The cost differential between gas
and coal is assumed to be $1.00/million
Btu. The amount of fuel fired is
increased by 0.8%, compared with
baseline operation, to account for the
slight loss in overall boiler efficiency.
Based on these assumptions, the
levelized cost is $908/ton of NOx
removed (constant dollar basis). These
economics do not include an allowance
for reduced SO2 emissions resulting
from the substitution of natural
gas (containing no sulfur) for a portion
of the coal feed. The reduction
in SO2 emissions may result in credits
on the SO2 emissions trading market,
which would lower the levelized cost
of NOx reduction.