Ethanol Production Processes

How is Ethanol Made?

The process of making alcohol has been around since virtually as long as man has been on this earth, though it has been refined and upgraded in recent years leading to improved efficiency. There are three main uses for ethanol (industrial, beverage and fuel) and the production processes vary slightly for each of them, but the main steps are the same. Examples of industrial uses of ethanol would include ethanol used in perfumes, aftershaves and for cleaners. Beverage ethanol is used for drinking and must meet strict production standards because it will be used for human consumption.

A vast majority of ethanol produced in the United States is used for fuel. It is blended with gasoline to increase the fuel blend’s octane or to produce a cleaner burning fuel. Most of the ethanol plants in the country utilize a dry milling process. The major steps are outlined below:

1. Milling: The corn (or barley or wheat) will first pass through hammer mills, which grind it into a fine powder called meal.
2. Liquefaction: The meal will then be mixed with water and alpha-amylase, and will pass through cookers where the starch is liquefied. Heat will be applied at this stage to enable liquefaction. Cookers with a high temperature stage (120-1500C) and a lower temperature holding period (950C) will be used. These high temperatures reduce bacteria levels in the mash.
3. Saccharification: The mash from the cookers will then be cooled and the secondary enzyme (gluco-amylase) will be added to convert the liquefied starch to fermentable sugars (dextrose), a process called saccharification.
4. Fermentation: Yeast will then be added to the mash to ferment the sugars to ethanol and carbon dioxide. Using a continuous process, the fermenting mash will be allowed to flow through several fermenters until the mash is fully fermented and leaves the final tank. In a batch fermentation process, the mash stays in one fermenter for about 48 hours before the distillation process is started.
5. Distillation: The fermented mash, now called ‘beer’, will contain about 10% alcohol, as well as all the non-fermentable solids from the corn and the yeast cells. The mash will then be pumped to the continuous flow, multi-column distillation system where the alcohol will be removed from the solids and the water. The alcohol will leave the top of the final column at about 96% strength, and the residue mash, called stillage, will be transferred from the base of the column to the co-product processing area.
6. Dehydration: The alcohol from the top of the column will then pass through a dehydration system where the remaining water will be removed. Most ethanol plants use a molecular sieve to capture the last bit of water in the ethanol. The alcohol product at this stage is called anhydrous (pure, without water) ethanol and is approximately 200 proof.
7. Denaturing: Ethanol that will be used for fuel is then denatured with a small amount (2-5%) of some product, like gasoline, to make it unfit for human consumption.
8. Co-Products: There are two main co-products created in the production of ethanol: carbon dioxide (CO2) and distillers’ grain. CO2 is given off in great quantities during fermentation and many ethanol plants collect that CO2, clean it of any residual alcohol, compress it and sell it for use to carbonate beverages or in the flash freezing of meat. Distillers’ grains, wet and dried, are high in protein and other nutrients and are a highly valued livestock feed ingredient. Some ethanol plants also create a ‘syrup’ containing some of the solids that can be a separate production sold in addition to the distillers’ grain, or combined with it. Ethanol production is a no-waste process that adds value to the corn by converting it into more valuable products.

Back

Ethanol: Issues & Objectives

Several countries like USA and Brazil for instance, have successfully used ethanol as a fuel substitute for automobiles. There is no reason why this fuel option cannot be explored and employed in India when there is a need to economize consumption of petroleum products. Perhaps an appropriate mix of petrol and alcohol (ethanol) in the fuel tank of vehicles is a right alternative for India. Another advantage about using ethanol is that it has a very high octane rating as compared to petrol. This helps in eliminating the use of lead additives and consequently helps in reducing vehicular pollution. Ethanol refineries could also be excellent economic development vehicles as they can create more jobs/employment than oil refineries.

To adopt a long-term strategy regarding the introduction of ethanol as an alternative fuel, the following questions need to be looked into:

• It is important to develop and adopt a systemic approach in setting and reviewing fuel standards including a sound understanding of the impact of fuel emissions, health impacts and the economic cost of these to society, and the final impact for producers, distributors and consumers.
• There is a great need for improving coordination within the Government, and between the Government and the Energy and Automotive Industry in developing a comprehensive policy on alternative fuels like ethanol.
• To facilitate the introduction of alternative fuels like ethanol, both technical and financial considerations need to be dealt with simultaneously.
• The use of any alternative fuel like ethanol will also be determined by local availability and pricing considerations. Detailed studies are required on the optimal use of incentives in the form of tax breaks and subsidies to promote the introduction and use of alternative fuels like ethanol. The study should address the current prices and taxation of conventional fuels. What is most important is that incentive packages and policies that cannot be sustained over extended periods should be avoided and an appropriate pricing and taxation structure should be evolved fully integrating the environmental cost of different types of fuels to ensure that alternative fuels get a fair chance in the market place. Another important aspect is that while such an incentive structure is being evolved, there is a need to facilitate an open dialogue between the Government, the private sector and various universities/institutions/academies and society at large on such alternative fuel options and environmental issues to overcome possible confrontation between various interest groups.

Courtesy: Mr S N Pattanayak, Deputy Secretary, Ministry of Road Transport & Highways, Transport Bhawan New Delhi- 110 001

The views and opinions expressed in this article are those of the author and do not reflect those of the Indian Government.

Back

Studying Viable Options to Reduce Air Pollution

Worldwide economic development has led to increased greenhouse gas (GHG) emissions that are beginning to effect global climate patterns. Developing countries like India and China are major contributors of GHG emissions, with India being the world’s second fastest growing GHG producer. A significant portion of India’s total carbon emissions is associated with the transport sector, making India’s cities some of the most polluted in the world.

With predominantly hot weather and high solar intensity in most parts of the country year-round, high ozone levels occur quite frequently in the urban areas. In the northern regions of the country, carbon monoxide (CO) emissions are greater during the winter. The principal air quality concerns arising from petrol-driven mobile-source emissions are ozone, toxic air pollutants and CO.

Estimating the impact of vehicular emissions on air quality is a complex science. It involves gathering data on tailpipe and evaporative emissions from each vehicle for each type of fuel used, estimating fleet characteristics and population driving patterns, and incorporating the effects of meteorological and geographic conditions to project the persistence of primary and secondary emissions.

Studies have shown that the benefit of adding ethanol is greatest with older cars and vehicles that operate on old technology. Ethanol is used in about 80% of the oxygenated fuels program in the US, which has been very successful in reducing urban CO emissions. USAID, under its Greenhouse Gas Pollution Prevention project will be conducting a study (to be completed by September 2002) in Hyderabad on various viable options to reduce emissions from vehicles.

Studies have shown that by blending ethanol with petrol products most toxic air pollutants decrease. More specifically, reductions in the values of CO, hydrocarbons, particulate, SOx and NOx have been found.

The Government of India has approved the use of ethanol produced from sugarcane and agricultural residues as an additive to motor fuels to reduce vehicular emissions. With bagasse being used as the desirable feedstock for ethanol production, the potential benefits of using it as a fuel additive for India will be - a reduction in the net emissions of carbon dioxide, improved air quality in cities, spurred rural economic development and improvement in the country’s energy security by reducing reliance on imported oil.

Courtesy: Mr Sandeep Tandon, Project Management Specialist, E3, USAID/India; Email: standon@usaid.gov Web: www.usaid.gov/in/

Back

A ‘Win-Win’ Fuel

Ethanol is a great product that is beneficial for the environment and the economy. This article describes the benefits to consumers, taxpayers, farmers and the energy/trade and environmental benefits to the United States.

Consumer Benefits

• US consumers use more than 15 billion gallons of high performance, cleaner ethanol blended gasoline each year.
• Ethanol and ETBE increase oxygenate supplies, reducing the need for MTBE imports and helping to reduce consumer costs.
• Ethanol is used by gasoline marketers - helping to keep this class of trade viable and creating competition for oil companies.

• The partial excise tax exemption for ethanol and ETBE blends available to gasoline marketers saves money. Reduced farm program costs and increased income tax revenues offset the cost of the incentive.
• The economic activity attributable to the ethanol industry will generate $3.5 billion in additional income tax revenue over the next five years - $1 billion more than the cost of the exemption. The US ethanol industry will create a net gain to the taxpayers of almost $4 billion over the next five years.

• More than $3 billion has been invested in 55 ethanol production facilities operating in 20 different States across the country.
• The ethanol industry is responsible for more than 40,000 direct and indirect jobs, creating more than $1.3 billion in increased household income annually.
• The ethanol industry directly and indirectly adds more than $6 billion to the American economy each year.
• The demand for grain created by ethanol production increases net farm income more than $12 billion annually.
• As the economic activity created by the ethanol industry ripples through the economy, it will generate $30 billion in final demand between 1996 and 2000.
• A 100 million gallon ethanol plant could create 2,250 local jobs.

• Industrial corn use, which includes ethanol and sweetener production, is now the second largest consumer of corn in America. Each $1 of up-stream and on-farm economic activity generates $3.20 in downstream economic stimulus attributable to ethanol processing, compared to just $0.31 when corn is exported.
• Ethanol production consumed 535 million bushels of corn in 1994 (5.3% of the record 10 billion bushel corn crop).
• The demand for corn created by the ethanol industry increases crop values - accounting for approximately $0.14 of the value of every bushel of corn sold, or $1.4 billion.
• If the market for ethanol did not exist, corn stocks would rise and net income to American corn farmers would be reduced by $6 billion over the next five years, or about 11%.
• Many farmers now own and operate ethanol plants, allowing them to add value to their own corn.

• Domestic ethanol and ETBE production reduces demand for imported oil and MTBE representing almost 80% of the US trade deficit.
• Currently, imported oil accounts for about 53% of oil used, and imported MTBE is at a record 31% of domestic production.
• Today, ethanol reduces the demand for gasoline and MTBE imports by 98,000 barrels per day. A 98,000 barrel/day replacement of imported MTBE would represent a $1.1 billion reduction to our annual trade deficit.
• Ethanol production also generates exports of feed co-products, such as corn gluten, further enhancing balance of trade.
• Ethanol production is extremely energy efficient, with a positive energy balance of 125%, compared to 85% for gasoline. Each Btu used to produce a Btu of gasoline could be used to produce 8 Btus of ethanol.

• 10% ethanol blends reduce CO better than any other reformulated gasoline blend - more than 25%.
• Ethanol is low in reactivity and high in oxygen content, thus reducing ozone pollution.
• Ethanol is a safe replacement for toxic octane enhancers in gasoline such as benzene, toluene and xylene.