UNDERGROUND COAL GASIFICATION

MOHAMMED KABIRUDDIN University of Petroleum & Energy Studies

UCG PRINCIPLES & ESSENTIALS

Underground Coal Gasification (UCG) converts coal into a gaseous form (syngas) through the same chemical reactions that occur in surface gasifiers

The economics of UCG look promising as capital expenses should be considerably less than surface gasification

Essentials:

Site location -biggest issue

Coal characteristics–operations

Technologies-connecting wells

INTRODUCTION

The technology was first widely used in the USA during the later 1800s.

India in Calcutta (Kolkata) and Bombay (Mumbai) in early

1900.

Lamplighters in many cities used to light streetlights by “town gas”, the product of early and relatively crude forms of coal gasification.

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INTRODUCTION

1912 Co. Durham UK First Test

1930’s Intensive Soviet Development

1950/60’s Early European Trials – inc.

1955 Newman Spinney – Ntl Coal Board

1970/80’s US Programme - 6 Major Trials

1980’s European Studies and First Trial

Early 1990’s First US commercial designs

Mid to late 1990’s El Tremedal, Spain

European Trial

DTI UCG Initiative (1999-2005)

Australian Pilot

Firth of Forth Feasibility Study

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WHY UCG NOW?

Security of supply

– indigenous coal

– Un - mineable coal

• Carbon Capture & Storage

– Pre-combustion processing

– Local storage options

Advances in UCG Technology

– Drilling, completion, control

Production Costs for clean syngas

– Competitive against natural gas

(EU, US)

Flexibility of Syngas for poly-generation

– Existing or new power stations, GTL,

SNG, H2 and other chemicals

FACTORS AFFECTING UCG DESIGNS

CRITERIA FOR UCG

UCG requires special properties of coal seam:

Coal seam lays underground between 100 and 600 metres (preferably more than 300 metres)

Thickness is more than 5 metres

Ash content is less than 60%

Minimal discontinuities in seam

No good water aquifers

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US SITE SELECTION CRITERIA

HOW DOES UCG WORK?

Step 1: Find the coal

Step 2: Drill the boreholes

Step 3: Link the boreholes

Step 4: Ignite the coal

Step 5: Inject the O2 and steam

Step 6: Extract the syngas

WORLD STATUS

WORLD SITES

UCG SITES

UCG SITES

US

31 tests involving DOE, Gulf, Texas A&M, GRI,

ARCO

Rocky Mountain Trial, 14,000 tons of coal 93

days

Oxygen Fired CV 9-11 MJ/m3

Commercial scheme for ammonia production

developed – not constructed

UCG HARNESS

Worldwide UCG operations experience with respect to coal seam

depth and thickness(2004).

ANGREN UCG POWER STATION, UZBEKISTAN

UCG Co-fired

Plant operating for 30 years

UCG used in dedicated 100MW steam turbine

Linc Energy have bought a majority stake in the plant

UCG IN SOUTH AFRICA Eskom UCG Trial at

Majuba Coal field, 3.5m thick at 300m depth (Jan 2007).

Air-blown co-fired 350MWe IGCC unit planned

Sasol initiated a new

UCG trial project at Secunda as a potential feedstock for CTL Plant.

CHINA

China has over 50 large coal gasification facilities nationwide.

China has executed at least 16 pilots since

1991,

And has invested in extensive research

programs at China University of Mining Technology in Beijing.

INDIA & WORLD

There is over 5 million PJ of resource for UCG gas in the United States, 2.2 million PJ of UCG gas in China, and 1.9 million PJ of UCG gas available in India.

The Lawrence Livermore National Laboratory (USA)

has estimated that recoverable reserves could be increased by at least 300% to 400% and that 1.6 trillion tons of un-mineable coal in the USA may be recoverable with UCG.

AUSTRALIA

The World Energy Council’s 2007 Survey on

Energy

Resources estimates that 45% of Australia’s

proven in place reserves, or 44 billion tonnes, is

available for extraction by UCG.

Applying this same proportion to Queensland’s

measured plus inferred sources of thermal coal,

suggests that there are possibly 16 billion tonnes

that may be available for UCG in Queensland.

AUSTRALIAN DEVELOPMENTS

Linc Energy,

– Successful share offering in 2006, now

worth $1.5B

– Development of a GTL plant is underway

– New projects starting in S Australia, Vietnam & USA (Dec 08)

Carbon Energy (2006)

– Joint venture with CSIRO gas now started

(Oct 2007)

Cougar Energy (2007)

– Site for 400MW CCGT Plant in S Australia

– Using Ergo energy.

THE CHINCHILLA UCG FACILITY

THE CHINCHILLA UCG FACILITY

AUSTRALIA

AUSTRALIA

OTHER FEASIBLE AREAS

Indonesia

Vietnam

Pakistan (Thar Coalfield Power & GTL)

Japan

Chinese Mining Companies, e.g. Xinwen, Ezhuang

Mongolia

New Zealand (Solid Energy)

INDIA

GAIL also plans to set up a coal gasification project in eastern India (Durgapur, Haldia, and Talcher) to produce 3.4 MSCMD of syngas.

In September 2005, GAIL has signed an memorandum with the Shaanxi Huashan Chemical Industry group of China to undertake coal gasification activities in the Shaanxi province.

INDIA

GAIL (India) Ltd has signed a memorandum of

cooperation with Ergo Exergy Technologies Inc., Canada, to explore UCG projects in India.

Ergo Exergy will help GAIL to

i) determine the technical and economic viability of each project ii) bring in efficient drilling techniques and

production of UCG gas in commercial quantity with quality.

NTPC VIEW

UCG IN INDIA

The Neyveli Lignite Corporation Ltd. (NLC), which has

got Government approval for taking-up a UCG Project

in lignite deposits of Rajasthan, has not been able to

get a suitable technical partner, so far.

• The Reliance Industries Limited (RIL) has been

exploring possibilities for taking up a UCG project in

India.

UCG IN INDIA

ONGC, while drilling in search of hydrocarbons, discovered large reserves of coal at depths more than 600m.

These are spread in Gujarat and West Bengal and

have been estimated to contain more than 350bt of coal deposit.

In Gujarat alone, these coal reserves have been

estimated to be around 63 bt in Mehsana-Ahmedabad block and 60 bt in Patan-Tharad block.

UCG IN INDIA

The energy estimated for Mehsana - Ahmedabad block alone, is equivalent to about 15,000 bcm of natural gas.

The ONGC is conducting a pilot test in Mehsana area

at an estimated cost of Rs 9.60 crores.

• An Information Well – UCG-1 – was drilled in 1986 to

a depth of 1005m at the selected site.

ESTIMATED RESERVES FROM WEC 2008

POSITIVE FACTORS

1. UCG is the only feasible technology, which enables exploitation of deep (> 700m) coal reserves, which are not amenable to known conventional mining methods.

2. UCG offers an environmentally clean way to harness energy from coal.

3. UCG brings no solid waste to the surface.

POSITIVE FACTORS

4. Even at shallower depths (< 500m), UCG can be more

economical than conventional mining.

5. UCG reduces capital investment, operating costs, and

the output gases cost by 25 to 50% as compared to

surface gasification.

6. Possibilities of transport of medium calorific value gas

over a distance of 100 km. exist.

POSITIVE FACTORS

7. Possibilities of using CO2 from the gas for enhanced

oil recovery exist.

8. Basic UCG technology is known.

9. Conditions in India are far more compelling for

adopting UCG than most locations in the world.

ANNUAL CASH FLOW FOR 1,000MW UCG GAS PLANT WITH CO2

CAPTURE (CO2 $20/TONNE)

Internal rate of return 25-30%, (with storage)

CO2credit 32% of

revenue Syngas Utilisation

Options

480 Mwe electrical

power 10,00 bb/d diesel

savings

ADVANTAGES:

Much higher coal extraction – up to 95%

No pillars

Multiple seams

Thick and thin seams

More economic – less capital expenditure

Economic on a smaller scale

Potential to be cleaner technology – smaller

environmental footprint

Little or no rehabilitation required

No fine coal

No Ash

Safer

DISADVANTAGES

Potential for contamination

Controllability of the reaction

CONCLUSION

Viable alternative mining method for otherwise unminable coal

Potential smaller environmental footprint than

conventional process

Better utilisation of coal reserves