• Jul 20th 2007 at 8:53AM
  • 15
Three friends from North Wales were trying to come up with a way to use carbon dioxide to help grow algae to feed a fish farm and may have stumbled across a breakthrough that could clean up greenhouse gas emissions. There has been a lot of discussion recently about carbon sequestration but these three guys from Wales may have developed a way to capture CO2 on board vehicles.

The Greenbox would be installed in the vehicle exhaust system and is supposed to be able to capture up to 95 percent of the greenhouse gases from a tankful of fuel. The box could be exchanged for an empty one at each fill up. The greenbox would be sent an algae bioreactor where the CO2 would be used to feed the algae. The algae would then be used to produce biodiesel. The fuel would then be used as a clean alternative to petroleum.

If this thing actually works it could both solve the problem of carbon emissions and renewable fuels. We'll just have to wait for some more independent test results.

[Source: Reuters, thanks to Manu for the tip]

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    • 1 Second Ago
      • 8 Years Ago
      Wouldn't the carbon capture container need to be about as big as your fuel tank for this to work? Actually, considerably bigger -- a gasoline car puts out 18 or 19 pounds of CO2 for each gallon (~6 pounds) of fuel, due to the mixing of hydrocarbons in the fuel with oxygen in the air. Since CO2 is obviously less dense than the fuel which generated it, you'll need a pretty big container. Wow, think of that, a car that gets heavier as you drive it along and use fuel!

      Of course, due to density, this problem is probably only a tenth as hard to solve as storing hydrogen in a vehicle, so I suspect it could work alright in situations where hydrogen and compressed natural gas vehicles are currently being used, mostly fleet situations where there are central maintenance and fueling locations.
      • 8 Years Ago
      Well, and if it is compressing the CO2, would that have an increase in backpressure to the motor, and a potential for damage ensuing?
      • 8 Years Ago
      A video demo can be seen here:

      It looks quite big but as the article says, it can be made small enough to fit under a car.
      • 5 Years Ago
      For vehicles I have been looking at using potassium hydroxide solution to capture carbon dioxide as the carbonate and bicarbonate. At the limit of solubility I estimate 11 kg of liquor could hold the carbon dioxide from the combustion of 1 litre of fuel. I reckon that makes it feasible as long as the liquor is changed out every 100 miles or so and sent for processing to recover and sequester the carbon dioxide and reform the hydroxide.
      • 5 Years Ago
      What if algal bioreactor sits on the car and fed by the direct emissions.
      Algae needs sunlight, some agitation, both problems will be solved in this way. if u r using genetically modified algae, try thermotolerant strain.
      • 8 Years Ago
      This system could be added on to an existing vehicle and overnight your carbon footprint is drastically reduced. It should be a mandatory add-on to all ICE vechicles. Perhaps as a condition of re-registering your vehicle. Of course, it should be mandated on new vehicles.
      • 8 Years Ago
      Awesome idea, but wouldn't it would make more sense to simultaneously pump out the CO2 while refueling instead of swapping out a box?
      • 8 Years Ago
      why not just add them to coal plants and give the entire US emission free made electricity? This would allow us to all use electric hybrid cars like the Volt, and would have no need for 90% of the gas stations. Instead have ethanol and biodiesel coop stations.
      • 8 Years Ago
      This sounds like it might be practical for stationary systems (like a power plant)

      But for a car there's three problems: Infrastructure, Infrastructure, Infrastructure!
      • 7 Years Ago
      Interesting paper (the first link posted). There's obviously some public-education due on this topic to get people behind it.

      1) The box is most defintely NOT "compressed CO2"... yet. The mechanical separation of CO2 from water vapor and other combustion byproducts is NOT going to happen. Beyond that, the pressure needed to trasport that much CO2 gas would be a DOT-certification hazard (though doable, as shown by 1000psi Nitrous bottles, and even 3000 psi CNG tanks). This carbon capture method, like almost ALL in development (outside of semi-permeable membrane R&D which likely won't work in a mobile environment for packaging reasons) requires CHEMICAL sequestering.

      As mentioned above, a typical gasoline molecule has about 8 carbons (give or take ~3 due to additives) which combust into 8 separate molecules of CO2. To be even close to a decent amount of storage you'd need a molecule that can sequester at LEAST that many carbon's, if not ~4 times more... OR a catalyst that can convert multiple CO2 molecules to a carbon-rich molecule which is easier to store. This is the R&D part that is so hard to do... but progress is being made.

      There IS another option though... capture AND conversion to compressed CO2. The idea is to use a carbon-sequestering solution to grab CO2 from the exhaust stream (much like hemeglobin grads O2 from our lungs), transport it to a "release" section which can use steam from engine heat (remember that over 60% of all energy from gasoline is lost to HEAT radiation). The MIT article touched on this idea, but excluded mobile solutions which I personally think was a mistake. IF you can liberate the CO2 from the solution using heat/catalyst, you can then pump it into a storage tank.

      The use of a chemical "scrubber" that can be used to liberate CO2 into a closed sytem for pumping into a storage tank would:

      a) make the expensive chemical solution FIXED in place meaning this large, heavy liquid filled box could be mounted anywhere best for safety/efficiency/weight distribution,

      b) if liberated/recycled fast enough, the amount of HEAVY liquid could be much reduced, and a slightly larger CO2 tank used in its place... remember, we're talking about compressing CO2 to over 200 times atmostpheric pressure! Even if you get that kind of sequestering in a chemical scrubber, you'll probably still need a liquid solvent to counter sideeffects such as corrosion, coagulation, etc... much in the same way coolant is needed to prevent issues with straight water.

      c) Make CO2 emptying a simple process... just plug in hose to a CO2 outlet and the pressurize CO2 tank does the work... no need to swap tanks! As was mentioned before, the idea of 'emptying CO2 while filling with gas' is a convienent idea.

      Only drawback to the compressed CO2 system of course is the added cost of a "CO2 liberator", teh pump, and the tank. But the weight savings from minimzing the liquid componants and reducing expensive (or possibly hazardous) chemcials for each car would probably pay for itself.

      Note of caution: compressed CO2 is NOT combustable and will NOT present a fire hazard in an accident... however it DOES displace oxygen, and is heavier than air. A large CO2 release could suffocate anyone in an enclosed space... this is actually a hazard of living in the shadow of a volcano... CO2 gases can roll down the slopes and "pool" in low lying areas killing plants, animals, and humans (although many microbes love the stuff).

      So what do you actually DO with sequestered CO2 after the station collects it? That's problem 2.

      Some like the idea of geologic storage. Pumping CO2 deep (800+ meters / 3000+ feet) into the earth in carefully selected areas. The idea is that the high pressures keep it dense and as it seeps through the earth CO2 loving microbes eat the stuff up... much like ALREADY exists with CO2 from volcanoes and magma domes. :)

      Other R&D is going into using this CO2 for plastics production or other chemical processes which could be useful.

      Both solutions are in testing of various forms.

      I personally don't belive carbon-sequestering is a pipe dream, it WILL be doable, however the energy cost of it may be more than we'd like. It may very well be that the solution to CARBON EMMISSIONs is the need for a carbon-free energy source ANYWAY.

      This isn't a great solution for large plants (which would be way ahead as nuclear, hydro, or wind powered anyway), but might actually be a great solution for mobile CO2 sources.

      Obviously a carbon-free power source (like nuclear) and the creation of electric motor vehicles would solve many problems, but large mobile vehicles will, for the next century at least, require energy-dense carbon compounds like diesel (imagine the battery packs nee
      • 8 Years Ago
      I don't get it. It doesn't make sense to capture the CO2 from biodiesel: If you're already using algae to pull carbon dioxide out of the atmosphere, then why waste all the energy required to capture and transport the C02? If you used this to capture CO2 from non-biological sources, then you're really only helping to delay the release into the atmosphere by a matter of months, hardly an improvement in the grand scheme of things.
      • 8 Years Ago
      I'm with pcubed on this... Moreover, you need energy to transport the CO2. What's the sense of this machinery? Either I'm missing something, or these guys are kind of nuts. Hum.

      Anyway, what's the efficiency of growing algae and using them to produce clean fuel as opposed as to using, say, photovoltaic cells to transform sunlight in electricity? After all, both system harvest sunlight's energy, in a way or another.

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