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Comment by bluejekyll | Hacker News Reader

I keep thinking about why we’re going through this effort rather that using trees, which can also be harvested for lumber and the sequester that carbon in construction.

My super rough math, from quick Google searches, this unit 1,000 tons per year. A mature tree is estimated to capture 48 pounds per year. That would be about 42,000 trees. At roughly, 100-200 trees per acre. Let’s just say 150, so that’s 280 acres of forest/trees to roughly match to performance of the system. Granted, it’s on much less land, but still.

That doesn’t seem like a lot of land when you consider that large protected parks like Yosemite are 759,620 acres.

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Let's say you jam your trees in at 40 foot spacing (you want large mature trees) - that gives you 27 trees per acre.

Assuming your math is right, and we need 42,000 mature trees per year capturing carbon, that means we need 1,555 newly planted acres of trees _per year_ to match this plant (and, there will be 25-30 years before the first batch to be planted actually matches in terms of capture). So you have a small problem of finding land that isn't already forested, finding labor to plant and maintain your growing forest, and continuing to do the same year after year.

And, bear in mind that this plant is just a rounding error on the problem in terms of capacity, so in reality you need to scale by orders of magnitude.

27 trees per acre is a low number, and based on my own experience with land returned to a forest with decent canopy, the 150 trees per acre is not unreasonable.

That said, even with my estimates you’re correct that this is a lot of land, but I wanted to quickly put it into perspective. We are losing forests all over the planet, and this can also help understand the impact of that.

Also, the labor you mention is probably a wash compared to the construction of this plant.

Edit: as an example, if you ever have a chance, go tour a maple tree farm as a good reference. Now, that said I did just google for maple farm tree density and they estimate 70 per acre.

No doubt we need to get deforestration under control. I'm just trying to point out that "just plant trees" is not a sufficient answer to climate change by itself. It helps, certainly.

No one thing is the answer. The answer is to do many things, for example, planting trees.

Many things, presumably including this facility?

Is it not a "thing"?

Yes, and also this facility should help as well.

Is it not a "thing"?

We're pointing out that this will help in addition to other things. This won't be the sole solution, however, it will help.

It isn't really viable as a carbon capture measure, and there's been a lot of research in recent years to show that decades of tree planting campaigns across the world have very often failed outright or--in some cases--been a net negative to communities, ecosystems and forest coverage, and/or atmospheric carbon levels.

Saplings are cheap. That's why planting trees is such an appealing "solution." All of the math is based on the assumption that the saplings survive until they can mature and start sucking in carbon. Most don't; one study found mean mortality rates of 44% after five years over 176 sites in tropical and sub-tropical Asia[0]. A Turkish effort saw over 90% of 11 million trees dead in under a year.[1] Other studies have found similarly horrible numbers, and that's not including the other ways[2] such projects can fail: degradation of grassland ecosystems that were already highly effective carbon sinks[3], decreased biodiversity, increased fire risks with non-native saplings, cultural and economic losses, etc.

There are wildly successful reforestation projects, but they take considerably more investment, local community support, and active long-term monitoring and intervention.[4] All of which undercut what originally made mass tree planting so appealing as a climate solution: the seemingly cheap cost.

We absolutely need to plant trees, both in urban environments because the quality of life benefits of urban trees are so numerous that it's an absolute no-brainer and as part of wider reforestation efforts, but it's never going to be a silver bullet for climate change. It's just one of many, many things we need to do.

0. https://royalsocietypublishing.org/doi/10.1098/rstb.2021.009...

1. https://www.theguardian.com/world/2020/jan/30/most-of-11m-tr...

2. https://www.vox.com/down-to-earth/22679378/tree-planting-for...

3. https://www.vox.com/down-to-earth/22662490/grasslands-better...

4. https://www.science.org/content/article/reforestation-means-...

Because someone is being paid, and someone is being given power/control that gets them paid.

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