3 ms·

Biofuel is the most striking example of why "renewable" is not always equivalent to "desirable". While you can indeed re-grow wood, combusting it at scale maint

Biofuel is the most striking example of why "renewable" is not always equivalent to "desirable". While you can indeed re-grow wood, combusting it at scale maintains an equilibrium level of CO₂ in the atmosphere (which causes climate change), and also releases a equilibrium level of particulate matter, which causes large numbers of deaths from lung and heart diseases.

jlawson 4y ago
You're right about the particulates, but I believe that burning wood can't really cause climate change. Wood is already in the biosphere. Even if we don't burn it, it will decompose and release all its CO2 that way, or burn in a forest fire. The CO2 of that wood is already circulating. It doesn't actually increase CO2 levels the way that digging up long-buried fossil fuels does.
- acidburnNSA 4y ago
  If you cut down and burn trees that take 50 years to grow in 3 seconds, you've increased the amount of CO₂ in the air. Sure it will eventually go away, but the thing that causes climate change is the CO₂ being in air at elevated levels, even if it's in a cycle. Biofuel is almost as bad as fossil at 230 gCO₂-eq/kWh. [1]. Compare to solar pv at 40 and nuclear at 12. [1] https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-iii.pdf https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5...
  - ZeroGravitas 4y ago
    The footnote on those numbers says: > Direct emissions from biomass combustion at the power plant are positive and significant, but should be seen in connection with the CO2 absorbed by growing plants. They can be derived from the chemical carbon content of biomass and the power plant efficiency. For a comprehensive discussion see Chapter 11, Section 11.13 https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_chapter11.pdf https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5... > have led to strong forest Carbon sinks in many OECD regions (Pan et al., 2011; Loudermilk et al., 2013; Nabuurs et al., 2013; Erb et al., 2013). However, the capacity of these sinks is being reduced as forests approach saturation (Smith, 2005; Körner, 2006; Guldea et al., 2008; Nabuurs et al., 2013; Sections 11.2.3, 11.3.2). Active forest management, including management for bioenergy, is therefore important for sustaining the strength of the forest carbon sink well into the future (Nabuurs et al., 2007, 2013; Canadell and Raupach, 2008; Ciais et al., 2008), although countries should realize that for some old forest areas, conserving carbon stocks may be preferential, and that the actively managed forests may for some time (decades) act as sources.
wodenokoto 4y ago
But burning fossil fuel does _not_ maintain an equilibrium level of CO₂ in the atmosphere (which is the main reason why we have climate change in the first place)
beachy 4y ago
> While you can indeed re-grow wood, combusting it at scale maintains an equilibrium level of CO₂ in the atmosphere (which causes climate change. True but meaningless. Sitting in my deck chair also maintains an equilibrium level of CO2, but it doesn't provide any heat or benefit to anyone. We can't look unfavorably on energy approaches just because they fail to actually reduce CO2. That's some kind of unrealistic purity test.
- acidburnNSA 4y ago
  It's not meaningless. CO₂ in the atmosphere causes the greehouse effect, which allows the sun to heat the earth more. To avoid greenhouse effect you can't have things that require CO₂ to constantly remain in the atmosphere. You need non-carbon sources like wind, solar, hydro, nuclear, geothermal, etc.
  - Someone 4y ago
    > To avoid greenhouse effect you can't have things that require CO₂ to constantly remain in the atmosphere. But we don’t want to fully avoid the greenhouse effect. https://en.wikipedia.org/wiki/Greenhouse_effect https://en.wikipedia.org/wiki/Greenhouse_effect: “Earth's natural greenhouse effect keeps the planet from having the below freezing temperature that it would have if there were no greenhouse gases”
    - cma 4y ago
      He's talking about the excess unnatural greenhouse effect.
      - Someone 4y ago
        I don’t see how one can read that from “To avoid greenhouse effect you can't have things that require CO₂ to constantly remain in the atmosphere.” The natural greenhouse effect has CO₂ constantly (I think at least since there’s any carbohydrate burning on earth) remaining in the atmosphere.

jlawson 4y ago

You're right about the particulates, but I believe that burning wood can't really cause climate change. Wood is already in the biosphere. Even if we don't burn it, it will decompose and release all its CO2 that way, or burn in a forest fire. The CO2 of that wood is already circulating. It doesn't actually increase CO2 levels the way that digging up long-buried fossil fuels does.

acidburnNSA 4y ago
If you cut down and burn trees that take 50 years to grow in 3 seconds, you've increased the amount of CO₂ in the air. Sure it will eventually go away, but the thing that causes climate change is the CO₂ being in air at elevated levels, even if it's in a cycle. Biofuel is almost as bad as fossil at 230 gCO₂-eq/kWh. [1]. Compare to solar pv at 40 and nuclear at 12. [1] https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-iii.pdf https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5...
- ZeroGravitas 4y ago
  The footnote on those numbers says: > Direct emissions from biomass combustion at the power plant are positive and significant, but should be seen in connection with the CO2 absorbed by growing plants. They can be derived from the chemical carbon content of biomass and the power plant efficiency. For a comprehensive discussion see Chapter 11, Section 11.13 https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_chapter11.pdf https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5... > have led to strong forest Carbon sinks in many OECD regions (Pan et al., 2011; Loudermilk et al., 2013; Nabuurs et al., 2013; Erb et al., 2013). However, the capacity of these sinks is being reduced as forests approach saturation (Smith, 2005; Körner, 2006; Guldea et al., 2008; Nabuurs et al., 2013; Sections 11.2.3, 11.3.2). Active forest management, including management for bioenergy, is therefore important for sustaining the strength of the forest carbon sink well into the future (Nabuurs et al., 2007, 2013; Canadell and Raupach, 2008; Ciais et al., 2008), although countries should realize that for some old forest areas, conserving carbon stocks may be preferential, and that the actively managed forests may for some time (decades) act as sources.

wodenokoto 4y ago

But burning fossil fuel does _not_ maintain an equilibrium level of CO₂ in the atmosphere (which is the main reason why we have climate change in the first place)

beachy 4y ago

> While you can indeed re-grow wood, combusting it at scale maintains an equilibrium level of CO₂ in the atmosphere (which causes climate change. True but meaningless. Sitting in my deck chair also maintains an equilibrium level of CO2, but it doesn't provide any heat or benefit to anyone. We can't look unfavorably on energy approaches just because they fail to actually reduce CO2. That's some kind of unrealistic purity test.

acidburnNSA 4y ago
It's not meaningless. CO₂ in the atmosphere causes the greehouse effect, which allows the sun to heat the earth more. To avoid greenhouse effect you can't have things that require CO₂ to constantly remain in the atmosphere. You need non-carbon sources like wind, solar, hydro, nuclear, geothermal, etc.
- Someone 4y ago
  > To avoid greenhouse effect you can't have things that require CO₂ to constantly remain in the atmosphere. But we don’t want to fully avoid the greenhouse effect. https://en.wikipedia.org/wiki/Greenhouse_effect https://en.wikipedia.org/wiki/Greenhouse_effect: “Earth's natural greenhouse effect keeps the planet from having the below freezing temperature that it would have if there were no greenhouse gases”
  - cma 4y ago
    He's talking about the excess unnatural greenhouse effect.
    - Someone 4y ago
      I don’t see how one can read that from “To avoid greenhouse effect you can't have things that require CO₂ to constantly remain in the atmosphere.” The natural greenhouse effect has CO₂ constantly (I think at least since there’s any carbohydrate burning on earth) remaining in the atmosphere.