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Featured Is Biomass Carbon Neutral?

  1. Jun 15, 2017 #1


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    I'm going to pick on Germany a bit here, based on someting I recently learned in the solar power thread: About 9% of Germany's power is produced by wood biomass burning, second only to wind in their "renewable" sector. Clearly, wood can be "renewable", but to me the more important question is: is it green?

    It appears that the EU considers biomass to be "carbon netural" and thus subsidizes it as a clean, renewable energy source. But the situation is not so clear in the US and there is debate about the issue (sources below).

    My first pass at the issue is that calling biomass "carbon neutral" and therefore "green" is figuratively and even quite literally missing the forest for the trees. Trees are renewable and carbon neutral in exactly the same way fossil fuels are -- they are, after all, one of the things that generates the "fossils" for fossil fuels. The main difference is the timescale. Trees sequester carbon and if they get buried deep, they sequester carbon for a very long time. Along those lines, an old forest is sequestering more carbon than a young forest and a tree that has been installed in support of a house is sequestering carbon for decades or even centuries longer instead of putting it immediatly back in circulation by burning it.

    So to me, while it is true that when viewed from a conservation of mass standpoint and only considering the power plant use in isolation that biomass is carbon neutral, the other ways to use trees are carbon negative or carbon sequestering. So the change of use is therefore carbon positive.



    US policy discussion by a biomass advocacy group:

    EU and biomass:
  2. jcsd
  3. Jun 15, 2017 #2


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    It seems pretty clear-cut to me: as an energy source biomass farming is carbon-neutral. As a sequestration device it's carbon-negative (tautologically). The point is, you need to get energy from somewhere, so whether you use biomass or e.g. solar panels, doesn't matter.
    Whether you then separately support sequestration initiatives is a completely separate issue. Using the sequestration argument against biomass can just as well be used against solar, and makes as much sense - after all, you could have planted vegetation on the site of your solar plant.

    This is assuming that net biomass consumed/replanted by the energy production process remains 0. If you start burning existing forests and not replacing them one for one (as the last article suggests happens), then you're doing the whole concept of renewable wrong.
  4. Jun 15, 2017 #3


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    Pun intended?
    By time I finished writing this post, I no longer believe that. I believe it is presented as carbon neutral on the basis of false and red herring assumptions.
    [/edit], and I asked the question in the OP knowing the obvious answer because that's how (in my limited research) I see the question presented. My thought path to this thread was essentially:
    Wow, Germany uses a lot of biomass!
    Why do they do that?
    Because it is carbon neutral.
    Oh, ok, great....
    ...er, wait, what? What does that really mean? Is that really all there is? Is it really good/green?
    Is it? I guess it depends on where you set your baseline.
    That is indeed the question I'm asking, but I'm struggling with your answer -- which does appear to be the dominant position.
    Again, I suppose it depends on your baseline. Are we starting with an empty field or a forest? If it is an empty field, then either planting trees or putting in solar panels is a positive step. If you start with a forest - and most of Europe was once forest, I think - then you have to weigh the released sequestered CO2 against the benefit of the solar farm, and I don't think that's an easy calculus. Generally, I think environmentalists cite deforestation as being a contributor to global warming.

    I think it also depends on what you define as the problem: to me, the problem isn't too much emission of CO2 it is too much CO2 in the atmosphere. Emission of CO2 makes the problem of too much CO2 in the atmosphere worse, but it isn't itself the problem.

    And then also it depends on how you frame the question. Too often questions like this are framed as yes-or-nos or either-or...and worse, the either-or is often presented wrong. We've had this issue in discussions of nuclear power where people will incorrectly claim saying no no nuclear power wasn't in the past saying yes to coal. It gets a little more complicated here:

    If we start with a forest and use it to power a biomass electric plant and shut down a coal plant, that's definitely in the long run a positive step: the loss of sequestration will be offset in probably a pretty short period of time by the savings in coal power. If we start with a field and plant a forest to use for biomass, we get sequestration and coal offset. Of course, if we plant trees on most of it and use a small amount for a solar farm, that would be even better (since solar uses less land per kWh). But then again, if we built a nuclear plant on the land, that would be the best possible carbon offsetting use of the land.

    I think therefore the question may hinge on whether existing or new forests are being used. The 3rd link in my OP says it is mostly existing forests, which means it is mostly releasing sequestered carbon. And due to the long time (many decades) it takes a tree to re-grow, that's a pretty significant step in the wrong direction in my view. Natural gas is being touted as a stop-gap solution to help us get off coal. To me, biomass still seems like it's the opposite: it would help some (versus coal) in the long run but hurt in the short run. Which to me still makes it a bad idea.

    ....still struggling with this though. Incidentally, I just checked Greenpeace's website to see their opinion on the matter, and they agree with me -- which is just about enough to convince me I'm wrong! A more respectable source says scientists are divided:

    At the very least, the claim of being carbon neutral should require a clear-cut (there it is again!) accounting that the forest is, in fact, being re-grown. It appears from the Science article that it isn't being done that way: the power is designated as carbon neutral without regard to where the wood came from or if new trees are being planted in their place.
    Last edited: Jun 15, 2017
  5. Jun 15, 2017 #4


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    It's an interesting question, and a lot of what I read in your links is surprising. Simply for economic sustainability, you'd expect energy generating companies to favor fast-growing biomass (like bamboo or other grasses) over old-growth forests. It looks like at least a few companies are trying to capitalize off agricultural and timber waste, but I'm not sure how big an operation you can run with only those types of biomass sources. With regard to carbon neutrality, I suppose you could make the argument that a source remains carbon neutral if the total biosphere can efficiently soak up the increased carbon emissions from it, but that seems kind of weak in the absence of pretty extensive modeling.
  6. Jun 16, 2017 #5


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    An IRS auditor once gave me this advice. "Never ever try to apply logic when dealing with the IRS." I say the same to you Russ when dealing with all things "green." It's 95% political and only 5% rational.
  7. Jun 16, 2017 #6


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    You are right of course, but I'm not wondering why others support it but rather whether or not I should...based on its merit.
  8. Jun 17, 2017 #7


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    My take on it is, if we all get on board with the effort to stop (or even slow) global warming, it will be much like each and every person signing a blank bank note and letting politicians fill in the amount, as they throw money at some crazy ideas in (what I think would be futile) attempts to make a difference.
    I won't live long enough to be affected, so I will link to what I believe is a possible solution that has some history and with some out of the box thinking will perform well enough to be part of the future solution.


    It has been suggested that this section be split out into another article titled History of pneumatic power. (Discuss) (November 2015)
    Citywide compressed air energy systems have been built since 1870.[15] Cities such as Paris, France; Birmingham, England; Dresden, Rixdorf and Offenbach, Germany and Buenos Aires, Argentina installed such systems. Victor Popp constructed the first systems to power clocks by sending a pulse of air every minute to change their pointer arms. They quickly evolved to deliver power to homes and industry.[16] As of 1896, the Paris system had 2.2 MW of generation distributed at 550 kPa in 50 km of air pipes for motors in light and heavy industry. Usage was measured by meters.[15] The systems were the main source of house-delivered energy in those days and also powered the machines of dentists, seamstresses, printing facilities and bakeries.

    • 1978 – The first utility-scale compressed air energy storage project was the 290 megawatt Huntorf plant in Germany using a salt dome.
    • 1991 – A 110 megawatt plant with a capacity of 26 hours was built in McIntosh, Alabama (1991). The Alabama facility's $65 million cost works out to $590 per kW of generation capacity and about $23 per kW-hr of storage capacity, using a 19 million cubic foot solution mined salt cavern to store air at up to 1100 psi. Although the compression phase is approximately 82% efficient, the expansion phase requires combustion of natural gas at one third the rate of a gas turbine producing the same amount of electricity.[17][18][19]
    • December, 2012 – General Compression completes construction of a 2 MW near-isothermal CAES project in Gaines, TX; the world's third CAES project. The project uses no fuel.[20]
  9. Jun 17, 2017 #8


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    To do wood for fuel above a couple percent of load is to inevitably to do it wrong. It's a return to the 18th century, where the countryside was denuded of trees for 50 miles around Boston.

    Wood chip exports to eu doubling yearly
  10. Jun 17, 2017 #9


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    Yeah, but I don't see anyone advocating using biomass to cover for all the energy needs of modern societies.
  11. Jun 17, 2017 #10


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    *All* is impossible, but ~1/5 could done for awhile, which would be a disaster in my view. Germany as Russ noted is near 10% biofuel.
  12. Jun 18, 2017 #11
    Ex definitione biomass burning should be carbon neutral, but in modern practice - it isn't. I didn't hear about biomass technology wchich gives even chance to be C - neutral (see below). In my opinion it goes from political history of bimass use as climate change remediation. The idea of substituting fossil fuels by biomass exploitation goes from science with some examples of tricky and effective technologies. Then it was elaborated by politicians, statemans and various lobbies, and appears as a law without technological directives. Biomass programs were dedicated to agriculture, forestry and energy sectors, without imposing use of dedicated tchnologies and equipment for low - energy and low - fuel use operation. In reality, all these sectors are public - donation thirsty and technically conservative. All are operated by profit maximization.
    So biomass enters existing fossil - fuel consuming factories and technologies without changes, read ineffectively. Co-burning of a woody biomass with fossil fuels in large electricity stations is an example of technical idiotism. To operate, such installation must burn fossil fuel, what means high temperature operation (coal to 1000 deg C, some fuels much more). Minor biomass burned separately gave exhaust gases with temperatures about 500 deg C. Burned with fossil fuels, wood loses competition for limited amount of oxygen and undergoes thermal degradation (similar to "dry distillation process"). Its gaseous products are oxygenates, so they burns in moderate temperatures, lowering thermal output of burning. Condensed products, similar to tar and coke, mainly resists burning in a limited time of appearance in the burning zone. They ends in trash and no one is interested in their content, rich of cancer - causing policyclic aromatic compounds. Low biomass content in fuel gave only donations for electricity stations, higher content would lower thermal output (and energy yield, see Carnot cycle). Burning dedicated to the biomass should give fossil fuel unchanged. Additionally, biomass contains NaCl and other highly corrosive salts and harms much of existing power plants.
    In my country (Poland) first bill introducing biofuel defined it as made from food-quality crops and imposing use of nutrients, pesticides, etc. same as for edible crops. Of course, ruling farmer's party wanted to enlarge crop prices, but after many years without peysans in power this didn't change. Now we have EU regulations, a bit more sustainable, but allowing many of such anti - social practices. Existing production and market systems are dedicated to maximization of scale, so the scale of biomass transport is also maximized (use of quality fuels for moving low energy - content biomass should be abolished).
    Even the biomass wonder - microalgae, can be planted in climate - harming way. The first such station in Poland was operated under constant all-day artificial light (to overcome solar instability). Taking photosynthesis yield as 8%, LED lamp effectivity as 50% and average power plant effectivity as 33%, one can obtain rather strange example of CO2 emission lowering. Another generally unsolved problem with biomass burning is drying and preservation from moisture. In agricultural practice it's strongly fossil fuel consuming.
    Assuming change of political decisions as improbable, one can preserve the climate in many more effective ways. Relatively unexplored are optimization of electromechanical sets performance, change of existing AC grid for DC one, and transforming rubbish into fuel and/or energy. Remember that in 2015 an UN report stated that possibilities of improvement of energy efficiency are in order of 50%.
    Greetings for everybody,
  13. Jun 19, 2017 #12


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    Permanent carbon sequestration in forests (carbon that would end up in fossil fuels) is negligible on land, especially in countries like Germany where all the area is managed somehow. All carbon that is bound is released again over years to decades.

    Some part of the biomass is just waste from agriculture - that is certainly carbon neutral.
    Some parts are from agriculture, where the fields are designed to produce as much biomass as possible - also carbon neutral, but a questionable land use.
    Concerning forests: The total area of forests in Germany is roughly constant. 2012 it was 32.0% of the area, 2002 it was 31.9%. That number doesn't take into account how much carbon is bound per area, but there is clearly no large-scale deforestation ongoing.

    Most biomass is (a) converted to gas and burned separately, (b) wood, and burned separately (for heating for example), or (c) converted to liquid hydrocarbons and added to fuel. That works reasonably well and saves some petroleum (not much, however).
  14. Jun 21, 2017 #13
    Permanent carbon sequestration in forests is a small part of large carbon flux in land. Anhropogenic emissions and diminishing of natural sequestration account for less than 20% of "natural" fluxes on Earth and are partially compensated by elasticity of natural processes. Danger for climate resulting from excess emission is that emissions to atmosphere enlarges natural feedback of heat flux regulation. From a tiny inequilibria in atmospheric composition we obtain the large changes in heat and matter fluxes. The main effect of CO2 content change is a large shift in water liquid-vapor equilibria, and water vapour is the real agent of Earth greenhouse effect.
    Most of carbon fluxes in Nature are poorly investigated, which results in large error margin in climatic computing. Climatologists rely on atmospheric measurements and phenomenological coefficients of feedbacks. These can give large errors, as biological feedbacks are nonlinear and changes its chemical mechanisms after passing relatively unknown ambient condition barriers (temperature, pH, etc).
    The most of known to me investigations of C content associated with agriculture and forestry gives C content in visible plants significantlty lower than in ambient soil (especially in microorganisms). These latter can change drastically after rain, fertilizer or pesticide application, and its dynamics is hours and days timescale. This relatively unknown research area must be filled by investigation, but these needs many years and we have no time for reconsidering climate policy assumptions. To save our civilization we must act NOW.
  15. Jun 21, 2017 #14
    Other than general reforestation being a good idea, surely somebody must have researched plant species which are particularly efficient for carbon sequestration?
    In other threads people are talking about colonies on Mars, and that will need those kind of plants.
  16. Jun 28, 2017 #15
    For every environment there exists many "relatively optimal" sets of plants and accompanying soil microorganisms. "Non-optimal" means non-stable, non-resilient or non-sustainable. There is no sense in planting other sets of organisms. One can choose the set optimal to his purposes. From the point of view of climate protection, CO2 assimilation from air is important criterion, but there exists another ones. The plant can be burned, substituting fossil fuels, and there are huge differences in various plant value as the fuels. The plants can be sources of construction materials, pharmaceuticals and chemicals otherwise produced with large expenses of fossil fuels. Of course, there are many examples of using synthetic ones because there are cheaper or easier to manufacture than "natural" ones.
    Any ecosystem has a range of possible effectiveness as "carbon trap", and position in these ranges occupied by given ecosystem depends on many factors dependent on humans (mainly the choice of plants, planting eucalyptuses in tropical jungle is a good choice, in tundra its a catastrophe), or relatively independent (climate during first month of growth, presence of generally unknown organism in a given soil, etc). Generally, we evan don't know many important factors, as this part of agroecology is developed mainly in some rich countries with strong science. So in a huge majority of the lands we have to rely on experience and intuition, not the science.
  17. Jul 2, 2017 #16


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    Forest management will influence the answer:
    Oregon has strict enforcement of tree replanting after harvesting timber:
    "Strict forest laws assure trees are planted and growing to replace timber harvested. Oregon has the highest private land reforestation compliance rate in the nation -- averaging 97%. For example, Oregon's landowners planted trees on a total of 150,879 acres in 1996 -- over half of this reforestation was done by private owners. More than 40 million seedlings were planted. That's 12 seedlings for every Oregonian."​

    This should in the long run (hundreds of years for old growth forests) bring it toward carbon neutrality. I don't know if that was one of the reasons for the Oregon law (it was enacted before I moved to the state). Other possible reasons might be reducing erosion (Oregon has its hilly parts) or some other reason.

    Most of the timber harvested will be turned into lumber for building and similar purposes. Thus it will largely remain sequestered for a while (decades maybe, in a house or whatever).
    That which is not could be burned but that would be a fraction of the whole.

    The immediacy of sequestration returns would also be affected by how old the trees are and when in their lives do they sequester the most carbon dioxide (old trees sequester more seems to be the answer).

    A question I have is what happens to the carbon when the trees die or parts fall off (how much becomes carbon dioxide and how much gets trapped in the ground or other growing plants or fungi, how long will it stay there).
    For example, this horizontal non-log in this picture from the Olympic Peninsula:
    small non-log.jpg
  18. Jul 4, 2017 #17


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    As I understand it small branches generate methane when they rot so burning them is carbon negative. However whole trees release their carbon much more slowly and if you include emissions from transportation they end up carbon positive when burnt. I'm sure it's not that simple though.
  19. Jul 6, 2017 #18


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    I agree with you, and further think a similar case corn based ethanol. Here, while there is not other use that carbon negative, the tradeoff is making a crucial food staple more expensive. I personally don't think either of these should be pursued much as part of the (unmentionable on PF) solution.
  20. Jul 7, 2017 #19
    Some wood can be extracted from a forest without severely damaging it. With this the sum of biomass will drop compared to the untouched forest (this part of the business releases carbon), but on long term the annually extracted wood is actually 'free carbon' (since it is no longer compared to an untouched, but to an used forest).

    The carbon neutrality of this 'free carbon' depends on the circumstances. How far is it transported, what it is used for.
    For example to import wood chips (which is actually not by- but main product in this regard) from Canada to Europe - well, is that even a question?
    Was it ever a question?

    About plants used as energy source: this is the same system which is used for food production, and THAT just turns fuel to food, with pretty bad efficiency (energy wise). To turn it back to fuel/energy - quite bad deal.

    About byproducts of food or other production: again, this depends on the circumstances, and cannot be discussed without details.
  21. Jul 7, 2017 #20
    Depending on how well it's managed burning biomass looks, in climate terms, to be at best "less bad" than fossil fuels, but for many environmentalists - them being a very diverse lot with varied priorities - the maximising of biodiversity values of land use may take precedence over biomass use displacing fossil fuels; I seriously doubt that it's hard core political environmentalism's choice to use forests that way, it is more likely that biomass burning is commercial forestry's choice. That would be choices made by interests other than "green" ones, in response to the broad challenges the climate problem present.

    Can forests sequester more than got released in the prior deforestation? I'm doubtful. Even when it's sequestered as wood products that won't be a permanent sink except by total mass of wood products constantly rising. Some rebound from more extreme deforestation practices of the past will only give an unsustainable illusion of dealing with emissions from ongoing burning of fossil fuels.

    Whilst the fundamental problem is an unparalleled environmental one, in human terms it's also an unparalled problem affecting long term economic prosperity and security; we shouldn't blame environmentalism for mainstream politics' inability to grasp with the issues effectively nor for the broad willingness to choose gestures over substance, nor blame them for the choices commercial interests have taken in response to the inadequate and compromised emissions policies that conflicted politics has produced. We certainly should not blame them for GHG emissions considerations making their inconvenient way into energy and other policy choices, no matter how we may disagree with those policies; science based knowledge independent of any political environmentalist agenda did that.
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