[Turtle]

Originally Posted by Gerrit

I would see it hooked up to a larger water storage tank in the basement that would then be drawn upon as needed to heat the house or a greenhouse in winter.

Some people heat their houses with wood from an outside furnace. Of course, the high pressure set-up for carbonization would be much more expensive than a wood furnace, and what is the value of the carbon char produced anyway?? Will people pay carbon credits to a home-owner? What is the value of the carbonized material for soil improvement? Too many questions...

No worries; all we have is time.

in thinking over my proposed setup along with your observations, i realized that the relief system presumes its use only in a situation where no relief results in an explosion. that is all well and good, and my system accomplishes its purpose.

now however, because you mentioned cooling, and the reaction is exothermic, then we can cool and control pressure in the reaction vessel while utilizing the heat as you suggest. we simply wrap the reaction vessel itself in copper tubing which is connected to whatever heat storage/use mechanism you care.

this would be a thermostatically and pressure controlled active heat exchanger, which is to say if the pressure or temperature in the reaction vessel rises above a set limit, a pump is turned on and coolant is pumped through the coils around the reactor until the the temp and/or pressure drops to nominal and then the pump stops.

the value of the carbon in this case seems in particular that it is nano-structured. yes, no? bucky ball stuff. carbon nano-tubes & buckminsterfulerenes...the new black gold. the value of a thing is what you give it.

[Turtle]

Originally Posted by Gerrit

It looks neat.

What's the reason for not streaming the steam directly into the water body? Wouldn't the steam be cooled/condensed virtually instantly as the water absorbs its heat? Would that be too turbulent an interface?

Sorry; I missed this question earlier. No particular reason when I drew it I guess. I suppose I wasn't considering any mixing and thinking only in terms of the pressure reactions. The idea is more or less to prevent an explosion and/or release of reactants to the air.

[Gerrit]

Turtle,

I think it's time we clarified a few details about the potential of this process with the researchers, before we take this too much further. I've drafted an e-mail to them as follows. Please give me your input.

Dear Mr. Markus Antonietti,

As members of the Petra Terra listserve of the Hypography.com Science Forum, we are excited by your work with carbonizing biomass for the purposes of building terra preta soils. We have read several articles on your work with the hydrothermal carbonization of plant material. After some discussion, we have a few questions for clarification purposes:

1. Types of materials that can be used: you mention that your process focusses on annual fast-growing plant materials. Thus, should we assume that woody or lignified plant materials are too dense for use in the 200 degree C steam pressure vessel? If they can be used, to what extent do they have to be ground/milled?

2. What is the cost of the catalysts per unit of output as used in the process? In the article "Back to Black", you mention catalysts of iron ions and iron oxide nanoparticles. Elsewhere there is mention of a PH conditioner - citric acid.

3. It takes a certain amount of heat to get the process started. At a certain point, an exothermic reaction takes over. What is the net energy output/dry weight of biomass?

Any suggestions for more questions before I send this off?

[Turtle]

Originally Posted by Gerrit

Turtle,

I think it's time we clarified a few details about the potential of this process with the researchers, before we take this too much further. I've drafted an e-mail to them as follows. Please give me your input.

Dear Mr. Markus Antonietti,

As members of the Petra Terra listserve of the Hypography.com Science Forum, we are excited by your work with carbonizing biomass for the purposes of building terra preta soils. We have read several articles on your work with the hydrothermal carbonization of plant material. After some discussion, we have a few questions for clarification purposes:

1. Types of materials that can be used: you mention that your process focusses on annual fast-growing plant materials. Thus, should we assume that woody or lignified plant materials are too dense for use in the 200 degree C steam pressure vessel? If they can be used, to what extent do they have to be ground/milled?

2. What is the cost of the catalysts per unit of output as used in the process? In the article "Back to Black", you mention catalysts of iron ions and iron oxide nanoparticles. Elsewhere there is mention of a PH conditioner - citric acid.

3. It takes a certain amount of heat to get the process started. At a certain point, an exothermic reaction takes over. What is the net energy output/dry weight of biomass?

Any suggestions for more questions before I send this off?

Looks like a fine introductory letter. Mail away.

[malcolmf]

Originally Posted by Gerrit

Before we get too excited, what is a "biomass dispersion?"

I noticed the same thing and worried the same worry. However some of the source text suggests that the process works on intact biomass and a photo on the Max Planck website shows a catalyst being added to a vessel containing solid biomass. I suppose it might be a blender rather than a cooker. To be investigated.

Does this mean that any substance used in the HTC process must first be ground up and milled to an extremely fine - perhaps colloidal - state in order for the process to work? If so, this would probably entail a prohibitive amount of energy and machinery costs in the preparation process, at least in the case of woody products.

I doubt that it is problematic even if it is necessary. After all, wood is ground and pelleted, requiring relatively little energy and still producing an economical fuel; coal is pulverised for burning in a power plant, ditto. And there would be copious energy from preceding batches if this were an ongoing process.

M

[malcolmf]

Originally Posted by Gerrit

Dear Mr. Markus Antonietti

I hope you have not sent this off yet. Antonietti is a German academic. Some German academics are sticklers for proper titles. If he is "Professor Doctor", or whatever, he may not take kindly to being addressed on a particular field by a title less than his status in that field, dismissing the sender as either insulting or not worthy of a response. Find out first. It should be in Back in the black.

Also that should be Terra Preta not Petra Terra, who is probably somebody's girlfriend
M

[malcolmf]

Originally Posted by Gerrit

This is one aspect not addressed in the article: how much heat is a by-product of the exothermic carbonization process. Is it enough for a larger unit to heat water in a storage tank to help heat a house or greenhouse, as well as carbonize biomass?

It is addressed in Back in the black, if indirectly. The chemical reactions must in theory release one third of the energy in the biomass. This calorific value is often measured as energy per unit weight. Materials vary. Straw, for example, contains 15 GJ/t gross or 12.8 GJ/t net. I think we can use the gross (or Higher Heating Value) figure because the energy in any vapourised water will be recovered over time by natural or designed condensation, as long as the system remains closed.

So the by-product energy from straw would be 5 GJ/t. Some of that would be used to run the process. Being pessimistic, lets say 3 GJ/t is left over. 3 GJ would replace a 2kW (output) greenhouse heater for slightly over 415 hours, or about 1/25th of the annual space and water heating of an average house in the UK.

You can start to draw practical conclusions from this. For example, the waste from a garden could probably not do much except heat a small greenhouse, but the waste from a farm could do a lot by way of heating buildings, drying crops, and heating polytunnels. The most fitting form of heating would seem to be underground storage and circulation. In temperate climates like northern Europe HTC-heated polytunnels might create a serious carbon-negative low-miles alternative to the import of exotic fruit and vegetables.

And that is before we figure out what the best output is: the so-called topsoil (I wonder how good it is) from 5 hours cooking or the bio-coal from 12 hours. From a global warming viewpoint the topsoil would reduce more carbon, and sequester it permanently. However the bio-coal might make up a shortfall in energy for a particular application.

Thoughts?

M

[Gerrit]

Is this even better than hydrothermal carbonization? It's faster...

Flash Carbonization™ process

Research at the University of Hawaii (UH) has led to the discovery of a new Flash Carbonization™ process that quickly and efficiently produces biocarbon (i.e., charcoal) from biomass. This process involves the ignition of a flash fire at elevated pressure in a packed bed of biomass. Because of the elevated pressure, the fire quickly spreads through the bed, triggering the transformation of biomass to biocarbon. Fixed-carbon yields of up to 100% of the theoretical limit can be achieved in as little as 20 or 30 minutes. (By contrast, conventional charcoal-making technologies typically produce charcoal with carbon yields of much less than 80% of the theoretical limit and take from 8 hours to several days.) Feedstocks have included woods (e.g., leucaena, eucalyptus, and oak), agricultural byproducts (e.g., macadamia nutshells, corncobs, and pineapple chop), wet green wastes (e.g., wood sawdust and Christmas tree chips), various invasive species (e.g., strawberry guava), and synthetic materials (e.g., shredded automobile tires). Results of these tests are described in a series of technical, peer-reviewed, archival journals paper that can be obtained by request to Prof. M.J. Antal.

We are now testing a commercial-scale, stand-alone (off-the-grid) Flash Carbonization™ Demonstration Reactor ("Demo Reactor") on campus (see photos below). The first successful test occurred on 24 November 2006. A canister full of corn cobs was carbonized in less than 30 min. This test proved that the Flash Carbonization™ process can be scaled-up to commercial size.

Recently HNEI received a two-year $215,000 research grant from the Consortium on Plant Biotechnology Research (CPBR) for "Flash Carbonization™ Catalytic Afterburner Development." The CPBR funding will enable us to make progress towards the elimination of smoke and tar from the reactor's effluent. We are also initiating studies of the use of the Flash Carbonization™ process for the disposal of waste tires.

[Gerrit]

According to Dr. Antanl from Hawaii U.:

"Our Flash Carbonization process takes minutes (not hours) and
realizes the theoretical yield of carbon from many feedstocks with no
catalysts. Also, as a result of the findings of one of my recent graduate
students (Sam Wade), we can engineer a Flash Carbonization reactor so that
there is absolutely no danger of explosions. This is why our State Boiler
Inspector has given us a permit to operate our Demonstration Reactor on
campus."

[malcolmf]

Originally Posted by Gerrit

Is this even better than hydrothermal carbonization? It's faster...

Flash Carbonization™ process

You'll find another link in the list of charcoal links that I posted to the original forum and then the charcoal-making subforum.

FC's advantages are speed and carbon extraction efficiency. However it is hi-tech and patented, which seem to limit it to high added value applications, and thus make it less likely to spread as far as having an impact on climate. Like HTC, there is no data on how suitable its product is for the agri-char approach to carbon sequestration. No good if the porosity collapses due to the pressure, or the residues that encourage micro-organisms are destroyed, for example.

The main difference between all pyrolysis methods and HTC is in the impact of moisture (in biomass and ambient) on their efficiency. Water is the basis of HTC, whereas it makes pyrolysis less productive, very much less when using fresh, undried material. You can use HTC at maximum efficiency direct from the harvest. Don't underestimate this parameter.

M