The Ethanol Impetus

Relevance: GS3 - Infrastructure: Energy,

(Source: Indian Express, 07/24/2023)

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Why in the news?

• Recently, Prime Minister Narendra Modi announced that India has rolled out 20% ethanol-blended petrol this year and aims to cover the entire country by 2025.
• There has been a significant diversification of feedstocks in ethanol production from C-heavy to B-heavy molasses and direct sugarcane juice, as well as rice and other food grains.

How is ethanol extracted?

From cane

• Route 1: The cane crushed by sugar mills has around 13.5 - 14% total fermentable sugar (TFS) content, of which 11.5% is recovered as sugar.
  • The final by-product of the sugar processing is C-heavy molasses which contains the remaining uncrystallized and non-recoverable 2-2.5% TFS.
  • Around 200-225 liters of ethanol can be produced from C-heavy molasses (40-45% sugar content).
• Route 2: Mills can recover 9.5-10% sugar instead of the maximum 11.5%.
  • The extra TFS can be diverted to B-heavy molasses (more than 50% sugar), which produces 290-320 liters of ethanol per tonne.
• Route 3: The entire 23.5-14% TFS in the cane can be fermented into ethanol.
  • This produces 80-81 liters of ethanol per tonne as compared to the B-heavy (20-21 L) and C-heavy methods (10-11 L).

From grains

• The starch in the grain is first converted into sucrose and simpler sugars like glucose and fructose.
• The sugars are then fermented into ethanol using saccharomyces cerevisiae or brewer’s yeast.
• The process of producing ethanol from grains is longer but produces more ethanol than from molasses.
  • This is because molasses already contain sucrose, glucose, and fructose.

Why is feedstock diversification necessary?

• Higher productivity: Ethanol production from grains is much higher than from molasses due to their higher starch content.

• Year-round production: Distilleries can now produce ethanol throughout the year by operating on multiple feedstocks.
  • During the crushing season, molasses can be used to produce ethanol while surplus grain, sourced from the open market or the FCI can be used to produce ethanol during the off-season.
• Economically beneficial: The diversification of feedstock for ethanol manufacture will reduce the supply and price volatility that was associated with ethanol.
  • Earlier, ethanol was solely dependent on sugarcane which is a seasonal crop.
• Beneficial for farmers: Feedstock diversification has increased the demand for various food grains.
  • Uttar Pradesh (sugarcane producer) and Bihar (maize producer) could supply rice, barley, and millets to distilleries.

Changes in pricing

• Up to 2017-18, Oil marketing companies paid a uniform price for ethanol, regardless of the feedstock from which it was produced.
• Since 2018-19, the Union government has adopted a differential pricing model in which ethanol produced from B-heavy molasses and whole sugarcane juice is charged a higher price.
  • This was meant to compensate mills for the loss in revenue due to the reduced production of sugar.
• As a result, the all-India average ethanol blending has increased from 1.6% in 2013-14 to 11.75% in 2022-23.
• The effect of El Nino on the domestic availability of cereals and sugar in 2023-24 will also affect prices.
  • The government has not imposed restrictions on the ethanol blending programme despite export bans on wheat, sugar, and non-parboiled non-basmati rice due to availability concerns.

How can the byproducts from distilleries be used?

• The liquid effluent or spent wash which is generated during the production of alcohol can have serious environmental problems unless they are properly treated before discharge.

Molasses-based distilleries

• They have multi-effect evaporator (MEE) units where the spent wash is concentrated to 60% solids.
  • The concentrated solids are used as a boiler fuel in a 70:30 ratio with bagasse.
  • The dry ash produced from the incineration contains 28% potash.

Grain-based distilleries

• The spent wash is passed into a decanter centrifuge, where liquids are separated from the solids.
  • The liquid is then concentrated in MEE units and dried along with the wet cake from the decanter.
  • DDGS or distillers’ dried grain with solubles, which is the by-product of the reaction, is also marketed as animal feed.

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FAQs

MCQs

Question: Consider the following statements about ethanol blending:

1. It is more efficient than petrol in terms of combustion.
2. It will reduce India’s dependence on fossil fuel imports.
3. It will contribute to a decrease in stubble burning.

How many of the above statements are correct?

(a) Only 1

(b) Only 2

(c) All 3

(d) None