Flex Fuel: How it works and its advantages
For the past few years, Union Road, Transport & Highways Minister Nitin Gadkari has been pushing for flex-fuel technology on automobiles to cut down the import of fuels and achieve carbon emission norms. The technology to achieve these twin goals is not only not complex, it has certain advantages over the fossil fuel variant.
Recently, the Toyota Innova became the first four-wheeler in the country to feature a flex-fuel engine capable of running entirely on ethanol. This launch has renewed the discussion about the mass adoption of this technology.
According to global auto component giant Bosch, flex-fuel vehicles (FFVs) have an injection system that can be operated with gasoline, with any mixture ratio of gasoline and ethanol, or with pure ethanol. This means that the FFVs have internal combustion engines capable of running on 100% petrol, 100% bioethanol, or a combination of both.
Research papers have shown that bioethanol, derived from plants, contains less energy per litre than petrol but has a similar calorific value (the energy contained in the fuel) of petrol when aided by advanced technology.
Ethanol added to the gasoline and the ethanol proportion for flex-fuel engines can vary between 5% and 85%. E100 is a fuel with 93% ethanol and 7% water, with no gasoline mixture.
How does the technology work?
Bosch notes that the tried-and-tested ‘inlet manifold fuel injection technology’ forms the basis for flex fuel and Flexstart systems in combustion engines. The networked system components precisely detect the ethanol proportion at all times.
The control unit adjusts the air-fuel ratio accordingly, in order to deliver the requested torque efficiently. The high anti-knock properties of ethanol (110 octanes) also allow vehicle manufacturers to implement a higher compression ratio and thereby a higher engine output.
Ethanol achieves an additional performance increase for turbocharged engines: E85 and particularly E100 with a 7% water content removes heat from the hot charge air upon evaporation (internal cooling). The air-gas mixture cooled as a result has a higher substance content for the same volume. This improves the engine’s volumetric efficiency, thereby additionally increasing the power output — perfect conditions for downsizing.
Advantages:
Clean: Ethanol being a cleaner fuel produces fewer toxic fumes and particles when burned
Sustainability: Ethanol and methanol are sourced from food crops like corn and sugar cane. This helps reduce the overall cost of the fuel.
Similar performance: Unlike CNG vehicles, flex-fuel cars’ performance is similar to petrol-run vehicles.
Disadvantage: Increased wear & tear of engine and lower mileage
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