Water, Energy and Food: Water’s Role at the Nexus of Three Critical Resources

For a long time, water management has been a story of silos. Drinking water, wastewater and stormwater systems are typically managed separately by local utilities, creating artificial boundaries that don’t exist in the natural water cycle. 

This siloed perspective, however, is gradually shifting. The challenges we face today – particularly climate change – demonstrate why integrated water management is critical. Water reuse programs, for example, cannot address water scarcity without collaboration across the traditional drinking water-wastewater divide, while comprehensive flood risk management requires coordinated planning at the watershed level.

With approximately 70% of climate change impacts expressed through the water cycle[i], recognizing water’s wider connectivity across our cities, industry, food, energy and the environment now requires greater attention. As Meike van Ginneken, Water Envoy of the Kingdom of The Netherlands, recently said: “Climate mitigation is CO2. Climate adaptation is H2O.” 

As we lay the foundations for a more prosperous and resilient future, managing water in this broader context is imperative. 

One way we can achieve this is through the Water-Energy-Food Nexus, which recognizes the global interconnectivity of these three critical systems. For instance, agriculture accounts for more than 70% of all freshwater withdrawals globally,[ii] while 90% of global energy production relies on water-intensive processes.[iii] Climate change and increased demands for water, energy and food are creating challenges for the near- and long-term security of each.

According to the U.N., integrated management of water, energy and food must be a top priority if we are to achieve the U.N.’s Sustainable Development Goals: “decision-makers in all three domains must cooperate on water resource management, ecosystem protection and water supply and sanitation.”[iv]

So, what role does the water sector play in supporting the Water-Energy-Food Nexus, and how can we use that perspective to collaborate more closely on cross-sector solutions? 

Reduce energy and emissions

We have made great strides in reducing the energy consumption of water and wastewater treatment processes and this will continue to be a focus as costs for energy rise and as new, advanced treatment solutions are implemented to address scarcity issues and emerging contaminants like PFAS. Innovations in membrane technologies and energy recovery devices have driven down the energy consumption of desalination processes, for example, but more can be done. We’ve applied AI-powered Digital OneWater solutions to wastewater treatment plant operations, driving plantwide power savings of approximately 20%. There’s also the opportunity to collaborate in the energy sector to leverage clean and economical renewable energy. One example is in Singapore, where the Public Utilities Board (PUB) has deployed one of the world's largest inland floating solar photovoltaic (PV) farms on the surface of Tengeh Reservoir to meet the energy demands of its advanced treatment facilities. 

While net-zero energy is in reach, there is still a significant gap to achieving net-zero emissions in the water sector because of process emissions – nitrous oxide (N2O) and methane (CH4) – produced as byproducts of wastewater and sludge treatment processes. This is a critical focus as we consider the water sector’s carbon footprint. 

Produce clean energy 

The water sector also has a unique role in generating renewable energy. Waste-to-energy projects are now well-established in the sector, with biogas produced in the wastewater treatment process used for power generation or to produce renewable natural gas. An example is VCS Denmark, which achieved carbon neutrality and energy independence at its Ejby Mølle WRRF. The facility now generates more than 150% of its energy demand, with surplus electrical energy fed back into the power grid. More sites are handling municipal food waste for co-digestion alongside wastewater biosolids to increase biogas yield – a true Water-Energy-Food Nexus solution. 

We can also collaborate to leverage wastewater treatment plant sites for clean hydrogen production. Like thermoelectric power generation, hydrogen production requires large quantities of water. Analysis by PA Consulting shows that the amount of water required can be up to six times greater than previously estimated.[v] With access to excess land, on-site renewable energy and abundant amounts of recycled water, wastewater treatment plants can be part of the solution. In Australia, we’ve explored this opportunity with Yarra Valley Water and were recently appointed by Barwon Water for the concept and feasibility design for using green oxygen at its Northern Water Reclamation Plant. Located next to a proposed hydrogen refueling station, Barwon Water’s plant is strategically positioned to provide recycled water for hydrogen production and use the green oxygen byproduct to reduce energy usage and lifecycle costs of the wastewater treatment process. 

Protect critical infrastructure 

Water’s role in the Water-Energy-Food Nexus is not simply one of supply. Climate change is resulting in severe flood events and sea-level rise that threaten energy and food production. In the U.S., 30% of power generation facilities are in coastal counties[vi] and many nuclear power plants globally are situated on the coast due to significant water requirements for cooling. Comprehensive coastal resilience solutions can protect critical infrastructure like power plants from damaging coastal threats, while the incorporation of nature-based solutions such as living shorelines and oyster reef restoration supports coastal habitats that are important to commercial fishing. Partnerships – like our work with the Nature Conservancy – are key to advancing these coastal resilience solutions. 

Partner with agriculture

Agriculture is the largest consumer of the world’s freshwater resources and must be part of the water scarcity solution. Consider areas like the Colorado River Basin in the U.S., where farmers use approximately 80% of water from the Colorado River to produce 90% of the nation’s winter vegetables.[vii] This underlines why there’s no easy solution to water shortages while meeting increased demand for food. Pumping and conveying water for agricultural irrigation also has a large energy footprint.[viii] What is clear is this challenge won’t be solved working in silos – we need collaborative solutions, like using municipal wastewater or seawater for agricultural irrigation to meet water demands while preserving valuable water resources. Urban farms can even be co-located with wastewater treatment plants to use recycled water and biosolids as fertilizer for food production.

Climate change has put the spotlight on water – demonstrating its complexities and its significance to other sectors. While this creates new challenges for us to solve, it is an opportunity to emphasize water’s value and the need for integrated, OneWater solutions that break down traditional barriers and silos. The Water-Energy-Food Nexus highlights the interconnectivity of critical resources and how we must work in novel, collaborative ways to co-create the world to come.