As environmental regulations tighten, cooling towers nationwide are turning to sustainable best practices set by the General Services Administration (GSA) and the Department of Energy (DOE). Today’s cooling tower operators are asked to minimize water and chemical use, but traditional solutions can’t keep up. As a result, they turn to alternative water treatment to meet these demands.
With the GSA and the National Renewable Energy Laboratory (NREL) rigorously evaluating this technology as part of the GSA’s Green Proving Ground (GPG) program, it has demonstrated significant potential for reducing water consumption, lowering costs, and meeting environmental standards. This case study explores the outcomes of that evaluation, revealing how this innovative water treatment solution is reshaping cooling tower operations across the United States.
The Challenge: Water & Chemical Use
Cooling towers are notorious for their high operational costs, excessive water use and substantial environmental impact. These challenges are amplified in the federal sector, where efficient resource management is crucial.
At the Denver Federal Center (DFC), Building 95—a 163,000 square foot, two-story office and laboratory facility—became a key site for testing alternative water treatment (AWT) technologies. From 2014 to 2017, the GSA saw a staggering 41% increase in water rates, underscoring the urgent need for a more sustainable cooling tower management strategy. Traditional chemical treatments were becoming increasingly costly and ineffective. A prior attempt with a non-chemical AWT system had led to problematic algae growth and higher maintenance demands.
Before the Clear Comfort (formerly Silver Bullet) AOP water treatment system was introduced, Building 95 struggled with persistent algae issues despite the use of biocides. This not only caused inefficiencies but also drove up maintenance costs.
The Solution: Cooling Tower AOP Water Treatment
Formerly known as Silver Bullet, the Clear Comfort AOP water treatment system offers an effective solution to the cooling tower sustainability challenges. This patented Hydroxyl-Based AOP water treatment technology is a non-chemical biocide that uses hydroxyl radicals to tackle minerals, bacteria, biofilm and other contaminants contributing to scale.
Unlike traditional chemical treatments, which can be costly and labor-intensive, the Clear Comfort AOP system integrates easily into existing cooling tower setups. It draws air from the environment, processes it with hydroxyl radicals and oxidants, and then uses this process to break down minerals and calcium buildup, kill bacteria (including Legionella), and prevent scaling.
This system reduces the need for frequent chemical additions. Instead, it only requires a small amount of biocide occasionally, such as when pollen or debris accumulate. Designed for easy installation and minimal maintenance, the AOP system is ideal for both large and small buildings, especially where a full-time mechanic or on-site cooling-tower contractor might not be available.
The Results: A Clear Win
The GSA, in collaboration with the DOE and the National Renewable Energy Laboratory (NREL), conducted a comprehensive evaluation of four water treatment technologies at Building 95. The Clear Comfort AOP water treatment system stood out among the alternatives, including electrochemical treatment, a salt-based system and chemical scale inhibition.
The results were impressive:
- Water Savings: The AOP system achieved an estimated annual cooling tower makeup water savings of 527,791 gallons, representing a 26.3% reduction. This translates to substantial water and sewer savings, particularly in climates that demand high cooling loads.
- Improved Water Chemistry: The system maintained water chemistry within GSA standards without the need for additional chemicals, except in rare cases. This improvement helped reduce the environmental impact of the chiller plant operations.
- Chemical Use Reduction: The system lowered the need for additional water-treatment chemicals, aside from minimal biocide doses, significantly reducing chemical costs and environmental impact.
- Operational Efficiency: The system helped improve chiller operations by reducing scale and biofilm, which enhanced heat-transfer efficiency and decreased energy consumption. By reducing scale and biofilm, the AOP system improved the heat-transfer efficiency of the chillers. A borescope view of the condenser tubes after two years of operation showed a significant decrease in fouling compared to traditional chemical treatments.
- Increased Cycles of Concentration (CoC): The AOP system increased the CoC at the DFC, with an annual average of 9.54, compared to the typical range of 3 to 6. Modeling indicates that a CoC of 10 captures 84% of the potential water savings.
- Maintenance and O&M Costs: Maintenance costs were reduced by $2,522 annually due to lower chemical expenses and a 50% reduction in operational hours. The ease of installation and minimal maintenance requirements further contributed to operational efficiency.
- Cost-Effectiveness: At the GSA’s average water and sewer costs, the Clear Comfort AOP system demonstrated a financially sound investment with a payback period of just 2.1 years and a savings-to-investment ratio (SIR) of 2.4. Even at the local water rate of $7.14 per kgal, the payback period for the AOP system is six years, while maintaining the same SIR of 2.4. However, at GSA’s average water/sewer cost of $16.76/kgal, the payback period dropped to just two years, with an SIR of 7.2. The system also reduced annual maintenance costs by $2,522 and cut the required O&M hours in half.
In comparison to other alternative water treatment (AWT) technologies evaluated, the Clear Comfort AOP system outperformed in terms of water efficiency, cost savings, and ease of use, making it the preferred choice for federal facilities.
Investing in the Future of Cooling Towers
The successful implementation of this system at the Denver Federal Center highlights its potential to revolutionize cooling tower management across the GSA’s facilities. With its quick return on investment and substantial reductions in water and chemical use, the Clear Comfort AOP water treatment system is a top choice for sustainable cooling tower management.
As the focus on sustainability grows, adopting advanced solutions like the cooling tower Clear Comfort AOP water treatment system is crucial for achieving long-term resource efficiency and cost savings. The success at Building 95 demonstrates how this technology can lead to a more water-efficient and environmentally responsible future.
Interested in how cooling tower AOP water treatment can benefit your facility? Join the upcoming GSA webinar to discover how the other alternative water treatment methods tested measured up to the Clear Comfort AOP water treatment system. To register for the GSA Webinar at 1p.m. on Thursday, August 29, 2024, click here now.
Want to dive deeper? Download the full case study to explore detailed results, insights, and the benefits experienced at the Denver Federal Center. To see the full case study details, click here now.
