Balancing clean water-climate change mitigation trade-offs

Abstract

Energy systems support technical solutions fulfilling the United Nations' Sustainable Development Goal for clean water and sanitation (SDG6), with implications for future energy demands and greenhouse gas emissions. The energy sector is also a large consumer of water, making water efficiency targets ingrained in SDG6 important constraints for long-term energy planning. Here, we apply a global integrated assessment model to quantify the cost and characteristics of infrastructure pathways balancing SDG6 targets for water access, scarcity, treatment and efficiency with long-term energy transformations limiting climate warming to 1.5°C. Under a mid-range human development scenario, we find that approximately 1 trillion USD2010 per year is required to close water infrastructure gaps and operate water systems consistent with achieving SDG6 goals by 2030. Adding a 1.5°C climate policy constraint increases these costs by up to 8%. In the reverse direction, when the SDG6 targets are added on top of the 1.5°C policy constraint, the cost to transform and operate energy systems increases 2%-9% relative to a baseline 1.5°C scenario that does not achieve the SDG6 targets by 2030. Cost increases in the SDG6 pathways are due to expanded use of energy-intensive water treatment and costs associated with water conservation measures in power generation, municipal, manufacturing and agricultural sectors. Combined global spending (capital and operational expenditures) to 2030 on water, energy and land systems increases 92%-125% in the integrated SDG6-1.5°C scenarios relative to a baseline 'no policy' scenario. Evaluation of the multi-sectoral policies underscores the importance of water conservation and integrated water-energy planning for avoiding costs from interacting water, energy and climate goals.

Integrated Solutions for the Water-Energy-Land Nexus: Are Global Models Rising to the Challenge?

“…Strategies for reducing energy-related water use include shifting to more water-efficient cooling technologies (e.g., recirculating and dry cooling), using alternative water resources (e.g., wastewater or seawater), constructing less water-intensive energy transformation technologies (e.g., gas instead of coal; wind and solar PV), and using distribution infrastructure (e.g., transmission lines) to import energy from other, possibly more water-abundant, regions. However, adapting to water scarcity is expected to increase energy prices and may significantly alter future energy transitions [13,116]. Meanwhile, regional studies suggest that the adoption of energy-intensive water supply technologies, such as water conveyance and desalination, could substantially increase energy demands and the cost of water supply while exacerbating the climate change mitigation challenges already faced by the energy sector in water-scarce regions [13,117].…”

“…However, adapting to water scarcity is expected to increase energy prices and may significantly alter future energy transitions [13,116]. Meanwhile, regional studies suggest that the adoption of energy-intensive water supply technologies, such as water conveyance and desalination, could substantially increase energy demands and the cost of water supply while exacerbating the climate change mitigation challenges already faced by the energy sector in water-scarce regions [13,117]. Thus, it is important that energy-economic models improve their representation of water-energy trade-offs in assessing energy transition pathways.…”

“…More recently, the economic impacts of cooling system choices were incorporated into a global energy-economic model to study the interactions between the SDG for clean water (SDG6) and the Paris Agreement 1.5 • C target [13]. The results indicate that combined policies drive power systems towards water-efficient low-carbon generation technologies (e.g., wind and solar) faster than if each policy was applied on its own.…”

“…Regional biomass potentials are typically represented by exogenously-derived supply curves that are not accounting for dynamic water and land trade-offs associated with their exploitation. However, several studies have recently coupled agro-and energy-economic models in an effort to better account for the emissions, land use, and water trade-offs [3,13,82,120]. Studies using these frameworks suggest that water constraints are expected to increase development costs in some regions due to water stress [99,110,111,121,122].…”

“…Models with global-scope are particularly important for capturing the influence of globalization and international trade, which are an increasingly critical aspect in the local pricing of fuel, food and materials [8,9]. National and international policy-makers are mainly using knowledge generated from global models to inform target setting in the context of climate change mitigation and adaptation [10], but there is further scope to apply the frameworks to study policy designs for a broader set of targets consistent with the sustainable development agenda [11][12][13].This paper reviews the challenges and opportunities for global models integrating resource management decisions (or solutions) across WEL systems. The review aims to answer the following research questions: (1) how are impacts and adaptation strategies currently represented in global models; and (2) what are the main opportunities for future research and model development?…”