Cascade use of biomass - a way out of the raw material trap?

The most important function of biomass is to use it as food. In addition, there is the material use of biomass - for example in the form of wooden building materials or packaging material - and the energetic use. The energetic use ranges from the utilization of biogas for electricity and heat, the production of biofuels for motor vehicles, as an energy source for Pellet heaters to the not entirely uncontroversial co-combustion in power plants.

The dispute over wood is becoming more acute

Biomass with its diverse uses is in demand like never before. There is also an increasing awareness of problems that arise from their use. The long-standing “tank or plate” discussion is just one aspect of the biomass discourse: wood is also currently experiencing a renaissance, whether as a building material or carrier Wood energy and here, too, the conflicts between market participants intensify. Interest in wood includes, among others, the paper and pulp industry, the sawing industry, the chemical industry, the wood-based materials industry and the industries that process or process wood for energy use, such as the pellet industry.

There is also competition within the same usage segment, for example in energy use - do I use biomass to produce liquid fuels (Biomass to Liquid - BtL) or to generate heat and electricity in CHP systems? And last but not least, there are justified claims of nature and environmental protection to protect more forest areas than before.

The raw material wood grows again - biomass is a renewable raw material (NawaRo), but at the same time only available in finite quantities on the market, because the cultivation areas and growth rates are limited. The pressure to make demands on the forest is growing from all directions and within this area of ​​tension a viable solution has to be found with which all those involved - producers, industry and ultimately the individual - can live.

Photo cascade use wood

We have to use our raw materials more intelligently

Of course, instinctively one would like to advise to reduce the consumption of the raw materials mentioned. Given the current situation, however, it is very unlikely that the consumption of wood will decrease. Consumption will increase rather than decrease. But in addition, one does not want to make oneself more dependent on imports from other countries than is absolutely necessary. So what else can you do?

We have to use the existing raw materials sustainably, with little waste and in a variety of ways, in one word: we have to deal with them more intelligently, even away from recycling interests. The aim is to leverage existing efficiency potential in order to reduce competition between the players and to maintain our biomass potential in the long term.

The Wuppertal Institute for Climate, Environment and Energy GmbH outlined three concepts for multiple use of biomass in its "Wuppertal Paper: Cascade use of renewable raw materials" (No. 180, August 2009):

  1. Plant parts are used differently from the main product (by-product and co-product use)
  2. Plant parts are separated into energetic and material usable products (parallel use of one product)
  3. The same raw material is first used materially, then energetically - cascade use!  

 

Principle of cascade use graphics

Cascade use increases space and resource efficiency

Numbers 1 and 2 are good methods of preventing waste of parts of biomass use, but cascading use goes further: the approach to cascading use is to use biomass in the form of a chain several times and as often as possible, instead of just using it to be used once, e.g. for direct firewood burning. For example, after the first material use by recycling or reprocessing the raw material, multiple uses could be added to the life cycle of the material before it is used for energy purposes.

An example: Wood is taken from the forest and initially put to material use, for example in the form of a shelf, which after its use is returned to the manufacturer for reprocessing and sold again. Only after the shelf has changed hands several times is the raw material used for energy.

Wood fiber insulation materials or wood as a building material also shift the energetic use of a given amount of wood in the recycling chain. The example of “house building” makes it clear that a certain amount of wood can be used as material for years or even decades before it is used for energy production.

Even harmless waste wood from bulky waste (furniture, etc.) can often still be used as material for chipboard or other products - as many steps as possible should lie between material use and energetic use. The more meaningful intermediate steps that are inserted into the use chain, the better the final raw material and area efficiency of land use - the potential for added value increases.

The advantages of cascade grooving: the competition between the manufacturing sectors is decreasing, the raw material is being used more efficiently, so there is more to be made from the given raw materials and the pressure on the forest is decreasing. With regard to the sustainable management of our natural resources, cascade use is a central component in the handling of biomass.

Cascade use alone is not the only way out of the scarcity of raw materials: we will not be able to avoid new technical, structural and organizational solutions. But only with innovative concepts such as cascade use can we really manage the energy transition and create a crisis-proof and strong energy generation.

Thorben Frahm, Online editor at Heizungsfinder.de, Solaranlagen-Portal.com & Daemmen-und-Sanieren.de.

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