissions from the production systems were determined using the IPCC Tier 2. The results revealed that the emissions values from enteric methane calculated with Tier 1 overestimated the emissions compared to Tier 2 methodology. LCA indicated a lower environmental impact of the MC on four of the seven categories analyzed, highlighting its lower contribution to climate change and reducing species loss. However, consumption of water and scarcity of fossil fuel resources increased. To achieve tropical sustainable livestock farming, further lines of research should be aimed at evaluating its economic impacts and propose management systems that guarantee better social and environmental performance.

Global process-based characterization factors of soil carbon depletion for life cycle impact assessment

Regionalization of land use (LU) impact in life cycle assessment (LCA) has gained relevance in recent years. Most regionalized models are statistical, using highly aggregated spatial units and LU classes (e.g. one unique LU class for cropland). Process-based modelling is a powerful characterization tool but so far has never been applied globally for all LU classes. Here, we propose a new set of spatially detailed characterization factors (CFs) for soil organic carbon (SOC) depletion. We used SOC dynamic curves and attainable SOC stocks from a process-based model for more than 17,000 world regions and 81 LU classes. Those classes include 63 agricultural (depending on 4 types of management/production), and 16 forest sub-classes, and 1 grassland and 1 urban class. We matched the CFs to LU elementary flows used by LCA databases at country-level. Results show that CFs are highly dependent on the LU sub-class and management practices. For example, transformation into cropland in general leads to the highest SOC depletion but SOC gains are possible with specific crops.

Empirical Characterization Factors for Life Cycle Assessment of the Impacts of Reservoir Occupation on Macroinvertebrate Richness across the United States

The transformation of a river into a reservoir and the subsequent occupation of the riverbed by a reservoir can impact freshwater ecosystems and their biodiversity. We used the National Lake Assessment (134 reservoirs) and the National Rivers and Streams Assessment (2062 rivers and streams) of the United States Environmental Protection Agency in order to develop empirical characterization factors (CFs; in Potentially Disappeared Fraction of species [PDF]) evaluating the impacts of reservoir occupation on macroinvertebrate richness (number of taxa) at the reservoir, ecoregion and country spatial scales, using a space-for-time substitution. We used analyses of variance, variation partitioning, and multiple regression analysis to explain the role of ecoregion (or regionalization; accounting for spatial variability) and other potentially influential variables (physical, chemical and human), on PDFs. At the United States scale, 28% of macroinvertebrate taxa disappeared during reservoir occupation and PDFs followed a longitudinal gradient across ecoregions, where PDFs were higher in the west. We also observed that high elevation, oligotrophic and large reservoirs had high PDF. This study provides the first empirical macroinvertebrate-based PDFs for reservoir occupation to be used as CFs by LCA practitioners. The results provide strong support for regionalization and a simple empirical model for LCA modelers.

Developing physicochemical property-based ecotoxicity characterization factors for silver nanoparticles under mesocosm conditions for use in life cycle assessment

Global production and consumption of silver nanoparticles (nAg) are forecasted to increase due to their applications in modern technologies. This situation raises concerns related to their environmental and human health...