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I've recently read they are classified as "clean energy", and some nations do not count the CO2 emissions it produces towards a national CO2 quota/limit. At this point I am a little confused. Won't increased CO2 emissions from biomass plants overwhelm the atmosphere with more CO2 than it can already handle?

Can anyone please clarify why we use biomass plants, when it leaves such a carbon footprint? I don't understand why they are considered such a viable alternative.

Thanks

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The article you mention in the comments under the other answer describes several ways in which (at least some forms of) biomass for energy are problematic from a carbon point of view. In summary:

  • Clear cutting of existing forest releases carbon now, which then takes decades or centuries to be recaptured by replacement trees.
  • Using every scrap of wood/energy crops grown reduces soil fertility and soil carbon storage.
  • Logging and farming machinery damages the soil structure, in particular compacting it which reduces its ability to store water. Clear cutting makes this worse.
  • (I didn't see this in the article, but they hint at it) agriculture, forestry, processing and transport all use fossil fuels. Wood pellets are being shipped between continents. Fertiliser and pesticide use (on some crops) adds to the carbon emissions.

But biomass seems like a good idea to politicians. Why?

  • Trees absorb CO2, so they must be good, mustn't they?
  • Early biomass methods relied on byproducts (sawmill waste etc.), which avoids many of the downsides of energy crops.
  • Political arguments like job creation, energy security, balance of payments. Don't forget that to many politicians etc., environmental arguments are a minor consideration compared to imminent financial arguments. Where there's money there's influence.
  • The hidden promise of even partially renewable energy sources: spend a bit of money and we can carry on as we are. This is a seductive argument, even though it's wrong.
  • Carbon capture and storage (CCS) at scale has been just around the corner for a couple of decades. There's a consistent and probably wrong assumption that this could be retrofitted easily, and combined with biomass energy into BECCS this could be a net carbon sink if it worked.

So the politicians and administrators who make biomass financially favourable see things from one end of the scale; they assume the best. You're close to assuming the worst if you essentially consider only the emission and not the absorption of carbon. My opinion: your scepticism is the right place to start. Some schemes, done well, can be helpful, but biomass energy is of very limited benefit overall. An example of good schemes is those that convert unproductive land, require neither fertiliser nor clearcutting (effectively permaculture), are used locally to avoid transport emissions, and can use low-grade heat (as well as electricity generation if present) to maximise efficiency.

Bioenergy from waste (food waste, sewage, etc.) is usually treated separately. It often avoids methane emissions, which are far worse than CO2. I don't think this is the focus of your question so I won't go into detail, but many of the same arguments apply.

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The carbon that gets released by burning them was first stored in the plants, so the CO2 was taken out of the atmosphere temporarily.

The idea is that if you do this continously, you create a carbon sink whose size corresponds to the total amount of plant material that is currently growing.

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    Every single molecule of CO2 emitted into the air from a biomass plant originally came from the air, so there is approximately no net increase in atmospheric CO2. Contrast with fossil fuels where every single molecule of CO2 came from the ground and emitted into the air – Christopher Gilmour Nov 25 '19 at 10:55
  • Hi, Thank you so much for your replies. Here is one of the articles I was shown, I can find another if necessary. Can you please provide your thoughts on this? blogs.ei.columbia.edu/2011/08/18/is-biomass-really-renewable (the link says 2011, but it was updated in 2016) – gunter Nov 25 '19 at 22:08
  • @gunter that link would be a good addition to the question – Chris H Nov 26 '19 at 8:29
  • @ChrisH No it is not - don't change the goal posts. It also asks for opinions and is too broad (provide your thoughts on this). Note that you are (also) answering the critiques in the article (now gone from the comments) and not just the question. This confirms my suspicions that we are having a good example of an X-Y problem here: Gunter asks X, but actually wants an answer to Y. – user2451 Nov 26 '19 at 8:53
  • @JanDoggen "I recently read" is how the question starts. It wouldn't be unreasonable, or moving the goalposts, to include the source(s) – Chris H Nov 26 '19 at 9:15
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On behalf of the global MSDS (Mustard Seed Day Society) initiative, I present our answer.

Before we can understand how biomass can be a viable alternative, we must first become intimate with the original meaning of the word, which describes all that is (or was) alive. The answer to your question can be found in a clump of turf. To help on that journey of the mind, your touchstone will be a simple point: Production of biomass holds the real solutions; Consumption does not.

Biomass is a pure, easy, simple form of solar energy production and storage, so it's a wonder how Bill Gates could recently say we need a miracle in storage before solar can be viable. It's right before our eyes, everywhere. In theory, every single human on Earth could build a solar collector with solar storage in less than a minute.

No one we know will ever build a 50 megawatt biomass consumption plant, but everyone we know can build a production plant with nothing more than a mustard seed, and we do not mean that figuratively.

On every scale, production is the imperative. Consider how you could produce enough biomass to supply a single breath of air, and build up from there according to your needs. We doubt you will ever get into the megawatt range because you will stop somewhere along the way when you've found your solutions.

At whatever level you stop (individual, family, neighborhood, village, etc.) your solution will depend on the previous levels. It feels lonely to shift our thinking from a top-down perspective because we are so dependent on civilization as our mother, but it is inevitable that we will grow up or die young. We must first reverse the general direction of flow in our infrastructure. It's only hard because it frightens those at the top who need us to remain dependent.

It's much easier if you consume your energy farther down in the food chain where you can produce it, and store it where you will need it. It's important to recognize that there are many different kinds of biomass energy generation strategies besides burning trees. Biomass energy can be supplied by methane, biodiesel, syngas, algae, animal waste, biogas, sewage, and other human waste streams, with minimal to positive impacts on the environment. The choice of which biomass solution to implement will depend a lot on your location.

The answer is different for each of us, but that's the only way it can be found, by understanding the old definition of the word "biomass" so we can consume greenhouse gasses to produce our energy. Our answer to your question is that it is not a viable alternative. It's an imperative.

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