The WULCA consensus characterization model for water scarcity footprints: assessing impacts of water consumption based on available water remaining (AWARE)

Abstract

Purpose Life cycle assessment (LCA) has been used to assess freshwater-related impacts according to a new water footprint framework formalized in the ISO 14046 standard. To date, no consensus-based approach exists for applying this standard and results are not always comparable when different scarcity or stress indicators are used for characterization of impacts. This paper presents the outcome of a 2-year consensus building process by the Water Use in Life Cycle Assessment (WULCA), a working group of the UNEP-SETAC Life Cycle Initiative, on a water scarcity midpoint method for use in LCA and for water scarcity footprint assessments. Methods In the previous work, the question to be answered was identified and different expert workshops around the world led to three different proposals. After eliminating one proposal showing low relevance for the question to be -017-1333-8 answered, the remaining two were evaluated against four criteria: stakeholder acceptance, robustness with closed basins, main normative choice, and physical meaning.Results and discussion The recommended method, AWARE, is based on the quantification of the relative available water remaining per area once the demand of humans and aquatic ecosystems has been met, answering the question BWhat is the potential to deprive another user (human or ecosystem) when consuming water in this area?^The resulting characterization factor (CF) ranges between 0.1 and 100 and can be used to calculate water scarcity footprints as defined in the ISO standard.Conclusions After 8 years of development on water use impact assessment methods, and 2 years of consensus building, this method represents the state of the art of the current knowledge on how to assess potential impacts from water use in LCA, assessing both human and ecosystem users' potential deprivation, at the midpoint level, and provides a consensusbased methodology for the calculation of a water scarcity footprint as per ISO 14046.

Life Cycle Assessment and Water Footprint of Hydrogen Production Methods: From Conventional to Emerging Technologies

“…At midpoint level, comparison of H 2 methods using Water Scarcity Footprint (WSF) with AWARE method [19] share the same trends as the ReCiPe 2016, indicating that technologies with a high WSF can cause a high impact on the environment both from a water consumption and overall environmental impact. The water consumption and associated damage impacts are reduced in high efficient technologies which use less or do not require water.…”

“…Midpoint water footprint profile was further quantified using Available WAter REmaining (AWARE) method [19]. The AWARE is water scarcity footprint (WSF) method for use in LCA and for water scarcity footprint assessments.…”

“…The method quantifies reduced water availability from consumption in a given watershed relative to the world average, after human and aquatic ecosystem demands have been met [19]. The WSF indicate potential environmental impacts related to each component of water used and is calculated by multiplying product of the inventory of water consumed (in m 3 ) with AWARE characterization factors (AWARE100, year_average) for water scarcity footprint [19,47]. Water footprint impact assessment results address potential environmental impacts related to water [48].…”

“…However, the use of hydrogen as a fuel input requires a reliable production technology and an efficient distribution network. Hydrogen can be produced from diverse feedstocks (renewable energy, nuclear energy, and state of the art of the current knowledge on how to assess potential impacts from water use in life cycle analysis at the midpoint level [19].…”

Product Environmental Footprint (PEF) Pilot Phase—Comparability over Flexibility?

“…Furthermore, several product category rules (or rather PEFCRs) were developed for new product categories (e.g., beer). Some of the methodological and practical challenges of the PEF method mentioned in previous publications (e.g., [3,4,9,10,14]) were tackled, e.g., by introducing more mature LCIA methods for the categories water use (for which now the AWARE method [15] is recommended), land use (for which now the LANCA method [16] is recommended), particulate matter (for which now the method by Fantke [17] is recommended) and resource use (for which now the ADP method based on ultimate reserves [18,19] is recommended) [2,6]. Furthermore, workshops were organized and cross cutting working groups were established to discuss issues like the modeling of the end-of-life (EoL) phase.…”