Essential Guide: The water-food-energy nexus; global thinking

Table of Contents

• What is the relationship between water and energy?
• Nexus Thinking and Eco-Systems
• What are the benefits of water-energy nexus thinking?
• Real-World Examples of Water-Energy Nexus in Action
• Corporations and the Water-Food-Energy Nexus
• Helping to Understand and Manage Trade-Offs
• Water-Energy Nexus Challenges

For too long, the fields of water, energy and food were seen as separate entities, working in silos in terms of policy and regulation, requiring different solutions to their own specific problems. This way of thinking has been changing, however, as it becomes apparent that these huge sectors are inter-related and impact on each other, along with many other facets of the modern world.

In this essential guide, we explore the basis of the water-energy nexus, look at some of the challenges and solutions, and discuss how and why agriculture is an essential component of the nexus.

What is the relationship between water and energy?

Solving the water crisis is not possible in isolation. Water requires energy, food requires water and energy, energy production requires water. Estimates vary, but some sources suggest energy use is responsible for around 30-40 per cent of total operating costs for water and wastewater utilities. An average of 15 per cent of the world’s water withdrawals are used in energy production. The figure for agricultural use is much higher.

We can understand this inter-relatedness in terms of a nexus; often referred to as the water-energy nexus, or energy-water nexus.

More recently, an even more holistic view of the interdependence of different systems has emerged in which food production is viewed as part of the same nexus. Food production requires vast amounts of water and energy, and all three are vital for humanity. Intensive land use for agriculture can also impact on soil quality, which affects water retention but also the quality of water being returned to rivers and other bodies of water, which require treatment.

An average of 15 per cent of the world’s water withdrawals are used in energy production. The figure for agricultural use is much higher.

With the world’s population rising and energy needs increasing, the demand for water use also rises. Energy production requires vast amounts of water: from cooling nuclear power facilities to steam condensing in thermal plants, from fossil fuels to fracking, all require significant water usage for extraction, cleaning, cooling, and more.

Biomass, which on the surface is more environmentally friendly than fossil fuels, requires huge volumes of water to grow the crops used for feedstock. Of course, crops grown in rain-rich areas will require less water extraction for irrigation than in drier areas.

At the same time, water treatment and production, for example, desalination, traditionally requires a great deal of energy.

Nexus Thinking and Eco-Systems

Understanding the nexus relationship between water, food and energy is important for a number of reasons.

First, it breaks down the silos between industries and even within industries. It requires holistic thinking to solve problems that have impacts beyond traditional boundaries.

Second, it focuses attention on eco-systems and the effect that, for example, overextraction of water on agricultural land can impact river systems and the communities and wildlife that depend on them. That this also has an impact on treatment costs and the types of treatment needed, which require energy. Conversely, with rising populations, energy production increases, which requires more water, which can affect agriculture. All of these things are linked to (and effect) the health of the eco-systems in their local environment.

Third, once energy, food and water are understood from a water-energy, or water-food-energy nexus perspective, it unlocks the potential to use ‘nexus thinking’ to solve problems and overcome challenges both across sectors and across political and geographical boundaries.

What are the benefits of water-energy nexus thinking?

By removing silos and promoting collaboration, nexus thinking can focus on sustainability and efficiency across all related processes. By utilising expertise in one area, say wastewater, you can work with providers in another area, say biogas, to find solutions to many common problems, i.e., how do you make wastewater treatment more sustainable, less energy-efficient; or how can desalination plants coexist with energy-producing plants to reuse water at source to prevent extracting dwindling freshwater supplies.

Nexus thinking is leading to innovation, which has benefits across and beyond the water-energy-food nexus. It fosters regional, national, political and social collaboration, with many multinational companies now examining how they interact with communities and resources in the water basins they operate in. It also helps to address 2030 sustainability goals.

Real-World Examples of Water-Energy Nexus in Action

In areas experiencing water scarcity, desalination plants play a vital role in supplying water to prevent extraction from freshwater sources. However, desalination is traditionally energy-intensive. Companies are now choosing to operate in the water-energy nexus when looking for solutions.

The Hassyan desalination plant in Dubai, when fully operational, will become the second-largest such plant in the world, but the largest to be fully powered by solar energy. Dubai Electricity and Water Authority (DEWA) and ACWA Power are working with Veolia to build and run the plant which will have a capacity of 818,000 m3/d and provide safe and reliable drinking water for two million people. The plant will reduce energy consumption by utilising reverse osmosis membranes.

Dubai has recognised the need to address both water scarcity and energy consumption in various strategy documents: UAE Water Security Strategy 2036; Dubai Urban Plan 2040, Dubai’s Integrated Water Resources Management Strategy 2030, Dubai Clean Energy Strategy 2050 and the Dubai Net Zero Carbon Emissions Strategy 2050. As part of the latter strategy, the use of renewable energy for seawater desalination is a national priority.

DEWA plans to produce 100 per cent of Dubai’s desalinated water using clean energy and waste heat by 2030.

The Saline Water & Food Systems Partnership, a collaboration between the Netherlands Water Partnership and the Netherlands Food Partnership, has approved three projects for seed money funding in low and middle-income countries that aim to tackle salinity issues that are affecting water and soil quality in Senegal, Bangladesh and Mozambique. The partnership will work with various national and local agencies and governments to share expertise, research and resources to tackle the water-food-energy nexus problems.

Hong Kong’s Tseung Kwan O desalination plant provides water to 137,000 homes. Solar panels are used to reduce reliance on energy from the grid; water recycling and reuse processes reduce freshwater consumption by 36.6 per cent, while installed water-saving devices will reduce freshwater use by 53 per cent.

Dubai has recognised the need to address both water scarcity and energy, and the use of renewable energy for seawater desalination is a national priority.

In South Korea, a project has been testing a fully integrated water management and carbon dioxide removal system at a desalination plant. The project will use atmospheric carbon capture during the desalination process, linking the climate, energy and water industries.

On a national level, the Korean government has set a goal of achieving carbon-neutrality by 2050. Regionally, the province has been suffering from water scarcity caused by severe droughts and a reliance on external water resources. The area around the facility is home to the Daesan Industrial Complex, which accounts for 40 per cent of South Korea’s total petrochemical production and produces large volumes of greenhouse gas emissions.

The plant will capture CO₂ from the atmosphere, recover freshwater, minimise brine discharge, and extract green chemicals from wastewater. Capture6’s process uses salt extracted from wastewater as a feedstock for a liquid sorbent. This traps CO₂ from the air, which is then mixed with calcium to produce a limestone, or chalk-like mineral, that keeps the greenhouse gas from escaping back into the atmosphere.

One by-product of the carbon removal process is fresh water. The technology also generates minerals like potassium and magnesium and produces 'green' chemicals such as hydrochloric acid and calcium carbonates. The latter are currently derived from fossil fuels and imported to South Korea, so the facility will help provide a local and sustainable supply of key industrial chemicals.

The system is designed to operate at more energy-efficient, ambient temperatures than most contemporary technologies, opening up the possibility of plants powered by renewable energy in the future.

Producing green hydrogen as a renewable energy source that has the potential to power the plant, creating a virtually sustainable closed-loop system.

Other companies have taken to the ocean to perform desalination. For example, Oneka Technologies is using sustainable desalination units to convert seawater to fresh water using the renewable energy of ocean waves.

Norway’s Ocean Oasis has been piloting offshore desalination buoys powered by wave energy alone.

In the UK, water utility Anglian Water is collaborating with OxyMem and Cranfield University to build a demonstration plant to trial a novel approach to treating wastewater that will reduce the amount of greenhouse emissions compared to current processes.

By coupling an electrolyser and MABR (Membrane Aerated Biofilm Reactor), Anglian Water aims to achieve a ‘triple carbon reduction’, in line with the aims of the Water UK Net Zero 2030 routemap, while producing green hydrogen as a renewable energy source that has the potential to power the plant, creating a virtually sustainable closed-loop system.

Corporations and the Water-Food-Energy Nexus

The above are just a few of the many projects around the world that are using the water-energy nexus as a means to achieve sustainability goals, reducing energy and water use.

As mentioned above, many global companies are taking water stewardship very seriously as they look to reduce costs and improve efficiencies, while meeting sustainability goals. The water-food-energy nexus is fundamental to the latest sustainable statements and future plans of companies like Google, Apple, Diageo, Microsoft, and more. As huge companies, their water and energy use is enormous. Their latest sustainability plans all look towards reducing energy consumption, reusing water, reducing extraction of freshwater, and improving eco-systems where they operate.

Helping to Understand and Manage Trade-Offs

Taking a nexus approach can help to understand the trade-offs that come from certain processes. For example, hydropower output is expected to increase in North America in the coming years, according to a report published in Environmental Research Letters. This comes at a time when the Biden-Harris administration has allocated €386 million for 293 hydroelectric improvement projects across 33 states.

Hydropower plants are a good example of the water-food-energy nexus in action. They provide water storage that can be used for crop irrigation and for urban and residential purposes, and of course, they produce electricity. However, new plants involve flooding of agricultural land and population migration; they also negatively affect eco-systems downstream, right down to coastal areas.

As mentioned above, biofuels have great potential for producing clean energy. However, biofuel crops need a lot of water to grow and energy to harvest. Land used for biofuel crops also takes away from food production.

So, by looking at food, water, and energy production through a nexus lens, it is possible to see potential negative trade-offs as well as benefits and to understand better how to manage them.

Water-Energy Nexus Challenges

Although using water-food-energy nexus thinking has obvious advantages, it is not without its challenges. Collaborative working is not always smooth, and accepting compromises and trade-offs is not always easy.

Putting theory into practice is not always easy and frameworks and regulations are not always aligned. Many projects are in their early stages or still being trialled and so knowledge is fluid and data gathering, management, and sharing may not always work smoothly when many different operatives are in play.