Cut cooling tower water use with groundwater heat exchange

Submitted through the COP31 Sustainable Transformation Awards · SKD Türkiye (WBCSD Global Network Partner)

The company is a flat steel producer in the manufacturing sector, with more than 1,000 employees.

The site consumes approximately 600,000 m3 of water a year, and the cooling towers account for 45 per cent of that. Evaporation losses in the towers drive a continuous demand for demineralised water, which in turn drives groundwater abstraction and the dosing of biocide-containing treatment chemicals.

There is no specific legal obligation to reduce evaporation losses in cooling towers. The company developed the initiative proactively under its own resource efficiency and sustainability objectives, with water management identified as one of its priority sustainability areas, so the work is a preventive response to water risk rather than a compliance measure.

The initiative began in 2024, using 2023 water consumption data as the baseline.

Location of the initiative: Gemlik, Bursa province, Türkiye

The initiative reduces evaporation by lowering the heat load reaching the cooling towers, rather than by treating or recycling more water.

Groundwater is already abstracted at the site, and it arrives at a low and stable temperature. That thermal potential was previously unused: the water was treated purely as a consumable process input. Heat exchangers were installed so that this water absorbs part of the process heat before the cooling towers see it. With a lower heat load, the towers evaporate less, and less demineralised make-up water is required.

Because biocide-containing chemicals are dosed in proportion to flow, the reduction in make-up water produces a proportional reduction in chemical consumption without any change to the treatment regime.

The work covered measurement, design, equipment selection, system integration, commissioning and monitoring through the site's supervisory control and data acquisition (SCADA) system. It combines existing technologies in a different configuration rather than introducing new technology.

Tower 4 was the pilot. After the results were verified, the approach was extended to Tower 5 in 2025.

Figure 1: Process Flow Diagram

Figure 2: Tower 4-5 Demineralised Water Consumption

Sustainability impact

Climate

The initiative targets Scope 1 and Scope 2 emissions associated with the site's own energy use, through the energy recovery effect of reducing the cooling load.

Approximately 140 tonnes of CO₂e of emissions reduction has been achieved over the period the initiative covers: implementation began in 2024 against the 2023 baseline year, Tower 4 was the pilot, and the application was extended to Tower 5 in 2025. The calculation follows an energy-saving-based approach applied in line with GHG Protocol principles.

Emissions are one of the four indicators tracked continuously alongside the water and temperature measures, using SCADA data and field meter readings, so the figure is updated as the application is extended to further towers.

Nature

Water is the primary environmental outcome. At Tower 4, annual demineralised water consumption fell by 1,400 m³, which corresponds to approximately 2,000 m³ less groundwater abstraction, and demineralised water use at that tower fell by 35 per cent.

Following the pilot, the application was extended to Tower 5 in 2025, where a further 3,820 m³ of demineralised water was saved. The higher saving at the second tower shows that the approach improved as the team learned from the first installation. Across the initiative, approximately 6,000 m³ of water is saved a year.

Because biocide-containing chemicals are dosed in proportion to flow, chemical consumption fell by the same 35 per cent at Tower 4, which reduces the chemical load reaching water ecosystems as well as the volume abstracted from them.

Reuse of existing equipment in the installation supports a circular approach to the plant's asset base.

Social

Reducing groundwater abstraction lowers pressure on a shared local resource in a water-constrained setting, which is the main effect beyond the site boundary.

Within the plant, the initiative was delivered through the coordination of utilities, production and maintenance teams, and the shared problem-solving involved has strengthened technical knowledge exchange between those teams.

Business impact

Benefits

The initiative reduces demineralised water production, groundwater abstraction and treatment chemical purchases at the same time, and it improves cooling tower temperature performance, which supports stable process conditions.

Investment requirement is low and payback is fast, which is what allowed the extension from Tower 4 to Tower 5 to be funded from operational budgets rather than through a separate capital case.

Because the approach uses existing technologies and integrates into existing infrastructure, it can be replicated internally without external project support.

Costs

The cost is the heat exchanger equipment, system integration and commissioning, together with the instrumentation required to monitor performance. The company describes the investment requirement as low relative to the saving.

Ongoing costs are limited to monitoring and the operational attention needed to manage water quality, since the change alters the thermal and chemical balance of the circuit.

The main dependencies are the availability of a sufficient temperature difference between the groundwater and the process, and the stability of water quality. Where these conditions are not present, the saving will be smaller.

Costs are contained by using the existing SCADA infrastructure for monitoring rather than installing a separate system, and by staging the rollout so that each installation is funded from the verified performance of the previous one.

Impact beyond sustainability and business

Co-benefits

Working with the heat exchanger supplier on equipment selection and system design built technical capability on both sides, and the approach developed is transferable to other plants in the same position.

The results are documented well enough to serve as a reference for similar facilities, which supports the spread of resource efficiency decision-making beyond the company.

Potential side-effects

Reducing make-up water changes the chemistry of the circulating water, so conductivity can rise and biological activity can increase if the balance is not managed. These risks are handled through conductivity tracking, dosage control, temperature monitoring and the automation infrastructure.

System integration into a live cooling circuit is the other constraint, since the work has to fit around production. Differences in water quality between sites mean the result achieved at one tower does not transfer automatically to another.

Medium-term extension to Tower 2 and Tower 3 is under assessment, with a total reduction potential of 65,000 m³ identified. That potential depends on the same temperature difference and water quality conditions holding at those towers.

Typical business profile

The approach applies to industrial facilities that operate cooling towers and that also abstract water at a temperature below their process return temperature. Steel, chemicals, energy, petrochemicals and comparable water-intensive sectors are the most direct fit.

It suits sites where water is already metered and where a control system is in place, because the case is built on before-and-after measurement rather than on modelled savings.

Delivery engages utilities, production and maintenance teams, supported by an equipment supplier for exchanger selection and system design.

Approach

1. Establish the water baseline: Identify total site consumption and the share taken by the cooling towers, and fix a baseline year from metered data so that the saving can be evidenced rather than estimated.

2. Look for unused thermal potential: Check whether any water already abstracted on site arrives at a temperature below the process return temperature, since this is the input the approach depends on.

3. Measure the boundary conditions: Record flow rates, temperatures and water quality across the circuit, and define the limits within which the change must operate.

4. Design and select the exchanger: Work with an equipment supplier to size heat exchangers for the available temperature difference, and confirm the integration points into the existing circuit.

5. Pilot on a single tower: Install on one tower first, commission it, and run it long enough to produce monthly performance data against the baseline.

6. Verify with the existing control system: Track demineralised water consumption, total water withdrawal, carbon emissions and cooling tower temperature performance through SCADA and field meters, using a before-and-after comparison.

7. Manage the chemistry: Control conductivity, dosing and temperature as make-up water falls, so that reduced flow does not create biological activity or scaling problems.

8. Extend on evidence: Take the decision to roll out to further towers on the measured results of the pilot, and expect the next installation to perform better as the design is refined.

Stakeholders involved

• Project leads: Senior management sponsors the resource efficiency and water management approach under which the initiative sits, and water management is one of the company's priority sustainability areas. Rollout decisions are taken on measured performance data rather than on projections, which places the decision point with the teams holding the operational evidence.

• Company functions: Utilities, production and maintenance teams coordinated the work. These teams defined process requirements, assessed site conditions, set the boundary parameters and made the system workable in practice, and they retain ownership of design and field application.

• Main providers: A heat exchanger supplier provided technical support on equipment selection and system design, working alongside the internal teams through design and commissioning.

• Other: Pilot results were reviewed with the relevant internal stakeholders and the feedback fed directly into technical improvements and the decision to extend, so that stakeholder involvement continued through implementation and scaling rather than stopping at design.

Key parameters to consider

The baseline is 2023 water consumption data, with monthly performance tracking from 2024. Tower 4 was the pilot and Tower 5 followed in 2025.

The four indicators are demineralised water consumption in m³, total water withdrawal in m3, carbon emissions in tCO₂e and cooling tower temperature performance.

The technical prerequisite is a suitable temperature difference between the abstracted water and the process. Investment requirement is low, payback is fast, and the installation integrates into existing infrastructure, which is what makes internal replication feasible.

Extension to Tower 2 and Tower 3 is under assessment, with 65,000 m³ of total reduction potential identified.

Implementation and operations tips

The insight that carries the initiative is treating abstracted water as a thermal resource rather than only as a consumable input. That reframing is what makes the saving available without new technology.

Piloting on one tower is worth the delay. The second installation saved more than twice the first, because the design was refined using measured data rather than assumptions.

Reduced make-up water changes water chemistry, so conductivity monitoring, dosage control and temperature tracking need to be in place before the flow is reduced, not added after a problem appears.

Using the existing control system for verification keeps the monitoring cost near zero and makes the results credible internally, because the data comes from the same source operations already trust.