SPECIAL PUBLICATION NO. 27


and generation of synthetic fuel gases. Reduced oxygen input and/or
water vapor injection are required to generate the fuel gases.

 GASIFICATION

 Peat is very reactive during gasification. Gasification can yield low to
medium BTU fuel gases, synthesis gases (those which can be further
upgraded by hydrocracking), fuel liquids, ammonia, sulfur and oil bypro-
ducts (napthalene, benzene and phenol) (U.S. Department of Energy,
1979; Minnesota DNR, 1981).
 Several basic designs of gasifiers are feasible for peat gasification,
however, data for peat gasification is primarily limited to laboratory scale
operations (U.S. Department of Energy, 1979). Entrained flow and fluid
bed gasifiers appear attractive. An example is the peat gas process
developed by the Institute of Gas Technology. Dry peat is fed to the
gasifier, and heated under pressure with a hydrogen rich gas. The carbon
in the peat reacts with the hydrogen to form hydrocarbon gases (primar-
ily methane and ethane). The gases produced can be upgraded to pipe-
line quality (Minnesota DNR, 1981). Byproduct oils (benzene, napthalene
and phenols), ammonia and sulfur are extracted in turn from the liquids
which are condensed during various gas upgrading processes (Minne-
sota DNR, 1981).
 The ratio of gaseous to liquid products is controlled by changes in
temperature, pressure and length of reaction time. Increased tempera-
ture and reaction time lead to gaseous product increases. With higher
temperature and longer reaction times, the large hydrocarbon molecules
comprising the liquid products are hydrocracked into lighter gaseous
molecules (U.S. Department of Energy, 1979).

 BIOGASIFICATION

 Biogasification is an anaerobic fermentation process. An important
advantage of biogasification is that dewatering is not required. Biogasifi-
cation is a two-stage process. In the first step, the peat-water slurry is
partially oxidized to break it down to simple compounds. Aldehydes,
ketones, organic acids and esters are the main products at this stage.
The pH is adjusted and the mixture is transferred to the fermenter (anaer-
obic biological reactor) where bacteria catalyze methane production.
Methane and carbon dioxide are produced in stoichometric proportions
(U.S. Department of Energy, 1979) with up to 95 percent of the material
being converted to methane or carbon dioxide (Minnesota DNR, 1981).
The resulting gas can be upgraded to substitute natural gas (SNG) by
scrubbing the carbon dioxide and hydrogen sulfide from the methane gas
(U.S. Department of Energy, 1979).
 The waste material from the fermentation process contains undigested
peat components, inorganic residues and residual bacteria. These materi-
als can be utilized for soil conditioners, animal feeds, or can be concen-