Biobased resourcing is hot. Which is understandable, of course, they grow by themselves, (its solar energy), they capture CO2, require little energy to process, and know multiple uses. You can built with then, heat, or create high-value resources, like in biochemistry. The high value by the way is relative, its because they are upgraded, via many industrial processes, embodying a lot of energy. High value is therefor misleading, they create a lot of low value energy. If it comes to high value, there are better options, in a combined use of energy and material for essential functions.
One discussion stands out currently, the use of biobased resources for energy generation. Last week the discussion in the Netherlands was fueled again by a report on “sustainable biomass”.
Which was the title of the report ! (in Dutch). The title already underlines the misunderstandings in this debate: Biomass is not sustainable, nor is it un-sustainable. Its the use that determines sustainability. Anyway, time to again explore how biomass works, in principle. I like to bring back questions to their basics, and from there analyse the arguments. So lets have a look at wood, and how that works. The essentials are quit simple: you have a hectare of land with a standing forest. Each year it yields some wood, in an amount that does not affect the forest. So you can use that wood, and the system remains in balance. Thats how people have for ages lived from the woods, and still in some places. That is the supply side of the story. There is also the user side: What to do with the yearly harvest? You can build a house, you can burn it, to cook or to heat the house, or to produce electricity. Its all no problem as long as there is balance, the growth equals the use. Which in principle also applies for the CO2: emitted is less or equals the stored CO2.
Mind that if the wood is first used to build a house, the energy value is not lost: it still is available after 100 years or so. Once burned, its lost permanently. But in both cases, if not more is used or burned as is regrown each year, no problem. Maybe someone builds a somewhat smaller house, to have some more wood for heating available , as long as there is balance.
There are currently however a few specific circumstances: Like: the balance is since long not neutral anymore; the availability and distribution is distorted; the CO2 emissions should not stabilize but decrease, and there is competition, in case of the use for energy, with materials: we will have to rely on biobased materials as well.
1 the world uses much more energy as can be justified on an annual basis, that is, more as is captured and stored by the sun-earth system. Fossil fuel was also once stored as biomass. However, we are eating in on and exhausting those stocks, and large new stocks are no longer found. We have feasted on the legacy of millions of years. So if we now aim to maintain that lifestyle, and fire up forests to maintain that imbalance, you do not need to do the math to realize its impossible.
2 A country like The Netherlands does not have that wood stock, being a country in the top 5 most populous countries. Which implies we have to get it from abroad, and do not have control over the management of the resources. And despite all the beautiful stories and certification schemes, thats a scenario for disaster ( despite a few good schemes).
3 We need to reduce CO2 emissions, a status quo is not enough. That means reducing and storing CO2 emissions, which is possible with more forests, not with less forests, or with the same amount. The reasoning behind burning wood while capturing the emitted CO2, is a fallacy: the CO2 was already stored and fixed. Apart from the fact that the capture and storage of CO2 follows the same route as the nuclear fusion story. In theory nice, but it is not working.
4 And perhaps the most underestimated factor: raw materials require energy to process. As long as the need for raw materials grows, and that is the prospect, 4 times as many in the decades to come, according to a recent OECD study , partly as a result of the transition to renewable energy (technology), energy demand of any kind is growing as well.
We also have to go to zero-CO2 with regard to materials. And the biggest consumer is construction (-industry). The solution for construction is to start building in wood: (relatively) little energy is required for processing, and the CO2 is stored in the wood constructions, resulting in a net decrease in CO2.
We could of course continue to build in steel and concrete, and use wood as an energy source for this, but then we end up in a double negative spiral: firstly, we would be firing up the wood, with at best net zero CO2 effect. But we do that to make a lot of energy-consuming building materials, which require substantially more wood burning than building directly in wood. And end up with buildings with no residual energy value.
5 Large-scale exploitation of forests leads to monotonous forests and loss of biodiversity. In fact, for a sustainable situation the wood acquisition should come from natural forests. That is an illusion in this globalized world, with its insatiable hunger for raw materials.
6 CO2 emissions are direct, which cannot be spread over the life of a product. If you remove wood for bioenergy by clear-cutting forests, the emissions are direct, the restoring of CO2 happens only in 50 or more years. That is of no use for us today. We increase CO2 emissions at a time when they need to be reduced.
The problems with most of the arguing regarding the use of biomass energy is they get stuck in discussions about structures, allocations, and such, to manage the flows within a globalized world. As well in the recent Dutch report, evaluating system boundaries, definitions, and how to account for biomass if this crosses borders. This way the in fact simple reasoning becomes enormously complex, leading to a vague trade practice and misty CO2 accounting, as a sum of partial interests.
In this report 5 perspectives are analysed in relation to the burning of “sustainable biomass” (.) All collected from a social perspective: Namely with a focus on: ‘Climate’; on ‘strictly renewable’; on ‘renewable raw materials’; on ‘ecology’; and on ‘sustainable development’.
The problem is that these are all secondary or subjective assessment frameworks. Climate is a consequence, not a cause; ‘ strictly renewable’ a non-issue, since everything is renewable, it is a matter of energy and mass investment related to time, the same applies to ‘renewable raw materials’, and sustainable development is a container concept, with dozens of sub-goals underneath. Ecology is the only one that still makes sense, but it is also subordinate to the only thing that is not discussed: the physical balance between what enters and exits a system. Of course, the potential of this depends on local ecological conditions, on which the system can exist sustainably, but it starts with the physical-energetic balance, if it is negative you do not have to look any further, the system will deplete in terms of potential.
In fact, we have made it impossible for ourselves to use biomass directly as energy. This was customary before the industrial revolution, but things were kept in balance, due to a lack of wood. Partly as a result of this, economic growth was very limited.  Civilizations have even perished due to a lack of wood like the Mayans, because the distances to forests and thus timber stocks presumably became too great to be able to supply them in the desired quantities. 
By deploying large-scale fossil resources, on the one hand we have increased our needs far above the potential renewable use of sources or energy from (including material impact thereof), and on the other hand have ended up in a situation that no longer requires a status quo, in which biomass could still play a role, but requires a decrease in CO2, which means that CO2 must first be captured and stored before we return to a level without the threat of climate disruption. Burning biomass ** is simply not an option in this regard.
Of course we do have a dilemma: where do we get our energy from: wind and sun perhaps, but that puts a huge stress on materials and the energy for production of wind and solar devices, which then has to come again from biomass for instance. In the meantime we don’t solve the CO2 emissions rise, so we have to accept climate change, as a legacy of the past 150 years: to be on the blisters. Or either we have to go straight into a CO2 lockdown, in other words reduce our energy demand by 90% or so directly. But I don’t see that happening that quickly either. However, you never know, seeing the current enforced corona conditions on life styles.
** Incidentally, one ‘sustainable biomass’ source is consistently disregarded: labor. We as humans are also biomass, and biomass that can do work. We always try to exclude that, we prefer to go to the fitness to waste energy… (‘why are we not allowed to open yet’, they shout…).
 PBL report: ‘Availability and application possibilities of sustainable biomass’ (Dutch)
*  http://www.ronaldrovers.com/bio-energy-mass-should-stay-mass/
 OECD: ‘Global Material Resources Outlook to 2060’
 Growth, From Microorganisms to Megacities, By Vaclav Smil, 2019, https://mitpress.mit.edu/books/growth
Energy and Civilization, A History By Vaclav Smil, 2017, https://mitpress.mit.edu/books/energy-and-civilization
 Guns, Germs, and Steel: The Fates of Human Societies, (Civilizations Rise and Fall), by Jared Diamond 1997