Performance of water utilities beyond compliance - Environmental dimension: quantifying ecological sustainability with life cycle assessment (LCA)
While analysis of alternative scenarios for establishing and operating urban water infrastructure by means of economical (monetary) investment and pay-back periods is well-known, the quantification of ecological sustainability is frequently considered novel. LCA — and more precisely, the impact assessment part of it (LCIA) — is a methodology for systematic quantification of pros and cons of potential environmental impacts, including water and energy resource consumption. Several examples of the use of LCA related to water supply and sanitation are referenced in the EEA report Towards efficient use of water resources in Europe (EEA, 2012b)
Figure 5.4 is an example presented at the expert meeting: four alternative scenarios are compared to a baseline, for extension of the water supply to Copenhagen. The scenarios include rain- and storm-water harvesting (A1), compensating actions to ensure environmental flows (A2), new well fields for groundwater abstraction, about 20 km from water-treatment plant (A3), and desalination of brackish water (A4). LCA profiles cover standard environmental impacts, freshwater withdrawal impacts (FWIs) and combinations.
The results indicate that rain- and storm-water harvesting are the most favourable alternatives for standard and combined LCA profiles. However, desalination ranks practically the same for combined LCA profiles, due to a positive contribution to the FWI. In Denmark, the drinking- water supply relies solely on groundwater abstracted and treated at waterworks before being distributed to the customers. The withdrawal of groundwater has an impact on the freshwater environment, and this study presents one way of integrating the impact into the standard LCA. Alternatives relying on non-freshwater options therefore obtain an advantage in the FWI category. This is where desalination of seawater and rainwater harvesting are preferable when combining the standard LCA with the FWI category. Although the FWI does not represent a standardised element in LCA methodology, the example illustrates the importance of setting the system boundaries and coverage of impact categories and parameters.
With the aim of further standardising LCA methodology related to water management, a draft ISO standard, ISO/DIS 14046, 'Environmental management — Water footprint — Principles, requirements and guidelines' (51) is under development. This standard combines both water quantity- and quality-related LCA impact categories into a 'water footprint', e.g. in parallel to 'carbon foot-printing'. Some methodologies and guidance documents for LCAs and carbon foot- printing, especially in water utility contexts, have also been developed in national contexts (UKWIR, 2012; Frijns, 2011; DANVA, 2012; Svensk Vatten Utveckling, 2014).
There is a potential synergy between the underlying European inventories developed in LCA contexts as proxy scenarios on water consumption and emissions to water, for instance, and similar European data sets in WISE.
See here, page 31.