POWER August 2012 - 59

ENVIRONMENTAL
will readily meet this rule while coal power
is left struggling to comply.
Even with CO2
emission rates for supercritical
pulverized coal plants much higher
than the rule allows, coal power plants can
still be constructed. Coal plants that obtained
preconstruction permits prior to proposal of
the regulation and that begin construction
before April 13, 2013, will not be affected.
However, for all other sources wishing to utilize
coal, additional control technology will
be required.
CCS technology-a feasible but not currently
economically viable technology, nor
one used on the scale needed by the power
industry-will be required to be implemented
in order to meet regulatory standards. The
EPA in its proposal has provided the option
to operate at the higher supercritical emission
rate for a period of 10 years. However, emission
rates for the following 20 years must be
no more than 600 lb CO2
30-year average 1,000 lb CO2
1 offers a comparison of CO2
/MWh to make the
/MWh. Figure
emission rates
for various types of power plants.
Although the purpose of this provision
may have been to provide additional time
to develop the technology required for coal
plants to comply, it ultimately results in capital
equipment being more expensive than necessary.
That's because the EPA assumes that
in a 10-year time frame, CCS will become a
readily available technology with costs lower
than what they are today. However, even if
this assumption were correct, the equipment
would need to be significantly oversized to
deliver emissions results at levels far below
the regulatory standard to maintain compliance.
This would result in a significant
amount of extra capital expenditure and a
higher operating cost in the form of auxiliary
load and maintenance.
From a permitting standpoint, this rule has
a direct effect on the technology selection for
pollution control through the best available
control technology (BACT) process. BACT
is an in-depth analysis applied to facilities
subject to Prevention of Significant Deterioration
(PSD) permitting on a case-by-case
basis that considers energy, environmental,
and economic impacts to control pollutants.
The process itself is performed in five steps:
identify all potentially applicable control
technologies, eliminate infeasible options,
rank remaining technologies by effectiveness,
evaluate the most effective technologies, and
propose BACT. Unless other technologies
move to gain commercial acceptance quickly,
the further development of CCS may be
the only technology to satisfy BACT.
This latest round of regulations also
will affect other power systems, such as
natural gas-fired boilers. A typical value
60
for CO2
boilers is estimated at 1,350 lb CO2
emissions from natural gas-fired
/MWh.
The EPA justifies setting an emissions limit
below this type of power generation by
stating that " it seems unlikely that utilities
would choose a natural gas-fired boiler as
the generation technology of choice when
[natural gas combined cycle] is a much
more efficient, less expensive, and more
widely used technology. "
Although this broad statement may be true
for large utilities, it doesn't necessarily apply
to other power generators. Independent power
producers, agricultural cooperatives, and
industrial users are normally significantly
smaller in size. Any of these groups that wish
to generate 25 MW or more may no longer
consider a natural gas boiler without CCS to
generate steam. The EPA indicates that an
analysis was performed (but not provided for
review) considering the economic impacts
on these entities. The results concluded that
implementing this rule would impose no significant
impact on these power producers.
Integrated gasification combined cycle
(IGCC) plants convert a solid feedstock (coal)
into a gaseous fuel (syngas) that is used to
drive a combined cycle power plant. Already
an expensive option, this form of power generation
also will not meet the proposed regulation.
It is expected that IGCC plants will emit
the same amount of CO2
into the atmosphere
as a pulverized coal supercritical plant. Because
its emission rates will not meet the standard,
a precombustion system to separate CO2
in the high-pressure syngas to meet the 1,000
lb CO2
/MWh standard will be required.
Greenhouse Gas Tailoring Rule
Closely related to the New Source Performance
Standards (NSPS) for electric generating
units is the already promulgated
Greenhouse Gas Tailoring Rule. Announced
on June 3, 2010, the rule was put in place
to regulate GHG emissions in three phases.
Unlike the NSPS, which regulate only CO2
emissions, the GHG Tailoring Rule regulates
emissions of multiple greenhouse gases.
In addition to CO2
, methane, nitrous oxide,
hydrofluorocarbons, perfluorocarbons, and
sulfur hexafluoride are grouped into the category
of GHGs and must be accounted for
as PSD pollutants, which are assigned a CO2
equivalency value (CO2
e).
According to an EPA news release, GHG
regulations were to be implemented in a
three-stage process. Table 1 shows a timeline
for implementation and GHG limitations
of the various phases along with the anticipated
final acceptance date of all portions of
the rule. The limits included in this regulation
are much higher than typical PSD limits.
Typical PSD limits are set at 100 tons/
year (t/yr) for sources falling under one of 28
listed source categories and 250 t/yr for all
other sources. Setting the CO2
e limits much
higher than the existing PSD limits is due to
the inherent nature of GHGs emission rates
being significantly larger than all other PSD
pollutants. Because of this, the rule had to be
" tailored " to include GHGs in the PSD permitting
process. As part of the third stage, the
EPA was to reevaluate the limits imposed by
the original regulation and determine if any
benefit would be realized by further lowering
the limits.
The potential lowered limit would have
included all new sources emitting more than
50,000 t/yr CO2
e to be categorized as PSD
sources. This would have forced a multitude
of sources that typically would have been
permitted as minor sources to be subject to
the PSD regulations. The EPA determined
that at this time there would be no additional
Table 1. Tight schedule. The deadline for implementing the GHG Tailoring Rule is coming
soon. Source: EPA
Date
Tailoring Rule phase
June 3, 2010 Implementation of the GHG Tailoring Rule
Step 1
Jan. 1, 2011 New source: N/A
PSD modification: Applies to sources increasing emissions by 75,000 tons/year CO2e
All sources already subject to Title V
Step 2
July 1, 2011 New source: Potential to emit 100,000 tons/year CO2e
Existing sources: Sources emitting at least 100,000 tons/year CO2e now subject to PSD and Title V
Step 3
Mar. 8, 2012 Evaluation of lower emission limits
July 1, 2012 Finalization of Step 3
July 1, 2013 Effective date of Step 3
www.powermag.com
POWER | August 2012

http://www.powermag.com

POWER August 2012

Table of Contents for the Digital Edition of POWER August 2012