An ethanol-diesel engine??

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.

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  1. I think something got lost in translation – this is from Scania’s press release :

    “The ethanol buses contribute strongly to lower emissions from public transport in Stockholm. They are also an economically viable alternative to diesel buses in terms of operating cost and reliability,” said Per Wikström, Vice President and Environmental Director of Busslink”

    E85 as alternative to diesel makes sense to me since ethanol is alcohol and biodiesel is extracted oil. I did find some references in wikipedia to using ethanol as an additive to biodiesel to aid with “transesterification”, but no more than 15% ethanol.

  2. On further review – it looks like the ethanol buses do use modified diesel engines (I’m not enough of a gearhead to know if the mods prevent the option of using normal diesel):

    “To use the E95 blend in the diesel engine, Scania raised the compression ratio from 18:1 to 28:1, added larger fuel injection nozzles, and altered the injection timing. Different gaskets and filters are required, as well as larger fuel tanks—the engines use 65% to 70% more ethanol than they would diesel. The intervals between oil changes is halved, and more scheduled maintenance is required.”

    P.S.: scroll down to the comments in the linked article for a laugh about GM 😉

  3. I´m not a big engine specialist, but as I rembember the Mercedes had similar project called diesotto, diesel engine running on gasoline. The concept vehicle F700 was shown in Frankfurt. I think that it should also work with ethanol and with ehtanol-hybrid technology. Saab should warm up his relations with his former brother and things can start happening.

  4. FYI – What Mercedes calls “diesotto” is called “HCCI” in GM speak. They (GM) have already demonstrated driveable prototypes to the press. When it becomes production feasible cannot imagine Saab would not get it.

  5. The consumption figures (6 l/10 km) are assumptions from the journalist. In comments to the article he later writes that the only figures he got from Scania was the efficiency (43 % compared to 44 %). Because of less energy in ethanol the consumption figures will be higher than with diesel but still lower than current E85/peterol engines (around 9 l/10 km).
    I am not a big fan of the big focus on ethanol here in Sweden but it is a fact that there are a lot of bonuses when you buy an ethanol car here like:
    – No traffic congestion in Stockholm
    – Lower taxation
    – Free parking in a lot of towns

  6. The writer of this article has got it all wrong. What Scania said was that with E95 in a diesel engine you get almost the same degree of efficiency as running on diesel. Diesel has more energy then petrol and petrol has more energy then ethanol if you look at the same amount of fuel. Diesel contain roughly 39 megajoule per liter, petrol 35 MJ/l, ethanol 24 MJ/l and E85 26 MJ/l. So if you look at this a diesel engine running on E95 would consume 165% more E95 in volume then it would if it was running on diesel. I other words a Saab 9-5 1.9TiD would require 14 l/100km running in a city on E95 compared to 8.6 on diesel. That may be good compared to the BioPower engine Saab has today but not as good as the writer of this article want’s it to look. There is no secret that Saab has said that they can make ethanol engines more efficient if then make them primarly for ethanol and not petrol, in other words increase the compression so it is more simular to a diesel engine.

    Oooops, Bengt beat me to it…

  7. @ Bengt P: you got me puzzled. How do you manage to avoid traffic congestion in Stockholm with a E85-engine? Do you get seperate lanes? Seperate traffic lights?

  8. Traffic congestion charges it is of course. (Couldn’t we all write everything in the famous, world-wide spread language Swedish?) 🙂

    Thanks Dave for the info. I just translated the article without any deeper knowledge about all the megajoules etc.
    I guess that we have to write some comments to the journalist Alrik Söderlind before he prints his assumptions in the paper version of Auto Motor & Sport magazine.

  9. I was watching the episode of Top Gear last night and it was the episode where they compete in different tractors to plow a field. There was some mention about one of the tractors running ethanol or diesel if I remember and I thought that seemed odd, but now I’m reading this…

  10. Regarding the author of this article he writes the following in the comments to his own article…

    “Insänd av: alrik söderlind

    Jag vet tyvärr inte hur det är exakt, de siffror jag fick från Scania gällde energieffektivitet, där man uppgav att diesel och E95 var lika bra (44 mot 43%) men det kan vara sant att det inte betyder samma sak i förbrukade liter, vilket efter lite eftertanke låter märkligt.
    Men som jag förstår det hela så är dieselmotor på E95 mycket energieffektivare än E85 med bensinbil.”

    Rougly translated…

    “Sent in by: alrik söderlind
    Fuel efficiency

    I don’t know how it exactly is, the numbers I got from Scania was regarding energy efficiency, where they claimed that diesel and E95 was equally good (44 against 43%) but it can be true that it don’t is the same thing in consumed amounts of fuel, which in retrospect sounds strange.

    But as I understand it all a diesel engine on E95 is more energy efficient then E85 on a petrol car.”

    He is really on top of it 😉

  11. The energy density of ethanol and diesel is different. This is expressed in megajoules per litre.

    In practical terms, all this means is that it will take longer to fill-up an E95 car. What consumers will be more interested in, of course, is the price per megajoule of each fuel (as opposed to the price per litre).

    Here’s roughly how the main contenders stack-up in MJ/L:
    diesel 41
    gasoline (E0) 32
    gasoline (E10) 28
    ethanol (E100) 19.5
    E85: 21.4

    This means that an engine that has a thermodynamic efficiency of 43% will use about twice as much E95 as it would diesel. As long as the two fuels are priced accordingly (which they won’t be), it’s a wash.

  12. Sorry mates,

    I don’t understand a single word of swedish, but scania-people seem to write in english as well.
    So here you go:

    Some related links:

    And a technical question fot the real technicians of you:

    Combination of E85-bioethanol in one tank and LPI in the other, does that work as it did with the standard LPI-installation were you can switch from regular petrol to liquid gas LPG ? Any of you knows about this ?

  13. Of course the big thing here in California (when you can find a diesel car) is to run it on french fry oil/grease. You can actually tell when they are around because they actually smell like french fries.

  14. ehall1: I believe they call that diesel engine conversion “SVO” (for “straight vegetable oil”) or “WVO” (for “waste vegetable oil”) in the case of recycled grease procured from the local fast-food restaurant fryer. WVO would be a pain-in-the-butt because you have to strain all your own fuel (removing all the food debris) using mesh and big buckets and such. That’s just too much work to me to be worth it. Plus, you need a lot of space to store the fuel at your home. I also believe that you have to pre-heat the vegetable oil. Usually people who run on SVO/WVO have two tanks installed in their trunk, one running biodiesel and the other a heated tank running vegetable oil. They start the car on biodiesel and once the oil in the heated tank gets up to a certain temp they then switch to running on vegetable oil.

    This is a noble thing, but seems like so much of a pain in the butt. I might warm to the idea if the car would automatically take care of switching tanks and pre-heating with some sort of controller, but I still wouldn’t want to store large containers of vegetable oil around my home. I think you also have to manually switch-back to running on biodiesel before you shut-off the car to evacuate all the fuel lines of vegetable oil or you can’t start the car again the next time you try.

    This would only be for the most hardcore of the hardcore, IMHO.

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