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Although biofuels prevent consumption of fossil fuels, they still contribute to CO2 emmissions. Another side effect is that the land resources used to grow thos

by acvny 7y ago

Although biofuels prevent consumption of fossil fuels, they still contribute to CO2 emmissions. Another side effect is that the land resources used to grow those biofuels are consumed. Also they lead to food prices increase and shortages. The good thing is when the raw material is made of leftovers from normal food oriented farming. However when farmers replace corn cultures with rapeseed that's bad.

oconnore 7y ago
That’s exactly why newer biofuels rely on sources that don’t require high investment crop land — e.g. switchgrass and other “weeds”. You could also plant switchgrass in highway medians, for example.
doctor_eval 7y ago
This doesn’t make sense to me. First, the CO2 released from burning farmed plants does not increase the CO2 in the atmosphere. It’s a cycle. Second, climate change will also cause food prices to increase. There is going to be an equilibrium point at which the increased cost of food due to land use changes outweighs the benefit of reduced emissions, but that point is almost certainly not zero. In theory, farmers could replace corn with rapeseed at no cost to consumers if doing so mitigates climate change, the main problem is that the net cost of doing so needs to be averaged out over decades :(
- revax 7y ago
  On your first point, that is not quite correct. While the CO2 released will eventualy come back, it takes an enormous amount of time. It may be a cycle but what matters is the CO2 concentration in the athmosphere or more precisely the radiative forcing at a given time.
  - vpribish 7y ago
    it takes one growing season for the rice, wheat, sugar cane, and soybean they were using.
  - Mirioron 7y ago
    If I burn a plant that contains 10 kg of carbon and then grow a plant that contains 10 kg of carbon then in terms of carbon in the atmosphere it should be a net zero effect. Plants take carbon out of the atmosphere to grow after all.
    - lazyjones 7y ago
      > If I burn a plant that contains 10 kg of carbon and then grow a plant that contains 10 kg of carbon then in terms of carbon in the atmosphere it should be a net zero effect. No, because the plant you burned would have pulled more CO2 from the atmosphere if it had stayed alive, there's plenty of CO2 around already to feed other plants in the mean time. So the net effect is negative. If you can't grasp the logic, think about what happens if you burn all the plants. Some will grow back, but not all.
      - Mirioron 7y ago
        That plant would pull in more CO2 and increase its own biomass based on it. When that plant then dies two-three-five years later then all of that carbon gets back into the atmosphere anyway. >If you can't grasp the logic, think about what happens if you burn all the plants. Some will grow back, but not all. The only way they don't grow back is if desertification happens or humans start using that area. Otherwise, the plant life returns on its own. Chernobyl is overrun by plants.
        lazyjones 7y ago
        > When that plant then dies two-three-five years later then all of that carbon gets back into the atmosphere anyway. No. If it fully decomposes at some point, arguably. But plants are eaten by various organisms (= C becomes part of the organism), are used for building houses, become fossilized. All of these make these "cycle" claims invalid. > The only way they don't grow back is if desertification happens or humans start using that area. No. Plants can also become extinct (= no seeds survive) or stop growing in some places due to more aggressive competition.
- acvny 7y ago
  >First, the CO2 released from burning farmed plants does not increase the CO2 in the atmosphere. It’s a cycle. But you can say the same about burning coal.. That CO2 will eventually be consumed by plants and stored there as carbon.. only it will take quite some time
  - Neeek 7y ago
    Except it won't, dead plants decompose and release their carbon back in to the atmosphere whether you burn it or not. Coal comes from an age where atmospheric carbon was much higher and nothing had evolved to decompose wood, digging it up and burning it means a net increase, growing something and burning it is net neutral.
    - adrianN 7y ago
      Technically it will, because there are geological processes that more or less permanently remove carbon from the atmosphere, but they take geological time (tens of thousands of years).
  - doctor_eval 7y ago
    Coal was laid down well before the current atmospheric equilibrium. The CO2 in coal and other fossil fuels has essentially been removed permanently from the atmosphere. Until we dig it up and burn it, anyway.
- lazyjones 7y ago
  > First, the CO2 released from burning farmed plants does not increase the CO2 in the atmosphere. It’s a cycle. Widespread nonsense. The CO2 emitted through burning plants does not magically turn into plants again. Plants have limited capacity to draw CO2 from the atmosphere and there's plenty of that around already, indistinguishable from "industrial" CO2. Any CO2 added through fires increases atmospheric CO2, any plant burned doesn't increase, but decreases the chances of CO2 removed from the atmosphere in the future.

by acvny 7y ago

oconnore 7y ago

That’s exactly why newer biofuels rely on sources that don’t require high investment crop land — e.g. switchgrass and other “weeds”. You could also plant switchgrass in highway medians, for example.

doctor_eval 7y ago

This doesn’t make sense to me. First, the CO2 released from burning farmed plants does not increase the CO2 in the atmosphere. It’s a cycle. Second, climate change will also cause food prices to increase. There is going to be an equilibrium point at which the increased cost of food due to land use changes outweighs the benefit of reduced emissions, but that point is almost certainly not zero. In theory, farmers could replace corn with rapeseed at no cost to consumers if doing so mitigates climate change, the main problem is that the net cost of doing so needs to be averaged out over decades :(

revax 7y ago
On your first point, that is not quite correct. While the CO2 released will eventualy come back, it takes an enormous amount of time. It may be a cycle but what matters is the CO2 concentration in the athmosphere or more precisely the radiative forcing at a given time.
- vpribish 7y ago
  it takes one growing season for the rice, wheat, sugar cane, and soybean they were using.
- Mirioron 7y ago
  If I burn a plant that contains 10 kg of carbon and then grow a plant that contains 10 kg of carbon then in terms of carbon in the atmosphere it should be a net zero effect. Plants take carbon out of the atmosphere to grow after all.
  - lazyjones 7y ago
    > If I burn a plant that contains 10 kg of carbon and then grow a plant that contains 10 kg of carbon then in terms of carbon in the atmosphere it should be a net zero effect. No, because the plant you burned would have pulled more CO2 from the atmosphere if it had stayed alive, there's plenty of CO2 around already to feed other plants in the mean time. So the net effect is negative. If you can't grasp the logic, think about what happens if you burn all the plants. Some will grow back, but not all.
    - Mirioron 7y ago
      That plant would pull in more CO2 and increase its own biomass based on it. When that plant then dies two-three-five years later then all of that carbon gets back into the atmosphere anyway. >If you can't grasp the logic, think about what happens if you burn all the plants. Some will grow back, but not all. The only way they don't grow back is if desertification happens or humans start using that area. Otherwise, the plant life returns on its own. Chernobyl is overrun by plants.
      - lazyjones 7y ago
        > When that plant then dies two-three-five years later then all of that carbon gets back into the atmosphere anyway. No. If it fully decomposes at some point, arguably. But plants are eaten by various organisms (= C becomes part of the organism), are used for building houses, become fossilized. All of these make these "cycle" claims invalid. > The only way they don't grow back is if desertification happens or humans start using that area. No. Plants can also become extinct (= no seeds survive) or stop growing in some places due to more aggressive competition.
acvny 7y ago
>First, the CO2 released from burning farmed plants does not increase the CO2 in the atmosphere. It’s a cycle. But you can say the same about burning coal.. That CO2 will eventually be consumed by plants and stored there as carbon.. only it will take quite some time
- Neeek 7y ago
  Except it won't, dead plants decompose and release their carbon back in to the atmosphere whether you burn it or not. Coal comes from an age where atmospheric carbon was much higher and nothing had evolved to decompose wood, digging it up and burning it means a net increase, growing something and burning it is net neutral.
  - adrianN 7y ago
    Technically it will, because there are geological processes that more or less permanently remove carbon from the atmosphere, but they take geological time (tens of thousands of years).
- doctor_eval 7y ago
  Coal was laid down well before the current atmospheric equilibrium. The CO2 in coal and other fossil fuels has essentially been removed permanently from the atmosphere. Until we dig it up and burn it, anyway.
lazyjones 7y ago
> First, the CO2 released from burning farmed plants does not increase the CO2 in the atmosphere. It’s a cycle. Widespread nonsense. The CO2 emitted through burning plants does not magically turn into plants again. Plants have limited capacity to draw CO2 from the atmosphere and there's plenty of that around already, indistinguishable from "industrial" CO2. Any CO2 added through fires increases atmospheric CO2, any plant burned doesn't increase, but decreases the chances of CO2 removed from the atmosphere in the future.