The long-running series in which readers answer other readers’ questions considers a change that might help the environment
This week’s question: Would equal pay create a better society?
If all the vehicles on the planet had their tyres pumped up with CO2, would this lock up enough carbon to lower the amount in the air significantly? Would there be other issues, such as the carbon cost of trapping it all into the tyres? Chris Coldwell, Lancaster
Send new questions to nq@theguardian.com.
Are we expecting the car tyres to stay pumped up for geological time, say the next 50,000 years? If they leak and go flat before then, they haven’t helped restore the natural carbon balance. It’s quite sobering how long the damage done by one generation of humans will persist in the environment. Randomusername222
An inflated car tyre will contain about 14g of air. CO2 weighs about 50% more than air, giving 21g of CO2 per tyre, or 105g per car. There are just short of 1.5bn cars on the planet. Multiplying this by 105g gives 157,700 tonnes of CO2 in all of the world’s car tyres. CO2 emissions in 2025 were 38.1bn tonnes, or about 100,000 tonnes per minute. DrLBlack
It would be interesting to compare the 157,700 tonnes stored here to the area needed to get the same carbon store in a rewilding project. I imagine that it would be a relatively small area of woodland on a map? KP8900
Four hundred tonnes per hectare per year. So, in very round terms, either thousands of hectares or thousands of years, to achieve capture of hundreds of thousands of tonnes. Which is well, well short of current emissions. mill1806
You have to pull the stuff out of the sky first and stop putting more there afterward. Locking it into tyres is a very short-term, fanciful solution. Bubble it through algae, trap it in basalt, turn it into bicarbonate and chuck it in the ocean. Plant one thing each day – preferably a tree. Turn it into kelp forests and sink it. Educate more girls. Make voting compulsory. king_tubby
First off, it is not easy or cheap to get carbon dioxide out of the air – certainly not easier or cheaper than just pumping air into the tyres. Plus, it does nothing about the other gases, such as methane, that are far more powerful drivers of climate change on a by-volume basis. If we could, we’d be better off extracting the CO2 and turning it into C and O2. Carbon is far easier to store and the O2 could be released to help dilute the CO2 remaining in the atmosphere. TotallyTukTuk
Actually while we are still using natural gas for heating, it would be useful to react captured CO2 with H2 to form methane, which then goes in the gas grid, reducing the amount of fossil gas needed. The energy to capture CO2, make hydrogen by electrolysis of water and run the combining reactions can be wholly renewable. canyoudoso
Err, but thermodynamics 101 says that the electricity you use to recreate the methane is equal or greater than the heat you gained by burning the natural gas. Electrolysis in particular is very wasteful of energy. Thermodynamics 102 says that a heat pump gives you four units of heat for every one of electricity you put in. So you’d be many times better off leaving the natural gas in the ground and heating your home with a heat pump instead. So the gas created in that way will be prohibitively expensive. Even an electric fan heater would be many times cheaper than synthetic methane. Randomusername222
The cost of collecting, transporting and storing CO2 for the specific purpose of filling car tyres would probably be astronomical compared to the current simple and cheap compressed air method. When punctured or removed, tyres release the same air back into the atmosphere. Billions of CO2-filled tyres would simply add to pollution levels upon deflation. There would be little or no point in using an esoteric gas in pressurised cylinders, particularly in the hands of unskilled operators on petrol station forecourts, etc. FrankieandDexy
No. The total volume of every car tyre on the planet is so much smaller than the size of the atmosphere that filling them all with 100% carbon dioxide would make no noticeable difference. Even if it did, the carbon would be held only until the tyre punctured or wore out, much quicker than the 100-year time carbon dioxide persists
in the atmosphere. Mark, Cambridgeshire
Probably not. When you change a tyre, or get a puncture or at the end of the vehicle’s life, the CO2 has to go somewhere. Maybe it could be reclaimed/recycled, but I suspect the cost would be prohibitive. Pointy_Haired_Boss
