1 reply to this topic

[TreeHuggingTreeCutter]

I've got a project in mind using a biochar reactor.  However I need to do some more math before I know if it is viable.  Can someone confirm or correct the facts I'm working with.  


Please correct me if I get this wrong.  When making biochar and having the wood itself provide the heat for the process, a percentage of energy contained in the wood is used to
1.  Evaporate the water contained in the wood
2. Char the wood
3. a percentage of energy is stored in the biochar
4. a percentage of the energy can be a byproduct of the process as heat

I'm speculating that depending on the feed stock, moisture content and efficiency of the process the percentages of energy mentioned above will vary.  

Does anyone have any advice on how to calculate these numbers for real world applications?

[HarryN]

TreeHuggingTreeCutter, on 11 July 2011 - 10:29 PM, said:

I've got a project in mind using a biochar reactor.  However I need to do some more math before I know if it is viable.  Can someone confirm or correct the facts I'm working with.  


Please correct me if I get this wrong.  When making biochar and having the wood itself provide the heat for the process, a percentage of energy contained in the wood is used to
1.  Evaporate the water contained in the wood
2. Char the wood
3. a percentage of energy is stored in the biochar
4. a percentage of the energy can be a byproduct of the process as heat

I'm speculating that depending on the feed stock, moisture content and efficiency of the process the percentages of energy mentioned above will vary.  

Does anyone have any advice on how to calculate these numbers for real world applications?

There are some other significant products as well:
- organic gasses
- light organic liquids, mostly acidic and water soluble
- heavier organic liquids, mostly acidic and non water soluble.
- Really thick crud / creosote

It isn't always so easy to separate some of these organics from the water and your "goal" materials, but it needs to be incorporated into your approach to biochar.

Logically, you are separating a relatively neutral pH material (wood) into (liquid + gas) acids (low pH) so naturally, you should expect that the remaining biochar will be very alkaline (high pH) and this is exactly what happens.

In South America where wood char has been incorporated into the soil and improved local growing conditions, part of this is because that soil has a high Al content.  The alkaline nature of the char acted in the same way as modern alkaline (lye) extraction of Al complexes, and drove them out of the top soil.  Since Al complexes can retard plant root growth, it helped that soil.

If your particular soil is already alkaline, as many western US soils are, the biochar actually risks causing pH problems unless you do something else to acidify it.  An example would be chicken manure, which is particularly high in uric acid.