4 ms·

> to produce one litre of petrol it takes 1.29 kg of oil, of which 85% (1.1 kg) is carbon. And as only 1/10,750 of the carbon remains from the plants that were

> to produce one litre of petrol it takes 1.29 kg of oil, of which 85% (1.1 kg) is carbon. And as only 1/10,750 of the carbon remains from the plants that were buried millions of years ago, our one litre of petrol is the result of 1.1 x 10,750 = 11,825 kg of carbon from ancient plants. Finally, as plants are approximately half carbon, that means that 23.65 tonnes of plants were required to make just one litre of the petrol available at your local station Wow, and this is a lower bound because it doesn't even consider manufacturing and distribution. My cognitive dissonance at the gas station is approaching an all-time high.

version_five 5y ago
Maybe a pedantic point: I think there is a difference between saying 24 tonnes of plants were "required" and saying 1 L represents 24 tonnes of plants. The same way 1 kg of iron represents some, I imagine incomprehensible amount of fusion. But if you want 1 kg of iron, you don't need to go out and expend that energy, any more than you need to go out and expend 24 tonnes if plants. Both are basically finite, with geological or astrophysical origins, rather than something we can make again on human timescales
- Robotbeat 5y ago
  The difference being that iron is recyclable and can be re-smelted (if oxidized) without needing to be fused in stars whereas with fossil fuels we aren’t so lucky. (However, synthesizing hydrocarbons IS feasible.)
  - throwaway09223 5y ago
    Recycling carbon is easy, we just use plants. Soybeans are a common way of capturing carbon from the atmosphere, using solar energy, to produce diesel.
- _3u10 5y ago
  Yeah, its almost as annoying as when people talk about "using" water. The cycle time is 9 days, in 9 days it comes back down as rain, very little water ever gets "used".
  - yetihehe 5y ago
    Because they typically omit "easily available". There's lot's of water in the ocean, why do people die from lack of water in the middle of big body of water?
    - _3u10 5y ago
      Honestly, because they don’t drink it soon enough / slow enough. There’s a pretty cool study on how you can drink seawater and remain hydrated if you do it right. I meant freshwater cycle time. Yes there are certainly places that run out of water, I meant more places like Vancouver where the city just doesn’t build a bigger reservoir and instead bemoans an annual water shortage.
  - dredmorbius 5y ago
    Economic and market discussions do a very poor job of distinguishing stocks and flows. At the risk of a major digression, one sees this constantly in discussions of inequality where net personal wealth or market capitalisation (both stocks) are compared to income or GDP (both flows). (And at the risk of digressing my own digression, economists aren't even settled on whether wealth is a stock or a flow. Adam Smith's definition is the latter.) With water, there is is a throughput in a given region. That flow is not uniformly available, and varies with time (further complications). It serves processes and consumers (in both economic and ecological senses), and changes to those flows and availability do have major impacts (whether surpluses or shortages). There are times when the critical need is getting rid of excess water (via dikes, pumps, and other control structures), others when the critical need is obtaining or preserving water (again: via pumps, reservoirs, cisterns, etc.). The total demand, flow, and impact are high enough that even modest deviations from normal experience or expectations are often devastating --- floods, droughts, and the like. Transporting water more than a few km / miles is tremendously expensive and typically requires major public infrastructure. It's best moved under gravity flow alone. If the litre of water you have used comes from an excess, there is no issue. If it won't be replaced for a year, it's the last litre available, and the nearest additional litre is 100km away ... you may be having a problem.
dredmorbius 5y ago
I very strongly recommend reading the underlying article itself. I've submitted that numerous times to HN, unfortunately PDFs seem not to have much uptake, in part because many readers arrive via mobile devices. https://www-legacy.dge.carnegiescience.edu/DGE/Dukes/Dukes_ClimChange1.pdf https://www-legacy.dge.carnegiescience.edu/DGE/Dukes/Dukes_C... I'd stumbled across this through my own research, trying to find literature with a detailed description of fossil-fuel formation. I've since found it referenced by numerous other works --- yes, one of my forms of entertainment is looking for familiar citations amongst footnotes. Smil's Energy and Civilization being one work citing Dukes. It's not just the material conversion that's staggering, there's the time of accumulation. For petroleum, humans burn in one year a quantity which took five million years to accumulate.
pvaldes 5y ago
> 23.65 tonnes of plants were required to make just one litre of the petrol available at your local station The correct number would be closer to 3.54 tonnes of plant material. The other 18.91 tonnes aren't spent. They are instead fully recycled and re-enter in the system (or go away out of the oil processing chain).

version_five 5y ago

Maybe a pedantic point: I think there is a difference between saying 24 tonnes of plants were "required" and saying 1 L represents 24 tonnes of plants. The same way 1 kg of iron represents some, I imagine incomprehensible amount of fusion. But if you want 1 kg of iron, you don't need to go out and expend that energy, any more than you need to go out and expend 24 tonnes if plants. Both are basically finite, with geological or astrophysical origins, rather than something we can make again on human timescales

Robotbeat 5y ago
The difference being that iron is recyclable and can be re-smelted (if oxidized) without needing to be fused in stars whereas with fossil fuels we aren’t so lucky. (However, synthesizing hydrocarbons IS feasible.)
- throwaway09223 5y ago
  Recycling carbon is easy, we just use plants. Soybeans are a common way of capturing carbon from the atmosphere, using solar energy, to produce diesel.
_3u10 5y ago
Yeah, its almost as annoying as when people talk about "using" water. The cycle time is 9 days, in 9 days it comes back down as rain, very little water ever gets "used".
- yetihehe 5y ago
  Because they typically omit "easily available". There's lot's of water in the ocean, why do people die from lack of water in the middle of big body of water?
  - _3u10 5y ago
    Honestly, because they don’t drink it soon enough / slow enough. There’s a pretty cool study on how you can drink seawater and remain hydrated if you do it right. I meant freshwater cycle time. Yes there are certainly places that run out of water, I meant more places like Vancouver where the city just doesn’t build a bigger reservoir and instead bemoans an annual water shortage.
- dredmorbius 5y ago
  Economic and market discussions do a very poor job of distinguishing stocks and flows. At the risk of a major digression, one sees this constantly in discussions of inequality where net personal wealth or market capitalisation (both stocks) are compared to income or GDP (both flows). (And at the risk of digressing my own digression, economists aren't even settled on whether wealth is a stock or a flow. Adam Smith's definition is the latter.) With water, there is is a throughput in a given region. That flow is not uniformly available, and varies with time (further complications). It serves processes and consumers (in both economic and ecological senses), and changes to those flows and availability do have major impacts (whether surpluses or shortages). There are times when the critical need is getting rid of excess water (via dikes, pumps, and other control structures), others when the critical need is obtaining or preserving water (again: via pumps, reservoirs, cisterns, etc.). The total demand, flow, and impact are high enough that even modest deviations from normal experience or expectations are often devastating --- floods, droughts, and the like. Transporting water more than a few km / miles is tremendously expensive and typically requires major public infrastructure. It's best moved under gravity flow alone. If the litre of water you have used comes from an excess, there is no issue. If it won't be replaced for a year, it's the last litre available, and the nearest additional litre is 100km away ... you may be having a problem.

dredmorbius 5y ago

I very strongly recommend reading the underlying article itself. I've submitted that numerous times to HN, unfortunately PDFs seem not to have much uptake, in part because many readers arrive via mobile devices. https://www-legacy.dge.carnegiescience.edu/DGE/Dukes/Dukes_ClimChange1.pdf https://www-legacy.dge.carnegiescience.edu/DGE/Dukes/Dukes_C... I'd stumbled across this through my own research, trying to find literature with a detailed description of fossil-fuel formation. I've since found it referenced by numerous other works --- yes, one of my forms of entertainment is looking for familiar citations amongst footnotes. Smil's Energy and Civilization being one work citing Dukes. It's not just the material conversion that's staggering, there's the time of accumulation. For petroleum, humans burn in one year a quantity which took five million years to accumulate.

pvaldes 5y ago

> 23.65 tonnes of plants were required to make just one litre of the petrol available at your local station The correct number would be closer to 3.54 tonnes of plant material. The other 18.91 tonnes aren't spent. They are instead fully recycled and re-enter in the system (or go away out of the oil processing chain).