Page 145 - Synthetic Fuels Handbook

CHAPTER 5

FUELS FROM COAL

Coal is a fossil fuel formed in swamp ecosystems where plant remains were saved by water
and mud from oxidization and biodegradation. Coal is a combustible organic sedimentary
rock (composed primarily of carbon, hydrogen, and oxygen) formed from ancient vegeta-
tion and consolidated between other rock strata to form coal seams. The harder forms,
such as anthracite coal, can be regarded as organic metamorphic rocks because of a higher
degree of maturation.
Coal is composed primarily of carbon along with assorted other elements, including
sulfur. It is the largest single source of fuel for the generation of electricity worldwide, as
well as the largest source of carbon dioxide emissions, which have been implicated as the
primary cause of global warming. Coal is extracted from the ground by coal mining, either
underground mining or open-pit mining (surface mining).
Coal is the one fossil energy source that can play a substantial role as a transitional energy
source as one moves from the petroleum- and natural-gas-based economic system to the future
economic system based on nondepletable or renewable energy systems. Coal has been used as
an energy source for thousands of years. It has many important uses, but most significantly in
electricity generation, steel and cement manufacture, and industrial process heating. In the devel-
oping world, the use of coal in the household, for heating and cooking, is important. For coal
to remain competitive with other sources of energy in the industrialized countries of the world,
continuing technologic improvements in all aspects of coal extraction have been necessary. Coal
is often the only alternative when low-cost, cleaner energy sources are inadequate to meet grow-
ing energy demand.
According to BP Statistical Review of World Energy 2006 figures (BP, 2006), global
consumption of coal grew from 2282 Mtoe in 1995 to 2930 Mtoe in 2005, an annual growth
rate of 2.6 percent. Coal accounts for about 28 percent (hard coal 25 percent, soft brown
coal 3 percent) of global primary energy consumption, surpassed only by crude oil (BGR,
2007). Developing countries use about 55 percent of the world’s coal today; this share is
expected to grow to 65 percent over the next 15 years (Balat and Ayar, 2004). In year 2050,
coal will account for more than 34 percent of the world’s primary energy demand.

5.1 OCCURRENCE AND RESERVES

Coal is found as successive layers, or seams, sandwiched between strata of sandstone and
shale. Compared to other fossil fuels, coal reserves are the largest ones and are more evenly
distributed worldwide.
With current consumption trends, the reserves-to-production (R/P) ratio of world proven
reserves of coal is higher than that of world proven reserves of oil and gas—155 years
versus 40 and 65 years, respectively. Total recoverable reserves of coal around the world
are estimated at 696 billion metric tons of carbon equivalent (Btce) or 909 billion tons.
Geographic distribution of coal reserves reveals that the largest deposits are located in the

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