Representing the Water-Energy Nexus With Decision Matrices

The global water nexus is still in the formative stages as a area of study. The needs are mostly clear: people need adequate water for drinking, for growing food, for cooling steam-based power plants, and for sustaining the natural habitats that keep the carbon and hydrologic cycles functioning properly. What has emerged is a growing awareness of how finite the earth’s water resources are and how this creates a complex set of interconnected challenges in both developed and developing nations. What has also emerged are predictions with increasing urgency for water and energy crises in the next 20–50 years, especially if these concerns are left unaddressed.The Water-Nexus is not new, but its emerging importance now is driven primarily by population growth, climate change, and our growing awareness of societal impact on ecosystems. Providing energy for buildings, homes, and transportation is an increasingly difficult task for the growing population and aging infrastructure. Most individual issues within the Water-Energy Nexus are fairly well known with quantifiable water impacts. What is lacking is a clear representation of the Nexus relationships that show how changes in one sector impact another. What is needed is a compact way to represent the interrelationships that provide both insight and perspective on how much influence one proposed change has compared to another. Such an understanding should surface the most strategic, viable methods for simultaneously meeting water and energy needs while being a good steward of finances and natural resources.We propose the use of decision matrices from engineering design to represent the interconnected relationships that form the Water-Energy Nexus. The customers in this case are water-centric stakeholders such as government and corporate decision makers, educators, and water-oriented development agencies. Both quantitative and qualitative research methods are used to integrate the nexus topics into the decision matrix. Both positive and negative correlations in water impacts are indicated with their relative level of influence. Common units are used when possible to quantify water consumption or savings.Decision matrices are presented for transportation fuels and utility power generation. The transportation fuels matrix includes evaluation criteria for water impact, sustainability, convenience, emissions, public opinion, and geographic considerations. The utility power decision matrix has similar evaluation criteria except capacity factor is considered instead of convenience. These criteria are intended to aid policy makers in strategically navigating the legislative and policy generation process to emphasize or reduce emphasis on different fuel types. Recommendations are provided for strategic, viable methods to mitigate future effects of the Water-Energy crisis.© 2014 ASME