Viewing a single comment thread. View all comments

[deleted] t1_j92ew0x wrote

Reply to comment by Cyber_Dan in Scientists have figured out a way to engineer wood to trap carbon dioxide through a potentially scalable, energy-efficient process that also makes the material stronger for use in construction by giuliomagnifico

Nah the amount of vegetation required would be way more than could fit to do anything significant. Plants don't use that much CO2, and I don't think CO2 levels change the structural properties of the plants, it just accelerates growth rate in general.

9

fleebleganger t1_j92uo06 wrote

A mature oak tree weighs somewhere around 2,000 tons.

The average American generates 16 tons of carbon a year. That’s 125 years of emissions covered.

So each tree does quite a bit

7

[deleted] t1_j92zbbe wrote

Most of that weight is not carbon though, it's mostly water. And I don't know how you think you're going to get mature oak trees in urban densely populated areas anytime soon.

8

jackzander t1_j94r9bs wrote

A mature oak tree does not weigh 4,000,000 pounds.

You fucked up some math.

1

bernyzilla t1_j96s0nq wrote

Thank you. 2,000 tones is an insane amount. A quick Google search puts the weight closer to 20,000 pounds or ten tons.

Which will dramatically change the calculus for carbon sequestration. Also remember that this only works for new trees, and that mature forests release as much carbon as they absorb.

Still, I am all for planning as much trees as we can possibly get away with. Climate change is an emergency and we should be doing everything possible to mitigate it.

2

danielravennest t1_j97fst3 wrote

Within reason, the individual tree weight doesn't matter. A "closed canopy" is when you look up in a forest and can't see any sky, just leaves and branches. That means all the available sunlight is being used by leaves.

So for a given soil and climate, a closed canopy maximizes the CO2 capture in tons per acre/hectare. If you want to produce durable wood products and store the carbon, you generally don't want a lot of little skinny trees. You want the trunks to be big enough to get useful pieces out of it.

1

iinavpov t1_j95aho0 wrote

More like 4 tonnes.

Also takes a century to grow.

1

danielravennest t1_j97e8rr wrote

That's a completely wrong number. An 80 foot red oak grown in a forest is about 10 tons. That assumes it is 2 feet in diameter at the base.

Source: former tree farmer, and now woodworker "from the tree". That means I harvest a tree, get it cut into lumber, and dry it. I know how much those logs weigh.

The biggest log I ever dealt with was a 3 feet in diameter x 20 ft long oak, which was 5 tons. That was a yard oak, rather than a forest oak. Lack of competition allowed big side branches and therefore a fat trunk.

A freshly cut southern red oak is about 42 pounds per cubic foot oven dry weight, and an equal amount of water when freshly cut. "Dried" wood contains 6-14% moisture in addition to the dry weight. Wood is porous, and exchanges moisture with air that has any humidity in it. So in practice the weight in a finished product is about 46 pounds per cubic foot.

1