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Name: Henry
Status: other
Grade: other
Location: FL

Why cannot an automobile muffler be a CO2 filter ( that is replaced every 15,000 miles? I know cost may be a factor, but there can be a tax deduction or some way to make this feasible. I have never heard of anyone even trying this.

The main reasons are weight, cost, and effectiveness. First, the filters are expensive -- and lithium is not the safest stuff in the world either. The filters weigh a lot, and would cause your car to get significantly worse gas mileage, causing you to burn more fuel. Moreover, car exhaust has many other harmful substances in it (like SOx and NOx) that the lithium filter does not clean -- and these pollutants would be increased due to the decreased gas mileage. Pollutants and particulates also serve to foul these filters much faster than in their current applications (e.g. submarines), so they would not work as long as they could without fouling. Considering all these problems, and with so many other sources of CO2 in the world (power generation, industrial combustion, agriculture, etc.), I would guess scientists and policy makers have determined that investing in LIOH filters is not the most effective use of money to reduce CO2.

I bet you could get a better, and more quantitative answer (mine is largely speculation) from the filter manufacturers themselves -- google "LiOH CO2 filter" and you can find contact information (I do not want to post it here). See what the real experts say! For instance, how much do they weight? Cost? How long could they last? Etc.

Hope this helps,
Burr Zimmerman

The problem is mass. Every gallon of gasoline, when burned completely, produces about 8 kilograms (17 pounds) of carbon dioxide. How often do you fill up your tank? How many gallons of gasoline are in a fill-up? How many gallons of gasoline are consumed in 15,000 miles of travel? How much would that weigh to carry around with your car? How much LiOH would be needed to trap the carbon dioxide produced by burning that much gasoline?

I do not think a tax deduction would make this feasible. Logistically, you would need to get rid of carbon dioxide produced at least as often as you purchase gasoline, not every 15,000 miles!

Richard Barrans, Ph.D., M.Ed.
Department of Physics and Astronomy
University of Wyoming


I am not familiar with the industrial process and cost for the production of lithium hydroxide. I do know that it is not a naturally occurring compound and is produced from brines containing lithium, usually in the form of lithium carbonate. This means that in order to produce lithium hydroxide from lithium carbonate an expenditure -not only of money, but also of energy (electricity)- would have to be made. If we consider that lithium hydroxide makes for a good carbon dioxide scrubber because it is very reactive, I can only surmise that it takes quite a bit of energy to produce it. As such, I imagine that the environmental cost of producing the electricity/energy needed to make lithium hydroxide (not to mention the packaging and delivery of the product) would offset the gains in getting rid of carbon dioxide from emissions.

Greg (Roberto Gregorius)

Hi Henry,

The reason you have not heard of anyone trying to put a CO2 "filter" on a car, is because it unfortunately is completely impractical. For every gallon of gasoline that is burned, there is about 19 pounds of CO2 produced. A typical car whose gas tank holds around 15 gallons of gasoline, will produce 285 pounds of CO2 each time it uses a tank of gas! That means that a CO2 filter must absorb that 285 pounds of CO2, for every single fill-up! This would require a huge "filter", that would need to be changed at every fill-up.

As you can see, this is clearly not practical! But the even if it were, the problem remains: what would you do with all the trapped CO2?

I assume your question results from your concern that manmade CO2 is claimed to cause global warming. Interestingly, there are many eminent scientists who have convincing evidence that this is simply not true. You might be interested in reading the report published by the Nongovernmental International Panel on Climate Change (NIPCC) that is titled "Nature, Not Human Activity, Rules the Climate". This report does a good job of addressing many of the hysterical claims you may have heard. Here is the link... it is a long report, but very interesting...

Bob Wilson

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