WHAT ARE THE BENEFITS OF THE ‘SMOKE’ EMITTED BY COOLING TOWERS?
The ‘smoke’ emitted by cooling towers is not actually smoke at all, but largely a mixture of water vapour (mist). In other words, rather than harmful gases, it consists of fine water droplets released into the air.
For this reason, the “benefits” are not direct like a product, but some indirect positive effects can be mentioned:
- Contribution to the Ambient Humidity Balance
As cooling towers release water vapour into the air:
- They can increase local humidity in very dry regions
- They can slightly reduce excessive dryness, particularly in summer
- Microclimate (Local Cooling) Effect
As heat is absorbed during evaporation:
- A slight cooling effect occurs around the tower
- This can locally reduce temperatures in industrial areas
- Dust Suppression (Limited Effect)
Moisture released into the air:
- May help dust particles in the immediate vicinity settle to the ground
- Provides a small advantage, particularly in open-air facilities
- Contribution to Energy Efficiency (Indirect Benefit)
The main benefit lies here:
- Processes operate more efficiently thanks to cooling towers
- This reduces overall energy consumption and indirect emissions
WHAT ARE THE REASONS FOR THE PERCEPTION THAT SMOKE EMITTED FROM COOLING TOWERS IS HARMFUL?
The main reason why the vapour emitted from cooling towers is perceived as harmful is the conflation of visual and psychological perception with technical knowledge. In fact, in most cases this ‘smoke’ is simply water vapour, but the following factors create a negative impression in people
- Confusion with Actual Smoke
- It looks very similar to combustion gases emitted from chimneys
- Especially when it appears as a dense white cloud, it creates the perception of “factory smoke”
- People automatically associate this with pollution
- Perception of Industrial Facilities
- Cooling towers are generally found in:
- Power stations
- Refineries
- Large industrial facilities
- Consequently, people make the generalisation that “anything emitted is harmful”
- Appearing Thicker in Cold Weather
- Especially in winter:
- The vapour condenses and appears as a much thicker cloud
- This situation:
- Is misinterpreted as “more smoke is coming out → it’s more harmful”
- Odour and Chemical Concerns
- Normally, the vapour is odourless, but:
- Due to chemicals used in the water (biocides, scale inhibitors, etc.)
- A faint odour may rarely occur
- This creates a perception of “poisonous gas” in people, but it is harmless
- Drift (Water Droplet Transport)
- Very small water droplets may be carried from the towers
- These droplets:
- Contain minerals (lime, etc.)
- People may perceive this as:
- “chemicals being sprayed”
- Media and Visual Impact
- In films and news reports:
- Large white clouds are generally portrayed as a symbol of “pollution”
- This creates a negative subconscious association
DOES THE SMOKE EMITTED HAVE A CHEMICAL COMPOSITION?
As the ‘smoke’ emitted from cooling towers is actually, in most cases, not smoke from combustion in the true sense but water vapour (mist/fog), it is not generally considered to be a fixed mixture of ‘chemical compounds’ in the conventional sense. However, let me explain clearly what it might contain:
- Main component (the largest part)
- Water vapour (H₂O)
- This is formed by the evaporation of hot water in the tower
- The white cloud we see is caused by small water droplets scattering light
- Substances that may be carried within the water droplets
Cooling towers do not operate entirely with pure water. Depending on the chemistry of the water inside, the following substances may be carried in trace amounts:
- a) Dissolved minerals
- Calcium (Ca²⁺)
- Magnesium (Mg²⁺)
- Sodium (Na⁺)
- Chloride (Cl⁻)
- Sulphate (SO₄²⁻)
These are generally present in very low concentrations (carried by drift)
- b) Chemical additives (water treatment chemicals)
Used in the cooling tower water:
- Biocides (to prevent bacteria)
- Corrosion inhibitors
- Antiscalants (to prevent limescale)
These too may be emitted as aerosols at very low levels
- The answer to the question “Is the smoke harmful?”
- In a normally operating tower:
- Over 99% is water vapour
- The chemical load is very low
- Why do people assume it is “chemical smoke”?
- White cloud = perception of industrial smoke
- Emitting from a flue
- Resembling thermal power station smoke in appearance
But:
No combustion → no actual smoke → essentially steam
ARE THERE ANY GASES (COMPOUNDS, ELEMENTS OR MOLECULES) İN THE SMOKE EMİTTED FROM THE COOLİNG TOWER STACK THAT ARE NOT PRESENT İN THE AİR?
WHEN THE SMOKE EMITTED FROM THE COOLING TOWER CHIMNEY DISPERSES INTO THE AIR, COULD ANY HARMFUL GASES FORM, EITHER ON THEIR OWN OR BY COMBINING WITH OTHER GASES?
- Yes, there may be some substances at the tower outlet that are not normally found in the air, but
- These are generally not gases, but are carried within water droplets (aerosols) and
- Their spontaneous transformation into new harmful gases is very limited.
Let’s clarify this technically:
- Are there ‘substances not normally found in the air’?
Yes, but the form is important:
Substances normally present in low concentrations or absent in the air
- Dissolved salts in water (Ca²⁺, Mg²⁺, Cl⁻, etc.)
- Chemical additives (biocides, inhibitors)
- Microorganisms (e.g. Legionella)
These are not in gaseous form,
but are carried within very small water droplets (drift/aerosol).
In other words:
These do not “mix into the air as gases”, but are carried by water droplets.
- Are harmful gases formed at the tower outlet?
Under normal operating conditions:
No, no significant production of harmful gases is expected
Because:
- No combustion
- No chemical reactions at high temperatures
- No strong conversion environment such as UV/ozone
However, there are some special cases
- Gas formation due to chemical dosing
If the wrong chemical is used:
Example:
- Chlorine-based biocides (NaOCl)
- Acidic environment
Reaction: Cl₂ (chlorine gas) may be released (very low probability but possible)
This gas: - Is irritant
- Is carefully controlled in industry
- Volatile chemicals
Some biocides or organics:
- May partially evaporate
- May enter the air
However:
Concentrations are generally very low; the likelihood of causing or spreading disease is negligible.
- Ammonia / amine derivatives
In some systems:
- As a result of pH control or chemical reactions
- NH₃ (ammonia) may form
However, this too:
Is rare and occurs at low levels
- Does a new harmful gas form through reaction in the air?
In practice: very low probability
Because:
- Concentration is very low
- Reaction time is short
- Rapid dilution occurs in the atmosphere
However, theoretically:
- Chlorine derivatives → oxidation
- Organics → photochemical reaction
But:
These effects cannot even be compared to industrial exhaust gases
- Conclusion
- Substances not normally found in the air may be released → YES
- Are these mostly gases? → NO (aerosols)
- Do new harmful gases form? → Normally NO
- In special circumstances → they may be present at very low levels,
