EPA approves the use of E15 in older cars: Analysis of the pros and cons

With a waiver for the Clean Air Act, the EPA recently approved E15 biofuel for use in cars made within the last ten years rather than only in cars made from 2007 onwards, a move that’s proving controversial, but is approval based only the age of the vehicle the best option?

On one side, one camp wants the EPA to approve E15 for use in even older cars than is currently allowed so that biofuels see wider use (with the change in the regulations approximately 62% of cars on US roads will be clear to use E15). The other is concerned about the performance and safety of E15 in petrol engines, as well as the usual concerns over food production and carbon emissions from the anti-biofuel camp. Both perspectives have important points to make.

As a chemical, hydrocarbon-chain fuels (such as gasoline) are very stable; apart from the fact that they burn well they have very few other reactions. In fact the word paraffin (the fuel I believe you call kerosene in the US) means “barely reactive”. This makes it fairly straight forward to build engines that won’t be corroded by the fuel. Alcohols are more reactive, which can potentially cause a problem. Alcohols can react with components in the engine; not quickly, but over time they will cause more wear and tear on the engine compared to one run on conventional gasoline. With E85, the engines are designed to handle high amounts of alcohol in the fuel. With E10 fuel, the alcohol in the mix is dilute so engine damage isn’t really an issue. There comes a point in blending though where the engine is going to suffer from the levels of alcohol in the mix. The big question here is whether this point is reached when the ethanol content of the fuel is increased to 15%. 

Some people opposed to the change are also worried over misfuelling; that people will be confused by the change and damage their cars by putting in the wrong fuel. The change in E15 regulations comes with requirements for clear labeling at the pump to minimise this risk, though there will most likely still be some cases of misfuelling.

EPA Administrator Lisa Jackson made the conclusion over E15 with the help of research done by the DoE “Recently completed testing and data analysis show that E15 does not harm emissions control equipment in newer cars and light trucks. Wherever sound science and the law support steps to allow more home-grown fuels in America's vehicles, this administration takes those steps."

Is determining the cutoff by year of manufacture alone the best method for determining which vehicles are suitable for fuelling with E15 however? There was no global change in automotive manufacturing methods in 2001, so the placement of this cutoff to some extent arbitrary, though a lot of data from the performance of engines over time with E15 was analysed by the DoE. The DoE has also only approved E15 for use in cars; it has not been approved in vehicles such as trucks and motorbikes for a lack of experimental data, showing that they have researched the issue in detail. However, the limit isn’t a rolling limit, (e.g. vehicles produced in the last X number of years rather than vehicles produced after year X), so concern over running “old worn engines” on ethanol fuel seemingly isn’t the reasoning for the limit being what it is. We might expect more variation in performance between engines from different manufacturers than from engines produced in consecutive years.

What would be ideal to my mind would be to approve cars for E15 use based on the model of the car and the year; actually testing the engine to see how the higher levels of ethanol in the fuel would affect it as it ages, though this would take more time and resources which at present would be impractical. Because of the ethanol blending wall, there has been pressure to get the restrictions lifted and for the sake of the growth of the ethanol industry it would be best if this wall was not reached; a market that can’t grow will hardly attract investors. So how would it be best for this to be approached? Determining which vehicles are suitable based on their age is the most straightforward method to enforce, though it might be that some suitable vehicles are not approved for E15 and some that are not suitable will be fuelled with E15. Perhaps if technical departments of individual automotive manufacturers were asked to have a hand in an approval process made on a manufacturer by manufacturer basis, it would be a relatively simple way to find an easily enforceable limit that reflects technical differences between engines.