India's ambitious Ethanol Blended Petrol (EBP) Programme has emerged as a cornerstone of the country's energy security and climate action strategy. By increasing ethanol blending in petrol, India aims to reduce crude oil imports, support farmers, and lower greenhouse gas emissions. However, as ethanol production expands rapidly, an important sustainability question is gaining attention: How much water does ethanol really consume?
Beyond the Distillery: Looking at the Full Water Footprint
A common misconception is that ethanol production requires enormous quantities of water within the distillery itself. In reality, modern ethanol plants are becoming increasingly water-efficient, requiring only about 3–5 litres of process water to produce one litre of ethanol. Many facilities now recycle and reuse water, further reducing freshwater demand.
The larger concern lies in the cultivation of feedstocks used to manufacture ethanol. When irrigation, rainfall, and crop water requirements are included, the total water footprint becomes significantly higher.
Water Footprint of Major Ethanol Feedstocks in India
Different feedstocks have dramatically different water requirements. The table below highlights the estimated water footprint associated with producing one litre of ethanol from various feedstocks commonly used in India.
FeedstockApproximate Water Footprint (L Water/L Ethanol)Rice (including broken rice)10,790 LMaize (Corn)4,670 LSugarcane Juice3,630 LMolasses2,000–3,000 LAgricultural Residues (Rice Straw, Bagasse, Crop Waste)Lowest footprint; minimal additional cultivation water
The data reveals that rice-based ethanol has the highest water footprint among commonly used feedstocks. Sugarcane and molasses-based ethanol perform relatively better, while maize occupies an intermediate position. Second-generation (2G) ethanol, produced from agricultural residues such as rice straw and bagasse, offers the most sustainable option because it utilizes waste biomass rather than requiring dedicated crop cultivation.
Why Water Footprint Matters
India is home to nearly 18% of the world's population but possesses only about 4% of global freshwater resources. Several ethanol-producing states, including Uttar Pradesh, Maharashtra, Karnataka, and Telangana, already face groundwater depletion and water stress.
As ethanol production scales up to meet national blending targets, feedstock selection will become increasingly important. Expanding production through highly water-intensive crops may create additional pressure on already strained water resources.
Pathways Towards Sustainable Ethanol
To ensure that ethanol remains a truly sustainable fuel, several measures are essential:
- Promote second-generation (2G) ethanol technologies using crop residues.
- Encourage drip irrigation and precision agriculture for feedstock cultivation.
- Improve water recycling and wastewater treatment in distilleries.
- Support region-specific feedstock strategies based on local water availability.
- Invest in research and innovation to improve crop productivity with lower water use.
Balancing Energy Security and Water Security
Ethanol offers significant economic and environmental benefits, from reducing fossil fuel dependence to creating new opportunities for farmers. However, sustainable biofuel development requires balancing energy goals with responsible water management.
As India progresses toward higher ethanol blending targets, understanding and reducing the water footprint of ethanol production will be critical. The future of biofuels will not only depend on how much energy they can generate but also on how efficiently they utilize the planet's most precious resource—water.
Example: Rice-Based Ethanol
- Water Requirement (Plant): ~3–5 L water per litre ethanol
- Water Footprint (Lifecycle): ~10,790 L water per litre ethanol
The large difference arises because most water is consumed during cultivation of rice rather than inside the ethanol plant.
Feedstock Comparison for India
Water Requirement (Plant)Water Footprint (Lifecycle)Rice: 3–5 L/L ethanol~10,790 L/L ethanol
Maize: 3–5 L/L ethanol~4,670 L/L ethanol
Sugarcane Juice: 3–5 L/L ethanol~3,630 L/L ethanol
Molasses: 3–5 L/L ethanol~2,000–3,000 L/L ethanol
Agricultural Residues (2G Ethanol): 3–5 L/L ethanol Lowest footprint