The Impact of Air Quality Regulations on Distributed ... - NREL

however, required that the BACT analysis be
performed using an emissions baseline <strong>of</strong> 105
ppm, apparently because that was what turbines
without a low-NOx combustor could be
expected to produce. On this basis, using the
higher level <strong>of</strong> emissions over which to spread
the cost <strong>of</strong> the add-on controls resulted in a per
ton cost which would be “cost effective,” even
though it was recognized that the turbine would
never emit at this level.
For example, a 5-MW turbine at 25 ppm NOx
has potential emissions <strong>of</strong> 22 tons <strong>of</strong> NOx per
year. An SCR system that removes 90% <strong>of</strong> the
NOx will reduce emissions by 20 tons. If the
SCR costs $192/kW or $352,600/year, that is
$17,700/ton removed—higher than the cost
threshold. If the baseline emissions are
37
arbitrarily assumed to be 105 ppm, however,
then the potential emissions would be 95
tons per year and the 90% reduction would
be 83 tons per year. For the same capital
cost, this yields a cost effectiveness <strong>of</strong> only
$4,200/ton—well within the threshold.
<strong>The</strong> company objected to the approach and
after extended negotiations the company
was able to obtain a permit at 15 ppm
without SCR, although the state has not
<strong>of</strong>ficially changed its analysis requirement.
This approach to BACT analysis is not
consistent with federal permitting guidance
and is a threat to the continued development
<strong>of</strong> pollution prevention technology as an
alternative to post-combustion control
devices.