Quantifying The Carbon-Sequestration And Evaporative-Cooling Services Of Sugarcane Agroecosystems In Six Sugar-Mill Catchments Of Bangladesh: Implications For Environmental Buffering In The Rooppur Nuclear Power Region

Bangladesh is simultaneously expanding electricity-generation capacity and facing increasing environmental and climatic pressures. Agricultural landscapes remain particularly important because vegetation provides ecosystem services extending beyond food and industrial production.

Sugarcane (Saccharum spp.) is one of Bangladesh’s major industrial crops. The Bangladesh Sugarcane Research Institute identifies Rajshahi, Pabna, Natore, Faridpur and Kushtia among the country’s important sugarcane-producing districts.

The crop is particularly relevant to environmental assessment because sugarcane is a high-biomass C4 crop. During active growth, it removes atmospheric CO₂ through photosynthesis, incorporates carbon into biomass and transfers large quantities of water from soil to atmosphere through evapotranspiration.

The latter process is especially important for local thermal regulation. Evapotranspiration converts part of the available surface energy into latent heat, reducing the proportion available for sensible heating of the land surface.

At the same time, Bangladesh is developing the Rooppur Nuclear Power Plant (RNPP) in Ishwardi, Pabna. RNPP consists of two VVER-1200 units. Official project information reports a thermal output of 3,212 MW for each unit. The IAEA’s PRIS database reports a thermal capacity of 3,200 MWt for each Rooppur unit.

Thus, the two-unit plant has a design thermal-output scale of approximately:

3,212 × 2 = 6,424 MWth

The existence of a large thermal power facility raises an important environmental question:

Can surrounding agricultural ecosystems provide measurable carbon and surface-energy regulation that contributes to environmental buffering in the broader region?

This study focuses on six sugar-mill-associated sugarcane systems:

1. Natore Sugar Mills Ltd.
2. North Bengal Sugar Mills Ltd.
3. Pabna Sugar Mills Ltd.
4. Rajshahi Sugar Mills Ltd.
5. Kushtia Sugar Mills Ltd.
6. Faridpur Sugar Mills Ltd.

The central objective is not to claim that sugarcane can physically neutralize all heat rejected by RNPP. Rather, the study seeks to quantify the magnitude of two ecosystem functions:

(1) atmospheric CO₂ fixation

and

(2) evapotranspirative energy transfer

and evaluate their relevance to environmental buffering.

2. CONCEPTUAL FRAMEWORK

The proposed environmental interaction can be represented as:

RNPP

→ thermal-energy rejection

→ local atmospheric/surface-energy environment

↓

Agricultural landscape

↓

Sugarcane canopy

↙　　　　　　　　　↘

CO₂ fixation　　　 Evapotranspiration

↓　　　　　　　　　　 ↓

Biomass carbon　　 Latent heat flux

↘　　　　　　　　　　 ↙

Environmental buffering capacity

This framework contains two distinct physical mechanisms.

Carbon mechanism

Atmospheric CO₂ is incorporated into plant biomass through photosynthesis.

Thermal mechanism

Water is transferred from soil and plant tissues to the atmosphere through evapotranspiration, consuming latent heat and thereby modifying the surface-energy balance.

These mechanisms should not be treated as identical.

3. RESEARCH QUESTIONS

Primary question

What is the quantitative carbon-sequestration and evaporative-cooling potential of sugarcane agroecosystems associated with the six selected sugar mills?

Secondary questions

1. How much sugarcane area is associated with each mill?
2. How much cane biomass is produced?
3. How much atmospheric CO₂ is represented by this biomass production?
4. How much water is transferred through crop evapotranspiration?
5. What latent-energy flux is associated with that evapotranspiration?
6. How does this environmental-service magnitude compare with the thermal scale of RNPP?
7. Can these agricultural systems reasonably be characterized as environmental buffers?

4. STUDY AREA AND DATA SOURCES

The study covers six sugar-mill systems distributed across important sugarcane-producing regions of Bangladesh.

BSRI identifies Rajshahi, Pabna, Natore, Faridpur and Kushtia among the significant sugarcane-producing districts.

The six selected mills are:

The study uses the following data hierarchy:

Tier 1: Officially reported cultivated area.

Tier 2: Officially reported cane-crushing quantity.

Tier 3: Published regional production data.

Tier 4: Derived estimates using a verified reference yield.

This hierarchy is important because the six mills do not currently have a single publicly accessible, same-year, mill-by-mill cultivated-area dataset.

5. SUGARCANE PRODUCTION BASELINE

The BSRI Annual Research Programme reports that in the 2023–24 cropping season, sugarcane was cultivated on approximately 40.73 thousand hectares in Bangladesh, producing approximately 2.016 million tonnes, corresponding to a national average yield of 48.95 t ha⁻¹.

This value was adopted as the reference yield for reconstructing area from reported cane quantities where direct area data were unavailable.

The relationship is:

Estimated area = Reported cane quantity / 48.95

6. MILL-LEVEL QUANTITATIVE DATASET

6.1 Natore Sugar Mills Ltd.

For the 2025–26 crushing season, Natore Sugar Mill set a target to crush approximately 110,000 tonnes of sugarcane. Cane was to be supplied through 48 centres in eight sub-zones.

Using the reference yield:

110,000 / 48.95 = 2,247 ha

However, a 2026 report states that Natore Sugar Mill authorities were working toward a target of 10,000 acres of sugarcane, equivalent to approximately:

10,000 × 0.404686 = 4,047 ha

The latter is a directly reported cultivation target and is therefore preferred for the land-area estimate.

Adopted area: approximately 4,047 ha.

6.2 North Bengal Sugar Mills Ltd.

North Bengal Sugar Mills in Lalpur, Natore targeted 200,000 tonnes of sugarcane crushing for the 2025–26 season.

Using the reference yield:

200,000 / 48.95 = 4,086 ha

Thus:

Estimated associated cultivated area = 4,086 ha

This should be regarded as a derived estimate rather than a directly reported field-area measurement.

6.3 Pabna Sugar Mills Ltd.

Pabna Sugar Mills stopped production in 2020 and had not resumed production as of December 2025.

Before closure, approximately 6,000 hectares of land were reported to have been under sugarcane cultivation in the Pabna mill-associated production area, producing approximately 100,000 tonnes of cane. After closure, production in the district fell dramatically; a 2022 report stated that only 40–50 ha were then under sugarcane cultivation.

For historical mill-catchment assessment:

Adopted reference area = 6,000 ha

This is explicitly treated as a pre-closure/historical baseline, not as a 2026 active cultivated area.

6.4 Rajshahi Sugar Mills Ltd.

A published report on Rajshahi Sugar Mills stated that sugarcane was cultivated on approximately 4,036 hectares in the mill’s region during the relevant season.

The mill subsequently reported a 2025–26 target of 75,000 tonnes of cane for crushing.

For consistency with the available mill-zone cultivation evidence:

Adopted reference area = 4,036 ha

6.5 Kushtia Sugar Mills Ltd.

Kushtia Sugar Mills has been inactive since the 2020 closure programme.

Historical operational records indicate that the mill targeted 100,000 tonnes of sugarcane during the 2013–14 crushing season.

Using the 48.95 t ha⁻¹ reference yield gives:

100,000 / 48.95 = 2,043 ha

Therefore:

Estimated historical reference area = 2,043 ha

This is a reconstructed historical estimate and should not be interpreted as current active cultivation.

6.6 Faridpur Sugar Mills Ltd.

Historical evidence reports approximately 4,200 hectares of sugarcane under the supervision/catchment of Faridpur Sugar Mills.

The mill serves sugarcane-producing areas of Faridpur and neighbouring districts.

Accordingly:

Adopted reference area = 4,200 ha

Again, this is a historical/reference value requiring current DAE/BSFIC verification before being presented as a 2026 cultivated-area figure.

7. Reconstructed Six-Mill Area

The six reference areas are therefore:

The total should therefore be described as a:

reconstructed six-mill reference area

rather than a verified 2026 cultivated area.

8. Cane Production Equivalent

Applying the reference yield of 48.95 t ha⁻¹ to the reconstructed areas gives:

Thus, under the reconstruction assumptions, the six-mill system represents approximately:

1.195 million tonnes of cane-equivalent annual production.

This is an analytical baseline, not a claim that all 1.195 million tonnes were actually crushed by the mills in the same year.

9. CO₂ FIXATION ESTIMATION

A national greenhouse-gas inventory methodology reported a carbon fraction of approximately 0.45 for dry plant matter and estimated that approximately 802 kg CO₂ were fixed per tonne of fresh sugarcane cane under the relevant biomass-accounting framework.

Accordingly:

Gross CO₂ fixation = Fresh cane production × 0.802

For the six-mill reconstructed production:

1,194,946 × 0.802

=

958,347 tonnes CO₂

Therefore, the reconstructed six-mill sugarcane system represents approximately:

0.96 million tonnes CO₂ of gross biological fixation per crop cycle

This is an important result.

However, it must be described correctly.

It is gross photosynthetic CO₂ fixation represented by biomass production, not automatically equivalent to permanent net ecosystem carbon sequestration.

10. MILL-WISE CO₂ FIXATION

Pabna contributes the largest value in this reconstructed scenario because its historical mill-associated cane area is the largest of the six reference areas.

11. EVAPOTRANSPIRATION AND ENVIRONMENTAL COOLING

Sugarcane cooling should be quantified through evapotranspiration rather than by treating the crop as directly absorbing reactor heat.

Published field research reports sugarcane crop evapotranspiration of approximately 1,438.23 mm over a crop cycle, with a mean daily ET of approximately 4.05 mm in the cited study.

This value is used here as a benchmark scenario, not as a Bangladesh-specific measured value.

For one hectare:

1 mm ET = 10 m³ water

Therefore:

1,438.23 mm = 14,382.3 m³ water ha⁻¹ crop⁻¹

For 24,412 ha:

14,382.3 × 24,412

≈

351 million m³ water per crop cycle

This represents the order of magnitude of water transfer if the benchmark ET rate applies to the reconstructed six-mill area.

12. LATENT-ENERGY FLUX

The latent heat of vaporization of water is approximately:

2.45 MJ kg⁻¹

Since one cubic metre of water has a mass of approximately 1,000 kg:

1 m³ water ≈ 2.45 GJ latent energy

Therefore:

351 million m³ × 2.45 GJ

≈

860 million GJ

or approximately:

860,000 TJ

of latent-energy transfer over the assumed crop cycle.

This is a very large number, but it must be interpreted correctly.

It does not mean that the sugarcane fields remove 860,000 TJ of RNPP waste heat.

The latent-energy flux is driven predominantly by solar radiation, atmospheric demand and water availability.

It demonstrates the scale of the crop’s evaporative energy-transfer capacity, not a direct heat-offset mechanism.

13. COMPARISON WITH RNPP THERMAL OUTPUT

RNPP has two units, each with a thermal output of approximately 3,212 MW.

Thus:

Total reactor thermal output = 6,424 MWth

If hypothetically operated continuously at full thermal output for one year:

6,424 MW × 8,760 h

=

56,274,240 MWh thermal

or approximately:

202,587 TJ thermal energy per year

The benchmark sugarcane evapotranspiration estimate is approximately:

860,000 TJ per crop cycle

This is several times larger in numerical energy magnitude than one year’s total reactor thermal output.

However, this does not mean sugarcane thermally neutralizes RNPP.

The two energy flows have different origins, spatial distributions and physical pathways.

The comparison instead demonstrates that the agricultural landscape has a potentially very large latent-energy flux capacity.

14. Why the “Balance” Concept Must Be Defined Carefully

The original research concept can therefore be reformulated scientifically.

The weak statement would be:

“Sugarcane fields absorb the additional heat generated by RNPP.”

This is not scientifically defensible without direct energy-balance measurements.

The stronger statement is:

“Extensive sugarcane agroecosystems may provide measurable environmental buffering through carbon sequestration and evapotranspirative modification of the local surface-energy balance.”

This distinction substantially improves the publication potential of the research.

15. ENVIRONMENTAL BUFFERING MECHANISM

The environmental-buffering function can be divided into three components.

15.1 Carbon buffering

Approximately:

958,347 t CO₂

of gross atmospheric CO₂ fixation is represented by the reconstructed cane production.

15.2 Evaporative buffering

Approximately:

351 million m³

of water transfer is represented by the benchmark ET scenario.

15.3 Surface-energy buffering

Approximately:

860 million GJ

of latent-energy transfer is represented by the benchmark scenario.

Together, these mechanisms indicate a substantial ecosystem service.

16. SENSITIVITY ANALYSIS

Because the evapotranspiration value is not Bangladesh-specific, a sensitivity analysis is more appropriate than presenting a single number as fact.

Assuming:

• Low ET = 1,000 mm/cycle
• Central ET = 1,438 mm/cycle
• High ET = 1,800 mm/cycle

the estimated latent-energy transfer would be: