Another Maccas quickie entry.
Bengt sent through a translation of an article from Auto Motor and Sport that mentions something that I, in my own ignorance, just didn’t think was even a remote possibility.
Running a diesel cycle engine on ethanol – and doing it efficiently.
Here’s the translation – thanks Bengt. I wonder if there’s something like this in a secret drawer somewhere in Trollhattan?
Scania has used ethanol in their diesel (!) buses for more than 20 years, now with their third generation of diesel engines running on E95. The interesting part is that they get almost the same efficiency with ethanol compared to diesel (43 % compared to 44%).
Everybody knows that an E85 car needs 30-40 % more fuel than an ordinary petrol car. And everybody knows that a diesel car uses 30 % less than a petrol car. So, should we convert diesel engines to ethanol instead of petrol engines?
Hasse Johansson says (playful) that he asks Saab CEO Jan-Åke Jonsson all the time: When are you going to build real ethanol engines?
Next year, Scania will sell smaller trucks running on E95. They will also test hybrid busses in larger scale in Stockholm. The combination hybrid and E95 sound like a really environment friendly solution. The E95 fuel contains 95 % ethanol, 5 % ignition enhancement. Hasse Johansson says that the conversion of a diesel engine to ethanol is a little bit more complicated than the conversion of a petrol engine where you only need to switch to materials that can tolerate the ethanol.
“In a diesel engine, the spraying nozzles (injectors?) also need to be modified for ethanol fuel, but this is no big problem” says Hasse Johansson.
On a question why we use ethanol in thirsty petrol engines instead of in more energy effective diesel engines, Hasse asks: “Saab people known too much about petrol engines, and too little about diesel engines”
The journalist Alrik Söderlind comments:
“My conclusion is that Sweden has chosen the E85-track because Saab was able to convince the former Swedish Prime Minister Göran Persson that E85 was the right (and only) way to go. Think if the Prime Minister had asked Scania, and if the Swedish truck manufacturers Scania and Volvo had a more close technical exchange with the Swedish car manufacturers Saab and Volvo . . . . Maybe we could, already today, drive real energy efficient cars on biofuel, and have an ethanol consumption of 6 L/10 km instead of 13 L/10 km that is the consumption of the thirstiest Saab E85 cars today.”
“We could drive twice the distance on a liter ethanol, if we used it in a diesel car. But it is not too late. Why not offer a free choice of ethanol mix? If you are running an E85 car, E85 is what you get. Many ordinary petrol cars are able to run on E15, but no E15 fuel is offered. If you drive a diesel car converted for ethanol, you get E95 with ignition enhancement.
So, who will be the first to offer an E95-diesel car?! I want one.”
It certainly makes for interesting reading, huh?
If I weren’t on holidays I’d look into it some more. Perhaps some of the visitors here that have an understanding of such things can explain it further as the possibility had never crossed my mind. In my own little bit of engineering ignorance I just figured you ran diesels on diesel fuel, be it oil-based or bio-based.