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

Table 2-2
Cost <strong>of</strong> Add-On NOx Controls
Gas Turbine Gas Turbine Large Lean- Small Lean- Rich-burn
with SCR with burn Gas burn Gas Gas Engine
SCONOx Engine with Engine with with 3-Way
SCR SCR Catalyst
Generator Size (kW) 5,200 5,200 2,000 500 500
Generator Cost ($/kW) $850 $850 $690 $690 $725
Total Cost ($) $5,746,000 $5,746,000 $1,794,000 $448,500 $471,250
NOx Emissions 15 ppm 15 ppm 0.7 g/bhp 1.5 g/bhp 14 g/bhp
(lb/MWh) 0.59 0.59 2.18 4.67 43.5
(tons/year) 13.5 13.5 19.1 10.2 95.4
Control Technology SCR SCONOx SCR SCR TWC
Cost ($/kW) $120 $339 $125 $210 $55
Total Cost ($) $998,400 $1,762,800 $250,000 $105,000 $30,888
% <strong>of</strong> generator cost 17% 31% 14% 23% 7%
Annual Control Cost ($) $351,558 $495,895 $157,518 $121,984 $14,969
% reduction (%) 88% 92% 88% 88% 99%
Reduction (tpy) 11.9 12.4 16.8 9.0 94.4
Control Cost ($/ton) $29,553 $39,874 $9,386 $13,568 $159
(12 tons), the cost <strong>of</strong> control is almost
$30,000/ton reduced – higher than even the
highest regulatory cost thresholds, which
typically range from a few thousand dollarsper-ton
up to $12,000 to $13,000/ton (see
Chapter 3).
Applying SCONOx to the same turbine yields
an even higher cost. <strong>The</strong> capital cost is higher;
31% <strong>of</strong> the cost <strong>of</strong> the turbine and the
annualized cost is almost $496,000 per year.
Although the NOx reduction is slightly greater
—over 12 tpy, the control cost is almost
$40,000/ton <strong>of</strong> NOx reduced.
<strong>The</strong> cost <strong>of</strong> SCR for the 2 MW and 500 kW
lean-burn gas engines ranges from about 14%
to 23% <strong>of</strong> the generator cost. This cost is much
higher for the small engine because the SCR
cost does not scale linearly with size. However,
because the baseline emissions <strong>of</strong> the gas
engines are 4 to 8 times higher than those <strong>of</strong> the
gas turbines, the cost <strong>of</strong> reduction is lower—
$9,400/ton for the 2 MW engine and
$13,600/ton for the 500 kW engine. <strong>The</strong>se
19
levels are still at the high end <strong>of</strong> the
regulatory cost thresholds, however.
<strong>The</strong> three-way catalyst applied to the richburn
gas engine has a much lower capital
cost, about $55/kW and very low operating
costs. <strong>The</strong> rich-burn engine also has a higher
uncontrolled emissions baseline, 95.4 tons
per year and a 99% removal efficiency. <strong>The</strong>
result is a very low control cost <strong>of</strong> $159/ton
reduced.
<strong>The</strong>se examples illustrate that the small size
<strong>of</strong> DG technologies results in high per-unit
costs <strong>of</strong> control technology. In addition, DG
technologies that have low baseline
emissions have even higher emission control
cost effectiveness levels ($/ton), typically
higher than the maximum regulatory cost
thresholds applied to larger technologies.
Figure 2-7 compares these control costs with
the cost <strong>of</strong> control for SCR on a large
combined cycle gas turbine. Based on data
from the EPA BACT/LAER clearinghouse,
the control cost for a large combined cycle is