Climate change is causing increased temperatures, water scarcity, food shortages, poverty and displacement, severe storms, increased drought, and loss of species.  As the crises heighten, the world is pushing for sustainability.  The United Nations in 2015 adopted the 2030 Agenda for Sustainable Development and in 2021 almost 200 countries came together for the UN Climate Change Conference to forge the Glasgow Climate Pact.  As a result of these global changes and change-making, many aspects of human life are being scrutinized for environmental sensitivity – including a demand for sustainable manufacturing processes and end products.  

Manufacturing typically consumes copious amounts of energy and water and emits significant quantities of greenhouse gasses – especially carbon.  In measuring consumption and emission, energy, water, and carbon values are typically measured separately from each other.  Like most concoctions, there are aspects of each that blend into the other.  As a result, supposed improvements may result in bigger problems opportunities for more impactful outcomes can be missed, and savings may either be greatly underestimated or overestimated.  The solution?  A systems-thinking approach.   

Systems thinking is a holistic approach to analysis that considers how a system’s constituent parts interrelate over time and within the context of larger systems.  Applied to energy, water, and carbon, a manufacturing operations solution that reduces energy, for example, may negatively impact water levels.  Evaluating the makeup of each, the carbon inherent in water may not be included in measuring energy savings – or expenditure.   

The Water + Energy + Carbon (WEC) Nexus provides a tool to frame the interaction between these three disparate yet interrelated components.  The Nexus is a model that accounts for how the effect in one of the WEC components can impact the output of the other(s). 

WEC Nexus, Defined 

The WEC Nexus is the dynamic interdependence of water, energy and carbon as shown in Figure 1. Water, energy, and carbon are interlinked. Carbon is emitted from energy and water.  Energy use and carbon in water supply systems depend on water quality, water sources, and water topography. For instance, any water or wastewater treatment process requires considerable energy resources. Abstracting (taking water from any source), treating, and conveying water requires significant amounts of energy, most of which is derived from fossil fuels including coal, gas, or natural gas. Energy production from these sources generates carbon dioxide, methane, and nitrous oxide. WEC analytic tools include the life cycle analysis, computable general equilibrium, input-output analysis, system dynamics model, optimization methods, and material flow analysis.

Wasmer considers the WEC Nexus imbedded in the manufacturing of a product.  When optimizing facilities and processes, methodologies are incorporated to address this interconnection. 

WEC Nexus, Case Studies 

The San Francisco Public Utilities Commission is decoupling water consumption from energy usage by incentivizing commercial users to upgrade or replace existing water-using equipment. Read More 

WEC Nexus, Tools 

 Rules of thumb for WEC Nexus.

Applying the WEC Nexus requires information regarding the interrelationships of the WEC properties such as the CO2 pounds equivalents per kWh, the water consumption per kWh, or the required kWh per million gallons. Also, it requires detailed water data, such as the evaporating water gallons per 100 tons of cooling.