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Yeah, I still remember the basic laws of thermodynamics ;). If only they taught those in high school too. Aside: sometimes I wonder if spending some time to te

Yeah, I still remember the basic laws of thermodynamics ;). If only they taught those in high school too. Aside: sometimes I wonder if spending some time to teach more advanced concepts of science in more "conceptual" ways wouldn't be a lot more useful for the general public than the current style of education. You can get a perfectly fine intuition and "first-principle" understanding of laws of nature running the world around you, without ever worrying about calculus, and it's quite useful.

maxerickson 9y ago
What do the basic laws of thermodynamics and intuition do to inform you about the EROI of biofuels?
- vanderZwan 9y ago
  That growing corn and then turning it into ethanol to burn in your cars is unlikely to be sustainable or more energy-efficient than extracting fossil fuels. Basic matter of thinking in terms of conversion losses. It probably helps to know that currently every calorie produced by Western agriculture costs about ten calories worth of fossil fuels, but still. EDIT: I realised just now that I took Michael Pollan's word on that 10:1 number without checking it, mea culpa. Quick search on the web gives me this though: http://people.uwplatt.edu/~dalecki/newperspectives.pdf http://people.uwplatt.edu/~dalecki/newperspectives.pdf and that graph on the sixth page (or "page 184") does look pretty damning on ethanol as a fuel (I'm making no statements on its qualities as an oxidizer).
  - Turing_Machine 9y ago
    "Basic matter of thinking in terms of conversion losses. " While it is true that Western agriculture uses a lot of fossil fuels, that isn't necessarily the case for all possible models of agriculture. Plants get their energy from the sun. They don't drink it from a gas pump. Yeah, there'll be "conversion losses" (i.e., less energy will show up in the plant than was produced by fusion in the core of the sun), but it's hard to see why that matters in any realistic sense.
    - vanderZwan 9y ago
      > that isn't necessarily the case for all possible models of agriculture. No, but then we change the discussion: we were talking about the (in)efficiencies of corn ethanol. Hence my Western agriculture qualifier, because that is the context in which it is generated as a biofuel. If we look more broadly, then a whole lot of alternatives look a lot better obviously.
      - maxerickson 9y ago
        The 10:1 likely rolls in animal products and low calorie vegetables, which aren't corn either.
        vanderZwan 9y ago
        Ah, fair point there. I had not considered that.
    - vanderZwan 9y ago
      Also, conversion losses do matter, because a lot of efficiency calculations cheat by forgetting (or perhaps "forgetting") to include them, as a hidden form of externalising energy costs. For example: > [If we compare] the thermal efficiencies from modern cooking stoves with those from stoves used in poorer households, we see that the improved biomass stoves in developing countries beat our "high-tech" cooking technology with a factor of two to three (graphic below). > The main discrepancy with these figures is caused when one doesn't take into account that electricity first needs to be produced in power plants which sometimes convert less than a third of the primary energy into electricity. This is not an issue with gas or biomass stoves, where a primary fuel is directly converted into heat for cooking. > Evidently, there is something wrong with the western approach to sustainability. Converting heat into electricity which is then converted back into heat, at 20-40% efficiency, is similar to building a Rube Goldberg machine; it's a needlessly complex operation compared to simply converting the primary fuel into heat to boil water. Essentially, any electric cooking device is an insult to the science of thermodynamics. http://www.lowtechmagazine.com/2014/06/thermal-efficiency-cooking-stoves.html http://www.lowtechmagazine.com/2014/06/thermal-efficiency-co... ... huh, I guess that's last sentence where I got my thermodynamics remark from.

maxerickson 9y ago

What do the basic laws of thermodynamics and intuition do to inform you about the EROI of biofuels?

vanderZwan 9y ago
That growing corn and then turning it into ethanol to burn in your cars is unlikely to be sustainable or more energy-efficient than extracting fossil fuels. Basic matter of thinking in terms of conversion losses. It probably helps to know that currently every calorie produced by Western agriculture costs about ten calories worth of fossil fuels, but still. EDIT: I realised just now that I took Michael Pollan's word on that 10:1 number without checking it, mea culpa. Quick search on the web gives me this though: http://people.uwplatt.edu/~dalecki/newperspectives.pdf http://people.uwplatt.edu/~dalecki/newperspectives.pdf and that graph on the sixth page (or "page 184") does look pretty damning on ethanol as a fuel (I'm making no statements on its qualities as an oxidizer).
- Turing_Machine 9y ago
  "Basic matter of thinking in terms of conversion losses. " While it is true that Western agriculture uses a lot of fossil fuels, that isn't necessarily the case for all possible models of agriculture. Plants get their energy from the sun. They don't drink it from a gas pump. Yeah, there'll be "conversion losses" (i.e., less energy will show up in the plant than was produced by fusion in the core of the sun), but it's hard to see why that matters in any realistic sense.
  - vanderZwan 9y ago
    > that isn't necessarily the case for all possible models of agriculture. No, but then we change the discussion: we were talking about the (in)efficiencies of corn ethanol. Hence my Western agriculture qualifier, because that is the context in which it is generated as a biofuel. If we look more broadly, then a whole lot of alternatives look a lot better obviously.
    - maxerickson 9y ago
      The 10:1 likely rolls in animal products and low calorie vegetables, which aren't corn either.
      - vanderZwan 9y ago
        Ah, fair point there. I had not considered that.
  - vanderZwan 9y ago
    Also, conversion losses do matter, because a lot of efficiency calculations cheat by forgetting (or perhaps "forgetting") to include them, as a hidden form of externalising energy costs. For example: > [If we compare] the thermal efficiencies from modern cooking stoves with those from stoves used in poorer households, we see that the improved biomass stoves in developing countries beat our "high-tech" cooking technology with a factor of two to three (graphic below). > The main discrepancy with these figures is caused when one doesn't take into account that electricity first needs to be produced in power plants which sometimes convert less than a third of the primary energy into electricity. This is not an issue with gas or biomass stoves, where a primary fuel is directly converted into heat for cooking. > Evidently, there is something wrong with the western approach to sustainability. Converting heat into electricity which is then converted back into heat, at 20-40% efficiency, is similar to building a Rube Goldberg machine; it's a needlessly complex operation compared to simply converting the primary fuel into heat to boil water. Essentially, any electric cooking device is an insult to the science of thermodynamics. http://www.lowtechmagazine.com/2014/06/thermal-efficiency-cooking-stoves.html http://www.lowtechmagazine.com/2014/06/thermal-efficiency-co... ... huh, I guess that's last sentence where I got my thermodynamics remark from.