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Ethanol

Value to Work Trucks

Ethanol poses a tremendous possibility for offsetting oil consumption. The use of ethanol is by far the most seamless of the alternative transportation fuels; it is simply blended into the fuel purchased by consumers at the pump (most gasoline-powered vehicles can be fueled with a maximum 10 percent blend). A whopping 13.2 billion gallons of ethanol – or 10 percent of the gasoline consumed in the U.S. in 2010 – were blended into gasoline in 2010. This bolstered efforts to offset oil imports, and also positioned the U.S. as the number one producer of ethanol.

With nine million E85 flex vehicles and many of the 200 million gasoline-powered vehicles on the road able to accept ethanol-blended fuel, this alternative transportation fuel takes the lead in the number of vehicles it is able to power in the U.S.

Strengths and benefits of ethanol include:

  • Renewable source – Ethanol is produced from various plant materials through fermentation.
  • Clean fuel – Ethanol is an approved, clean fuel. Direct source carbon dioxide emissions are the same as for gasoline. Ethanol-fueled vehicles produce significantly less carbon monoxide and hydrocarbons than gasoline-powered vehicles.
  • Petroleum offsets – The use of ethanol as a transportation fuel will reduce U.S. petroleum consumption by approximately 70 percent compared to an equivalent gasoline-fueled vehicle.

Glossary Definition

Ethanol (ETOH) is classified as a renewable fuel. It is typically produced from various plant materials–or "biomass"–through a process of fermentation.

Ethanol fuel and drinking alcohol share the same molecular formula –C2H5OH. Ethanol must be denatured (made unfit for human consumption) in order to be designated as a transportation fuel and avoid taxation associated with alcoholic beverages. This can be achieved by blending five percent gasoline with ethanol to produce E95. In the U.S., ethanol is commonly blended with gasoline at low levels (typically 10 percent) to oxygenate the fuel and reduce air pollution. This level of concentration is suitable for use in all modern gasoline engines. 

When blended at a rate of 85 percent ethanol to 15 percent gasoline, ethanol fuel is referred to as “E85” and is considered to be a standalone alternative fuel. E85 should only be used in vehicles equipped with fuel systems specifically designed to accommodate such a high concentration of ethanol. Vehicles so equipped are referred to as “flexible fuel vehicles.”

Recent government studies estimate that ethanol and other biofuels could satisfy at least 30 percent of U.S. gasoline demand by 2030.

E85 Specifications – The American Society of Testing and Materials (ASTM) developed E85 fuel specifications to ensure proper vehicle starting, operation, and safety. E85, like gasoline and diesel fuels, is seasonally adjusted to ensure proper starting and performance in different geographic locations. For example, E85 sold during colder months often contains 70 percent ethanol and 30 percent petroleum to produce the necessary vapor pressure for starting in cold temperatures.

Source Information
 
Resource – Ethanol is classified as a simple alcohol. Chemically, it is derived from ethane gas by the addition of a hydroxidol ion (“OH”) which displaces one of the hydrogen atoms (therefore the name Ethanol). However, the vast majority of the ethanol consumed worldwide is produced through the fermentation of plant sugars by yeast. The two largest producers of ethanol are the U.S. and Brazil. As of Dec. 31, 2010, approximately 96 percent of the ethanol used in the U.S. was produced domestically.

Origin – The specific process utilized for the production of ethanol varies depending on the feed stock utilized. Currently, the majority of the ethanol produced in the U.S. is produced by converting the starches in corn to sugar and then fermenting the sugars.  This can be accomplished through a dry milling or a wet milling process. The majority of ethanol produced for fuel in the U.S. is produced using the dry milling process. For more information, visit the U.S. Department of Energy (DOE) Alternative Fuels Data Center web site.

The production of ethanol in Brazil (the second largest producer) is based on the use of sugar cane, which has high natural sugar content.  This eliminates the need to convert crop starches to sugars and, as a result, the process is somewhat more energy efficient. 

Energy Balance – The need to convert crop starches to sugar when using corn as a feed stock has caused some groups to question the total energy balance of the corn-based ethanol production process. In general, these studies focus only on the actual ethanol production and ignore other aspects of the overall process. A number of high level studies have found that the dry mill production of ethanol for use as a transportation fuel has a 2.3 to 1 positive energy balance. 

Current Supply – Ethanol is a renewable fuel; its supply is primarily constrained by the availability of feed stocks and by economic pressures related to the growth of these feed stocks such as production, transportation and alternative opportunity costs.

While 90 percent of the ethanol currently produced in the United States is derived from corn, other viable feed stocks include plants such as corn, wheat, and milo. Limited availability and high alternative opportunity costs (value as a food product) make the use of sugar-based feed stocks, such as sugar cane and sugar beets, currently uneconomical in the U.S. 

Future Supply – Ethanol production from starch- and sugar-based feed stocks will most likely be limited by concerns as to the long-term impact on land use and food costs.  The development of economical ethanol production processes which utilize cellulosic feed stocks will probably become dominant in the future, which will in turn eliminate the majority of concerns associated with current processes.

Plants contain cellulose and hemicellulose which are complex polymers that form the structure of plant stalks, leaves, trunks, branches, and husks. These polymers contain sugars within their structure but they are more difficult to biochemically convert into ethanol than starch- and sugar-based feed stocks. Cellulose resists being broken down into its component sugars. Hemicellulose is easier to break down, but the resulting sugars are difficult to ferment. Cellulosic feed stocks also contain lignin which interferes with the fermentation process.

The DOE and other government and industry groups are focusing on research to develop processes that economically break down these components of biomass. Significant progress has resulted in biochemical conversion processes to break down cellulose and hemicelluloses, and thermochemical conversion processes to break down lignin. Together, these processes could unlock the potential of cellulosic feed stocks for ethanol production. (Source – DOE)

Cellulosic feed stocks suited to ethanol production include:

  • Agricultural residuecrop residues such as wheat straw and corn stalks, leaves, and husks
  • Forestry residuelogging and mill residues such as wood chips, sawdust, and pulping liquor
  • Grasseshardy, fast-growing grasses such as switch grass grown specifically for ethanol production
  • Municipal and other wastesplant-derived wastes such as household garbage, paper products, paper pulp, and food-processing waste
  • Treesfast-growing trees such as poplar and willow grown specifically for ethanol production

Cellulosic feed stocks have many advantages over starch- and sugar-based feed stocks:

  • Relative abundance means that they can be used to produce more substantial amounts of ethanol to meet U.S. fuel demand. 
  • Some are products of waste from other operations, or—in the case of trees and grasses—are grown specifically for ethanol production.
  • They can be grown on marginal lands not suitable for other crops.

In addition, it is expected that cellulosic feed stocks will have a better overall energy balance and their use will not impact the cost or production of food products. 

The above process flow diagram shows the basic steps in production of ethanol from cellulosic biomass. Note that there are a variety of options for pretreatment and other steps in the process and that several technologies combine two or all three of the hydrolysis and fermentation steps within the shaded box. -- Chart from the National Renewable Energy Lab (NREL).

Environmental Impact – E85 is an approved, clean fuel listed in the 1990 Clean Air Act and the Energy Policy Act of 1992. Direct source CO2 emissions for ethanol are the same as for gasoline (approximately 70.88 kilograms per million BTU). 

Tests conducted by the U.S. Environmental Protection Agency show that ethanol-fueled vehicles (E85) produce 18 percent to 22 percent less carbon monoxide and about eight percent  to 18 percent fewer hydrocarbons than gasoline engines per BTU of energy produced. These values vary considerably depending on the specific vehicle in question.
 
Product Development – The development of ethanol as an internal combustion fuel is supported by a number of industry trade associations, including:

Performance Information

E85 is a liquid fuel that is stored and handled using the same basic equipment as gasoline, assuming the distribution components are resistant to the chemical properties of the product. 

Energy density – One gallon of pure ethanol produces around 80,000 BTU. A gallon of E85 contains around 87,000 BTU of energy (gasoline=125,000 BTU). This gives E85 an energy density of approximately 70 percent of gasoline.

On-Board Vehicle Storage – E85 is stored onboard a vehicle as a conventional liquid fuel assuming the vehicle is designated as a “Flex-Fuel” vehicle. Starting with the 2008 model year (2006 for GM) Flex-Fuel vehicles have a yellow fuel tank fill cap and typically have a “Flex-Fuel” logo displayed on the exterior of the vehicle. 

Octane rating – 110+

Fuel Efficiency – The fuel efficiency of a vehicle operating on E85 varies significantly depending on the specific design of the system. Typically, mileage, when operating on E85, will be between 70 percent and 80 percent of that achieved with conventional gasoline. Engines designed for the exclusive use of E85 may achieve better mileage due to the fuel’s higher octane rating.

Supply Source – Ethanol is produced throughout the United States. The majority of production facilities are located in the midwest, due to the close proximity to feed stock (corn) sources. Local distribution may be by means of tank trucks; national distribution is mostly achieved through railroad tank cars. For a number of reasons, it is not practical to transport ethanol long distances via pipeline; however, tests are being conducted to determine the feasibility of using dedicated pipelines. 

Petroleum Offsets – According to data provided by the Argonne National Labs, the use of E85 as a transportation fuel will reduce U.S. petroleum consumption by approximately 70 percent compared to an equivalent gasoline-fueled vehicle. 

Lifecycle Greenhouse Gas Reduction – Studies sponsored by the DOE – Argonne National Labs, show that ethanol's source-to-wheels emissions of CO2  is approximately 20 percent less than for gasoline (some sources claim up to 35 percent reduction).

Tangible Benefits of E85

  • Reduced greenhouse gas emissions
  • Minimal environmental impact in the event of a spill
  • Reduced need for imported petroleum fuels

Intangible Benefits of E85 

  • Primarily domestically sourced
  • Purpose-built engines with higher compression ratios (equivalent octane rating of 110+) provide improved performance and fuel economy

Limitations of E85

  • Limited availability
  • Relatively low energy density

Financial Issues

Lifecycle Cost Factors of E85

  • In general, the cost of Flex Fuel vehicles are only marginally higher (if at all) than conventional gasoline fueled vehicles
  • Minimal difference in infrastructure costs
  • No significant driver or vehicle maintenance issues

Economic Drivers

Pricing varies significantly by region due to feed stock costs, transportation costs, and regional demand. View current pricing by geographic region.

Potential factors such as carbon credits, tax incentives, etc., will have a significant impact on the future economic viability of ethanol as an engine fuel. The Renewable Fuels Association Web site provides additional information on current tax and incentive issues. 

Other Information Resources

Analysis of CBO Study: Using Biofuel Tax Credits to Achiee Energy and Environmental Policy Goals (Renewable Fuels Association)

Economic Impacts of Ethanol Production (American Coalition for Ethanol)

Effects of Increased Biofuels on the U.S. Economy in 2022 (U.S. Department of Agriculture)

Ethanol Fact Book (Clean Fuels Development Coalition)

Flexible Fuel Vehicles: Providing a Renewable Fuel Choice (DOE)

Handbook for Handling, Storing, and Dispensing E85 (DOE)

Identification and Review of State/Federal Legislative and Regulatory Changes Required for the Introduction of New Transportation Fuels (American Petroleum Institute)

Lifecycle Analysis of Greenhouse Gas Emissions from Renewable Fuels (U.S. Environmental Protection Agency)

Suppliers

Vehicles – Practically all major manufacturers of gasoline powered vehicles produce flex-fuel vehicles. Full listing available from the DOE.

Equipment  – When installing infrastructure for E85 facilities, it is critical to ensure that all components meet the requirements for use with E85. These components are readily available through conventional fuel distribution equipment suppliers and should be “listed”according to existing codes. For more information, visit the DOE Alternative Fuels and Advanced Vehicles Data Center web page.