BUREAU OF GEOLOGY


gasification process increases with increased volatile content. The fixed
carbon content of the peat is responsible for much of its combustion
energy.
 Ash is the amount of materials in a fuel which remains after combus-
tion. The amount of ash varies for different types of peat. Peats which
receive their moisture primarily from precipitation are usually lower in ash
than those which are nourished by surface waters. In times of flood,
surface waters may carry large sediment loads onto the peatlands where
sediment is trapped in the peat.
 Peat's high moisture content can be a major problem which must be
considered in its utilization. Even a drained and solidified bog may con-
tain 70 95 percent moisture and for some uses peat will require addi-
tional drying which will, in turn, require energy.

 THE ACCUMULATION OF PEAT

 by
 Paulette Bond

 The Process of Peat Formation

 Peat forms when the rate of accumulation of plant matter exceeds the
rate at which decomposing organisms metabolize it. The conversion of
fresh plant material to peat takes place over a period of time as peat
becomes enriched in fixed carbon while evolving water, carbon dioxide
and methane (U.S. Department of Energy, 1979). Peat is comparatively
increased in fixed carbon as opposed to cellulose, and the process by
which this takes place is referred to as carbonization. It is this enrichment
of carbon which makes peat desirable as a fuel source (Figure 3). The
Peat Prospectus (U.S. Department of Energy, 1979) compares peat with
wood and various grades of coal in terms of fixed carbon and heating
value (in British Thermal Units, BTU). The following values are taken
from Figure 3 of the Peat Prospectus and are approximate (U.S. Depart-
ment of Energy, 1979). One pound of wood has a fixed carbon content
of approximately 20 percent and generates 9,300 BTU on a moisture and
mineral free basis. An equivalent amount of peat contains 28 percent
fixed carbon and generates approximately 10,600 BTU. These values for
peat and wood contrast with values for lignite which yields about
12,400 BTU and has a fixed carbon content of approximately 47 per-
cent.

 Geologic Conditions Associated with Peat Accumulation

 As was previously noted, peat forms when the accumulation of plant
material exceeds its destruction by the organisms which decompose it.
Since plant matter is usually decomposed before significant accumula-
tions develop, it is instructive to examine the set of circumstances which
allow peat to form. Certain geologic, hydrologic and climatic conditions