Common ethanol fuel mixtures

E15

As a result of the Energy Independence and Security Act of 2007, which mandates an increase in renewable fuels for the transport sector, the U.S. Department of Energy began assessments for the feasibility of using intermediate ethanol blends in the existing vehicle fleet as a way to allow higher consumption of ethanol fuel. In a preliminary report released in October 2008, the NREL presented the results of the first evaluations of the effects of E10, E15 and E20 gasoline blends on tailpipe and evaporative emissions, catalyst and engine durability, vehicle driveability, engine operability, and vehicle and engine materials.

In March 2009 a lobbying group from the ethanol industry, Growth Energy, formally requested the U.S. Environmental Protection Agency (E.P.A.) to allow the ethanol content in gasoline to be increased to 15 percent from 10 percent. Organizations doing such studies included the Energy Department, the State of Minnesota, the Renewable Fuels Association, the Rochester Institute of Technology, the Minnesota Center for Automotive Research, and Stockholm University in Sweden.

In October 2010 the EPA granted a waiver to allow up to 15% of ethanol blended with gasoline to be sold only for cars and light pickup trucks with a model year of 2007 or later, representing about 15% of vehicles on the U.S. roads. In January 2011 the waiver was expanded to authorize use of E15 to include model year 2001 through 2006 passenger vehicles. The EPA also decided not to grant any waiver for E15 use in any motorcycles, heavy-duty vehicles, or non-road engines because current testing data does not support such a waiver. According to the Renewable Fuels Association the E15 waivers now cover 62% of vehicles on the road in the US, and the ethanol group estimates that if all 2001 and newer cars and pickups were to use E15, the theoretical blend wall for ethanol use would be approximately 17.5 billion gallons per year. EPA is still studying if older cars can withstand a 15 percent ethanol blend.

As EPA waiver authorize but does not require stations to offer E15, a practical barrier to the commercialization of the higher blend is the lack of infrastructure, similar to the limitations suffered by sales of E85, as most fuel stations do not have enough pumps to offer the new blend, few existing pumps are certified to dispense E15, and there are no dedicated tanks readily available to store E15. Also some state and federal regulations would have to change before E15 can be legally sold. || E20-25 |- style="text-align:center;" | style="background:#cfc;"|2001 || E22 ||style="background:#cfc;"|2011 || E18-E25 |- style="text-align:left;" | colspan="4" |Source: 1937-2007, J.A. Puerto Rico (2007), Table 3.8, pp. 81–82 Due to this mandatory minimum gasoline blend, pure gasoline (E0) is no longer sold in Brazil. A federal law was passed in October 1993 establishing a mandatory blend of 22% anhydrous ethanol (E22) in the entire country. This law also authorized the Executive to set different percentages of ethanol within pre-established boundaries, and since 2003 these limits were fixed at a maximum of 25% (E25) and a minimum of 20% (E20) by volume. and this has been the standard gasoline blend sold throughout Brazil most of the time as of 2011. However, as a result of a supply shortage and the resulting high ethanol fuel prices, in 2010 the government mandated a temporary 90-day blend reduction from E25 to E20 beginning February 1, 2010. As prices rose abruptly again due to supply shortages that took place again between the 2010-2011 harvest seasons, some ethanol had to be imported from the United States, and in April 2011 the government reduced the minimum mandatory blend to 18 percent, leaving the mandatory blend range between E18 to E25. All Brazilian automakers have adapted their gasoline engines to run smoothly with these range of mixtures, thus, all gasoline vehicles are built to run with blends from E20 to E25, defined by local law as "Common gasoline type C". Some vehicles might work properly with lower concentrations of ethanol, however, with a few exceptions, they are unable to run smoothly with pure gasoline which causes engine knocking, as vehicles traveling to neighboring South American countries have demonstrated. Flexible-fuel vehicles, which can run on any mixed of gasoline E20-E25 up to 100% hydrous ethanol (E100 or hydrated ethanol) ratios, were first available in mid 2003. In July 2008, 86% of all new light vehicles sold in Brazil were flexible-fuel, and only two carmakers build models with a flex-fuel engine optimized to operate with pure gasoline (E0): Renault with the models Clio, Symbol, Logan, Sandero and Mégane, and Fiat with the Siena Tetrafuel.

Thailand introduced E20 in 2008, however, shortages in ethanol supplies by mid-2008 caused a delay in the expansion of the E20 fueling station network in the country. By mid 2010 there were 161 fueling stations selling E20 and sales have risen 80% since April 2009.

E70, E75

For temperature below -15 ° Celsius (5 °F) all E85 flex vehicles require an engine block heater to avoid cold starting problems.

E85

Thailand introduced E85 fuel by the end of 2008, and by mid 2010 there were only four E85 filling stations, with plans to expand to 15 stations by 2012.

ED95

As of 2010 the Swedish ED95 engines are in its third generation and already have complied with , without any kind of post-treatment of the exhaust gases. The ethanol-powered engine is also being certified as Environmentally Enhanced Vehicle (EEV) in the Stockholm municipality. The EEV rule still has no date to enter into force in Europe and is stricter than the Euro 5 standard.

Nottingham became the first city in England to operate a regular bus service with ethanol-fueled vehicles. Three ED95 single-deck buses entered regular service in the city in March 2008. Soon after, Reading also introduced ED95 double-deck buses. trial bus operating in São Paulo, Brazil]] Under the auspices of the BioEthanol for Sustainable Transport (BEST) project, more than 138 bioethanol ED95 buses were part of demonstration trial at four cities, three in Europe, and one in Brazil, between 2006 and 2009. In Brazil, the first Scania ED95 bus with a modified diesel engine was introduced as a trial in São Paulo city on December 2007, and since November 2009 there were two ED95 buses in regular service. The Brazilian trial project run for three years and performance and emissions were monitored by the National Reference Center on Biomass (CENBIO- ) at the Universidade de São Paulo. The first ethanol-powered buses were delivered in May 2011, and the 50 buses will start regular service in June 2011 in the southern region of São Paulo. The 50 ED95 buses had a cost of R$ 20 million () and due to the higher cost of the ED95 fuel and the lower energy content of ethanol as compared to diesel, one of the firms participating in the cooperation agreement, Raísen (a joint venture between Royal Dutch Shell and Cosan), supplies the fuel to the municipality at 70% of the market price of regular diesel.

E100

The first commercial vehicle capable of running on pure ethanol was the Ford Model T, produced from 1908 through 1927. It was fitted with a carburetor with adjustable jetting, allowing use of gasoline or ethanol, or a combination of both. At that time, other car manufactures also provided engines for ethanol fuel use. after testing with several prototypes developed by the Brazilian subsidiaries of Fiat, Volkswagen, General Motors and Ford. Since 2003, Brazilian newer flexible-fuel vehicles are capable of running on pure hydrous ethanol (E100) or blended with any combination of E20 to E25 gasoline (a mixture made with anhydrous ethanol), the national mandatory blend. An improved flex engine generation was developed to eliminate the need for the secondary gas tank by warming the ethanol fuel during starting, and allowing flex vehicles to do a normal cold start at temperatures as low as minus 5 ° Celsius (23 °F), the lowest temperature expected anywhere in the Brazilian territory. The Polo E-Flex, launched in March 2009, was the first flex fuel model without an auxiliary tank for cold start. The warming system is called Flex Start and was developed by Robert Bosch GmbH.

Swedish carmakers have developed ethanol only capable engines for the new Saab Aero X BioPower 100 Concept E100, with a V6 engine which is fuelled entirely by E100 bioethanol, and the limited edition of the Koenigsegg CCXR, a version of the CCX converted to use E85 or E100, as well as standard 98 octane gasoline, and currently the fastest and most powerful flexible fuel vehicle with its twin-supercharged V8 producing 1018 hp when running on biofuel, as compared to 806 hp on 91 octane unleaded gasoline.

The higher fuel efficiency of E100 in high performance race cars resulted in Indianapolis 500 races in 2007 and 2008 being run on 100 percent fuel grade ethanol.

Modifications to engines