The fate of nitrogen during pyrolosis?

[Munin]

My question is what happens to the organic nitrogen contained in green biomass when it is pyrolized(sp).

 

It seem likely to me that is simply released as NOx. Obviously not a desirable outcome. We want that N fertilizing out crops not trapping heat in the earth. If this is the case and the nitrogen is released with the other gases (CO2, CO, H2) than it would be important to only pyrolize low nitrogen biomass (brown stuff) and save the high nitrogen biomass (green stuff) for a more normal compost pile.

[HydrogenBond]

When N2 is burned with O2 we end up with NOx or various nitrogen oxide compounds. These will dissolve and react with water, such as in rain, to form nitric and nitrous acids. When they hit the ground, the limestone in the soil will neutralize them, to form nitrates and nitrites. This is now food for the plants. There are also nitrogen fixing bacteria in the soil that will covert these nitrates back into N2.

 

This last point is interesting in that the O2 of the atmosphere is assumed to come from bio-activity, namely photosynthesis. But the N2 is more dominant in the earth's atmosphere and may have also formed from bio-activity such as NOx conversion into N2. The fact that N2 is about three times higher in concentration than O2, suggests that plant life came second, with some type of N2 producing bacteria coming first. These got a head start on the partial pressures supported by the earth atmosphere, putting a cap on the O2 that the plants would be able to generate. Maybe as the bacteria lowered the nitrates, the plants were able to get into gear. The original concentrations could have been toxic to plants, as is witness by too much (NOx) acid rain causing plants to belly up.

 

When the nitrate concentrations got more reasonable, the plants began to evolve. The production of O2 and plants, caused fires and conversion of some of the N2 back to nitrates. This allowed the plants to compete for the partial pressure within the atmosphere. It is an interesting balance in that more O2 makes more fire, which makes more NOx, which allows more plants to fix N into proteins and DNA, to make more O2, shifting the balance.

 

There are certain plants, like some beans, that take N2 out of the air and make their own nitrates. These plants are often used as a soil conditioner, during off years, to help enrich the soil with extra nitrates. These plants sort of cut out the fire middleman and go right for the N2.

[Munin]

Yes, the nitrogen biogeochemical cycle is very nifty like that. But it is in the interest of a farmer to keep the nitrogen in fields to stimulate crop growth instead of wafting around the world. The question then relating the the production of bio-char via pyrolosis, is whether this process releases significant amount of nitrogen. Since it in anaerobic maybe it does not.

 

cheers

[Philip Small]

...important to only pyrolize low nitrogen biomass (brown stuff) and save the high nitrogen biomass (green stuff) for a more normal compost pile.

 

Certainly agree, in principal, and would add that it is important, on the same principal of minimizing harm, to promote charmaking processes that burn the syngas produced to reduce emissions of green house gases more potent than carbon dioxide.

 

On the other hand, some biochar workers are exploring the importance including a mix of feed stock types and this invariably includes some greens with the browns. They should not be discouraged. In the whole scheme of things the nitrogen content of the feedstock is not of overriding importance to GHG production from charcoal making.

 

Combustion with atmospheric oxygen always involves some level of nitrous oxide production simply because the atmosphere is mostly nitrogen. Thus the NxO/NOx produced from making charcoal is not necessarily from the biomass feed stock.

 

Biochar has been shown to reduce soil production of nitrous oxide.

 

Nitrous oxide production from soil (and receiving sediments) increases in association higher levels of nitrogen fertilization. Nitrogen use efficiency world wide is about 50%, and can be significantly improved. TP can play an vital role in that improvement.

 

Placing these thoughts in perspective, our soil carbon stock in North America (my place) is already 10-30% char-based, and it was placed there by fairly uncontrolled pyrolysis. Barring excessive erosion, the proportion of char-C "in the wild" is building with age. Our intent to increase these levels further is far more in step with the planet than we give it credit for.

[diazotrophicus]

Certainly agree, in ...

 

Biochar has been shown to reduce soil production of nitrous oxide.

 

Nitrous oxide production from soil (and receiving sediments) increases in association higher levels of nitrogen fertilization. Nitrogen use efficiency world wide is about 50%, and can be significantly improved. TP can play an vital role in that improvement.

 

Placing these thoughts in perspective, our soil carbon stock in North America (my place) is already 10-30% char-based, and it was placed there by fairly uncontrolled pyrolysis. Barring excessive erosion, the proportion of char-C "in the wild" is building with age. Our intent to increase these levels further is far more in step with the planet than we give it credit for.

 

Hi,

nitrous oxide N2O stems mainly from adding chemical nitrogen fertilizer blindly onto the sol, where bacteria convert part of that ammonium into laughing gas. Old hat.

 

The Nobel prize winner Crutzen recently blamed this on biofuels, utter rubbish. It is chemical fetilizer, independent of the later use of the plants grown. He never campaigned against the N2O from the fertilizer for export wheat or corn. Very strange.

 

The better way to fetilize is inside the green plant, with my namesake

Gluconacetobacter diazotrophicus, as found in sugarcane, sweet sorghum, coffea arabica (for us coffee guzzlers), pineapple, mangroves, carrots and other useful plants.

 

Go to the site of Prof. Christina Kennedy for a nice picture.

 

But for pyrolysis: that is charring in the absence of oxygen by adding heat from the outside. No oxygen, no oxides. If you burn the resulting gas at equivalence ratio of 1 through a three-way catalyst, like in a gasoline engine in your car, any NOx will be reduced to N2.

 

 

The same applies for gasification by partial combustion (that is the correct scientific term) as used in wood gas gasifiers, which actually only work properly when fed with lumpy charcoal. And you need horse manure as filter. But the three-way catalyst can get any NOx out and also serve as post-combustor, if you really want to go the hitec pathway.

diazotrophicus

[Michaelangelica]

I think BEST Energies have some research on this with Chicken Manure Char

 

It is quite fascinating and does change with char temperature from memory.

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[Rev]

And to add to all this of course

if looking at the bigger global N cycle and the greenhouse effects of oxides of nitrogen

 

provided the mass of carbon sucked out offsets the greenhouse value of the nitrous oxides

and the liming effect of the char offsets the acidity caused by acid rain

 

then char rich soils have already shown increased nodulation of plants with nitrogen fixing root bacteria

and the effect of turning crop wastes to C:N ratio neutral carbon, thus negating the usual nitrogen drawdown effects when stubble is incorporated into soil

 

provided all this is balanced and accounted for then i suspect we may still be winning with char

[Michaelangelica]

A good pyrolysis system should be as "closed looped" as possible.

Garbage in = Gold Out.

The ones on sale at the moment are like the first computer was in 1944.

But even now they can be designed to capture 95%+? of what goes into them in terms of energy and useful soil amendment (char)

or if you have to; the char can be used as fuel. I don't know how it stacks up against coal. We better hope it doesn't (stack up environmentally or energy wise) otherwise there will be none left for you soil.

 

You need to talk to a pyrolysis engineer or go to the Canadian conference next week