Diesel Station Wagon Runs On Plastic

Old diesel engines from various car manufacturers like Mercedes and Volkswagen are highly prized even in modern times. Not only were these engines incredibly reliable and mechanically simple, but they can easily be modified to run on a wide variety of fuels. It’s common to see old Volkswagen Jettas or Mercedes 300Ds running on used vegetable oil or any other free flammable liquid that might otherwise end up in the garbage. [Gijs Schalkx] has an diesel Volvo 240 wagon, and rather than compete with all the other diesel owners looking for cooking oil, he modified this one to run on plastic waste instead. (Google Translate from Dutch)

While our Dutch language skills aren’t the best, what we gather about this project is that it uses standard solid plastic waste for fuel, but an intermediate step of cooking the plastic into a liquid is first needed. The apparatus on the roof is actually a plastic refinery which uses a small wood fire to break the plastic molecules into usable hydrocarbons, which are then sent to the engine for burning. The car is street legal and seems to operate like any other diesel of this vintage, although the fuel delivery system may not be able to provide it enough to get it going at very high speeds.

While it is possible to use wood to produce wood gas for fuel in an internal combustion engine like this wood gas-powered lawnmower, the hydrocarbon strings in plastic are essentially stabilized hydrocarbons from refining oil and have potentially much more available energy. Releasing this energy is generally difficult enough that used plastic is simply landfilled. [Gijs Schalkx] has made plenty of alternative fuel vehicles, too, like this moped that used locally-harvested swamp gas to ride around town.

Thanks to [Lucas] for the tip!

57 thoughts on “Diesel Station Wagon Runs On Plastic

  1. Quick translation from Dutch on how it works is that is heats up the plastic in an enclosed container where there is no air (or oxygen, word in Dutch can mean both). And then it becomes gas form, goes trough a condenser to become liquid and that powers the car.

    No word on how much energy is used to heat the plastic and if it is actually energy positive.

    1. Yes it is and by a lot. The process is well know, it’s a pyrolysis and it happens at around 500°C. Calorific energy of mixed plastic is between 30 to 40 MJ/kg versus 43MJ/kg for fuel oil.

      Heating up the plastic require 1.7kJ/kg/°K so it would take 0.80MJ to heat 1kg of plastic from 25°C to 500°C (with perfect efficiency). Once transformed, it would release 30 to 40MJ.

      That being said, it would be probably a lot easier to use the combustion of some of the produced fuel to heat up the plastic so you don’t need to bother with 2 different combustible.

        1. Throw the setup in the way-back (as we called it in the 740 we had growing up) and switch to exhaust heat once it comes up to temp.

          Regulating the temperature is another problem though.

        1. Benzene and dioxins would be a concern to have in the air around where other drivers, cyclists and local residents could receive exposure. And while not carcinogenic, toluene is also pretty bad for you to inhale long-term, and can cause brain lesions.

        2. I would most concerned by residues left on the plastic by previous products and things like Teflon coatings. Not to mention unless he is filtering the exhaust via something like a static trap, this thing is spewing microplastics in some capacity be it from the primary and/or secondary phase . Just microwaving a plastic bowl releases a ton of microplastics.

      1. That was my first thought. That could probably be engineered around for a specific type of plastic but it sounds like they are just tossing in whatever. Combine that with all the random residues from the previous products contained in said plastic and you really have a recipe for a carcinogen lottery machine.

        Neat project but probably best to keep it to one car in Europe.

    2. “air (or oxygen, word in Dutch can mean both)”

      No, not really.
      Air = lucht.
      Oxygen = zuurstof.

      People use it interchangeably sometimes though. Like when lay people talk about scuba diving with oxygen tanks.

  2. ” Releasing this energy is generally difficult enough that used plastic is simply landfilled. ”

    No, MSW (municipal solid waste), particularly when segregated from yard and food waste and partially dried, has a high enough energy value that power plants in various trash-rich locations (Northeast US, some parts of Europe) use it directly in fluidized-bed coal combustors as fuel. Amusingly, the Iru plant in Estonia (which was purpose-built to run on MSW) has had to import “fuel” from as far away as Ireland to keep going.

    1. Where I live, burning trash has a NIMBY problem. There are plans to build a CHP power station near Wrocław in Poland, but home owners around the selected site have organized to stop the construction – they are fighting it in court and telling lies about it.

    1. +1

      Thinking about all those unmodified vintage cars make me sick.
      No catalytic converter, no particle filter.

      Diesels are great as emergency electric generators, though.
      And to power big things like agricultural machinery (tractors etc).

        1. We’ve learned that in The Zombie Apocalypse a whole lot of people would insist on gathering in large groups with close contact with the infected without taking precautions. :P

  3. I’m thinking the refinery could be stationary, producing liquid fuel at home, and then the car could just be fueled up as normal. Perhaps solar energy could be used to power the pyrolysis. Maybe there’s something about the fuel produced that prevents this, though.

    1. agreed. the wind loading alone of that portable refinery would be terrible for mpg. garage54 recently made one of these, running on old car tyres. the first fuel that came out of it was black and sticky, but they managed to reprocess it enough to give a clear fuel.
      I wouldn’t mind attempting this, assuming i wasn’t arrested for pollution because it pays for itself and the inputs are free and plentiful. i’ve had persons offer to deliver used tyres to my door at no charge.

      1. A scrapyard in my area built a tire pyrolysis unit in the late 90s early aughts. The owner said the fuel worked fine in small engines it was tested in. Apparently keeping air out was more difficult than expected and the 2nd or 3rd explosion caused a big enough fire that the authorities shut it down. I was hoping it would come back after modifications but no.

  4. thermal depolymerization has been known about since the 90’s. At that time, changing world tech was trying to work it to turn waste feeds directly to diesel. They used additional water and high pressure. The process would produce enough methane to fire the next batch. No microplastics, no brittle plastics. Just usable hydrocarbons. But that didn’t have a cool name like BioDiesel, nor did it change the polymer back to its monomer form, so it wasn’t considered useful by the usual bad decision makers. Its off patent at this point so anyone can use it. This article is about a concept that is still fundamentally thermal depolymerization even if water/pressure are not used and burning is prevented by other means. At its heart, this is still using elevated temperature to depolymerize polymers. Same concept.

    Now, can we actually decide to use a useful technology for a change?

  5. Dude just solved the plastic recycling issue but everyone’s gonna pretend this doesn’t exist because it doesn’t fit the green urban utopia aesthetic. Yes, you can totally burn plastic as fuel. Power plants can do it too. If you think burning plastic is bad, wait until you find out about coal.

    1. “If you think burning plastic is bad, wait until you find out about coal.”

      Wait a minute, isn’t burning coal considered to be the absolute no-go?
      A horrible mistake of the past generations?
      Historically, wasn’t burning coal/wood causing smog which made citys like old London look grey and wasn’t it also the cause of asthma among children?
      Didn’t dust from the coal plant make the laundry in the countryside turn black?
      If so, something “a bit less horrible than coal” doesn’t cut it. 😕

      1. >Wait a minute, isn’t burning coal considered to be the absolute no-go?
        No? There are coal power plants everywhere. Turns out you can burn the stuff without blowing soot everywhere (the soot is fuel too!). Who would’ve thought.

      1. But it still solves the issue of recycling.

        The problem is that there isn’t really an effective and economical process that would return used plastic back to original quality. Downcycling to inferior products isn’t actually recycling, since it isn’t a closed loop. It inevitably ends either in landfill or incinerator. Alternatively, if downcycling counts as recycling then this is too.

  6. “The car is street legal”

    Yeah, the car. The fuel system is incredibly illegal and could land you in jail here in the Netherlands. It’s called an economic crime if you don’t pay taxes on fuel. Same with using other types of oils as diesel. If he’s caught he has to pay back the estimated taxes, which, based on 20k/year and 5 years (average fine), is 8668 euro’s in taxes based on current tax on diesel. The hefty fine comes on top of that. Other people used to use different oils to drive cheaply and got fined that way.

    It’s a great idea though. I’ve seen video’s of farmers in the US distilling plastics, to make diesel for their tractors. It’s a great idea with a ton of potential. But driving that on the road here is an absolute no-go.

    1. In the freedom-loving United States, this is also a crime for similar reasons. You can’t run an internal combustion engine on public roads without paying fuel excise tax. To the degree that you can buy special fuel for agriculture or recreation that has a dye added, and may have different taxes or no taxes applied (varies by state). And tax-exempt heating oil has to have even more dye added to a degree such that it looks like KoolAid.
      In the unlikely scenario that the authorities find traces of dye in your regular highway vehicle’s tank the fines are quite steep. All this is balanced by American culture being quite tolerant of scofflaws and tax evasion. We have a lot of crimes that aren’t enforces and that most citizens would never report. Mainly the dye laws go after farmers and business owners who use enough fuel to have a financial incentive to evade the significant taxes.

      1. Yes; legally, you have to pay the tax no matter what fuel you use. However, you can pay the government directly; there are even forms for it. The fuel can be biodiesel, ethanol, propane… or electricity. When I lived in Michigan, I had a separate meter for my electric car. I paid the road taxes on the state’s “sales and use tax” form. After a few years of this, the state said to forget it; the tax was too low to bother to collect.

        1. We’re still trying to figure out how tax electric cars in California. We’ll probably end up with GPS trackers. We’ve killed multiple bills over the years but it keeps coming up. I feel like electric cars know exactly how much power has gone into them for charging and there is a serial protocol for the charging port that can exchange lots of useful information between the charging station and car. The technology exists to add a few pennies tax now that we have fairly capable interfaces for charging. The legislature only needs to set a date for manufacturers to be compliant.
          I’m not a lawyer or politician. I’m just a somewhat science literate software engineer. So I’m totally unqualified to think about tax policy ;-)

          1. The tax on fuel is supposed to be a “road tax”, hence the exempt “agricultural” diesel. Rather than taxing the electricity, it should be based on miles driven on said roads. In any case, since no electronic system is 100% secure, it’s going to amount to a barely-enforceable honor system (just like the aforementioned agricultural fuel).

          2. Same here in Minnesota, where I live now. Rather than pay a fuel tax, the state decided to collect a $75 annual fee for an EV. For me, that is *far* more than the 8.2% tax on gasoline. I charged my EV with PV panels purchased in 1994 as surplus from the dismantled Carizzo Plains CA solar plant.

            They are also debating on raising the tax to $200/year for EVs. Why? Because they can. The tax is more punitive than rational.

          3. I find it amazing how everyone rules out just using the odometer, which we’ve had forever and which is commonly collected when a car is serviced or inspected for registration, etc. Sure, it wouldn’t exclude offroad miles, but those will be fewer and maybe if you have a significant number of offroad miles due to being a rural rancher, maybe you file with your county about your road tax just like you already do for property tax and agricultural exemptions and all that.

  7. Very impressive, but I’d favour a larger, fixed, community scale, solar thermal unit that converted people’s plastic waste and paid them back in “fuel” in proportion to the weight of the plastic they provided.

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