Acid Rain

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Acid Rain

• Presentation 8

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What is Acid Rain?

• Broad term used to describe several ways that
  acids fall out of the atmosphere
• More precise term is acid deposition, which has
  two parts wet and dry
• Wet deposition refers to acidic rain, fog, and
  snow
• Affects a variety of plants and animals
• Magnitude depends on many factors
• How acidic the water is
• The chemistry and buffering capacity of the soils
  involved
• Types of fish, trees, and other living things
  that rely on the water
• Dry deposition refers to acidic gases and
  particles
• 1/2 of acidity in the ATM falls back to earth
  through dry deposition
• The wind blows these acidic particles and gases
  onto buildings, cars, homes, and trees
• Dry deposited gases and particles can also be
  washed from trees and other surfaces by
  rainstorms
• When that happens, the runoff water adds those
  acids to the acid rain, making the combination
  more acidic than the falling rain alone

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Acid Rain

• Prevailing winds blow the compounds that cause
  both wet and dry acid deposition across state and
  national borders, and sometimes over hundreds of
  miles
• Sulfur dioxide (SO2) and nitrogen oxides (NOx)
  are the primary causes of acid rain
• In the US, About 2/3 of all SO2 and 1/4 of all
  NOx comes from electric power generation that
  relies on burning fossil fuels (coal)
• Combustion
• Acid rain occurs when these gases react in the
  atmosphere with water, oxygen, and other
  chemicals to form various acidic compounds.
• Sunlight increases the rate of most of these
  reactions.
• The result is a mild solution of sulfuric acid
  and nitric acid

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Acid Rain Formation
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Measuring Acid Rain

• The pH Scale
• The lower a substance's pH, the more acidic it
  is.
• Pure water has a pH of 7.0
• Normal rain is slightly acidic because carbon
  dioxide dissolves into it, so it has a pH of
  about 5.5.
• As of the year 2000, the most acidic rain falling
  in the US has a pH of about 4.3.
• Acid rain's pH, and the chemicals that cause acid
  rain, are monitored by two networks, both
  supported by EPA.
• The National Atmospheric Deposition Program
  measures wet deposition, and its Web site
  features maps of rainfall pH (follow the link to
  the isopleth maps) and other important
  precipitation chemistry measurements.
• http//nadp.sws.uiuc.edu/isopleths/
• The Clean Air Status and Trends Network (CASTNET)
  measures dry deposition.
• Its web site features information about the data
  it collects, the measuring sites, and the kinds
  of equipment it uses.
• http//www.epa.gov/castnet/sites.html

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What is the pH scale?

• Measures the concentration of H and OH-
• Defined as a negative logarithm of the H
  concentration

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What Causes Acid Rain?

• Normal Rain
• H20 CO2 H2CO3
• pH of 5.6
• Acid Rain
• 2SO2 O2 2H2O 2H2SO4
• 4NO 3O2 2H2O 4HNO3
• pH approximately 4.0

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Acid Rain
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Typical Acid Rain in Northeastern US

• Sulfuric Acid 65
• Nitric Acid 30
• Other Acids 5

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Effects on Lakes and Streams

• Many lakes and streams examined in a National
  Surface Water Survey (NSWS) suffer from chronic
  acidity, a condition in which water has a
  constant low pH level.
• The survey investigated the effects of acidic
  deposition in over 1,000 lakes larger than 10
  acres and in thousands of miles of streams
  believed to be sensitive to acidification. (660
  x 660)
• Of the lakes and streams surveyed, acid rain
  caused acidity in 75 percent of the acidic lakes
  and about 50 percent of the acidic streams.
• Several regions in the U.S. were identified as
  containing many of the surface waters sensitive
  to acidification.
• They include the Adirondacks and Catskill
  Mountains in New York state, the mid-Appalachian
  highlands along the east coast, the upper
  Midwest, and mountainous areas of the Western
  United States.
• In areas like the Northeastern United States,
  where soil buffering capacity is poor, some lakes
  now have a pH value of less than 5.
• One of the most acidic lakes reported is Little
  Echo Pond in Franklin, New York.
• Little Echo Pond has a pH of 4.2.

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Effects on Lakes and Streams

• Acidification is also a problem in lakes that
  were not surveyed in federal research projects.
• For example, although lakes smaller than 10 acres
  were not included in the NSWS, there are from one
  to four times as many of these small lakes as
  there are larger lakes
• In the Adirondacks, the percentage of acidic
  lakes is significantly higher when it includes
  smaller lakes

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Effects on Lakes and Streams

• Streams flowing over soil with low buffering
  capacity are as susceptible to damage from acid
  rain as lakes
• Approximately 580 of the streams in the
  Mid-Atlantic Coastal Plain are acidic primarily
  due to acidic deposition
• In the New Jersey Pine Barrens, for example, over
  90 percent of the streams are acidic, which is
  the highest rate of acidic streams in the nation
• Over 1,350 of the streams in the Mid-Atlantic
  Highlands (mid-Appalachia) are acidic, primarily
  due to acidic deposition

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Effects on Lakes and Streams

• The acidification problem in both the United
  States and Canada grows in magnitude if "episodic
  acidification" is taken into account.
• Brief periods during which pH levels decrease due
  to runoff from melting snow or heavy downpours
• Lakes and streams in many areas throughout the
  United States are sensitive to episodic
  acidification
• In the Mid-Appalachians, the Mid-Atlantic Coastal
  Plain, and the Adirondack Mountains, many
  additional lakes and streams become temporarily
  acidic during storms and spring snowmelt
• For example, approximately 70 percent of
  sensitive lakes in the Adirondacks are at risk of
  episodic acidification
• This amount is over three times the amount of
  chronically acidic lakes
• In the mid-Appalachians, approximately 30 percent
  of sensitive streams are likely to become acidic
  during an episode
• This level is 7 times the number of chronically
  acidic streams in that area
• Episodic acidification can cause "fish kills."

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Effects on Lakes and Streams

• Emissions from U.S. sources also contribute to
  acidic deposition in eastern Canada, where the
  soil is very similar to the soil of the
  Adirondack Mountains, and the lakes are
  consequently extremely vulnerable to chronic
  acidification problems
• The Canadian government has estimated that 14,000
  lakes in eastern Canada are acidic

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Effects on Aquatic Life

• Acid rain causes a cascade of effects that harm
  or kill individual fish, reduce fish population
  numbers, completely eliminate fish species from a
  water body, and decrease biodiversity
• As acid rain flows through soils in a watershed,
  aluminum is released from soils into the lakes
  and streams located in that watershed
• So, as pH in a lake or stream decreases, aluminum
  levels increase
• Both low pH and increased aluminum levels are
  directly toxic to fish
• In addition, low pH and increased aluminum levels
  cause chronic stress that may not kill individual
  fish, but leads to lower body weight and smaller
  size and makes fish less able to compete for food
  and habitat
• Some types of plants and animals are able to
  tolerate acidic waters.
• Others, however, are acid-sensitive and will be
  lost as the pH declines
• Generally, the young of most species are more
  sensitive to environmental conditions than adults
• At pH 5, most fish eggs cannot hatch
• At lower pH levels, some adult fish die
• Some acid lakes have no fish

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Ph Scale

• Not all fish, shellfish, or the insects that
  they eat can tolerate the same amount of acid
  for example, frogs can tolerate water that is
  more acidic (has lower pH) than trout but frogs
  eat mayflies

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Effects on Trees and Forests

• Acid rain does not usually kill trees directly
• Instead, it is more likely to weaken trees by
  damaging their leaves, limiting the nutrients
  available to them, or exposing them to toxic
  substances slowly released from the soil
• Quite often, injury or death of trees is a result
  of these effects of acid rain in combination with
  one or more additional threats.
• Acidic water dissolves the nutrients and helpful
  minerals in the soil and then washes them away
  before trees and other plants can use them to
  grow
• At the same time, acid rain causes the release of
  substances that are toxic to trees and plants,
  such as aluminum, into the soil
• Scientists believe that this combination of loss
  of soil nutrients and increase of toxic aluminum
  may be one way that acid rain harms trees
• Such substances also wash away in the runoff and
  are carried into streams, rivers, and lakes

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Effects on Trees and Forests

• More of these substances are released from the
  soil when the rainfall is more acidic
• Even if the soil is well buffered, trees can be
  damaged by acid rain
• Forests in high mountain regions often are
  exposed to greater amounts of acid than other
  forests because they tend to be surrounded by
  acidic clouds and fog that are more acidic than
  rainfall
• Scientists believe that when leaves are
  frequently bathed in this acid fog, essential
  nutrients in their leaves and needles are
  stripped away
• This loss of nutrients in their foliage makes
  trees more susceptible to damage by other
  environmental factors, particularly cold winter
  weather

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Effects on Forests and Trees
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Why is Acid Rain Harmful?

• Damages architecture
• Limestone and marble is turned into gypsum
• Bridges corroding at a faster rate
• Causes paint to peel on automobiles

An analysis of federal data shows that 14 percent
of the nation's bridges are structurally
deficient, meaning that they show significant
deterioration to decks and other major
components. 26 of Nebraska's bridges are
structurally deficient or functionally obsolete.
(ASCE)
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Why is Acid Rain Harmful?

• Health problems in people
• Not directlyyou can still sing in the rain, and
  swim in an acidic lake
• SO2 and NOX emissions cause respiratory illness
• Asthma
• Chronic bronchitis
• Dry coughs
• Headaches
• Eye, nose and throat irritation

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What Can You Do?

• Conserve Energy
• Turn off lights and other electrical equipment
  when not in use
• Buy equipment with the Energy Star label
• Limit use of air conditioning

• Minimize the miles
• Carpool (12 )
• Take public transportation (5)
• Walk or ride bike (4)

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The Acid Rain Program

• Part of the Clean Air Act set a goal of reducing
  annual SO2 emissions by 10 million tons below
  1980 levels
• To achieve these reductions, the law required a
  two-phase tightening of the restrictions placed
  on fossil fuel-fired power plants
• Phase I began in 1995 and affected 263 units at
  110 mostly coal-burning electric utility plants
  located in 21 eastern and midwestern states
• An additional 182 units were added to Phase I of
  the program, bringing the total of Phase I
  affected units to 445
• Emissions data indicate that 1995 SO2 emissions
  at these units nationwide were reduced by almost
  40 below their required level

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The Acid Rain Program

• Phase II, which began in the year 2000, tightened
  the annual emissions limits imposed on these
  large, higher emitting plants and also set
  restrictions on smaller, cleaner plants fired by
  coal, oil, and gas,
• encompassing over 2,000 units in all
• The program affects existing utility units
  serving generators with an output capacity of
  greater than 25 megawatts and all new utility
  units
• CAA also called for a 2 x 106 ton reduction in
  NOx emissions by the year 2000 (more later)

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OPPD
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The Acid Rain ProgramOperating Principles
Feasible, Flexible, Accountable

• The Acid Rain Program is implemented through an
  integrated set of rules and guidance designed to
  accomplish three primary objectives
• Achieve environmental benefits through reductions
  in S02 and NOx emissions.
• Facilitate active trading of allowances and use
  of other compliance options to minimize
  compliance costs, maximize economic efficiency,
  and permit strong economic growth
• Promote pollution prevention and energy efficient
  strategies and technologies
• Each individual component fulfills a vital
  function in the larger program
• the allowance trading system creates low-cost
  rules of exchange that minimize government
  intrusion and make allowance trading a viable
  compliance strategy for reducing SO2
• the opt-in program allows nonaffected industrial
  and small utility units to participate in
  allowance trading

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The Acid Rain Program

• Each individual component fulfills a vital
  function in the larger program..continued
• the NOx emissions reduction rule sets new NOx
  emissions standards for existing coal-fired
  utility boilers and allows emissions averaging to
  reduce costs
• the permitting process affords sources maximum
  flexibility in selecting the most cost-effective
  approach to reducing emissions
• the continuous emission monitoring (CEM)
  requirements provide credible accounting of
  emissions to ensure the integrity of the
  market-based allowance system and to verify the
  achievement of the reduction goals
• the excess emissions provision provides
  incentives to ensure self-enforcement, greatly
  reducing the need for government intervention
• the appeals procedures allow the regulated
  community to appeal decisions with which it may
  disagree
• Together these measures ensure the achievement of
  environmental benefits at the least cost to
  society.

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The Acid Rain ProgramEnvironmental Benefits

• Acid rain causes acidification of lakes and
  streams and contributes to damage to trees and
  many sensitive forest soils
• In addition, acid rain accelerates the decay of
  building materials and paints, including
  irreplaceable buildings, statues, and sculptures
  that are part of our nation's cultural heritage
• Prior to falling to the earth, SO2 and NOx gases
  and their particulate matter derivatives,
  sulfates and nitrates, contribute to visibility
  degradation and impact public health
• The Acid Rain Program confers significant
  benefits on the nation
• By reducing SO2 and NOx, many acidified lakes and
  streams will significantly improve so that they
  can once again support fish life
• Visibility will improve, allowing for increased
  enjoyment of scenic vistas across our country,
  particularly in National Parks
• Stress to our forests that populate the ridges of
  mountains from Maine to Georgia will be reduced
• Deterioration of our historic buildings and
  monuments will be slowed
• Most importantly, reductions in SO2 and NOx will
  reduce fine particulate matter (sulfates,
  nitrates) and ground level ozone (smog), leading
  to improvements in public health

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The Acid Rain ProgramAllowance Trading

• The Acid Rain Program represents a dramatic
  departure from traditional command and control
  regulatory methods which establish specific,
  inflexible emissions limitations with which all
  affected sources must comply
• Instead, the Acid Rain Program introduces an
  allowance trading system that harnesses the
  incentives of the free market to reduce pollution
• Under this system, affected utility units are
  allocated allowances based on their historic fuel
  consumption and a specific emissions rate
• Each allowance permits a unit to emit 1 ton of
  SO2 during or after a specified year

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The Acid Rain ProgramAllowance Trading

• For each ton of SO2 emitted in a given year, one
  allowance is retired
• That is, it can no longer be used
• Allowances may be bought, sold, or banked.
• Anyone may acquire allowances and participate in
  the trading system.
• However, regardless of the number of allowances a
  source holds, it may not emit at levels that
  would violate federal or state limits set under
  Title I of the Clean Air Act to protect public
  health
• During Phase II of the program (now in effect),
  the Act set a permanent ceiling (or cap) of 8.95
  million allowances for total annual allowance
  allocations to utilities
• This cap firmly restricts emissions and ensures
  that environmental benefits will be achieved and
  maintained
• For more information on how allowance trading
  works in the Acid Rain Program, the allowances
  fact sheet
• For more information about trading in general,
  see the trading section home page
• How much do they cost?

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The Acid Rain ProgramAnnual Reconciliation

• Process by which EPA compares a unit's annual
  emissions with its allowances owned
• At the end of each year, units are granted a
  60-day grace period to ensure that they have
  sufficient allowances to match their SO2
  emissions during the previous year
• If they need to, they may buy allowances during
  the grace period
• Units may sell allowances that exceed their
  emissions or bank them for future years
• For more information, see the annual
  reconciliation page

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The Acid Rain ProgramThe Allowance Tracking
System (ATS)

• EPA has instituted an electronic recordkeeping
  and notification system called the ATS to track
  allowance transactions and the status of
  allowance accounts
• ATS is the official tally of allowances by which
  EPA determines compliance with the emissions
  limitations
• Any party interested in participating in the
  trading system may open an ATS account by
  submitting an application to EPA
• Accounts contain information on unit account
  balances, account representatives (which must be
  appointed by each trading party), and serial
  numbers for each allowance
• ATS is computerized to expedite the flow of data
  and to assist in the development of a viable
  market for allowances
• For more information, see the allowance data page.

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The Acid Rain ProgramAuctions and Direct Sale

• EPA holds an allowance auction annually
• The auctions help to send the market an allowance
  price signal, as well as furnish utilities with
  an additional avenue for purchasing needed
  allowances
• The direct sale offered allowances at a fixed
  price of 1,500 (adjusted for inflation)
• Prior to 1997, anyone could buy allowances in the
  direct sale, but independent power producers
  (IPPs) could obtain written guarantees from EPA
  stating that they had first priority
• These guarantees, which were awarded on a
  first-come, first-served basis, secured the
  option for qualified IPPs to purchase a yearly
  amount of allowances over a 30 year span
• This provision enabled IPPs to assure lenders
  that they would have access to the allowances
  they needed to build and operate new units
• The direct sale was eliminated in 1997 because
  this provision proved to be unnecessary

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The Acid Rain ProgramVoluntary Entry The Opt-in
Program

• This program expands EPA's Acid Rain Program to
  include additional sulfur dioxide (SO2) emitting
  sources
• Recognizing that there are additional emission
  reduction opportunities in the industrial sector,
  Congress established the Opt-in Program under
  section 410 of the Clean Air Act Amendments of
  1990
• Allows sources not required to participate in the
  Acid Rain Program the opportunity to enter the
  program on a voluntary basis and receive their
  own SO2 allowances
• The participation of these additional sources
  will reduce the cost of achieving the 10 million
  ton reduction in SO2 emissions mandated under the
  Clean Air Act
• As participating sources reduce their SO2
  emissions at a relatively low cost, their
  reductions -- in the form of allowances -- can be
  transferred to electric utilities where emission
  reductions are more expensive

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The Acid Rain ProgramVoluntary Entry The Opt-in
Program

• The Opt-in Program offers a combustion source a
  financial incentive to voluntarily reduce its SO2
  emissions.
• By reducing emissions below its allowance
  allocation, an opt-in source will have unused
  allowances, which it can sell in the SO2
  allowance market
• Opting in will be profitable if the revenue from
  the sale of allowances exceeds the combined cost
  of the emissions reduction and the cost of
  participating in the Opt-in Program
• For more information, see the Opt-in Program page.

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The Acid Rain Program Nitrogen Oxides (NOx)
Reductions

• The Clean Air Act Amendments of 1990 set a goal
  of reducing NOx by 2 million tons from 1980
  levels
• The Acid Rain program focuses on one set of
  sources that emit NOx, coal-fired electric
  utility boilers
• As with the SO2 emission reduction requirements,
  the NOx program was implemented in two phases,
  beginnning in 1996 and 2000
• NOx program embodies many of the same principles
  of the SO2 trading program, in that it also has a
  results-oriented approach, flexibility in the
  method to achieve emission reductions, and
  program integrity through measurement of the
  emissions
• However, it does not "cap" NOx emissions as the
  SO2 program does, nor does it utilize an
  allowance trading system

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The Acid Rain Program Nitrogen Oxides (NOx)
Reductions

• Emission limitations for the NOx boilers provide
  flexibility for utilities by focusing on the
  emission rate to be achieved (expressed in pounds
  of NOx per million Btu of heat input).
• In general, two options for compliance with the
  emission limitations are provided
• compliance with an individual emission rate for a
  boiler
• averaging emission rates over 2 units to meet an
  overall emission rate limitation
• These options give utilities flexibility to meet
  the emission limitations in the most
  cost-effective way and allow for the further
  development of technologies to reduce the cost of
  compliance

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The Acid Rain Program Nitrogen Oxides (NOx)
Reductions

• If a utility properly installs and maintains the
  appropriate control equipment designed to meet
  the emission limitation established in the
  regulations, but is still unable to meet the
  limitation, the NOx program allows the utility to
  apply for an alternative emission limitation
  (AEL) that corresponds to the level that the
  utility demonstrates is achievable
• Phase I of the NOx program began on January 1,
  1996 and applied to two types of boilers (which
  were already targeted for Phase I SO2
  reductions)
• Dry-bottom wall-fired boilers
• Limitation of 0.50 lbs of NOx per mmBtu averaged
  over the year,
• Tangentially fired boilers
• Limitation of 0.45 lbs of NOx per mmBtu, again,
  averaged over the year.
• Approximately 170 boilers needed to comply with
  these NOx performance standards during Phase I.

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The Acid Rain Program Nitrogen Oxides (NOx)
Reductions

• Phase II of the NOx program began in 2000.
• These regulations
• set lower emission limits for Group 1 boilers
  first subject to an acid rain emissions
  limitation in Phase II, and
• established initial NOx emission limitations for
  Group 2 boilers, which include boilers applying
  cell-burner technology, cyclone boilers, wet
  bottom boilers, and other types of coal-fired
  boilers.
• For more information, see the fact sheet about
  Phase II NOx Reductions
• For information on boiler types, click here

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The Acid Rain ProgramEmissions Monitoring And
Reporting

• Each unit must continuously measure and record
  its emissions of S02, NOx, and CO2, as well as
  volumetric flow and opacity
• In most cases, a continuous emission monitoring
  (CEM) system must be used
• There are provisions for initial equipment
  certification procedures, periodic quality
  assurance and quality control procedures,
  recordkeeping and reporting, and procedures for
  filling in missing data periods

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The Acid Rain ProgramEmissions Monitoring And
Reporting

• Units report hourly emissions data to EPA on a
  quarterly basis
• This data is then recorded in the Emissions
  Tracking System, which serves as a repository of
  emissions data for the utility industry
• The emissions monitoring and reporting systems
  are critical to the program
• Instill confidence in allowance transactions by
  certifying the existence and quantity of the
  commodity being traded and assure that NOx
  averaging plans are working
• Also ensures, through accurate accounting, that
  the SO2 and NOx emissions reduction goals are met

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Emission Monitoring

• Typical power plant has 3-4 boilers
• Each smoke stack counts as a source
• 3-4 CEM packages
• 60 K each source
• data acquisition software 25 K

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The Acid Rain ProgramExcess Emissions

• If annual emissions exceed the number of
  allowances held, the owners or operators of
  delinquent units must pay a penalty of 2,000
  (adjusted for inflation) per excess ton of SO2 or
  NOx emissions
• In addition, violating utilities must offset the
  excess SO2 emissions with allowances in an amount
  equivalent to the excess
• A utility may either have allowances deducted
  immediately or submit an excess emissions offset
  plan to EPA that outlines how these cutbacks will
  be achieved

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Is it working?
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