When we talk about sustainability in manufacturing, water conservation is a hot topic—but we’re often missing a huge piece of the puzzle: the energy hidden in evaporative wastewater. Industries around the world are losing massive amounts of both water and energy through evaporation, and recovering this “latent heat” could be a game-changer. Imagine a world where manufacturing industries save billions in energy costs, drastically reduce their CO₂ emissions, and conserve precious water resources—all by capturing the energy potential in evaporative wastewater.

In simple terms, latent heat is the energy needed to transform water from liquid to vapor. This energy doesn’t change the water’s temperature; it’s “hidden” in the vapor, which escapes into the air during evaporation. When we capture this latent heat from evaporative wastewater, we’re not just saving water; we’re reclaiming energy that can be reused to power industrial processes. This approach could save manufacturers significant energy costs and reduce emissions at an impactful scale.

Take the pulp and paper industry, for instance. This sector consumes over 1.1 trillion liters of water every year, much of which is evaporated in the process of concentrating black liquor (a byproduct of pulping). Globally, 5-10% of this water is lost to evaporation, each liter carrying approximately 2,260 kilojoules (kJ) of latent heat. Capturing and reusing that heat could reduce energy needs by as much as 10%, cutting global CO₂ emissions by around 15 million metric tons annually. That’s the same as taking more than 3 million cars off the road every year.

Similarly, chemical manufacturing relies heavily on evaporation for processes like solvent recovery and material concentration. This sector alone accounts for 10-12% of global industrial energy use, and advanced recovery systems could capture up to 20% of the latent heat embedded in evaporative wastewater. This change would mean energy savings in the hundreds of terajoules (TJ) annually, with the potential to prevent up to 20 million metric tons of CO₂ emissions. It’s a game-changer for an industry that has been traditionally energy-intensive.

Let’s not overlook food and beverage processing, which uses around 800 billion liters of water each year in evaporation-intensive tasks like concentrating juices, dairy, and sauces. With around 5-15% of water lost to evaporation, the potential energy hidden in this wastewater is vast. Implementing heat recovery in this industry could cut energy demand by up to 15%, reducing CO₂ emissions by roughly 5 million metric tons annually—equivalent to the emissions from over a million homes’ electricity use.

If evaporative wastewater recovery systems were implemented globally across these manufacturing industries, the potential impact is staggering. Together, these sectors could save up to 300 TWh of energy every year, which is comparable to the energy consumption of several mid-sized countries. And, critically, the CO₂ emissions reduction could exceed 40 million metric tons annually—like taking nearly 9 million cars off the road.

This isn’t just about water anymore; it’s about energy, emissions, and cost. When industries unlock the potential of evaporative wastewater, they’re not just conserving water; they’re making strides toward a more sustainable, cost-effective, and climate-friendly future. It’s time for manufacturing sectors to tap into the hidden power of latent heat, because every drop we save could mean a cleaner, more energy-efficient world.

Jonas Wamstad,

Water innovator & Co-founder of Drupps