As PhD students and aspiring academics in the energy-water nexus from different corners of the US, we would link up at national conferences about twice a year to discuss research ideas, challenges, academic life, and the job hunt. Our dissertation topics were related, but we often took very different approaches to our research. Our conference discussions always aided both our independent research topics and usually ended with a comment about future collaboration. We just needed to find the right topic. Catching up at the American Geophysical Union Fall Meeting in December of 2018, we finally found a research topic for us to build a collaboration – the water impacts of global energy trade.

The energy-water nexus is a simple notion with complex interactions describing the dependencies of energy on water resources and water on energy resources. Water is withdrawn and consumed in the extraction and refinement of fossil fuels, for cooling of thermoelectric power plants, and, in the obvious case, hydroelectric generation. Consequently, changes in hydrology (low flows or high temperature water) can impact the ability to generate electricity. Additionally, electricity and other fuels are consumed for the supply, treatment, distribution, heating, and collection of water resources around the globe. Energy is, therefore, integral in the resilient and sustainable supply and treatment of clean water resources. Finally, these resource interdependencies create indirect consumptions or embedded resources, creating water and energy footprints that can be compared and calculated on a local, regional, national or international scale.

Recently, water footprints have been applied to commodity trade (virtual water) to understand the globalisation of water resources, predominantly in the agricultural sectors. The late Arjen Hoekstra from TU Delft was instrumental in this field and his legacy was felt across the world and particularly inspired us in our research. The globalisation of water, as understood through water footprinting analysis, provides insights on how production of a good for consumption in other locations impacts the local environment. These research areas inspired us to think about global impacts of energy and their impacts on often-scarce water resources. We then embarked on creating a database of global virtual water trade associated with the energy sector. Providing this global context of water resources enables an understanding of the localised water impacts of production—particularly in the context of water scarcity (see figure below) and global climate change.

In our analysis, we scoured several international databases and the existing literature to compile a dataset of country-level water intensities for 11 different energy commodities. We then paired these water intensity values with international trade data from the United Nations’ Comtrade database to evaluate virtual water trade of energy from 2010-2018 (Peer & Chini 2020, Chini & Peer 2021). The global virtual water trade of energy has increased over time and now equates to about 1/3 of the total outflow of the Mississippi River each year. This virtual water trade is largely dominated by the trade of fuelwood and biodiesel.

Through our initial work, we have discovered important opportunities to expand the systems-level understanding of water resources with a water footprint and energy-water nexus perspective. In particular, we believe there are three specific areas worthwhile of concentrated further investigation:

1. Global changes of water for energy across the years, forecasting for energy transitions and policy implications.
2. Intra-annual or seasonal variations in water resources, particularly surrounding hydroelectricity production.
3. Enhanced understanding of regional variations for water footprints for energy through local data collection and publication.

These opportunities will further engage research in the energy-water nexus with opportunities for policy and decision-making at a local/regional scale to enable a global perspective of water resources. In this and future works, we and other researchers around the world strive to advance our understanding and management of global water resources. This research is especially important as we consider the projected future impact on water availability, water quality, and water security across the globe. Future environmental changes and impacts, coupled with the societal importance of our global energy and water systems, is a prime motivator for our continued collaboration in the field. 

References:

Chini, C.M. & Peer, R.A.M. (2021) The Water Footprint of Global Energy Trade from 2010-2018. Scientific Data.

Peer, R.A.M. & Chini, C.M. (2020) An integrated assessment of the global virtual water trade network of energy. Environmental Research Letters, 15, 114015.

Mekonnen, M.M. & Hoekstra, A.Y. (2011) National water footprint accounts: the green, blue and grey water footprint of production and consumption, Value of Water Research Report Series No.50, UNESCO-IHE, Delft, the Netherlands.