Introduction

 

Throughout
the world thermal power plants in addition to emits greenhouse gases, are a
major source of local pollution and health problems. APROPOS news reports (July
25 and 28), the Punjab government will set up big  power plants in Karachi to producing 3,000
megawatts of electricity through coal. It will also set up four to three coal
power plants at Gadani to generate 2,400 MW of electricity. While it is not
known why Punjab is setting up coal-fired power plants in Sindh, Baluchistan
and, and not in Punjab, one thing is for sure: the coal-fired power plants are
massive environmental pollutants.

 This is true about the coal-fired power
plants, which generate 45 percent of the world’s electricity (IEA 2008). In the
United States, after three / four decades of regulation, coal-fired power plants
were estimated to cause between 11,000 and 31,000 deaths annually, due to
emitting  of sulfur dioxide (SO2),
nitrogen oxides (NO x) and directly emitted particulate matter (PM). 

 In the United States, the benefits of further
to reduce the emissions from coal-fired power plants have been studied.
However, only by causing its very serious health and environmental effects can
coal-fired power be considered a low-cost energy source. Setting aside the fact
that coal has less practical utility as a transportation fuel and therefore
will have a ignorable the impact on our nation’s addiction to oil, coal-fired
power is one of the most polluting forms of energy available, particularly when
compared to renewable energy alternatives such as wind, solar and geothermal
power.

The
regulation of power plant emissions raises several policies a lot of questions:
the first is which pollutants should be treated and how strengthen they should
be regulated. In the United States, regulation and treating sulfur dioxide
(SO2) to control fine particles and on nitrogen oxides (NOx) to control fine
particles and reduce ground-level ozone.

In
India, environmental regulations control the particulate emissions, and two
states have begun to establish markets to control directly emitted particulate
matter.2 however there are no direct limitations on emitting the SO2 or NOx
from coal-fired power plants. An important question is whether more emphasis
should be placed on controlling SO2 and NOx. 
The answer to this question depends on the benefits of reducing
emissions from these pollutants relative to the costs. To help determine this,
we estimate the health damages causes from SO2, NOx and directly emitted fine
particles from individual power plants in India.

Our
analysis suggesting that most deaths attributable to power plants in India are
associated with SO2, followed by NOx and directly emitted PM. The average
number of deaths per plant associated with each pollutant in 2008 was
approximately 700 for SO2, 125 for NOx and 40 for PM2.5. Whether this implies
that more emphasis should be placed on controlling SO2 and NOx depending on the
cost of measures to control these pollutants and upon how effective the various
measures would be in less emission.

Air
Pollution

Coal
fired power plants supply 50% of the nation’s electric energy but this plant
also produces air pollution. Coal plants produces about 87% of NOx pollution,
94% of SO2 and 98% of mercury pollution. Compared with others pollutants coal plants
are the largest source of sulfur dioxide, mercury, air toxic emissions and
second largest source of nitrogen oxide pollution. These pollutants emitted
from coal plants are combined to form secondary pollutants such as ozone and
particulate matter that are fatal to public health.

Sulfur
dioxide (SO2)

            In US, Coal plants are biggest
source of SO2 pollution, which is fatal to public health. It forms small acidic
particles by combining with air that is fatal for human lungs and also soaks up
by bloodstream. An uncontrolled Coal plants rejects about 14,100 tons of
SO2/year and a controlled coal plants emit 3,300 tons of SO2/year.

Nitrogen
Oxides (NOx)

            NOx pollution may cause ozone or
smog, which causes eye, nose, throat and chronic respiratory diseases. An
uncontrolled coal plant emits 10,300 tons of NOx/year on the other hand a
controlled coal plant emits 3,300 tons of NOx/year.

Particulate
Matter

            Particulate matter causes eyes,
lungs, and chronic respiratory type disease, and ultimately leads to loss of
human life. An uncontrolled coal plant emits 500 tons of small airborne
particles every year. Baghouse can capture 99% of the small particulate matters.
Coal plants are responsible for nearly 24,000 loss of lives every year.

Mercury

            In US coal plants cause more than
half emission of Hg. It may cause brain damage, heart problems, and attention disorders
in children. An uncontrolled coal plant rejects about 170 lbs. of Hg every
year. Activated carbon technology can minimize Hg emission up to 90% when
combined with baghouses. Just 1/70th of mercury deposited on 25 acre area makes
the fish unsuitable to eat. 

Radiation
Exposure

            Coal may have small level of
uranium, thorium and other naturally occurring radioactive isotopes that may
leads to radioactive pollution of environment. These may cause human diseases
and may effect to plants and crops. Emitted radiation by coal derived fly ash
delivers 100 times more to the environment than normal productive nuclear
plant. The 1000 Mega Watts coal power plant rejects nuclear radiation dose of
490 person-rem/years, compared to 136 person-rem/years for other nuclear power
plant including uranium mining, reactor operation and waste disposal.

River
Water Pollution

            Coal power plant produces ash
containing calcium oxides. It dissolves in water forming slaked lime and
carried by acid rain to rivers. It removes bicarbonates hardness of water but
maximizes sodium ions that change the fertile land into alkaline soil.

Ozone
Pollution

            Ozone pollution is formed when NOx
reacts with volatile organic compounds in the presence of sunlight. In US 1/3rd
of populations living in unsuitable ozone contents areas. Smog may cause health
problems like respiratory diseases, coughing and chest pain and ultimately
leads to loss of human life.

Global
Warming

            Coal-fired power plants are
significant source of CO2 emissions, producing approximately 40% of total US
carbon dioxide pollution. Carbon dioxide has no primary effect on human health
but it can harm global warming that can cause different diseases in human.
World Health Organization (WHO) predicts that approximately 150,000 loss of
lives occurred due to temperature change.

Techniques to Reduce the
Environmental Impacts:

To
control the environment effect we have to monitor the emission from the plant,
that is to capture and remove the CO2 from the emission.
As the zero emission depend on the capturing and removal of CO2 one
types of the example of power plant is Elsam power station at Esbjerg, Denmark.
Also one types of recommendation is to use a clean coal in power plant. By
clean means that is chemically washed and treated. The cost effective method to
run coal power plant efficiency is to operate power plant on diverse types of fuel.
For example a conversion to biomass or municipal was base power plant. From these
types of power plant the emission level is estimated is about 20% less carbon
dioxide as compare to coal fired unit operating at a same capacity.

Combined heat and power:

It
is the method in which electricity and heat is generated. Is stead of to
release heat at higher temperature as compare to normal temperature, it is used
to heat abuilding. This method is commonly used in some country like Denmark
and other Scandinavian countries and parts of Germany. CHPDH is the lowest cost
method of reduction in carbon emission.

Options for fossil fuel power
plants:

The
options other than coal-fired power plants contain hydroelectric power, nuclear
power, solar power, wind power, geothermal power, and tidal and new renewable
energy techniques. Some of the power generating technologies are proven on
large industrial scale (i.e., hydroelectric, nuclear, wind, and tidal power)
while others are in prototype stage.

Cost by power generation source:

The
cost which is based on fossil fuel power plant of life about from 30 year to 50
years is very attractive for the inventors because it has low investment cost.
i.e., about 1000 to 1300 dollar per kilowatt electricity as compared to 2000 dollar
per kilowatt from an onshore wind farm. So these cost when calculated is when
it include cost of electricity and which does not include the supplementary to
the pollutant generated due to fossil fuel burning burning (e.g., increased
respiratory diseases).

Particulate matter control:

These
particles are mostly classified as PM 2.5 and PM 10. PM 2.5 who’s size about
2.5 micrometers or less than that. The class of particulate matter PM10 has a
size of about 10 micrometer or less and it also includes PM2.5. As compare to
courser particle the PM2.5 is more harmful to health.

A
particulate matter control device design to control the emission of particulate
with the exhaust stream of gas. It remove the collected PM and does not allow
it to reinter the the stream. The main particulate matter control devices are Electrostatic
Precipitators (ESP), Fabric Filters (FF), Mechanical Collectors (MC) and Venture
Scrubbers (VS). Each type is designed to control a specific size of particulate
matter.

As
the FF has a filter bags which control the PM by a fine filters in these bags ,
The ESP remove the PM by creating electromagnetic field, the cyclone separator
remove the particulate matter by using centrifugal force, Electrostatic
Precipitators, Fabric Filters, are more reliable to fulfill the requirement of
EPA of high efficiency and reliability.

NOx control:

The
conventional NOx is now a days new ones which is low NOx
burner. This low NOx burner use advance fluid dynamics and flame
thermodynamics methods due to which flame temperature is decreased and thus low
NOx is produced. NOx can be controlled by using selective
catalytic reduction or non-catalytic reduction system. In these process system catalectic
is added to the system reduce NOx to N2 and H2O.
Usually the most common catalyst used in the selective non catalytic reduction
system is urea and ammonia. . selective non catalytic reduction system
introduce offer  urea into temperature
range of 760°C to 1100°C (1400°F to 2012 °F)., urea may react with available
oxygen to form NOx  Within this range and
in this way the NOx removed about from 15% to 35%.

SO2 control:

The
emissions of SO2 can be controlled by three methods.

 1) Blending of fuel.

 2) Switching fuel, with a fuel having lower
sulfur contents.

3)
Removing the SO2 from the flue gases.

There
are several of technologies which remove SO2. The most common technologies are,
wet flue gas desulphurization (FGD), dry flue gas desulphurization. The dry use
a spray dryer absorber (SDA) or circulating dry scrubber (CDS), or dry sorbent
injection (DSI).