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GASIFICATION UNDERGROUND COAL GASIFICATION: CONVERTING UNMINEABLE COAL TO ENERGY WWW.GASIFICATION.ORG

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Gasificationunderground coalgasification:converting unmineablecoal to energy

w w w . g a s i f i c a t i o n . o r gw w w . g a s i f i c a t i o n . o r g

4301 North Fairfax Drive, Suite 300

Arlington, VA 22203

703.276.0110

4301 North Fairfax Drive, Suite 300

Arlington, VA 22203

703.276.0110

©Copyright by the GTC 2012.

w w w . g a s i f i c a t i o n . o r g 1

IntroductIon

currently, about 1.5 billion people –almost a quarter of the world’s popu-

lation—are without electric power. The International Energy Agency

estimates that world energy demand (for all forms of energy, including

transportation fuels) will increase by 36 percent by 2035 and fossil fuels, such

as coal, will continue to play a critical role in meeting this demand.

GasIfIcatIonUndergroUnd Coal gasifiCation:Converting UnmineableCoal to energy

(Courtesy of the UCG Association)

GasIfIcatIon Converting Unmineable Coal to energy2

However, only about 15 percent of the known coal deposits in the world

are economically mineable. Thus, about 85 percent of the world’s coal

resources (about 1.7 trillion tonnes) are “unmineable” because of economic,

environmental, or technical reasons. For example, such coal may be too

deeply underground or buried offshore. This “stranded” coal represents an

untapped energy source. Underground coal gasification (UCG) can unlock

the energy potential in this stranded coal while performing well within all

environmental requirements.

GasIfIcatIon ProductsAbove-ground gasification has been used worldwide on a commercial scale

for more than 75 years by the chemical, refining, and fertilizer industries and

for more than 35 years by the electric power industry. More recently, it is being

adopted in smaller-scale applications and in new settings to solve the problem

of waste disposal by extracting the valuable energy contained in that waste,

and to utilize alternative renewable feedstocks, such as biomass.

The syngas produced from UCG is similar to that produced by above-ground

gasification and it can likewise be combusted in a gas turbine to produce

electricity or further processed to produce chemicals, transportation fuels,

substitute natural gas, hydrogen, or fertilizers.

w w w . g a s i f i c a t i o n . o r g 3

What Is GasIfIcatIon?Gasification is a unique process that transforms any carbon-based material,

such as coal, other fossil fuels, biomass, or secondary recycled materials,

into energy without burning it. Instead, gasification converts materials into

a gas by creating a chemical reaction. This reaction combines those carbon-

based materials (known as feedstocks) with small amounts of air or oxygen,

breaking them down into a gas composed of relatively simple building block

molecules—called synthesis gas or “syngas”. The syngas consists primarily of

hydrogen and carbon monoxide and, depending upon the particular gasifica-

tion technology and feedstock used, may also contain smaller quantities of

methane, carbon dioxide, hydro-

gen sulfide, and water vapor.

Any pollutants and impurities

contained in the raw syngas can

typically be readily and substan-

tially removed leaving a clean

“synthesis” gas (syngas) that can

be converted into electricity and

valuable products.

In traditional gasification, the

feedstocks and air or oxygen are

injected into a gasifier where a

combination of heat and pressure

causes the gasification reaction.

The resulting syngas is then

cleaned to remove any impurities

and the clean syngas can then be

converted into electricity and/or

other valuable products.

VITRIFIED SLAGBY-PRODUCT

SULFURBY-PRODUCT

GASIFIER

FEEDSTOCK OXYGEN PLANT

GAS CLEAN-UP

CLEAN SYNGAS

TO POWER TO PRODUCTS

THE GASIFICATION PROCESS

GasIfIcatIon Converting Unmineable Coal to energy4

What Is underGround coal GasIfIcatIon?With UCG, the actual gasification process takes place underground, generally

below 1,200 feet depth. Recent advances in well drilling technologies are now

enabling UCG development of coals in the 4000-6000 foot depth range, with

increased environmental protection and process efficiency benefits at these

depths. The underground setting provides both the feedstock source (the

coal) as well as pressure comparable to that of an above-ground gasifier. With

most UCG facilities, wells are drilled on two opposite sides of an underground

coal seam. One well is used to inject air or oxygen (and sometimes steam) into

the coal seam to initiate the gasification reaction. The second well is used to

collect the syngas that is formed from the gasification reaction and to pipe it

to the surface for additional processing and use. A pair of wells can last as long

as fifteen years.

The UCG reactions are managed by controlling the rate of oxygen or air that is

injected into the coal seam through the injection well. The process is halted by

stopping the injection of the oxygen or air. After the coal is converted to syngas

in a particular location, the remaining cavity (which will contain the leftover

ash or slag from the coal, as well as other rock material) may be flooded with

w w w . g a s i f i c a t i o n . o r g 5

saline water and the wells are capped. However, there is a growing interest in

using these cavities to store carbon dioxide that could be captured from the

above-ground syngas processing. Once a particular coal seam is exhausted,

new wells are drilled to initiate the gasification reaction in a different section

of the coal seam.

UCG operates at pressures below that of the natural coal seam pressure, thus

ensuring that materials are not pushed out into the surrounding formations.

This is in sharp contrast to hydraulic fracturing operations in oil and gas

production, where pressures significantly above natural formation pressure are

used to force injectants into the formation.

FEEDSTOCK

HYDROGEN FOROIL REFINING

CONSUMERPRODUCTS

SUBSTITUTENATURAL GAS

CHEMICALSFERTILIZERS

TRANSPORTATIONFUELS

POWER

STEAM

SYNGAS

GA

SIFI

CA

TIO

N

GASIFICATION PRODUCTS

GasIfIcatIon Converting Unmineable Coal to energy6

Converting Unmineable Coal

The International Energy Agency estimates that developing countries will

account for 93 percent of the projected increase in global energy demand and

that global demand for fossil fuels, including coal, will account for over 50

percent of the increase in total primary energy demand. (See www.iea.org.)

UCG can help meet this rising energy demand by converting coal to energy and

other products, utilizing resources that otherwise would be too deep, of poor

quality or simply not economical enough to mine. Estimates from the U.S.

Department of Energy’s Lawrence Livermore National Laboratory suggest that

UCG could help increase the recoverable coal reserves in the U.S. by as much

as 300-400 percent, without the need to develop coal mines to tap this energy

source. The World Energy Council estimates that UCG could potentially

increase the world’s recoverable coal reserves by 600 billion tonnes. In addi-

tion, UCG effectively utilizes up to 85 percent of the original heating value of

the coal; a much higher overall efficiency than conventional coal mining and

subsequent combustion boilers.

Carbon dioxide

In the traditional gasification system, carbon dioxide can be captured using

commercially available processes before it would otherwise be vented to the

atmosphere. For most gasification applications, except electric power genera-

tion, carbon dioxide capture is actually required by the process design as part

of the overall syngas cleaning. For electric power generation, and as part of

the process to adjust syngas composition for other gasification applications,

a process, called the water-gas shift reaction, (illustrated next page) is used to

convert the carbon monoxide in the syngas stream into carbon dioxide mol-

ecules that can be captured. Capture of carbon dioxide from syngas has been

commercially practiced for decades in the non-power gasification applications,

such as for the production of chemicals, fertilizers or hydrogen.

w w w . g a s i f i c a t i o n . o r g 7

Capturing the carbon dioxide prior to combustion is more economical than

removing carbon dioxide after combustion, effectively “de-carbonizing” or, at

least, significantly reducing the carbon in the syngas. Captured carbon dioxide

can be injected into declining oil fields for enhanced oil recovery and perma-

nent carbon dioxide storage. The oil industry has been using this technique

with naturally occurring carbon dioxide for over thirty years to increase the

output of older production fields.

co2 removal floW

GasIfIcatIon Converting Unmineable Coal to energy8

In addition, captured carbon dioxide can be injected into other deep coal

seams for enhanced coal bed methane recovery. The injected carbon diox-

ide displaces the methane (used as a substitute natural gas) and the carbon

dioxide is then absorbed into the coal itself.

Carbon dioxide can be captured from UCG operations as well using the same

capture technologies as used in traditional gasification plants. This captured

carbon dioxide can then be used for enhanced oil recovery or enhanced coal

bed methane permanent geologic storage. One advantage of UCG is that the

depleted coal seams used for UCG may also potentially be used as locations

for permanent sequestration or storage of any carbon dioxide produced and

captured from the process.

UCg’s eConomiC benefits

There are a number of significant economic benefits associated with UCG that

include:

ÂÂ No need for coal mining

ÂÂ No need for coal handling

ÂÂ No need for coal transportation

ÂÂ No need to prepare the coal to be fed into a reactor

ÂÂ No need for ash or slag disposal

ÂÂ Carbon dioxide can be captured and used for Enhanced Oil Recovery

or Enhanced Methane Recovery or other permanent geologic storage

w w w . g a s i f i c a t i o n . o r g 9

UCg’s environmental benefits

ÂÂ Minimal land use

ÂÂ Underground saline water may be used to reduce the use of drinkable

groundwater or freshwater

ÂÂ Fewer environmental impacts traditionally associated with coal

mining and handling

ÂÂ Coal seams being gasified are located well below fresh drinking water

supplies (the deeper the UCG, the greater the degree of isolation from

fresh water aquifers)

ÂÂ Significantly reduced criteria air pollutants compared to conventional

coal combustion plants

•Â All or a substantial portion of the sulfur, mercury, arsenic, tar, ash

and particulates found in coal remain underground

•Â Any sulfur or metals that reach the surface do so in a chemically

reduced state, making them easier to remove

ÂÂ No landfill disposal is required for ash or slag

UCg market

UCG was first developed in Europe in the late 1800s, but not commercially

developed until the 1920s and utilized primarily in the former Soviet Union.

Today, with the advancement of new drilling technologies from the oil and

gas industry, the UCG market is global. There are currently commercial scale

projects in Europe, Australia, and South Africa, plus others at the pre-commer-

cial pilot feasibility stage in the USA, New Zealand, Russia, Pakistan, United

Kingdom, Eastern Europe, Chile, Turkey and China. China has the most

extensive modern UCG development program to date. (see map next page)

GasIfIcatIon Converting Unmineable Coal to energy10

 

Ru

ssia

: 2

01

1 P

roje

ct

sta

rte

d in

Kem

ero

vo,

Sib

eri

a. L

on

g h

isto

ry o

f U

CG

act

ivity

Bel

giu

m:

EU

tri

al a

t T

hu

lin in

1

98

7. N

o f

urt

he

r U

CG

act

ivity

. R

ese

arch

inte

rest

Ser

bia

: L

oo

kin

g to

sta

rt r

ese

arc

h

soon

. P

ote

ntia

l co

al s

ou

rce

s in

vest

iga

ted

Po

lan

d:

EU

HU

GE

p

roje

ct,

incr

ea

sin

g in

tere

st a

nd

re

sea

rch

, su

itab

le

com

me

rcia

l site

s id

en

tifie

d.

Ch

ina:

Lo

ng

his

tory

of

pilo

ts, t

rain

ing

of m

any

. N

ew

pro

ject

s p

lan

ne

d a

t Y

i He

co

al f

ield

an

d

Ula

nch

ap

Inn

er

Mo

ng

olia

. O

the

r p

roje

cts

in r

eg

ion

at

pla

nn

ing

sta

ge

.

Slo

van

ia:

UC

G u

nde

r re

vie

w f

or

suita

bili

ty.

Kaz

akh

stan

:

Site

s id

en

tifie

d b

ut

com

plic

ate

d a

pp

rova

l p

roce

ss h

amp

ers

pro

gre

ss

Bu

lgar

ia:

Tw

o p

roje

cts

un

der

re

vie

w.

Ext

ens

ive

re

sea

rch

so

me

with

EU

b

ack

ing

.

Tu

rkey

: U

CG

pro

ject

at

pla

nn

ing

sta

ge

, se

vera

l su

itab

le s

ites

ide

ntif

ied

.

Can

ada:

Ad

van

ced

re

sea

rch

in

Alb

ert

a a

nd

No

via

Sco

tia.

Sw

an

n H

ills

pilo

t at

se

con

d

sta

ge

. M

an

y su

itab

le c

oa

l se

am

s id

en

tifie

d.

US

A:

Pro

ject

at

Co

ok

Inle

t,

pla

ns

to g

o co

mm

erc

ial i

n 2

015

Lo

ng

his

tory

of r

ese

arc

h/

pilo

t st

ud

ies

& m

ajo

r tr

ials

in 1

95

0s

an

d 1

98

0s.

Su

bst

an

tial i

nte

rest

a

nd

ne

w p

roje

cts

pla

nn

ed

for

Wyo

min

g,

Mo

nta

na

, N

ort

h

Da

kota

, C

olo

rad

o,

Ala

ska

.

Bra

zil:

De

mo

nst

ratio

n

pro

ject

pla

nn

ed,

te

chn

ica

l re

sea

rch

co

ntin

ue

s,

seve

ral s

uita

ble

site

s kn

own.

C

hile

: Jo

int

UC

G

pro

ject

to s

tart

20

12.

Co

lom

bia

: U

CG

pro

ject

p

lan

ne

d, s

eve

ral s

uita

ble

si

tes

ide

ntifi

ed

, co

ntin

uin

g re

sea

rch

.

So

uth

Afr

ica:

UC

G

pro

ject

at

Ma

jub

a is

th

e m

ost

ad

vanc

ed

. E

xte

nsi

ve h

isto

ry o

f re

sea

rch

an

d h

ug

e

am

ou

nt

of in

tere

st

an

d e

xpe

rie

nce

.

Bo

tsw

ana:

UC

G s

een

as

key

to m

axi

mis

ing

its

21

0

bill

ion

to

ns o

f co

al.

No

p

roje

cts

yet

an

no

unce

d.

Se

vera

l la

rge

are

as

suita

ble

.

Ind

on

esia

: S

eve

ral M

OU

s si

gn

ed

aft

er a

pp

rop

ria

te s

ite

sele

ctio

n.

La

ck o

f lic

ensi

ng

st

ruct

ure

.

Ind

ia:

Go

vern

me

nt

loo

kin

g a

t U

CG

to

util

ise

the

60

%

of

its 2

70

bill

ion

ton

ne

s o

f u

nm

ina

ble

co

al.

Ma

ny

suita

ble

New

Zea

lan

d:

Pilo

t p

roje

ct c

ont

inu

es

at

Hu

ntly

We

st,

no

w in

its

thir

d y

ea

r. O

ther

o

pe

rato

rs s

ee

kin

g

po

ten

tial s

ites.

Au

stra

lia:

UC

G

pro

ject

s in

Qu

ee

nsl

an

d,

at

Ch

inch

illa

&

Blo

od

wo

od

Cre

ek.

V

icto

ria

an

d S

ou

th

Au

stra

lia a

lso

d

eve

lopi

ng

pro

ject

s .

Ban

gla

des

h:

UC

G a

ctiv

ity

pla

nn

ed

bu

t no

lic

en

ces

yet

aw

ard

ed

.

Vie

tnam

: T

wo

pro

ject

s in

Re

d R

ive

r D

elta

re

gio

n a

t pla

nn

ing

sta

ge

. H

isto

ry o

f re

sea

rch

.

Uzb

ekis

tan

: W

orl

d’s

o

lde

st U

CG

(5

0+ y

ears

) a

t A

ngr

en

.

EU  trial  at  Tremedal  

finished  1998.  Further  

research  continues  for  

I  licence  awarded  in  Dublin  

18  UCG  licences  awarded,  all  

coastal  regions,  all  off  shore.  

Licensing  and  regulations  

Irel

and

: O

ne

lic

en

ce D

ub

lin B

ay.

Sp

ain

: E

U t

ria

l at

Tre

med

al

finis

hed

199

8.

Fu

rthe

r re

sea

rch

co

ntin

ue

s fo

r su

itab

le s

ites.

UK

: 1

8 U

CG

lice

nce

s a

ll o

ff s

ho

re.

Lic

ensi

ng

a

nd

re

gu

latio

ns.

a

dva

nce

d.

Cze

ch R

epu

blic

: U

CG

un

der

re

vie

w

as

suita

ble

site

s id

en

tifie

d.

Hu

ng

ary:

Th

e M

ecs

ek

Hill

s p

roje

ct c

on

tinu

es.

F

urt

her

site

s a

nd

exp

an

sio

n o

f a

ctiv

ity

pla

nn

ed

in 2

01

2.

Ro

man

ia:

Te

chn

olo

gy

be

ing

re

view

ed.

Jap

an:

Incr

ease

d

rese

arc

h a

nd

site

id

en

tific

atio

n.

Pak

ista

n:

Th

ar

Sin

dh

Pro

vin

ce,

UC

G p

ilot

pro

ject

e

xpe

cted

to

p

rod

uce

10

0M

W

of

ele

ctri

city

by

the

en

d o

f 2

01

3.

Slo

vak

Rep

ub

lic:

re

sea

rch

, su

itab

le

site

s, M

oU

s si

gn

ed

(Cou

rtes

y of

th

e U

nd

ergr

oun

d C

oal G

asifi

cat

ion

Ass

ocia

tion

)

w w w . g a s i f i c a t i o n . o r g 11

UCG does face a number of issues, including:

ÂÂ A number of coal seams may not be suitable for UCG because of

geologic or hydrologic conditions, particularly at relatively shallow

depths.

ÂÂ Project economics may be uncertain until a number of UCG projects

are in commercial operation.

ÂÂ Site selection needs to be done properly to avoid any potential for

groundwater contamination and surface subsidence for shallow UCG

projects.

These issues can be mitigated through careful project design, site selection,

and monitoring and these are not usually issues for deep UCG projects. UCG

has enormous potential to allow the world to take advantage of coal resources

that would otherwise be too expensive or difficult to reach. UCG can help

address the global energy challenge.

For more information about gasification see www.gasification.org.

For additional information on UCG, see www.ucgassocation.org.

GasIfIcatIon Converting Unmineable Coal to energy12

Gasificationunderground coalgasification:converting unmineablecoal to energy

w w w . g a s i f i c a t i o n . o r gw w w . g a s i f i c a t i o n . o r g

4301 North Fairfax Drive, Suite 300

Arlington, VA 22203

703.276.0110

4301 North Fairfax Drive, Suite 300

Arlington, VA 22203

703.276.0110

©Copyright by the GTC 2012.