The Water-Energy Nexus: A Blueprint for Sustainable Industrial Growth

Water and Energy are the two pillars of modern civilisations that are not only closely intertwined but lie at the core of sustainable industrial growth. Energy is needed in every step of the water cycle, from extraction to conveyance, and later, collection and treatment. Just as harnessing energy from different sources, from biofuels to renewables, requires an abundance of water for varied purposes. The interconnectivity of the two is well-established, yet at the national, international, technological and industrial level, they are still often considered separately.

Water is the essence of life, and energy the crucial driver of economic development. Even so, billions of people worldwide struggle to secure clean water for basic needs, like drinking and sanitation, and approximately 675 million people lack access to electricity. What is unfortunate is 80% of the wastewater discharged remains untreated.

Here is an opportunity for countries, particularly developing nations like India, which is still advancing infrastructure, to integrate water and energy planning to meet SDG 6 (clean water and sanitation) and SDG 7 (affordable and clean energy).

Co-locating Renewable Energy with Water Access

Solar thermal and bioenergy require large amounts of water for cooling or irrigation purposes, whereas photovoltaics and wind turbines are much less water-intensive. Developing renewable energy facilities, such as solar, wind, or bioenergy plants, near water bodies or industries that discharge significant volumes of wastewater is a strategic move to improve water and energy efficiency and reduce the demand for freshwater.

Reusing Water and Zero Liquid Discharge (ZLD)

For renewable sectors that consume or discharge huge amounts of water, the adoption of water reuse and Zero Liquid Discharge (ZLD) systems is crucial. ZLD systems that combine advanced membrane treatments, evaporators, and crystallisers allow facilities to recycle water and recover valuable by-products.

In renewable-linked water processing systems, like cooling towers in biomass plants or fluid polishing in semiconductor manufacturing, a ZLD set-up ensures water is recovered and reused in the cycle. It turns the effluent into a resource rather than a discharge to be eliminated, promoting a circular system. When powered by solar or wind, ZLD-based desalination and purification systems create self-sustaining water-energy loops, recycling water without wasting energy or contributing to greenhouse gas emissions.

Water prioritisation challenges

A significant policy challenge is prioritising demands for water across domestic, agricultural, and clean energy uses. Up to 70% of global freshwater is used for agricultural purposes, followed by industry with roughly 20% and domestic use at about 12%, as suggested in the UN World Water Development Report 2024. This unregulated distribution of water is one of the primary causes of its uneven availability across the region, leaving people in vulnerable areas struggling with acute shortages. Water distribution needs to be prioritised to ensure balance.

The first priority, without a doubt, should be meeting domestic and ecosystem needs. The next is agriculture, where freshwater usage could be minimised with the integration of smart irrigation and reuse systems. Lastly, clean energy projects should be allowed only if they are water-efficient or use treated/reclaimed water. This approach would reduce their dependency on freshwater and ensure water is available everywhere throughout the year.

Linking Reuse and ZLD Again

Using reclaimed municipal or industrial wastewater (non-potable) in the agriculture sector, especially where high-grade water is not vital (like irrigation, dust suppression, and concrete mixing), would reduce the need for freshwater. Similarly, in clean energy and industrial settings, ZLD would allow for complete recycling, thereby helping not only to conserve water but also to meet regulatory limits on discharge, recover valuable resources, and reduce environmental impacts.

Using Renewable Energy to Treat and Produce Clean Water

Solar and wind-powered desalination and advanced water treatment systems are increasingly viable. For example, solar-driven RO (reverse osmosis) or evaporation systems provide clean water with a minimal carbon footprint, even in arid zones.

Some pilot projects integrate solar PV arrays with ZLD desalination, producing water for industrial cooling or potable water while eliminating brine disposal through crystallisation and resource recovery. Biomass-based power platforms are also being designed to utilise wastewater heat or reuse streams to treat water and generate electricity concurrently, closing both water and energy loops.

The water-energy nexus is an efficient operational roadmap for sustainable industrial expansion. When supported by the right policy framework, industrial collaborations, and infrastructure design, this association could become an engine of sustainable industrial growth in areas with limited freshwater availability, particularly in developing regions worldwide.