Flexible fuel vehicle
A Flexible Fuel Vehicle ( FFV , sometimes also called Fuel Flexible Vehicle ) - in English, for example, "vehicle that can be adapted to fuel" - is a vehicle that can be operated with gasoline , the alcohols methanol and ethanol and any mixtures of these three fuels. The term must be clearly differentiated from the multi - fuel engine , which sounds similar in German and burns a wide variety of fuels, and from engines that run on diesel fuel or biodiesel .
The purpose of such a concept is the preferential use of (bio) alcohols, whereby gasoline operation is also possible if they are temporarily or regionally unavailable and therefore mobility for the vehicle operator is guaranteed in contrast to pure alcohol vehicles.
technology
Essential modifications of an FFV compared to gasoline-powered vehicles are:
- Adaptation of mixture formation and ignition to the respective fuels
- Use of a sensor to determine the current alcohol content in the fuel (alcohol sensor)
- alcohol-resistant materials in the fuel circuit (tank, fuel pump, fuel lines, injection valves)
- possibly special engine oils and material adjustments
While vehicles for gasoline-alcohol mixed fuels or pure alcohol operation were developed and put into operation as early as the 1980s (mainly in Brazil), the development of FF technology began in the early 1990s after suitable alcohol sensors became available. In the USA, especially in California, extensive fleet tests were then carried out with the methanol fuel M85 ( CEC's Light-Duty Methanol Fuel Flexible Vehicle Demonstration Program ), in which the German car manufacturers Mercedes-Benz and Volkswagen also took part. The latter also developed the first FFV designed for the US market and specifically for E85 ethanol fuel , which were then used by the Illinois Corn Marketing Board for demonstration and test purposes. The operator wanted to motivate the domestic auto industry to develop such concepts.
Due to the foreseeable reduction in crude oil reserves and the increasing environmental pollution, there has been increased interest worldwide in FF technology for several years, but now with a focus on the use of bioethanol to reduce greenhouse gas emissions ( carbon dioxide ).
A capacitive alcohol sensor suitable for FFV was developed by Siemens in cooperation with Mercedes-Benz and Volkswagen after the optical sensors had not proven themselves due to system-related problems. This sensor measures the change in capacitance, the conductivity and the temperature of the fuel and uses this to calculate the alcohol content, which is passed on to the control unit as a digital output signal so that the injection quantity and ignition timing are adjusted according to the current fuel composition. Because of the lower calorific values of alcohols compared to gasoline, almost twice the amount of fuel is required per injection in the M85 operation, and around a third more in the E85 operation; The fuel system must be adapted accordingly (delivery rate of the fuel pump, larger fuel tank, etc.).
Both methanol and ethanol fuel contain an addition of 15 percent special volatile hydrocarbons or, in the simplest case, gasoline (hence the designation M85 or E85 ). This addition is mainly used to improve the cold start and cold running properties below about 15 ° C, which are critical for pure alcohols, as well as to shift the upper explosion limits for safety reasons. In the case of pure alcohols, under certain conditions this could lead to the ignition of fuel vapor in the tank.
Emissions
Today's FFVs are equipped with the latest technology for exhaust aftertreatment, for example with lambda control and vehicle catalytic converters as well as knock control . FFV must meet the applicable emissions laws for gasoline operation and the respective alcohol fuel M85 or E85 as well as for mixtures. Since azeotropic mixtures (fuel anomalies) with increased vapor pressure are formed with certain mixing ratios (for example with M35), this must be given special consideration with regard to emissions and driving behavior. In the USA, measurements of the evaporative emissions from the fuel system are therefore prescribed specifically with this critical fuel (SHED test). Furthermore, it must be taken into account that increased aldehyde emissions (formaldehyde or acetaldehyde) occur when using alcohol . A limit value is prescribed in the USA for formaldehyde, which is critical to health.
On the other hand, the low emissions of aromatics (benzene or toluene), polycyclic aromatic hydrocarbons (PAHs, American PAH / PNA) and the lower ozone formation potential due to the lower number of reactive Non Methane Organic Gases (NMOG) components in the exhaust gas are advantageous in alcohol operation . This “harmful ozone” near the ground (in contrast to the “useful ozone” in the stratosphere) is the main component of photochemical smog .
When assessing different fuels, the CO 2 -equivalent emissions of the entire chain, from the provision of the primary energy to the combustion in the engine ( well-to-wheel CO 2 -equivalent emissions ), are important. According to the current state of knowledge, various studies show the following CO 2 -equivalent emissions compared to petroleum-based gasoline :
- for methanol from natural gas about 10% lower emissions (mean value) with a range of −10% / + 10% to the mean value
- for methanol from cellulosic biomass around 70% lower emissions with a range of −10% / + 30%
- For ethanol from starchy biomass, emissions are around 5% higher with a range of −50% / + 30%
- For ethanol from cellulose-containing biomass, emissions are around 50% lower with a range of −30% / + 30%
The sometimes large bandwidths are mainly due to different conversion technologies and energy supplies (keyword: electricity mix) as well as the availability of different biomasses, whereby especially with fast-growing energy crops, breeding, fertilization and harvesting lead to a high proportion of CO 2 equivalent emissions.
distribution
In Brazil , gasoline is only offered with an ethanol content of 20 to 25% (E25), which the government sometimes adjusts to stabilize prices due to the market situation. Vehicles for this mixed fuel or for E95 fuel (denatured raw ethanol) have been on the market since the early 1980s. Technical problems, supply problems and the associated price increases soon allowed the proportion of new cars with pure alcohol engines, which had temporarily risen to more than 90% due to tax incentives, to fall again. When supply bottlenecks arose in the mid-1990s, ethanol and methanol had to be purchased abroad, mainly in the USA. At that time, sales of vehicles powered only by E95 fuel fell sharply: to less than 2% around the year 2000. If these engines weren't better suited for operation with natural gas, which is also increasingly being promoted, because of the higher compression, they wouldn't state requirements such as If, for example, taxis were to be used in Rio de Janeiro (taxis were only allowed to drive with alcohol, today only with natural gas), they would probably have disappeared from the market. In mid-2003 Volkswagen offered the first FFV on the Brazilian market; Since then, all of the car manufacturers represented there have been producing FFVs that can react flexibly to fluctuating fuel offers. At the end of 2006, the number of FFVs was already estimated at around 3,000,000. By the end of 2007, the share had risen to more than 80% of new vehicles - many models are only offered as FFVs. As a special feature compared to the FFV, which are only designed for up to 85% alcohol, the FFV in Brazil have a small additional tank for gasoline in the engine compartment. Gasoline is used for cold starts when the alcohol content in the tank is very high. Because of the risk of fire in the event of accidents and possible incorrect operation (run empty, gasoline has become old, accidentally mistaken for the windscreen washer fluid tank), this additional tank is the greatest weak point in the system, which is why the development is moving towards a better startability at lower temperatures by means of electrical heating of the injection valves. However, earlier tests have shown that the electrical energy of the on-board network is insufficient to achieve significant improvements in cold start behavior through fuel preheating. Such a system is therefore unsuitable for higher comfort requirements.
Instead of using a fuel sensor, the data from the lambda probe is used to identify the mixture ( adaptive systems ).
In the US by the mid-1990s, there were around 15,000 FF vehicles in service, which were supplied by around 100 M85 filling stations, mainly in California. E10 fuel (so-called gasohol ) is currently available almost everywhere in the USA , and conventional vehicles can tolerate it with restrictions. In addition, according to ACE, around 6,000,000 FF vehicles are already in operation. 2,100 of the total of around 170,000 filling stations now offer E85 ethanol. American automakers have promised to offer at least 50 percent of their vehicle production as FF vehicles from 2012.
Sweden is a pioneer in the blending of ethanol in Europe. Ethanol fuel E85 is now also offered there. At the beginning of 2005, there were already around 11,000 FF vehicles in Sweden.
At the end of 2007, around 80 ethanol filling stations for E85 fuel were in operation in Germany; there are now over 350 (as of April 2011). In Germany, flexible fuel vehicles are still a “niche product” in contrast to Brazil, but various manufacturers offered configurations of their vehicles for the E85 fuel. Since the expiry of the tax relief for E85 in 2011, the number of E85 petrol stations in Germany has virtually decreased to zero.
Vehicles that are available as FFV on the German market (as of 2010):
| Manufacturer | model |
|---|---|
| Audi | |
| A4 2.0 TFSI flexible fuel | |
| A4 Avant 2.0 TFSI flexible fuel | |
| BMW | |
| X1 sDrive20i ActiveFlex | |
| 328i ActiveFlex | |
| Bentley | |
| Continental: GT, Supersports, GTC, Flying Spur, Series 51 | |
| Dacia | |
| Logan MCV 1.6 16V 105 | |
| Daimler Benz | |
| E-Class Coupe / Cabrio E350 / E400 for the US market | |
| ford | |
| Mondeo Flexifuel | |
| S-Max Flexifuel | |
| Galaxy Flexifuel | |
| Focus Flexifuel | |
| Opel | |
| Insignia Limousine 2.0 Turbo bioethanol | |
| Insignia Sports Tourer 2.0 Turbo bioethanol | |
| Renault | |
| Laguna III E85 | |
| Saab | |
| 9-3 BioPower sports sedan | |
| 9-3 SportCombi BioPower | |
| 9-3 Cabriolet BioPower | |
| 9-3X XWD BioPower | |
| 9-5 Sedan BioPower | |
| Volvo | |
| C30 FlexiFuel | |
| S40 FlexiFuel | |
| S80 FlexiFuel | |
| V50 FlexiFuel | |
| V70 FlexiFuel |
It should also be noted that manufacturers offer different versions of their vehicles depending on the market (such as the spread of E85 filling stations, demand for FFVs, etc.). For example, the new Passat Multifuel (E85) is not available on the German market, but for example in Sweden. In Brazil, 90% of new vehicles are FFVs.
At the beginning of 2011, for reasons of climate protection, the ethanol admixture permitted in accordance with EN 228 was increased from 5% to 10% in regular and premium petrol. According to the manufacturer, most of the vehicles on the market at the time could easily handle this fuel. Nevertheless, the ADAC advised to inquire about compatibility with the manufacturer.
It is worth mentioning in this context that vehicles with electrical injection systems from the 1990s that do not yet have an OBD-II exhaust gas monitoring system can generally be operated with pure E85 with only minor restrictions in cold start behavior and increased consumption. A practical example of this is the Ford KA built from 1996 onwards.
literature
- H. Menrad, A. König; Alcohol fuels ; Springer-Verlag Vienna-New York 1982; ISBN 3-211-81696-8
- G. Decker, H. Heinrich et al .; Field Experience and Progress of Volkswagen's Multi Fuel Vehicles ; Tenth International Symposium on Alcohol Fuels; Colorado Springs 1993
- D. Hüttebräucker, M. Stotz et al .; The flexible fuel concept from Mercedes-Benz ; VDI report 1020, page 113-130; VDI-Verlag GmbH, Düsseldorf 1992, ISBN 3-18-091020-8
- L.Brabetz, M. Siedentop et al .; The SIEMENS Alcohol Fuel Sensor - Concept and Results ; 9th Int. Symp. On Alcohol Fuels (ISAF); Firenze 1991
- G. Decker, J. Beyersdorf et al .; The ozone formation potential of different vehicle and fuel concepts ; ATZ Automobiltechnische Zeitschrift 98 (1996) 5
- Van Walwijk, M. Brückmann et al .; Automotive Fuels Survey, Part 3, Comparison and Selection ; Automotive Fuels Information Service IEA / AFIS; 1998
- Current reports in daily, weekly and specialist magazines as well as information material from the vehicle manufacturers
Web links
- www.e85.biz The E85 portal
- Revolution in the tank. Brazil's drivers show how a country can make itself more independent of oil - other nations want to follow suit; Süddeutsche Zeitung, January 3, 2006
- Ford Focus FFV and Focus C-MAX FFV
- Saab FFV
- Samba in the car tank: sometimes gasoline, sometimes alcohol , feature in the DW-TV series “Made in Germany”, March 16, 2010, ARD media library
- CropPower85 fuel for FFVs
- Current market overview of FFV available on the German market (as of 2015)
Individual evidence
- ↑ Archive link ( Memento of the original from July 30, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , Link broken on March 20, 2018.
- ↑ http://gain.fas.usda.gov/Recent%20GAIN%20Publications/Biofuels%20Annual_Sao%20Paulo%20ATO_Brazil_8-11-2010.pdf (PDF; 1.1 MB; 52 pages), accessed on March 20, 2018 .
- ↑ Archive link ( Memento of the original from December 8, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , Link broken on March 20, 2018.
