ENVIRONMENTAL IMPACT OF THERMAL
POWER PLANTS
DR.M. H. FULEKAR
PROFESSOR &DEANSchool of Environment and Sustainable Development
&
DIRECTOR
Central University of Gujarat, Gandhinagar
Thermal Power Stations
At present, about 55% percent of total electric power produced in India is obtained from thermal power stations, most of which use Coal as a fuel
Trends in Coal Consumption for Power GenerationIndia Coal Production Year wise(1980-2011)
India Coal Consumption Year wise (1980-2011)
The present coal consumption in Thermal power stations results in adding an estimated 12.21 million tonnes of Fly Ash into the environment a year, of which a third goes into the air rest is
Characteristics of Fly ash
Analysis of Indian Coals on Air-dried Basis
Analysis of Indian Coals on Air-dried Basis
Continued ->
Chemical Composition of Indian Coal Ash
Continued ->
Chemical Composition of Indian Coal Ash
Composition of Coal and Fly Ash in ppm
Classification of Trace Elements present in Fly Ash into Three categories
• Melt Becoming Fly Ash or Slag- Al, Ba, Ca, Ce, Co, Eu, Fe, Hf, K, La, Mn, Pb, Sc, Sm, Sr, Ta, Th, Ti
Class I: Elements that form melt instead of volatilizing in
a combust ion zone
• Condense or absorb on the Fly Ash as flue gas cools leading to depletion of slag and concentration of Fly Ash- As, Ce, Cu, Ca, Pb, Sb, Se, Zn
Class II: Elements that are volatilized on combustion
• Hg, Se, Cl, Br
• Cr, Sc, Na, Ni, U, V are intermediate in behavior and placed between classes I and II
Class III: Elements that remain completely in gas
phase
Concentration of Heavy Metals in sized Fractions of Fly Ash
Heavy Metal Concentration in Pulverized Coal and Corresponding Fly Ash Used as Thermal Power Stations (Average Metal Concentration µg/g )
Fly Ash Disposal
Dry Disposal of Fly Ash on Open GroundsWet Disposal of Fly Ash into Ash
Pond/River
Air Pollution by Fly Ash
Air pollution from Coal-fired Power Plants is caused by the burning of Coal Inhalation of smaller particles as well as larger particles pose a major health hazards . Presence of Fly Ash particles causes serious environmental contamination
Fly Ash pollution at the Coal-fired Power Stations is found within the house, and particles which are spewed out of the chimneys can be carried by winds for several miles, leaving in its wake a thin carpet of black particles on roads, trees, houses, agricultural lands, water systems and even foodstuff
On combustion of Coal many of the naturally occurring trace elements (present in coal) get enriched in the fly ash, which in turn get deposited around the industry upto several tens of kilometers distance
Trace Elements Concentration of Typical Indian Coal and Fly Ash Samples (4)
Trace Element Concentration
Elemental Concentration in Fly Ash
*The table demonstrates that 83% Chromium; 84% Magnesium; 50% Nickel; 35% lead retained in Fly Ash and rest of the quantity (unaccounted) of these metals is possibly released in the atmosphere
Effect of Fly Ash Water System
Location of Sampling Stations in Ash-Effluent Drainage System
Case Study: Ash Effluents Along Stream Bed Flow To Jamuna River
Release of Trace Elements in Ash Effluents along Stream Bed Flow to Jamuna River
Key
A) Effect on River
B) Effect of Fly Ash on Pond
•Ash Effluent is allowed into impounding lagoons or ponds, where the dissolved and suspended material carried by the effluent from the settling basin creates Environmental impact of Fly Ash Disposal
•Sluicing precipitated Fly Ash to the settling basin will contribute additional factors which may promote environmental stress and also pose potential toxicity to biota in the drainage system
Location of Sampling Stations in Ash Effluent Disposal Basin
River and Sea Pollution Due to Fly Ash Effluent Disposal
Outlet reaching the river
Effluent drainage pipes Ash laden water
River water Contamination
River Contamination
Sea Contamination
Leachability and Solubility
The Movement of Toxic Elements through the Geo-cycle and their Availability to
Microorganisms and other plants and animals
Soil Contamination by Fly AshChemical Composition of Fly Ash and Soil
Chemical Composition of Fly Ash and Soil
Continued ->
Physicochemical Characteristics of Fly Ash Leachetes
Heavy Metal Concentrations in Fly Ash Leachetes at Various Concentrations
Rhizofiltration Of Heavy Metals (Cd, Pb and Zn) FROM Fly Ash Leachates Using Water Hyacinth (Eichhornia crassipes)
CASE
STUDY
Concentration of Cd, Pb and Zn (μg g-1dry wt) accumulated in the roots and shoots for 30 days upon exposure fly ash leachates
Concentration of Cd, Pb & Zn after 0th, 1st, 7th, 14th, 21st &30th day of expt
Heavy Metal Concentrations (mg/L) in various percentages of Fly Ash Leachetes
Variation in Heavy Metal Concentrations (mg/L) in various percentages of Fly Ash
Leachetes
Cd, Pb and Zn accumulation in the dry biomass of roots and shoots of Eichornia
plants
Removal % of heavy metal (Cd, Pb, and Zn) from 10%, 20% and 40% fly ash leachates after 0th, 1st, 7th, 14th, 21st and 30th day of treatment
Name Formula Percentage
Silica SiO2 62
Alumina Al2O3 26
Iron oxide Fe2O3 63
Calcium oxide CaO 1.13
Magnesium oxide MgO 0.49
Sodium oxide NaO2 0.28
Potassium dioxide KO2 1.28
Titanium dioxide TiO2 1.80
Phosphate Pento-oxide P2O5 0.40
Sulphate SO4 0.36
Rhizofiltration of Heavy Metals from Coal Ash Leachate
Table 1: Chemical Composition of Fly-Ash
Case Study:
Element Concentration in ppm Element Concentration in ppm
Coal Fly - ash Coal Fly - ash
Na 300 1300 Se 22.9 106
K 2075 18275 Zn 540 2027
La 47.6 238 Fe 20890 106670
Ce 30.2 145 Ta 1.5 5.1
Hg 11.0 48 Co 33.4 128
Pb 1.8 8.1 Eu 1.0 5.6
Th 5.3 25 Sn 0.065 2.29
Cr 62.8 404 Au 0.14 0.69
Hl 7.1 32.6
Table 2: Trace Elements Concentrations of Typical Indian
Coal and Fly-Ash Samples
Coal Ash
Concentration
pH DO TDS E.C. Sulphate
(g/L)
Phosphate
(g/L)
Ammonia
(mg/L)
Alkalinty
(mg/L)Initial readings
0% 8.05 4.5 0.2 0.33 6 13.2 1 0.48
5% 11.5 4.9 0.39 0.6 6 14 42 0.48
10% 12 4.6 1.162 1.768 11 13 40 0.48
20% 11.5 3.1 1.51 2.23 10 10.8 38 0.48
30% 10.57 2.9 2.14 3.25 9.6 14.4 31 0.48
40% 10.85 2.5 2.92 4.45 12 9.8 24 0.48
First week
0% 8.07 4.5 0.22 0.36 5 12 1 0.48
5% 8.03 2.8 0.665 1.012 6 13 45 1.6
10% 7.87 2.7 1.108 1.682 6.2 10 43 1.6
20% 8.04 2.3 2.2 3.35 7.2 9.9 39 0.88
30% 7.7 2 3.45 5.25 15 9.3 35 0.88
40% 7.09 1.5 3.63 5.53 18.8 8 29 0.56
Second week
0% 8.1 4.9 0.18 0.4 5.2 13.8 1.2 0.48
5% 8.12 4.7 1.06 1.62 6.2 13.1 40 0.88
10% 7.94 4.5 1.38 2.12 9.2 10.9 42 0.88
20% 8.02 4 2.48 3.78 7.2 9.7 40 1.12
30% 8 3.2 3.53 5.39 15 9.9 30 0.88
40% 8.68 3.1 4.02 6.12 18 8.5 25 0.72
Third week
0% 8.06 3 0.23 0.5 6.4 34.2 1 0.47
5% 8.57 4.9 1.25 2.04 16 27.2 49 0.8
10% 8.67 4.7 1.9 2.88 9.6 26.6 45 0.88
20% 8.42 4.4 3.67 5.56 9.6 24 43 1.04
30% 8.39 4.3 4.68 7.3 16.8 24 39 0.72
40% 8.68 4.2 6.5 10.03 19.2 25 29 0.96
Fourth week
0% 8.06 3 0.26 0.65 6.8 17.4 1.6 0.46
5% 8.05 3.7 0.646 0.981 7.2 17.4 62 0.72
10% 7.18 3.8 1.76 2.69 11.2 16 58 0.56
20% 8.11 4.6 1.909 2.89 16.8 12 46 0.56
30% 7.6 4.9 2.58 3.92 18.2 15.2 44 0.56
40% 7.9 5.1 2.74 4.16 19.6 11.8 33 0.72
Table 3: Parameters 0f Coal Ash Leachate at various Concentrations of
Coal Ash and Different Time Intervals
Coal ash percentage Zn
(ppm)
Cr
(ppm)
Cu
(ppm)
Water hyacinth
0 3.23 - -
5 3.76 - 0.31
10 2.76 - 0.3
20 3.3 - 0.25
30 3.29 - 0.32
40 6.25 0.25 0.3
Duckweed
0 3.22 - -
5 4.53 0.25 0.3
10 4.14 0.25 0.27
20 3.56 0.25 0.35
30 4.34 0.25 0.61
40 10.65 0.28 0.25
Pistia
0 8.6 - 0.37
5 16.33 0.25 0.5
10 9.83 0.26 0.52
20 11.34 0.26 0.3
30 7.58 0.53 0.4
Table 4: Results of Uptake of Heavy Metals by Aquatic Plants
Bioaccumulation
Fig: Zn, Cr, Cd accumulation in the dry biomass of plants A (Water hyacinth), B (Duck weed)
and C (Pistia) cultivated in hydroponics media containing different coal ash percentage
8.6
16.33
9.8311.34
7.58
11.89
0.25 0.26 0.26 0.53 0.280.37 0.5 0.52 0.3 0.4 0.47
0
5
10
15
20
0% 5% 10% 20% 30% 40%
(Co
nce
ntr
atio
n in
pp
m)
(Coal Ash Percentage)
C (Pistia)Zn Cr Cu
3.22
4.53 4.143.56
4.34
10.65
0.25 0.25 0.25 0.25 0.280.3 0.27 0.35 0.61 0.25
0
2
4
6
8
10
12
0% 5% 10% 20% 30% 40%
(Co
nce
ntr
atio
n in
pp
m)
(Coal Ash Percentage)
B (Duck weed) Zn Cr Cu
3.233.76
2.763.3 3.29
6.25
0.250.31 0.3 0.25 0.32 0…
0
1
2
3
4
5
6
7
0% 5% 10% 20% 30% 40%
(Co
nce
ntr
atio
n in
pp
m)
(Coal Ash Percenrage)
A (Water hyacinth)Zn Cr Cu
Fly Ash Utilization
Coal fly ash management poses a serious environmental problem for India and requires a mission-mode approach
Considerable research and development work have been undertaken across the country towards confidence building and developing suitable technologies for disposal and utilization in construction industries
As a result, fly ash utilization in the country has increased from 1 million tonneper year to more than 45 million tonne/year during 2005
Utilization of Fly Ash
Fly Ash Bricks/ Blocks
Cellular Concrete Products
Light Weight Aggregates
Concrete and Mortar
Cement Making
Asbestos Products Manufacturing
Road Construction
Embarkment/ Land Development
Controlled Low Strength fill
material (CLSM)
Use in Agriculture
Mine Filling
Manufacture of Fertilizer