UNL study finds non-flex fuel vehicles can adapt to E30 gasoline without performance compromise; fuel efficiency comparable to E15

Source: By Green Car Congress • Posted: Monday, August 9, 2021

A team at the University of Nebraska-Lincoln has investigated the long-term adaptability and economic feasibility of non-flex-fuel vehicles—vehicles designed to use fuel blends containing 85% ethanol (E85) or less—to consume a 30% ethanol (E30) fuel blend. Their results indicated that although modest changes can be observed in the behavior of a subset of engine operating parameters, overall engine performance and adaptability are not compromised by using E30.

They also determined that an average price difference of 2.5% is sufficient to offset the mileage loss caused by the increased ethanol concentration. An open-access paper on their work is published in the journal Fuel.

The researchers used a data-driven approach in which 16 diagnostic and operating parameters were collected through on-board-diagnostic (OBD) trackers over a one-year period from vehicles operating on both E30 (test) and E15 (control) fuel blends. They used statistical and data analysis methods including sparse regression and neural networks to compare the behavior of these parameters temporally and between the two fuel types.

They also collected data on the average mileage per gallon for each fuel type to explore the economic feasibility of utilizing E30.

Among their findings:

  • Although differences in the performance metrics were statistically significant, the magnitude of these differences were minimal. This was evident both for parameters that were expected to remain constant (fuel trim, oxygen sensor, and coolant temp), and the combinatorial behavior of parameters which were constantly changing.
  • The difference in oxygen content between the two blends caused the long-term fuel trim of vehicles operating on E30 to be higher. However, the magnitude of this change was below the limit set by most car manufacturers (20–25%).
  • The change in fuel trim allowed the vehicles’ control modules to control for the amount of unburnt oxygen. This indicates that the control system of non-flex fuel vehicles is capable of handling ethanol concentrations up to 30%.
  • Analysis of transiently behaving parameters showed that according to the performance metric chosen (absolute load), no difference could be observed between the performance of vehicles operating on either fuel blend.
  • The use of E30 leads to an average decrease in fuel efficiency of approximately 0.64 MPG compared to E15. This minor variation in efficiency is usually offset by the lower price of E30 compared to E15.
  • 10% of the US’ on-road fleet switching from E10 to E30 every year would result in an average reduction of approximately 34 megatons of CO2emitted every year.

A strategy of introducing E30 fuel and gradually shifting from E15 to E30 consumption will have appreciable environmental effects due to reductions in greenhouse gas emissions. The slow turnover of vehicles currently on the road requires the proposal of immediate solutions compatible with the present infrastructure and engine design. Therefore, implementation of such a strategy can act as a buffering solution to reduce the rate of greenhouse gas emissions until improved fuel technologies and electric vehicles become more widespread.

This study constitutes a good starting point towards ensuring the safety of using 30% ethanol in non-flex fuel vehicles. Future studies can build on this demonstration in two ways: by (i) replicating this analysis on a broader range of vehicles makes and models (coarse-grained analysis), or (ii) investigating the physical effect of long-term E30 use on the fuel system under real-life driving conditions (fine-grained analysis). Studies looking into the physical effect of consuming E30 should compare the long-term accumulation of particulate matter in the fuel pump and fuel injectors between vehicles operating on E15 and those operating on E30. Both types of analysis will provide valuable information and will ensure the safety and feasibility of using higher ethanol blends in non-flex fuel vehicles.

—Alsiyabi et al.

Resources

  • Adil Alsiyabi, Seth Stroh, Rajib Saha (2021) “Investigating the effect of E30 fuel on long term vehicle performance, adaptability and economic feasibility,” Fuel, Volume 306, doi: 10.1016/j.fuel.2021.121629

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