34 votes

Engineers develop a recipe for zero-emissions fuel: soda cans (aluminium), seawater and caffeine

22 comments

  1. drannex
    Link
    [..] I had heard that adding caffeine to lithium batteries can speed up and reduce needs for lithium, but that it extends out to producing hydrogen is absolutely fascinating. I've written before...

    In a study appearing today in the journal Cell Reports Physical Science, the researchers show they can produce hydrogen gas by dropping pretreated, pebble-sized aluminum pellets into a beaker of filtered seawater. The aluminum is pretreated with a rare-metal alloy that effectively scrubs aluminum into a pure form that can react with seawater to generate hydrogen. The salt ions in the seawater can in turn attract and recover the alloy, which can be reused to generate more hydrogen in a sustainable cycle.

    The team found that this reaction between aluminum and seawater successfully produces hydrogen gas, though slowly. On a lark, they tossed into the mix some coffee grounds and found, to their surprise, that the reaction picked up its pace.

    In the end, the team discovered that a low concentration of imidazole—an active ingredient in caffeine—is enough to significantly speed up the reaction, producing the same amount of hydrogen in just five minutes, compared to two hours without the added stimulant.

    [..]

    "We're showing a new way to produce hydrogen fuel, without carrying hydrogen but carrying aluminum as the 'fuel,'" Kombargi says. "The next part is to figure out how to use this for trucks, trains, and maybe airplanes. Perhaps, instead of having to carry water as well, we could extract water from the ambient humidity to produce hydrogen. That's down the line."

    "The researchers believe they have the essential ingredients to run a sustainable hydrogen reactor. They plan to test it first in marine and underwater vehicles. They've calculated that such a reactor, holding about 40 pounds of aluminum pellets, could power a small underwater glider for about 30 days by pumping in surrounding seawater and generating hydrogen to power a motor."

    I had heard that adding caffeine to lithium batteries can speed up and reduce needs for lithium, but that it extends out to producing hydrogen is absolutely fascinating. I've written before that I believe the best future solid energy is going to be Hydrogen, but aluminum hydrogen? I hope this helps energize the integration of this wonderful fuel.

    20 votes
  2. [6]
    Fiachra
    Link
    My first thought was how efficient is this fuel? Hydrogen fuel is already better than petrol in terms of energy per kg, so that's promising BUT how much salt water does 1 gram need? Are you...

    My first thought was how efficient is this fuel?

    They estimate that just 1 gram of pellets would generate 1.3 liters of hydrogen in the same amount of time

    Hydrogen fuel is already better than petrol in terms of energy per kg, so that's promising BUT how much salt water does 1 gram need? Are you getting a pellets + water mix every time you refuel, or is it more like changing the oil in your car? Might not matter much for marine craft but could be a limiting factor for use inland, which probably motivated the idea to pull moisture from the air:

    "Perhaps, instead of having to carry water as well, we could extract water from the ambient humidity to produce hydrogen. That's down the line."

    But if this pans out as described it could be great for shipping. Replacing a tank of liquid fuel with a much smaller stockpile of small metal pellets leaves more room for valuable cargo. Spilling aluminium pebbles into the sea isn't as costly to the PR and insurance premiums as an oil spill. This has potential.

    The downside of course is, where are they going to get enough gallium and indium to make this work?

    13 votes
    1. [2]
      Minori
      Link Parent
      Therein lies the rub. I'd need to see the math behind the catalysts they're using to prepare this aluminum. It really might be a massive improvement, but I've known many a researcher to hide the...

      The aluminum is pretreated with a rare-metal alloy

      Therein lies the rub. I'd need to see the math behind the catalysts they're using to prepare this aluminum. It really might be a massive improvement, but I've known many a researcher to hide the costs in fine print. So goes the funding treadmill.

      25 votes
      1. Englerdy
        Link Parent
        At least the catalyst isn't consumed in the reaction when using a salt solution. Though Gallium Indium doesn't sound very cheap. And reprocessing the spent fuel sounds like it might be kind of...

        At least the catalyst isn't consumed in the reaction when using a salt solution. Though Gallium Indium doesn't sound very cheap. And reprocessing the spent fuel sounds like it might be kind of energy intensive. Closing the fuel loop when using aluminum as the "fuel" seems essential.

        In the team's new work, they found they could retrieve and reuse gallium indium using a solution of ions. The ions—atoms or molecules with an electrical charge—protect the metal alloy from reacting with water and help it to precipitate into a form that can be scooped out and reused.

        5 votes
    2. [3]
      bendvis
      Link Parent
      1.3 liters of hydrogen sounds impressive for 1 gram of aluminum pellets, but that's 0.108 grams of gas (assuming the volume is at 1 atmosphere and room temperature). To fill a fuel cell EV's 5 kg...

      1.3 liters of hydrogen sounds impressive for 1 gram of aluminum pellets, but that's 0.108 grams of gas (assuming the volume is at 1 atmosphere and room temperature). To fill a fuel cell EV's 5 kg hydrogen tank would require 46 kilograms of treated aluminum. The mass of aluminum required to power a cargo ship would be enormous.

      3 votes
      1. Fiachra
        Link Parent
        I guess the question then is: which is a bigger factor for a cargo ship, weight or volume?

        I guess the question then is: which is a bigger factor for a cargo ship, weight or volume?

        2 votes
      2. AugustusFerdinand
        Link Parent
        However hydrogen also has triple the specific energy of gasoline/diesel and almost triple that of natural gas, methane, and propane. Part of the issue has always been storage and transport.

        but that's 0.108 grams of gas (assuming the volume is at 1 atmosphere and room temperature).

        However hydrogen also has triple the specific energy of gasoline/diesel and almost triple that of natural gas, methane, and propane. Part of the issue has always been storage and transport.

        2 votes
  3. [5]
    kacey
    Link
    As a lay person, I’m curious whether the thermodynamics of this make sense vs. using an aluminum-air battery? Since this appears to just be oxidizing aluminum (ie stealing the O in H2O to attach...

    As a lay person, I’m curious whether the thermodynamics of this make sense vs. using an aluminum-air battery? Since this appears to just be oxidizing aluminum (ie stealing the O in H2O to attach to an aluminum atom) to liberate a hydrogen molecule, which is then … burned back into H2O? Fed into a fuel cell to be converted into power? But if the latter, why not skip the inefficiencies and middlemen …

    4 votes
    1. [4]
      nukeman
      Link Parent
      Aluminum-air is a primary cell. You can’t recharge it by plugging in, you have to grind it up and remanufacture them.

      Aluminum-air is a primary cell. You can’t recharge it by plugging in, you have to grind it up and remanufacture them.

      4 votes
      1. [3]
        kacey
        Link Parent
        Yeah, but this is grinding up aluminum and feeding it into sea water to generate hydrogen to burn to turn turbines to generate electricity, I think? So it has the same issue of needing to smelt...

        Yeah, but this is grinding up aluminum and feeding it into sea water to generate hydrogen to burn to turn turbines to generate electricity, I think? So it has the same issue of needing to smelt the aluminum again, but also goes through an extra step …

        4 votes
        1. [2]
          nukeman
          Link Parent
          You can use hydrogen for electricity generation, but I suspect it’s main use will be in the chemical industry along with niche transportation applications (think aircraft and marine propulsion).

          You can use hydrogen for electricity generation, but I suspect it’s main use will be in the chemical industry along with niche transportation applications (think aircraft and marine propulsion).

          6 votes
          1. kacey
            Link Parent
            Fair enough! The paper itself speculates about a handful of usages, but I supposed I was fixated on the transport and energy applications (which seem better served from an energy + power density...

            Fair enough! The paper itself speculates about a handful of usages, but I supposed I was fixated on the transport and energy applications (which seem better served from an energy + power density perspective by running on battery electric/ aluminum air) rather than the potential industrial applications. Although if that’s being considered, I wonder how this stacks up against plain old electrolysis? I suppose this would be more selective for hydrogen generation, at least.

            3 votes
  4. [8]
    BeanBurrito
    Link
    I confess, I didn't read the article. Aluminum is a finite resource. I don't know about contemporary times, but aluminum was one of the first metals that I remember that recycling was promoted...

    I confess, I didn't read the article. Aluminum is a finite resource. I don't know about contemporary times, but aluminum was one of the first metals that I remember that recycling was promoted for. I can't remember whether it was the huge amount of energy to refine it or it being in short supply.

    2 votes
    1. [2]
      skybrian
      Link Parent
      The aluminum isn't lost. This process converts aluminum to aluminum oxyhydroxide, which is normally found in aluminum ore. So, I think it could be refined again by adding energy? If that works and...

      The aluminum isn't lost. This process converts aluminum to aluminum oxyhydroxide, which is normally found in aluminum ore. So, I think it could be refined again by adding energy? If that works and the energy comes from a renewable source, then it's a renewable process.

      This would be a way of transferring energy, like a battery, not an energy source.

      Reports about fundamental research like to talk up applications, but we don't know if it's practical yet.

      14 votes
      1. BeanBurrito
        Link Parent
        Thank you. It would be interesting to know if you still come out ahead in regards to energy by spending energy to reprocess the aluminum.

        Thank you. It would be interesting to know if you still come out ahead in regards to energy by spending energy to reprocess the aluminum.

        2 votes
    2. stu2b50
      Link Parent
      The reaction doesn’t use up the aluminum or anything. The only resource being exhausted is the water - or, well, the hydrogen atoms in the water.

      The reaction doesn’t use up the aluminum or anything. The only resource being exhausted is the water - or, well, the hydrogen atoms in the water.

      10 votes
    3. [2]
      Tardigrade
      Link Parent
      The reason it is pushed for recycling is the cost difference for recycling (cheap (comparatively)) vs producing virgin aluminum (expensive) is a lot higher than for other raw materials whereas for...

      The reason it is pushed for recycling is the cost difference for recycling (cheap (comparatively)) vs producing virgin aluminum (expensive) is a lot higher than for other raw materials whereas for other materials the recycling process can end up being more expensive or producing a worse product for example recycled plastic is often not as strong as virgin plastic.

      2 votes
      1. BeanBurrito
        Link Parent
        The reason it is cheaper is the cost of the copious amounts of electricity to refine virgin aluminum.

        The reason it is cheaper is the cost of the copious amounts of electricity to refine virgin aluminum.

        1 vote
    4. [2]
      conception
      Link Parent
      Aluminum is the most common metal in the earths crust. There’s a lot.

      Aluminum is the most common metal in the earths crust. There’s a lot.

      1. BeanBurrito
        Link Parent
        ...but it takes a lot of energy to refine. Most common doesn't mean limitless, and sadly our race is known for greed.

        ...but it takes a lot of energy to refine.

        Most common doesn't mean limitless, and sadly our race is known for greed.

        1 vote
  5. [2]
    imperator
    Link
    I wonder if this is similar to the works "bombs" we used to make in high school. There you add aluminum foil to a water bottle and added the works toilet bowl cleaner. It created a chemical...

    I wonder if this is similar to the works "bombs" we used to make in high school. There you add aluminum foil to a water bottle and added the works toilet bowl cleaner. It created a chemical reaction and produced a gas to cause the water bottle to explode.

    1 vote
    1. Englerdy
      Link Parent
      Yeah I think it's pretty close. The primary ingredient at work there is the sodium hydroxide in the toilet cleaner reacts with the aluminum and produces hydrogen gas. I don't remember if the water...

      Yeah I think it's pretty close. The primary ingredient at work there is the sodium hydroxide in the toilet cleaner reacts with the aluminum and produces hydrogen gas. I don't remember if the water is split, but I think the hydrogen source for that reaction is just from the sodium hydroxide itself.

      The reaction produces a LOT of heat so eventually the hydrogen ignites and the bottle blows up.

      3 votes