What images come to mind when you think of environmental pollution? Likely one of them is a power plant cooling tower. These enormous concrete shells billowing thick plumes into the atmosphere have become an enduring symbol of pollution. However, scientists and engineers are quick to point out that there are widespread public misconceptions about what cooling towers actually do. The plumes from these towers are water vapor, not unlike natural clouds, instead of what most people assume to be carbon dioxide or other pollutants. Even so, towers are not environmentally harmless. Especially in water-scarce areas, new solutions are needed to address the toll that these towers take on local water supply.

For example, El Paso County, Texas has around 850,000 people and uses around 40billion gallons of water per year. The county borders the Rio Grande, which is drying upas nearby cities divert its water unsustainably. Its single largest user of water is the El Paso Electric Company, which uses about 7.5 billion gallons per year, about 19% of the total water consumption. The water is used as a coolant in the company’s power plants and is later released into the atmosphere from their cooling towers. Local electricity demand is only growing, especially as the area becomes a hub for data centers.

The problem comes down to the science of how heat-generating power plants work. For every unit of useful energy a plant produces, thermodynamics dictates that it must shed an amount of heat. Current systems do this task by evaporating water from a cooling tower— referred to as “wet cooling.” Over time, El Paso Electric could reduce their water footprint through switching to renewables, like wind and solar, that generate electricity directly. But this transition will take time, and the county cannot afford to wait, as the Rio Grande gets drier every year. That’s why retrofits to reduce water demand at existing power plants are essential not only in El Paso, but also across the country.

Reducing water use at power plants without sacrificing energy production requires rejecting heat without evaporation—referred to as a “dry cooling.” Dry cooling sheds heat directly into the air through contact with a closed loop of circulating water. These towers are typically larger, more energy intensive, and less efficient than traditional wet towers. Even so, existing wet towers can be modified with dry cooling components to divert some of their heat shedding directly to air, thus reducing their water needs.

Given the scale of these projects, they will require large upfront capital investment. This means that the challenge of switching from wet to dry cooling is as much a policy issue as a technical one, as counties like El Paso will need to find ways to attract the necessary capital. But as local water supplies deplete and rates continue to climb, power plants with wet cooling will become increasingly unprofitable and damaging to their communities.

Solving water use issues in places like El Paso will be difficult without addressing energy’s immense water demand and will require retrofitting existing power plants to reduce their water needs. As no two power plants are the same, no two retrofits will be identical. The situation calls for creative engineering solutions that add dry cooling elements to existing towers both cheaply and non-invasively, alongside government incentives to attract capital for retrofits and investment from hyperscalers that use local water and energy.  Even if it may not come easily, these are essential steps to ensure that future generations will enjoy the same water resources that we do.