GASES RELEASED IN PYROLYSIS PROCESSING OF ALFALFA

The short answer is...

“...shows that the four major species, CO (carbon monoxide), CO_{2 (carbon dioxide)}, H_{2 (Hydrogen)},

and H₂O (water, as steam)“ http://www.springerlink.com/content/0744700706364223

Other references state various others (gases, trace elements,depending on the paricular biomass utilized)..appreciable quantities of CH4 (methane)...and (N) nitrogen, Nitrogen can be scrubbed and further processed into sulfuric acid, and marketed...”

Along with various aromatic hydrocarbons, of interest because some, such as Toluene (gives airplane glue it'scharacteristic odor, and Salicylic Acid (the solvent in super glue) as well as others, are marketable commodities. The downside of course, is that that some of these “VOC^s” (volatile organic compounds) are proven carcinogens. Bioenergy producers (as well as regulatory agencies) employ proven technologies (closed systems, scrubbing, etc.,) to ensure containment and conversions to ensure high standards of safety and guarantee environmental benchmarks maintained.

Since the percentage of nitrogen released is low, comparatively, I assume that it becomes a concern only when production of biochar reaches scale required for viable bi-product capture and refining.

More on gas refining:

Gasification as a method for extracting energy from many different types of organic materials.

http://en.wikipedia.org/wiki/Gasification

...is a process that converts carbonaceous materials, such as coal, petroleum, biofuel, or biomass, into carbon monoxide and hydrogen by reacting the raw material, such as house waste, or compost at high temperatures with a controlled amount of oxygen and/or steam. The resulting gas mixture is called synthesis gas or syngas and is itself a fuel...

Syngas may be burned directly in internal combustion engines, used to produce methanol and hydrogen, or converted via the Fischer-Tropsch process into synthetic fuel. Gasification can also begin with materials that are not otherwise useful fuels, such as biomass or organic waste. In addition, the high-temperature combustion refines out corrosive ash elements such as chloride and potassium, allowing clean gas production from otherwise problematic fuels.

Gasification of fossil fuels is currently widely used on industrial scales to generate electricity. However, almost any type of organic material can be used as the raw material for gasification, such as wood, biomass, or even plastic waste.

Gasification relies on chemical processes at elevated temperatures >700°C, which distinguishes it from biological processes such as anaerobic digestion that produce biogas.

(read full article...) http://en.wikipedia.org/wiki/Gasification

What is Syngas?

(See articles on their site: http://biofuel.org.uk/what-is-syngas.html )

Syngas is the abbreviation for Synthesis gas. This is a gas mixture that comprises of carbon monoxide, carbon dioxide and hydrogen. The syngas is produced due to the gasification of a carbon containing fuel to a gaseous product that has some heating value. Some of the examples of syngas are as follows – gasification of coal, waste to energy gasification, steam reforming of natural gas to generate hydrogen.

The name syngas is derived from the use as an intermediate in generating synthetic natural gas and to create ammonia or methanol. Syngas is also an intermediate in creating synthetic petroleum to use as a lubricant or fuel.

 Wiki Illustration

Syngas has 50% the energy density of natural gas. It can be burnt and is used as a fuel source. The other use is as an intermediate to produce other chemicals. The use of syngas as a fuel is accomplished by the gasification of coal or municipal waste. In these reactions, carbon combines with water or oxygen to give rise to carbon dioxide. This carbon dioxide combines with carbon to produce carbon monoxide. 

Syngas is used as an intermediate in the industrial synthesis of hydrogen and ammonia. During this process, methane (from natural gas) combines with water to generate carbon monoxide and hydrogen. As a residue of energy gasification, syngas is produced and this is used as a fuel to create electricity.

 If syngas consists of a considerable quantity of nitrogen, this nitrogen must be separated. Both carbon monoxide and nitrogen have similar boiling points and thus, recovering pure carbon monoxide by cryogenic processing is very difficult.  

The gasification process is used to convert any material that has carbon to a syngas that is made up of carbon monoxide and hydrogen. One of the uses of this syngas is as a fuel to manufacture steam or electricity. Another use is as a basic chemical building block for many users in the petrochemical and refining industries. Gasification is a very vital process. It raises the value of low value feedstocks by transforming them to marketable products and fuels.

The general raw materials used for gasification are coal, petroleum based materials or other materials that would be rejected as waste. From these materials, a feedstock is prepared. This is inserted to the gasifier in dry or slurry form. In the gasifier, this feedstock reacts in an oxygen starved environment with steam and oxygen at elevated pressure and temperature. In this way, syngas is manufactured. This syngas comprises of 85% of carbon monoxide and hydrogen and small amounts of methane and carbon dioxide.

The syngas so produced may contain some trace elements of impurities. These are removed from the syngas. Further, they are recovered or redirected to the gasifier. For example, sulfur is recovered in the elemental form or as sulfuric acid and both of these can be marketed.

If the syngas is to be put to use to generate electricity, then it is generally used as a fuel in an IGCC (integrated gasification combine cycle) power generation configuration. There are commercially available technologies to process syngas to generate industrial gases, fertilizers, chemicals, fuels and other products.

Here's where you can get much more detailed chemical analysis data:

Journal of Analytical and Applied Pyrolysis

http://www.sciencedirect.com/science/journal/01652370