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Thank you for your interest in getting the facts about Catoctin
Power. We hope the information here helps to answer any questions
you might have, while providing a greater understanding of
the partnership we are proposing between Sempra Generation,
Eastalco and the residents of Frederick County, Md.
Please note that many of the questions featured in this section
are questions you have asked us directly through community
meetings. We welcome more of your questions and comments.
Feel free to submit
more questions you may have about this proposed project.
Again, we welcome your feedback.
Last updated on August 24, 2004.
Air
quality
- What air-quality requirements
are there for power plants?
Power plants, and most industrial processes, are subject
to thorough environmental regulations, including those for
air quality. The air-quality regulations require New Source
Review and compliance with Federal Clean Air Act provisions.
The requirements depend upon the status of current air quality
in an area and state regulations. Most of the time, projects
in Frederick County are required to:
- lessen air emissions via emission
controls (Best Available Control Technology [BACT] or
Lowest Achievable Emission Rate [LAER]) on the equipment,
- show that their emissions will
not cause adverse impacts to human health or the environment,
and
- lessen emissions by getting and
providing emission reductions for certain pollutants.
The project must also show that it won't have an adverse
impact air quality in the area. Also, the regulations require
ample public participation.
- Does an air-cooled plant have
higher emissions?
Air-cooled plants are generally less efficient during
high summertime temperatures and will produce more emissions
during this season than a comparable, wet-cooled plant.
- Are there any carbon-dioxide (CO2)
regulations that would apply to the power plant? If so,
what are they?
There are no regulations that govern CO2 emissions.
It's vital to note that this plant will produce many fewer
emissions than standard, fossil-fueled plants now running
in Maryland. That's because it will use clean-burning natural
gas as a fuel and it will use the latest, state-of-the-art
electrical generating techonlogy.
- What will the emission rate be?
Emission rates depend on the size of the plant being
built. Modern combustion turbines fueled by natural gas
provide the cleanest, most efficient electrical generating
technology. The plant would also have to meet Best Available
Control Technology and Lowest Achievable Emission Rate to
lessen its emissions. We expect, for instance, that oxides
of nitrogen emissions from the plant will total 2.5 parts
per million (ppm) or less. This means that for every 1 million
parts of air, there are 2.5 parts of oxides of nitrogen.
- What is air-dispersion modeling,
and how is that done?
Air-dispersion modeling is the process of taking a project's
physical characteristics (stack height, emissions, stack
temperature) along with meteorological data taken over a
2-year period (wind speed, temperature, relative humidity)
and terrain characteristics (ground height), and entering
this data into a computer-based model.
The model simulates the plant's emissions and physical characteristics
as well as all of the meteorological conditions and calculates
the concentrations that would result at predefined places.
The results of the modeling are then added to the current
background levels of air quality, then compared to the National
Ambient Air Quality Standards set by the U.S. Environmental
Protection Agengy (EPA). If you show that the project's
impacts will not exceed these ambient air-quality standards,
the project may get approved.
A source-impact analysis based on the above was done, and
it was found that the project would not result in major
ambient air impacts beyond the boundary of the project site.
Because of this, the source's impacts are assumed to not
have a major adverse impact on air quality, and more modeling
isn't required.
Major impact levels have been set for each of the criteria
pollutants. Impacts are presented in table
6.3-4 in the application and were predicted at less
than the major impact threshold levels for all criteria
pollutants. The project's impacts are 3 percent or less
of the Ambient Air Quality Standards.
To learn more, see the 5/13/04 Community
Meeting Presentation and chapter
6 of the CPCN application.
- How do we know if Catoctin Power's
emissions are safe?
The EPA has developed National Ambient Air Quality Standards
(NAAQS). These are levels of emissions in the ambient air
believed to protect public health and the environment, taking
into account sensitive receptors such as children and the
elderly, with an adequate margin of protection. The Maryland
Department of Environmental Protection has the mandate and
the authority to enforce those standards in Maryland. See
the NAAQS charts from the 5/13/04 Community
Meeting Presentation.
These regulations say that if emissions are shown at below
significance levels, the project is considered to have no
major impact on the environment. Catoctin Power has shown
that its emissions are below this threshold.
But, the project must also meet many other air-quality-related
requirements, such as technology- and emission-offset provisions
to protect public health and the environment.
- What will be the impact of plant
air emissions on homes in Adamstown?
There aren't any data that meet the EPA's or the state's
rigorous requirements for Adamstown specific background
air quality. Due to the absence of such data, the state
of Maryland required the use of data from the Dulles International
Airport as representative of background air quality in Adamstown.
The modeled ground-level emissions from Catoctin Power are
then added to those background levels to figure out the
project's overall impact on air quality.
The modeling results show that the change in ambient air
quality from Catoctin Power is not enough to measure. In
other words, the project's contribution to ambient air will
be so small that measuring equipment won't register the
impact of plant air emissions on the community. Due to the
effects of air dispersion, the further away from the power
plant, the lower the exposure to any emissions.
- Doesn’t the current air
quality qualify as a "nonattainment zone," meaning
that no new emissions sources can be permitted without offsets?
How does this emissions-offset program work?
Frederick County is classified as a "nonattainment"
area for ozone. This doesn't mean that new emissions' sites
can't get permits in the area. It does mean that any project
built in the nonattainment area will have to undergo a more
stringent analysis of its emissions, including providing
mitigation for its emissions through the use of emission
"offsets."
Emission "offsets" are emission reductions that
are made to occur at current sources of air emissions. Catoctin
Power will have to obtain certificates proving that emissions
have been reduced from these current sources of air emissions
before it can begin operations. For the Adamstown area,
the regulations require that we obtain emission reductions
for Catoctin Power for oxides of nitrogen (NOX) and volatile
organic compounds (VOC) at a rate of 130 percent of its
projected emissions. This will result in an overall air-quality
benefit, because the emissions in the area will have been
reduced by 30 percent after Catoctin Power starts running.
- Where will you get these offsets?
As much as it can, Catoctin Power intends to obtain emission
reductions locally, and has started talks with area firms
to obtain these emission offsets”. If it can't get
emission offsets locally, then the regulations allow Catoctin
Power to obtain the required emission offsets on a regional
basis.
- What about formaldehyde emissions?
In a power plant like Catoctin Power, formaldehyde is produced
from the combustion of natural gas. As part of the regulatory-review
process, the project has been required to model formaldehyde
emissions to find out the potential health impacts. That
modeling shows that formaldehyde emissions from the power
plant will be greatly below levels of concern.
- How will high humidity affect
the emission levels?
The air-emission modeling for Catoctin Power took into account
the hourly weather for the past 5 years and the worst-case
scenario within that period. In all, 65,000 data points
were taken into account during this modeling, including
varying meteorological conditions such as humidity levels.
- Have you taken into consideration
the increase in local humidity caused by the amount of warm,
moist air emitted from the cooling tower?
In a power plant, humidity is mostly produced by two methods:
the combustion of fuel and the use of water to cool the
plant. Water vapor is a natural byproduct of the combustion
of fossil fuel. Water is also evaporated in the power plant
cooling tower when warm water is circulated in the cooling
tower.
The increase in humidity from both of these sources is not
enough to measurably change the humidity levels in the ambient
air. Humidity levels right next to the cooling tower may
be slightly higher than further away, but this higher humidity
is quickly absorbed into the environment and reaches equilibrium
with the humidity in the nearby air.
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