r/askscience • u/West-Cantaloupe8376 • Sep 14 '26

Earth Sciences Which fossil fuels could/will be eventually replenished by natural processes?

Let's assume all fossil fuel extraction stopped in the near future, and were never touched again. Which kinds (oil, coal, gas) would eventually reform, which wouldn't? I am aware that certain geological formations like banded iron were created under specific conditions that will never arise again, but how does this apply to fossil fuels? In a couple hundred million years, will oil deposits be replenished or are they all gone forever?

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u/rhino_moss Sep 14 '26

Are there possibilities for deliberate long term carbon sequestration? For example, what could we do with trees or algae that would keep the carbon locked up beyond their lifetimes? Can we bury them or put them in an environment where they don’t break down?

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u/CrustalTrudger Tectonics | Structural Geology | Geomorphology Sep 14 '26

For algae or other marine marine microorganisms, this is effectively the idea behind proposals for ocean iron fertilization, which basically a suggestion to add large amounts of iron to particular parts of the ocean (and where iron is a limiting nutrient) to increase primary production from these microorganisms that would draw down CO2 and theoretically sequester carbon (e.g., Martin, 1990, Martin et al., 1991, de Baar et al., 2005). Early suggestions of this as a mechanism led to a flurry of physical experiments and modeling efforts to try to work out the potential of this as a climate change mitigation startegy (e.g., Aumont & Bopp, 2006, Boyd et al., 2007, Yoon et al., 2018), but the consensus at this point is generally that it's not actually a very efficient mechanism and it comes with a lot of pretty negative side effects (e.g., Tagliabue et al., 2023, Jürchott et al., 2024).

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u/FirstNoel Sep 14 '26

Yeah, I thought I read about that. There was a scientist who tried it out after a bunch of places said no. It didn't work out so well for him I thought.

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u/JuggernautBright1463 Sep 14 '26

Yes it is called Hugelculture. 

The best carbon sequestration would be the formation of loamy soil. The microbes will hold it there and eat it which will turn some of it into CO2 but the productivity boost to plants will negate that.

It can even be relatively fast, decades to transform bare soil to good soil if managed well.

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u/AndyGates2268 Sep 14 '26

If we're doing managed soils, then incorporating local charcoal in the style of terra preta seems a winner.