Coal Gasification- Energy

8/9/2019 Coal Gasification- Energy

1/37

1

.

COAL GASIFICATION FOR SUSTAINABLE DEVELOPMENT

OF ENERGY SECTOR IN INDIA

o 1. Introduction o 2. Merits of Coal Gasification Technology

o 3. Sustainable Development Through Coal Gasification :

3.1 Coal Washing

3.2 Power Generation

3.3 Integrated Gasification Combined Cycle (IGCC)

Electric Power Generation.

3.4 Integrated Gasification Fuel Cell

3.5 Other Technologies

3.6 Synthetic Oil

3.7 Natural Gas Substitution

3.8 Steel Making

3.9 Coal chemicals :

3.10 Once Through Methanol

3.11 Underground Coal Gasification

3.12 Miscellaneous Uses

o 4. Strategy & Approach

4.1 Immediate

4.2 Short Term

4.3 Long Term 4.4 Financial Aspects

o 5. Conclusions

o References

o Summary

8/9/2019 Coal Gasification- Energy

2/37

2

COAL GASIFICATION FOR SUSTAINABLE DEVELOPMENT OF

ENERGY SECTOR IN INDIA, RAO, O.P.,

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH,

New Delhi, India

1. Introduction

India has relatively large reserves of coal (202 billion tonnes)

compared to crude oil (728 million tonnes) and natural gas (686

billion cubic meters). Coal meets about 60% of the commercial

energy needs and about 70% of the electricity produced in Indiacomes from coal [1]. The coal resources which are in substantial

commercial use and their utilisation technologies will be vital factors

in shaping economic and societal progress, as India moves into the

next millennium. Advanced technologies when applied to Indian coal

resources, can improve the efficiency and minimise environmental

impacts of coal utilisation. A balance is necessary between short term

imperatives and long term possibilities to enable sustainable

development. To pursue such a strategy technologies are available

and are also under development.

Though coal is relatively a long lasting fuel, the quality in general is

inferior with mineral content as high as 50%. Since reserves of oil and

natural gas are meager, they need to be substituted with coal to theextent feasible. At the same time all the three fuels, specially coal

needs to be conserved for the future generations. The energy sector,

requires efficient, clean and dependable energy supplies. Hence coal

has to be utilised with multi pronged strategy i.e. higher efficiency,

8/9/2019 Coal Gasification- Energy

3/37

3

environmental acceptance, prolonging its availability and as

replacement for oil etc. which is possible only through sustainable

development and gasification is the best option to achieve it.

2. Merits of Coal Gasification Technology

Gasification of coal is an old, and well proven technology that has

attracted renewed interest and is now undergoing modernisation. In

the early part of this century a large number of coal gasifiers werecommercially operated in several countries. With the availability of

abundant and inexpensive natural gas and crude oil most of the coal

gasification units were abandoned by mid 50's. The oil crises

situation and together with the potential capability of integrated

gasification combined cycle power plants to compete favourably with

direct coal combustion for electric power generation have significantly

increased the attractiveness of coal gasification technology and

reduced its economic risk.

Coal gasification offers a practical means of utilising coal for meeting

stringent environmental control requirements. In the gasification

process sulfur present in the coal is converted to hydrogen sulfide

(H2S) and minor amounts of carbonyl sulfide (COS). These sulfur

compounds can be easily and economically removed from gas

streams by a wide variety of commercially available processes (i.e.

acid gas removal systems). From the acid gas, elemental sulfur is

recovered. After the acid gas removal treatment only few ppms of

8/9/2019 Coal Gasification- Energy

4/37

4

sulfur remains in the coal gas. Nitrogen oxides (NOx) are not formed

to any appreciable extent in the reducing atmosphere of coal

gasification. The particulate content in the fuel gas after gasification is

negligible since the gas cleaning steps (hot cyclones, water scrubbingor hot gas cleaning) capture almost all the particulate. Except hot gas

cleanup, other two systems are commercially established and

practised. The waste waters from gasification plants can be

effectively treated. The coal gasification plants do not produce any

scrubber sludge which need careful and costly disposal. Coal ash

from gasifier is not hazardous and its leaching effect is low.

Coal gasification process has several other advantages besides

minimum environmental impacts which are briefly mentioned here. A

broad range of coals with varying ash content, coal fines, middlings

and washery rejects can be successfully gasified. Variation in the

feed coal quality has minimal adverse effects on gasification process.

Coal can be fed to the gasifier in the form of crushed coal up to 50mm size, coal fines, pulverised coal or coal water slurry depending

upon the generic type of gasification process (i.e., moving bed,

fluidised bed and entrained bed). Air or oxygen can be used as

gasification medium. Carbon conversion efficiency of as high as 99%

can be attained in the gasification process.

The major advantage of gasification is that coal is converted into agaseous fuel which is easy to handle and is a clean form of energy. In

the gaseous form it enables to substitute petroleum products and

natural gas. The synthesis gas has wide range of applications. It can

be used in a combined cycle system for efficient and clean generation

8/9/2019 Coal Gasification- Energy

5/37

5

of electric power. It is suitable for the manufacturing of hydrogen and

chemicals such as ammonia, methanol, acetic acid; as substitute

natural gas, and as a reducing gas for metallurgical purposes etc. It

can be used in multipurpose plants for the simultaneous production ofelectric power, chemicals/fertilisers and fuels which also improve the

economics of coal gasification.

3. Sustainable Development Through Coal Gasification:

According to the World Commission on Environment and

Development, Sustainable Development is the exploitation ofresources (i.e. coal resources), the orientation of technological

developments (i.e. coal utilisation technologies) and the direction of

investments must be in harmony to enhance both current and future

potential to meet human needs (i.e. energy). Sustainable

development aims to promote economic growth, efficient use of

natural resources and their secured long term supply and protection

of environment to ensure survival of the future generations.

3.1 Coal Washing

Bulk of the coal reserves (i.e. about 73%) in India are of inferior grade

non coking coals with ash content as high as 45-50%. Coal for Indian

power plants is supplied from these reserves. With utilisation of

relatively good quality coal over a period of time, the average ash

content of coal being mined at present has gone up to 40-45% and

the average calorific value has come down to around 3500 kcal/kg.

Opencast mining has been adopted on large scale (i.e. 75% of coal

8/9/2019 Coal Gasification- Energy

6/37

6

production) to meet the demand of power sector as a result the

quality of coal is further deteriorating with the addition of dirt and

stones etc. from the overburden. The emphasis on opencast coal

mining is likely to continue. Hence it is expected that in future, coalproduced may have higher ash content than what is produced now.

Likely trend of production of different quality coals in future is given in

Table 1 [2].

Washing of coal particularly when long distance transportation is

involved, has distinct advantages in the performance of power plants

which have been demonstrated. However, washing also creates

problems of its own like increased production and handling of rejects

etc. The rejects must be utilised to improve economics of washing

and reduce pollution. It is now required that except for pithead plants

or power plants located within few hundreds of kilometres from coal

mines, all projects located more than 1000 kms away from the coal

sources and also the plants located in urban areas will be required touse washed coal with ash content of about 34%, which still appears

to be quite high. An important issue to be addressed in this context is

the agency for establishing washeries, whether it is coal company or

power plant or independent agency. The issue needs to be resolved

for wider application of coal washing for power generation in India.

Washing of coal on commercial scale for power generation is yet to

commence in India.

To make matters worst, such high ash coals are usually very difficult

to wash by ordinary washing technologies because the mineral

matter is finely intergrown with the fine physical material of coal and

8/9/2019 Coal Gasification- Energy

7/37

7

are not easily liberated unless ground to very fine sizes. Fine coal

washing requires expensive dewatering systems and the benefits of

washing are lost by the presence of moisture in the washed fines.

The presence of large amount of near gravity material to the extent of70-80% causes migration of large amount of sinks in floats and floats

in sinks. As a result the yield of clean coal is less and the

middlings/rejects are more making the washing of coals techno-

economically unattractive specially when the ash content aimed is

below 25%. Wide fluctuation in ash content of coal seams require

design of washing circuits capable of dealing with wide variations in

mineral matter. On account of these factors, coal washing not only

poses technical challenges, but economically also the washing plants

may be costlier than those in other countries for comparable

throughputs. Hence technology of utilising raw and unwashed coal is

attractive to India. Coal gasification is such a technology.

3.2 Power Generation

About 70% of the electricity generated in India comes from coal and

the power sector continues to be the major consumer of coal for

years to come. Projections on coal based installed capacity and coal

requirement up to the year 2006-07 are given in Table 2 [3].

Power generation from coal in India is based on combustion in

boilers. Coal when directly combusted generates air emissions that

must be controlled particularly sulfur dioxide and nitrogen oxides

8/9/2019 Coal Gasification- Energy

8/37

8

which cause acid rain, smog and ozone depletion etc. Methods to

control sulfur emissions with flue gas scrubbers encounter several

operating problems and high costs. Capital cost of flue gas

desulfurisation in wet scrubber is around US$120-210 /KW andconsumes 1 to 3% of auxiliary power. Luckily sulfur in Indian coals is

low generally below 0.5% except coals found in north eastern region.

Hence flue gas desulfurisation is not required at present for Indian

power plants. Even when it is necessary coal gasification technology

is inexpensive and attractive for Indian coals, since the process has

inbuilt removal/control capabilities for sulfur/nitrogen emissions. The

technologies of low NO x burners and overfire air are practised to

control NO x emissions. Both the technologies combinedly can reduce

NOx by 40 to 60% only, and cost about 200-400 US$ per ton of NO x

removed. On the other hand coal gasification has inherent

characteristics of removal of sulfur emission up to 99% and NO x by

60-90% without incorporating special and costly external control

systems [4].

The high mineral matter content in Indian coals posses several

problems such as low calorific value, delayed combustion, corrosion,

erosion, deposits, fouling and slagging. The fly ash in Indian coals

has significant amounts of mullite (5 to 30%) and quartz (up to 30%)

which are mainly responsible for causing erosion specially of

pulverisers, boiler tubes and I.D. fans etc. [5]. Due to poor quality of

coal, Indian power plants are achieving only 63% PLF while it is

above 80% in advanced countries. Similarly the specific coal

consumption i.e. kg of coal consumed per kwh of power generated is

8/9/2019 Coal Gasification- Energy

9/37

9

very high in India, of the order of 0.8 compared to 0.5 in advanced

countries. According to a study conducted in one of the power plants

in India, the boiler availability reduced by 1.5% at the ash level of 32-

35%, 6% at ash level of 36-38% and 12% at the ash level of 40% [6].Not only poor quality, but its unlimited variation in the parameters like

moisture, volatile matter and ash often experienced are more

detrimental to the performance of power plants i.e. it results in

increased oil consumption etc. Higher mineral content results in more

forced outages and high maintenance cost. Thus there is a need for

power generation technology which can use high ash coals with wide

fluctuation in quality more efficiently and with least pollution. The coal

gasification route in place of direct combustion is a promising

technology for Indian coals to achieve these objectives since it has

inherent characteristics of complete removal of particulate without the

help of an electro staticprecipitator.

3.3 Integrated Gasification Combined Cycle (IGCC) ElectricPower Generation

Coal based electric power generation (i.e., direct combustion of coal

in stoker fired and pulverised coal fired boilers) has historically been

the backbone of the electric utility industry and this technology is well

proven. But the technology has reached a plateau of maximum

efficiency with only marginal potential for further improvements due totechnical limitations.

In addition to this limitation on efficiencies, tightening of

environmental control requirements have resulted in substantial

8/9/2019 Coal Gasification- Energy

10/37

10

increase in both capital and operating costs to reduce emissions from

conventional coalfired power plants and also in lowering plant

efficiency and reliability, on the otherhand coal gasification

technology has emerged as the most environmentally benign andcompetitive way of coal utilisation. Thus it would be of enormous

benefit to the electric utility industry to find some practical means for

combining the high efficiency of combined cycle system with the

clean coal gasification-process for utilising coal which is a low cost

and abundantly available fossil fuel. This has lead to the development

of IGCC Power system.

IGCC is the technology designed to meet the higher efficiency and

stringent environmental regulations required in the 21st century.

IGCC systems have the potential to compete economically with

conventional coalfired steam plants and have lowest possible level of

pollution. As environmental control requirements increase, the

economic advantages of IGCC would correspondingly increase.Similarly with further developments in coal gasification and gas

turbine technologies taking place, the economic and performance

benefits of IGCC would increase significantly. The efficiency of IGCC

which is now around 40-45% is likely to increase to 55-60%. The

capital cost of large and mature technology IGCC plants and PC

plants with FGD are projected to be nearly same. IGCC is the most

economical system when compared to the conventional pulverised

coal fired plant for removal of sulfur and nitrogen. With high sulfur

coals the efficiency difference between the two plants is higher since

the auxiliary power consumption for the sulfur removal is up to 3% in

8/9/2019 Coal Gasification- Energy

11/37

11

the flue gas desulfurisation (FGD) unit of coalfired plant and

negligible in the IGCC plant.

IGCC plants require less water than coal fired plant as approximately

60% of power is generated from gas turbine. IGCC plants also

require less land. IGCC systems are highly modular which enable

phased construction and higher plants availability up to 85% or about

7400 hours per year of plant operation [7] and economy at smaller

capacities of the order of 250 MW. Introduction of IGCC technology to

utilities can create new business opportunities in the co-production of

electricity with chemicals, liquid fuels etc.

As the global demand for coal increases, worldwide carbon emissions

will also increase. It is estimated that if all power producers were to

use the most efficient clean coal technologies, IGCC being one of

them, global carbon dioxide emissions could be cut by more than

half, compared with the levels that would be emitted by the existing

power plant technologies, i.e. pulverised coalfired [8].

The expert group on IGCC technology appointed by Govt. of India

has prepared a Techno-Economic Feasibility Report (TEFR) in the

year 1991 comparing the operational performance and economics of

IGCC and PC based power generation for a 600 MW capacity plant

with 35% ash coal. According to the results of the study given inTable 3 IGCC is more efficient, pollution is very less and capital and

generation costs are comparable with PC plant [7].

IGCC technology is now moving from drawing board to commercial

8/9/2019 Coal Gasification- Energy

12/37

12

scale. A 250 MW IGCC plant of Tampa Electric Co. USA has

successfully completed one year of commercial operation. The

wabash project in USA of 262 MW IGCC plant began its commercial

operation in November 1995. Sierra pacific pinion pine IGCC project,USA of 107 MW capacity is undergoing operation trials. A 250 MW

IGCC plant at Buggenum, Netherlands has entered its final

demonstration year. The capital cost of IGCC plant now is around

$2000/kW which is likely to come down to $1500/kW. The global

market for IGCC is expected to be 41 GW by 2004 [9].

3.4 Integrated Gasification Fuel Cell

Fuel cell is the most efficient and the least polluting system of power

generation. Out of the 3 fuel cell systems based on the type of

electrolyte used i.e. Phosphoric Acid Fuel Cell (PAFC) Molten

Carbonate Fuel Cell (MCFC) and Solid Oxide Fuel Cell (SOFC), the

latter two are suitable to utilise coal gas which resulted in the

development of Integrated Gasification Fuel Cell (IGFC) System.

PAFC is nearly commercial and the other two (MCFC and SOFC) are

at development stage.

IGFC can attain efficiencies up to 60% and are cool enough to

prevent NO x formation. Sulfur and particulate present in the coal are

removed during the gasification process before feeding the fuel gasto the fuel cell. A comparison between the emissions of a coalfired

conventional power plant and IGFC system is given in the table 4

which shows that fuel cell generates extremely clean power [10].

8/9/2019 Coal Gasification- Energy

13/37

13

There are two major challenges with respect to commercialisation of

fuel cell: initial cost and reliable life. The two problems have to be

solved to improve the economics of fuel cell.

3.5 Other Technologies

In addition to IGCC, two other relevant technologies for power

generation are : Pressurised Fluidised Bed Combustion (PFBC) and

High Concentration Coal Water Slurry (HCCWS). The PFBCtechnology is demonstrated in 80-100 MW scale abroad. The PFBC

is dependant on hot gas cleaning for the removal of particulate from

the flue gases or on a heavy duty gas turbine which can tolerate

particulate matter in the flue gases. Both hot gas cleanup and heavy

duty gas turbine are under development. IGCC also incorporates a

hot gas cleanup system which increases the overall efficiency, but

wet scrubbing by water can be employed in place of hot gas cleanup

with some loss in efficiency. Thus PFBC compared to IGCC is

constrained by availability of hot gas cleanup technology. Another

major disadvantage with PFBC is that more power is generated from

steam turbine which is less efficient compared to gas turbine.

Whereas in IGCC, more power is generated from the gas turbine and

hence is more efficient. Continuous developments are taking place inthe gas turbine technology which could result in higher efficiencies in

IGCC beyond 50%. Such improvements in the steam turbine are

limited.

8/9/2019 Coal Gasification- Energy

14/37

14

HCCWS consisting of 70% solids and 30% water is used for power

generation either through combustion or gasification route. High ash

content in the coal thermally penalises the conversion processes of

coal slurry resulting in lower and uneconomical efficiencies. Thereforethe coals have to be necessarily washed to bring down the ash

content to around 15% to improve the efficiency and economics. But

the cost of preparation of slurry itself depends upon the techno-

economics of washing which are at present unattractive for high ash

coals. Thus application of HCCWS technology to high ash coal

mainly depends on technoeconomics of washing the coal.

3.6 Synthetic Oil

The commercial application of liquefaction of coal for production of oil

had taken place in unusual circumstances where price had been a

less critical factor than secured or strategic supply. This was in

Germany, during world war II when a wide range of transportation

fuels were produced from coal to supply the war machines. Since

1955 South Africa is producing liquid fuels from coal due to lack of

petroleum and natural gas reserves but abundance of coal reserves

and political factors. Efforts at commercial production of liquid fuels

from coal have taken place in the US (Synfuels program), UK and

Japan without actual full scale development. The main reason for not

going up to commercial operation in these countries has been theavailability of inexpensive petroleum supplies in abundance both

domestic and imported.

The consumption of petroleum products in India has been increasing

8/9/2019 Coal Gasification- Energy

15/37

15

at a rapid pace. It has increased from 30.9 million tonnes in 1980-81

to 57 mt in 1991-92 @ annual compound growth rate of 5.7%. The

growth rate increased further to 7% after 1991-92 after liberalisation

of economy and the consumption reached 80 million tonnes in 1996-97. Out of the total consumption of petroleum products, the middle

distillates account for 63% in 1995 [1,4] Several reasons for steep

rise in demand for petroleum products in general and middle

distillates in particular are i) Change over from coal to oil as primary

source of energy ii) Unprecedented growth in personal vehicles (iii)

electric power shortages which prompted industrial and commercial

establishments and large residential complexes to install diesel

generators and agricultural consumers to install diesel pump sets as

standby measure (iv) rising share of diesel based transport both road

and rail transport (v) increase in kerosene consumption for household

sector due to low availability of traditional fuels (vi) subsidies on

prices.

The indigenous petroleum production which had also grown

correspondingly from 6.8 mt in 1970-71 to 32.9 mt in 1996-97 could

not meet the demand. To bridge the gap India is importing large

quantities of crude oil and petroleum products. In 1985-86, India's net

imports were 16.5 mt which has increased steeply to 43.4 mt in 1996.

In the year 1996-97 the import bill towards petroleum and petroleum

products was US$10,081 million which was 26% of the total import

bill. With the depreciation of rupee, the share in rupee terms was

even higher. On the basis of current trends, the total consumption by

the year 2010-2011 could be close to 200 million tonnes which is

8/9/2019 Coal Gasification- Energy

16/37

16

about 3 fold increase from the present consumption. Import is much

more than indigenous production. The extent of self sufficiency in oil

which was peaking at 70% in 1984-85 has been consistently

declining which reached to 40% in 1996-97 and is likely to declinefurther to 35% in a couple of years [1,13]. The trend is causing

concern since India is emerging rapidly as a major consumer of oil

products.

As experienced on several occasions, petroleum supplies and prices

are greatly influenced by political policies. There have been several

price hikes in oil since 1971. In all the cases, India was one of the

hardest hit countries. It is possible that OPEC countries can reduce

direct export of crude and substitute with finished petroleum products

so that the exporting countries can reap the benefits of maximum

value addition. In such a situation, oil may not be available in

adequate quantities and also at affordable prices. Economy of India

which is highly dependent on oil imports will suffer a great setback.The infrastructure for oil refinery available in India would be under

utilised.

The success of liberalisation policy and economic reforms introduced

in the country is largely dependent on adequate availability of energy

resources at affordable prices and oil has a significant place in it.

Therefore any disruptions in oil supplies would hamper progress ofthe country. Thus from consideration of national self reliance, security

and assured energy supply, production of oil in India from alternate

source i.e. coal is justified.

8/9/2019 Coal Gasification- Energy

17/37

17

There are 3 routes for liquefaction of coal i.e., direct hydrogenation of

coal, hydrogenation of coal tar and gasification followed by Fisher-

Tropsch (F-T) synthesis. The process of direct hydrogenation of coal

requires coal with very low ash content, below 10% and hence is notsuitable to India due to very high ash content in Indian coals. The

process of hydrogenation of tar obtained from coal carbonisation is

also not applicable due to inadequate availability of tar. The route of

gasification followed by F-T synthesis is the most suitable one for

Indian coals. South Africa at Sasol is producing liquid fuels from coal

based on gasification and F-T synthesis. The gasification process

adopted at Sasol is moving bed process which is also proven with

Indian coals. The successful operation of Sasol plant gives more

confidence to India for adopting gasification route for producing oil

from coal [11].

The option of conversion of coal into synthetic liquid fuels, had been

under the consideration of the Government of India since 1950.Several committees appointed by the Government had examined the

feasibility of producing oil from coal and recommended for setting up

commercial plants of capacity up to 1 million tonnes per year in the

country. The proposals did not materialise mainly due to economic

reasons. For example the estimates made in 1982 had indicated a

capital cost of Rs.16,110 million ($1667 million) for 1 mtpa plant and

cost of production of $35 per barrel [11].

Coal accounts for 69% of world's fossil fuel reserve, while it is only

17% for oil [8]. Major consumption of oil is in the transport sector.

Hence many scientists and engineers believe that coal liquefaction

8/9/2019 Coal Gasification- Energy

18/37

18

would be required to meet the demand for liquid transportation fuels.

However, world development of coal liquefaction will depend upon

both economics and the reliability of petroleum and natural gas

supplies from the middle East and other main exporting areas.

3.7 Natural Gas Substitution

The emerging role of natural gas in Indian energy sector is evident

from the increase in its share in primary energy supply from 2% in

1989 to 8% in 1996 and also increase in its production from 3.1 to

19.4 billion cubic meters during the same period. Natural gas is usedin India for both energy and non energy purposes. The major

consumers are: 42% for fertiliser production, 38% for power

generation and 13% as industrial fuel. At present about 5500 MW of

gas based power plants are in operation in the country [1]. The total

installed capacity of gas based power plant is proposed to be about

13,300 MW by the year 2001-02. The gas is in short supply for the

power plants to the extant of 50%. The import of gas has been

considered but so far large scale imports have not materialised.

Liquid fuel has been used to supplement natural gas in the power

plants. It appears that generation of power with liquid fuels is

economically not very attractive and power generation using imported

naptha is higher than the cost of power generation using domestic

coal almost at all locations. For example the cost of power generationwith domestic coal and imported naphtha at Delhi are estimated at

Rs.1.99 & 2.57 (5.1 & 6.8 cents) respectively [3]. Natural gas is a

preferred fuel for the manufacture of fertilisers, petrochemicals, and

sponge iron etc. The natural gas used for power generation can be

8/9/2019 Coal Gasification- Energy

19/37

19

used for these purposes if it can be replaced by an alternate fuel gas.

The fuel gas produced by gasifying coal would be suitable to burn in

the existing gas turbines of the combined cycle plant. The conversion

from natural gas to coal based fuel gas needs addition of a coalgasification system in the combined cycle plant.

3.8 Steel Making

A serious concern regarding coking coal resources in the country isthe limited reserves of prime coking coal and its quality, the gross

reserves of which are estimated at 5.3 billion tonnes (2.6% of total

coal reserves). Bulk of this prime coking coal is of high ash content

and requires washing prior to coke making. The reserves of medium

coking and semi coking coals are relatively better placed at about 18

billion tonnes. But in view of the limited reserves of prime coking coal,

the medium and semi coking coal cannot be used in its totality as

ternary blend for manufacture of metallurgical coke. As a result, India

is relying on imports of low ash prime coking coals to blend with

Indian washed coking coals. Indian coking coals have ash content

varying from 15% to 35% and are also difficult to wash. Due to poor

quality of mined coal, the washed coal is having higher ash content of

22-23%, against the designed value of 17%, which is adverselyaffecting the productivity and economics of steel production. To

reduce the ash content in the coal blend, higher quantity of imported

coal is being used. The imports of coking coal are steadily going up

on the plea that the domestic coking coals are deficient in quality and

8/9/2019 Coal Gasification- Energy

20/37

20

quantity. Coal imports & during the past 8 years i.e. between 1989 to

1997 have almost doubled from 4.7 to 9.2 million tonnes [13].

In India the reserves of non coking coal are abundant (174 billion

tonnes) compared to coking coal (30 billion tonnes). It would

therefore be a good strategy to use more of non coking coal for

metallurgical purposes so as to conserve coking coals and reduce

their imports. Fuel gas generated from the gasification of inferior

grade non coking coals, can be injected into the blast furnace which

reduces the coke rate. Fuel gas acts as a reducing agent as well as

an energy source and therefore a complete replacement for coke. As

particulate and sulfur are completely removed from coal in the

gasification system, the fuel gas injection into the blast furnace can

reduce the flux requirement and ferromanganese addition. Fuel gas

from coal gasification is also used for production of sponge iron which

is a substitute for scrap and also a raw material for steel production.

There is shortage of scrap in the country which is met by imports.

3.9 Coal chemicals:

Coal was the main source for a variety of chemicals like benzene,

toluene, xylene, naphthalene, anthracene, phenol etc. till the second

world war. These chemicals present in coal tar obtained by

carbonisation of coal were the raw material for the production ofpharmaceuticals, dyes, resins, plastics, and explosives. The first

polyethylene plant of Dupont was based on ethylene from coal gas.

There are three important routes to convert coal to useful chemicals,

one of them is gasification technology to produce synthesis gas as a

8/9/2019 Coal Gasification- Energy

21/37

21

feed material for chemicals. The wide spectrum of possible chemicals

from synthesis gas include ethylene, methanol, formaldehyde, acetic

acid, ethylacetate, etc. The synthesis gas opens up the field for C1

chemistry. At Sasol in South Africa, chemicals ranging from alpha-olefins, waxes, solvents, paraffin, ketones, alcohols and acids are

produced from synthesis gas obtained from coal gasification.

Ammonia has also been made from the hydrogen present in the

synthesis gas obtained from gasification of coal. A number of such

coal based fertiliser plants have been setup in many countries

including 3 plants in India.

Petroleum and natural gas are currently the principal sources of basic

organic intermediates namely ethylene, propylene, butadiene,

benzene, toluene, xylenes and methanol. The organic chemical

industry which depends upon petrochemical building block could face

a serious feedstock problems due to any disruptions in oil supplies. In

such situations, synthetic gas from coal can be a suitable feedstock.

Technologies are available in India for production of coal chemicals.

3.10 Once Through Methanol

This concept was conceived at EPRI in an effort to devise a scheme

for the economic production of a storable fuel from coal. This concept

involves co-production of methanol and electricity in an integrated

gasification combined cycle power plant. Electric utilities are

interested in methanol because it is an excellent fuel for meeting the

peak load demand. Further more, it is easily stored, efficient and

8/9/2019 Coal Gasification- Energy

22/37

22

environmentally clean coal fuel. It has been tested as a fuel for both

gas turbines and boilers. Methanol produced from once through plant

can displace the petroleum fuels. Based on the experience so far, it

can be said that co-production of methanol and electricity by the oncethrough scheme promises to be an economically attractive solution

for electric utility for a clean burning, and storable fuel offering

longterm security of supply. Methanol is also a feedstock for several

chemicals like ethanol and ethylene glycol etc.

A study carried out by EPRI had shown that methanol produced in

the once through mode, integrated with an IGCC power plant owned

by a regulated utility can be cheaper by 38% than dedicated

methanol manufactured by a non regulated company [12].

3.11 Underground Coal Gasification

This technique can be applied to generate energy from coal seams

occurring deep below the surface generally not amenable, technically

or economically, to extraction with known mining techniques. In a

workshop organised on underground coal gasification at Delhi, in

India in September 1987 it was opined that the technology is highly

relevant and very promising to India. Two sites in India one in

Rajastan and another in Bengal-Bihar initially appear to be suitable

for application of underground coal gasification. Many more areas

could be amenable.

8/9/2019 Coal Gasification- Energy

23/37

23

3.12 Miscellaneous Uses

Fuel gas from coal gasification can find many uses in industry and

domestic sectors for heating and energy purposes. In 1996, 4.6

million tonnes of furnace oil which was 10% of total petroleum

products was consumed in the industry. Fuel gas can supplement the

furnace oil in firing of industrial furnaces. Fuel gas as town gas can

be piped to homes and hotels for cooking supplementing the LPG

presently used whose consumption was 1.2 million tonnes in 1996.

The town gas can also reduce demand for kerosene whose

consumption in 1996 was 4.7 million tonnes.

4. Strategy & Approach

A three pronged approach i.e. immediate, short term and long term is

suggested for India for sustainable development of energy sector

through the application of coal gasification technology.

4.1 Immediate

The immediate targets are to establish coal gasification and IGCC

technologies for commercial application.

Indian scientists and engineers have gained experience in the

gasification of coals through moving bed process on pilot /

demonstration scale. The moving bed process (Lurgi dry ash

process) is commercially proven for high ash coals in Germany and

8/9/2019 Coal Gasification- Energy

24/37

24

South Africa for power generation, manufacture of synthesis gas,

chemicals and liquid fuels. Therefore it may be a low risk or mostly no

risk strategy to pursue with moving bed gasification process. The first

priority of use of coal gas should be for power generation. India needto build the first IGCC plant based on moving bed process of size

around 60 MW to accommodate one train of gasification and power

islands. The plant should be extensively instrumented and thoroughly

experimented with various coals to develop full indigenous capability

for setting up of large scale plants in India.

Fluidised bed gasification process is superior to moving bed process

for utilisation of high ash Indian coals through gasification route. The

experience on fluidised bed process is very limited in the country.

Internationally also, the experience gained so far is only for low ash

coals. The first IGCC demonstration plant of 107 MW based on air

blown, pressurised, fluidised bed process (i.e. KRW process) has

been established at Reno, USA (Pinion pine IGCC power project).Operation of the plant has been initiated. Results and performance of

this plant would be very useful to India in adopting the fluidised bed

process.

India can go in for hybrid concept i.e. a combination of moving bed

and fluidised bed gasification processes at one location to select the

best among the two. By the time the first IGCC demonstration plant of60 MW capacity based on moving bed process is commissioned, the

results from Pinion pine project are likely to be available, based on

which a fluidised bed coal gasification system can be added by the

side of moving bed plant at the same location. India is a vast country

8/9/2019 Coal Gasification- Energy

25/37

25

having coal as the major energy source. It will be advantageous to

adopt two coal gasification processes. The hybrid concept results in

the economy of coal since all the coal supplied to a power plant can

be utilised i.e. 6 to 50 mm sized coal for moving bed and the coalbelow 6 mm for fluidised bed. Moreover moving bed cannot tolerate

more than 10% of coal fines due to operational problems.

4.2 Short Term

The targets for short term can be: i) to construct commercial scale

IGCC plants of capacity 250 MW and above ii) converting existingthermal power plants to IGCC iii) use of synthesis coal gas for

production of chemicals, fertilisers and steel.

The IGCC demonstration plant is likely to give enough confidence for

the design of commercial plants in five years period from the date of

commencement of its construction. Once the IGCC technology is

established in the country, all future coal based power plants can bein IGCC mode. A plant of 250 MW capacity IGCC appears to be

economical on commercial scale.

The conventional coal based thermal power generation is well

established in the country and is a major infrastructure in the power

sector. Its output and environmental conditions can be improved by

converting them into IGCC plants through repowering by putting up a

coal gasification system and gas turbine. A beginning can be made in

this direction by converting the large number of small capacity (20-30

MW) plants which were set up during sixties and seventies.

8/9/2019 Coal Gasification- Energy

26/37

26

Indians have experience in the production of chemicals from tar

obtained from coal carbonisation in coke ovens and fertilisers through

coal gasification. This experience will be helpful in the manufacture of

chemicals from the synthesis gas produced from coal gasification.The same IGCC demonstration plant, after it generates enough data

on IGCC, can be utilised for establishing the production of chemicals

and fertilisers from synthesis gas. For this purpose, adequate

demonstration facilities need to be added by planning them well in

advance.

4.3 Long Term

The long term targets can be: i) Replacing the natural gas with coal

gas in the existing combined cycle power plants ii) Establishment of

advanced power generation technologies based on coal gas i.e., fuel

cell. iii) Commercial plants for coal to oil and coal refinery. iv) Self

reliance and security in energy sector v) Substitution of exhaustible

with renewable energy sources.

Natural gas is being used for power generation in the country and it is

rightly so for accelerated growth of power sector. There are plans for

import of liquefied natural gas (LNG) and naphtha etc. for power

sector mostly by independent power producers. This could be

allowed as a short term measure as dictated by the market forces.But as a long term measure the natural gas and liquid fuels need to

be replaced by coal gas.

Fuel cell is highly efficient and an ultra clean power generation

8/9/2019 Coal Gasification- Energy

27/37

27

technology from coal. The country needs it in highly environmentally

sensitive areas or strategic locations. These technologies are now at

infant stages of development in advanced countries. It may reach the

commercial stage when India needs it. At that time India canestablish/adapt the technology for Indian coals and conditions.

India is highly dependent on imported oil with a heavy drain on

foreign exchange earnings. This trend is not likely to change very

much in foreseeable future. Finding of any large reserves of oil in the

country is not in sight. Oil can be substituted with coal, but for certain

applications it has to be converted into liquid form. Several experts

have already recommended the coal gasification route for liquefaction

of Indian coals. Considering several aspects, the option of coal to oil

seems to be an unavoidable strategy for India.

The setting up of coal to oil conversion plants should not be

evaluated purely from commercial angle, but security, self reliance

and conserving oil should merit serious consideration. Coal to oil

technology can be considered on the same footing as atomic energy

which had paid dividends by bringing the country to self reliant status.

A concept of coal refinery is mooted now and may be put in practice

as a long term strategy to substitute the imported oil.

Besides coal, oil and natural gas, India has vast thorium resources of

over 360,000 tonnes which can sustain about 300,000 MW for about

300 years. Regarding renewable energy resources, India has

potential of hydro 84,000 MW, wind energy 20,000 MW, biomass

8/9/2019 Coal Gasification- Energy

28/37

28

17,000 MW and small hydro 10,000 MW etc. Only about 25% of the

renewable energy potential is exploited so far.

To meet the long term perspective in energy sector the strategy

should be the maximum utilisation of renewables and minimum use of

exhaustible in order to conserve them specially coal and oil since

they have more essential uses which cannot be met by other energy

sources. The substitution measures can also relate to replacement of

one exhaustible i.e. oil by another exhaustible i.e. coal. This strategy

must be temporary. But the long term strategy should be to

supplement them with renewable energy sources.

4.4 Financial Aspects

Large amounts of capital are required to setup commercial plants to

produce fuel gas from coal gasification as a feedstock for gaseousand liquid fuels and chemicals etc. Majority of the technologies

available on commercial scale for production of the above products

are based on coals with different characteristics than that of Indian

coals specially ash content and ash fusion temperature which are

low. Therefore these technologies cannot be applied directly to Indian

coals but have to be adapted through indigenous demonstration and

R&D before setting up large commercial scale plants in the country.

Thus India needs capital for R&D, demonstration of technology with

Indian coals and for commercial plants. India is short of funds for

capital investment. Foreign or Indian entrepreneurs seldom come

8/9/2019 Coal Gasification- Energy

29/37

29

forward to invest in R&D and demonstration of foreign technologies

with Indian coals. They would be interested only in business to get

profitable returns on investment. It therefore becomes main

responsibility of the Government to fund demonstration activities.

An option that can be followed by India for funding demonstration

activities is to adopt the strategy followed by the U.S. Department of

Energy for the Clean Coal Technology Program (known as the CCT

program). It is a model of Government and industry partnership for

technology advancement. The industry is sharing 65% of the cost.

The demonstration plants are setup at commercial scale in the user's

premises. Industry retains intellectual property rights. The

Government's share in the cost of a project is refunded by the

industry only upon commercialisation of the technology. It means the

risk involved is funded by the Government. It is felt that such a type of

arrangement is necessary in India. In addition to this Government can

also give incentives to the builders of demonstration / commercialplants in India to promote coal gasification and its application

technologies.

5. Conclusions

Coal is relatively a large fossil fuel reserve in India meeting about

60% of the commercial energy needs and accounting for 70% ofpower requirements. Supremacy of coal in India's energy sector

would continue. Majority of Indian coals are of inferior quality with ash

content as high as 45-50% and are difficult to wash. The present use

of coal mostly through direct combustion is inefficient with high levels

8/9/2019 Coal Gasification- Energy

30/37

30

of pollution. The efficiency cannot be improved much due to

technological limitations and it is very expensive to control the

pollution. India is looking for alternate technologies, more efficient,

environmentally benign and economically attractive. Coal gasificationfits into these requirements. IGCC technology is the best alternate

option for power generation in India.

India is highly dependent on imported oil and petroleum products.

The trend is likely to continue due to very limited indigenous reserves

and high growth rate in consumption. India, a developing country,

requires secured oil supplies to achieve the targeted growth. This is

possible by producing oil within the country from abundantly available

indigenous coal resources. Coal gasification route is most suitable for

conversion of coal to oil in India.

Coal is a source for wide variety of chemicals. Synthesis gas

produced from coal gasification is the feed stock for production of

chemicals. There is a vast scope for coal chemicals in India.

Like oil, reserves of natural gas are very limited in India. Synthesis

gas from coal will be an appropriate supplement to natural gas.

Coal gasification opens up several avenues for coal utilisation and

enables to use coal as a raw material to improve the economics

through cogeneration/co-production of electricity, chemicals and

liquid fuels etc.

Fossil fuels (coal, oil and gas) are exhaustible, hence they need to be

utilised judiciously through the principle of sustainable development

8/9/2019 Coal Gasification- Energy

31/37

31

and coal gasification route is the best option to achieve it.

References

1. "Teri Energy Data Directory & Year Book, 1997/98", Pub. TataEnergy Research Institute, 1997.

2. Mishra B.C. "Indian Coal Resources, Its Exploitation and

Beneficiation" Proc. Indo-US Workshop on Coal Beneficiation,

New Delhi, February, 1996.

3. "Integrated Coal Policy, 1996" Report of Chari Committee.

4. "Clean Coal Technologies for Developing Countries, 1995",World Bank technical Paper Number 286, September, 1995.

5. Nanda Kumar, K and Raju, C.R. "Inorganics of Indian coal and

their Influence on Boiler Performance", Proc. Coal Utilisation:

Trends & Challenges, Dhanbad, India, December, 1989.

6. Ashok Kumar and Singh, C.P. "Coal Beneficiation- A Pressing

Need for Power Sector", Proc. Coal Prep India, 1998, New

Delhi - India, January, 1998.

7. "Feasibility Assessment of Integrated Gasification Combined

Cycle (IGCC) Power Generation Technology For High Ash

Coals", Steering Committee Report, February, 1992.

8. "Clean Coal Technologies Research Development and

Demonstration Program", Pub. U.S. Deptt. of Energy.

9. Ann chambers "IGCC: From the Drawing Board to CommercialService", Journal, Power Engineering International,

January,/February 1998.

10. Rao, O.P. "Green Power From Coal Through Fuel Cells",

Proc. 1st International Conference Green Power, New Delhi,

8/9/2019 Coal Gasification- Energy

32/37

32

India, February, 1997

11. "Conversion of Coal to Gaseous and Liquid Fuels", Expert

Group Report, May 1984.

12. "Coal Gasification Systems: A Guide to status, Applications, and Economics", Final Report, EPRI AP-3109,

June 1983.

13. "Monthly Review of the Indian Economy, January 1998",

Pub. Centre for Monitoring Indian Economy.

Table 1: Qualitative Trend of Production

Quality of Coal 1996-

97

1999-

2000

2004-

2005

Ash content

(35-50%)

75% 78% 79%

Ash content

8/9/2019 Coal Gasification- Energy

33/37

33

MW 3 8 68

Coal

requirement,

mt

215 350 500

Table 3: Plant Performance and Cost Comparison

PC

Plant

IGCC

Plant

Overall thermalefficiency, %

32.9 42.3

Capital required,* 1.0 1.14

Cost of generation *

* PC as base

1.0 0.99

Table 4: Relative Emissions (g/Mwh)

Pollutan

t

Coal fired

Fuel cell

Particula

te410

6

8/9/2019 Coal Gasification- Energy

34/37

34

NOx

2890

20

SOx

4950

26

HYPERLINK "http://www.worldenergy.org/wec-

geis/publications/default/tech_papers/17th_congress/2_3_28.asp" \l

"top" INCLUDEPICTURE "COAL GASIFICATION FOR

SUSTAINABLE DEVELOPMENT OF ENERGY SECTOR IN

INDIA_files/top_of_page.gif" \* MERGEFORMATINET

Summary

Coal is the major fossil fuel in India and continues to play a pivotal

role in the energy sector. Oil and natural gas are very limited hence

India is a net importer of hydrocarbons. India is heavily dependent on

oil imports and the trend is likely to remain same. Economic growth of

the country is tied up with regular supply of oil and any disruptions

could drastically arrest the growth. Oil imports is a drain on foreign

exchange reserves since they constitute about 26% of import bill.

More and more of natural gas is being used for power generation

leaving lesser allocations for fertilisers and chemicals etc where it is

8/9/2019 Coal Gasification- Energy

35/37

35

essential and convenient. Indian coals in general are of inferior

quality.

Present use of coal is inefficient and polluting. Hence there is need

for technologies for utilisation of coals efficiently and cleanly,

substitution of lesser reserves of oil and gas with abundantly

available coals and prolonging the reserves of all the fossil fuels for

use of future generations. These requirements can be met through

application of coal gasification technology and following the principle

of sustainable development. Paper is based on the two issues.

Paper describes the merits of gasification technology for inferior

Indian coals with respect to efficiency and environmental aspects.

Application of synthesis fuel gas from coal gasification for power

generation, production of liquid fuels, chemicals and fertilisers, and

steel making have been described in the paper. Advantages and

disadvantages of each application have been discussed. Suggestions

have been made for substitution of oil and natural gas by coal

gasication.

Strategy & approach have been suggested for application of coal

gasification in the energy sector with reference to immediate, short

term and long term timeframe. Specific technologies have been

indicated in the 3 periods. Regarding finances for implementation, theparticipation of industry in a big way is necessary. Incentives to

industry could promote the technologies.

The paper concludes that coal gasification has a significant role in

8/9/2019 Coal Gasification- Energy

36/37

36

sustainable development of energy sector in India.

INCLUDEPICTURE "COAL GASIFICATION FOR SUSTAINABLE

DEVELOPMENT OF ENERGY SECTOR IN INDIA_files/dot_gray.gif"

\* MERGEFORMATINET

HYPERLINK "http://www.worldenergy.org/wec-

geis/wec_info/about_wec/about_wec.asp" WEC INFORMATION

HYPERLINK "http://www.worldenergy.o rg/wec-geis/edc/"

ENERGY INFO CENTRE HYPERLINK

"http://www.worldenergy.org/wec-

geis/news_events/news/news.asp" NEWS & EVENTS

HYPERLINK "http://www.worldenergy.org/wec-

geis/focus/default.asp" FOCUS

HYPERLINK "http://www.worldenergy.org/wec-geis/publications/default/default.asp" PUBLICATIONS

HYPERLINK "http://www.worldenergy.org/wec-

geis/members_only/members/member_services/work_areas/work_

areas.asp" MEMBER SERVICES HYPERLINK

"http://www.worldenergy.org/wec-geis/ghg2001/ghgmain.asp"

GHG REDUCTION PROGRAMME

HYPERLINK "http://www.worldenergy.org/wec-

geis/wec_info/about_wec/tandc.asp" Conditions of use

HYPERLINK "http://www.worldenergy.org/search/" search

8/9/2019 Coal Gasification- Energy

37/37

HYPERLINK "http://www.worldenergy.org/wec-geis/global/sitemap/"

sitemap contact home

Copyright 1999-2003. World Energy Council

5th Floor, Regency House, 1-4 Warwick Street, London W1B 5LT,

UK

Tel: (+44 20) 7734 5996 Fax: (+44 20) 7734 5926