Biochemicals from Pyrolysis
Syngas from biomass gasification may contain hundreds of different biochemical substances. Some of these can be quite valuable and therefore simply using the syngas only for energy (e.g. if burned in a Babington Burner) may be wasteful . Depending on the amount of syngas produced, it may be worthwhile to separate out the complex biochemicals from simpler components (incl. methane, carbon monoxide, hydrogen). The spectrum of biochemicals varies with feedstock and conditions, such as gasifier temperature, duration, pressure etc.
Other components include: organic acids (formic acid, acetic acid, propionic acid, butyric acid, etc); phenol group; carbonyl group (formaldehyde, acetaldehyde, etc.); alcohol (ethanol, methanol, etc); neutral materials (levoglucosan, acetol, maltol, etc); base (acidic substances like ammonia, methylamine, dimethylamine, etc.)
One major component from the dry distillation of wood is acetic acid, which has many applications and can even be used as an organic herbicide.
After gasification, the syngas is first cooled down for distillation ("gas-to-liquid"). As coolants, water or external air may be used. Simple, low-tech, open-source methods of separation are needed. Biological methods for catalysis of CO and H to ethanol are being developed at large scale (e.g. Coskata), which turn the various syngas components into ethanol using a bioreactor. This demonstrates a useful principle: distillation products are further processed using (micro-)biological means. Methanol is another useful and frequent component. Upgrading to biodiesel is possible but may not be practical. The big question is: can this be scaled DOWN to village-scale ? If so, the products (incl. biochar from pyrolysis) may become important sources of revenue for the resilient community. Being able to create a large number of different potential products with a single separation mechanism would be significant in terms of autonomy and resilience.
Possible Applications
- organic acids (e.g. formic acid, acetic acid)
- Sugars, Flavors
- Pharmaceuticals
- Bioplastics
- Wood preservative [1]
- Fibers, Resins, Dyes
- Adhesives
Possible Feedstocks
- various kinds of biomass (corn stalks, straw, wood, leaf litter, algae)
- manure incl. humanure
- animal waste, bones
Important questions
- will it scale down ?
- which feedstocks produce which biochemicals in reasonable quantity ?
- gasifier design / pyrolysis conditons etc.
- distillation and separation of products; one extraction method is using methanol as a solvent [2]
- further processing of products