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The Eskom UCG Experience
Presented at :
6th Annual CTL & Coal Gasification 2011 Conference
28th Feb to 1st Mar 2011, Brisbane, Australia
Chris GrossDr Mark Van der Riet
Corporate Services DivisionEskom Holdings LtdSouth Africa
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Content
1. Context
2. Eskom’s UCG Strategic Drivers
3. Majuba Coalfield, South Africa
4. Eskom UCG Program
5. Environmental Impacts
6. Risk Status
7. UCG Performance
8. Conclusions
Context
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Context
• Coal is one of South Africa’s largest primary energy resources.
• Eskom presently generates 88% of its electricity from coal.
• This predominance will decrease, with the introduction of alternative energy carriers to mitigate the impact of the continued usage of coal.
• Coal will however remain a predominant, albeit reducing primary energy carrier for the foreseeable future in RSA.
• Eskom has therefore run a comprehensive Clean Coal Technology research and development program for several decades, to explore, identify and demonstrate solutions for continued coal usage.
• Underground Coal Gasification (UCG) is one of the advanced clean coal technology options being demonstrated by Eskom
2012/02/28 52012/02/28 Eskom Holdings Limited Reg No 2002/015527/06 5
Context - Eskom Plant mix
TOTAL 27 stations 44 175MW
Type Number Nominal capacity
Wind energy 1 station 3MW
Coal-fired
Gas/liquid fuel
turbine
Hydroelectric
Pumped storage
Nuclear
13 stations
4 stations
6 stations
2 stations
1 station
37 755MW
2 426MW
661MW
1 400MW
1 930MW
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Context - Eskom Primary Energy
2009/10 : 246,566 GWh Net
Eskom’s UCGStrategic Drivers
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Eskom Strategic Direction
• Becoming a high performing organisation
• Leading and partnering to keep the lights on
• Reducing our carbon footprint and pursuing low carbon growth opportunities
• Securing our future resource requirements, mandate and the required enabling environment
• Ensuring our financial sustainability
• Setting up for success
Purpose : To provide sustainable electricity solutions to grow the economy and improve the quality of life of
people in South Africa and in the region.
Vision : One of the World’s Top 5 Power Companies
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Eskom’s UCG Strategic Drivers
1. Security of supply
2. Clean energy
3. Flexibility
4. Utilize Unminable Coal
5. Lower cost option
Lower C02
Emissions
Modularity, lead time
Competitive R/MWh
Potentially 350GWe
Baseload option
Better utilisation than conventional
mining
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Potential RSA Applications
27 Potential Sites
• RSA coal resources quoted at 194.4 Bt (1998, DME Bulletin 113)
• Eskom geological records for coal offers received but considered unminable coal = 45 Bt= potentially 350 GW
• The remaining coal resources :194.4 Bt – mined –minable = 100 Bt ?
Source : S Walker, Major Coalfields of the World, IEA CCC/32, June 2000
Majuba Coalfield,South Africa
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Majuba Colliery at closure : 1993
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Why choose Majuba for UCG ?
• Majuba coal field was found to be unminable by conventional means due to dolorite intrusions, heat affected coal and seam displacements
• Coal seam 280-300 metres deep
• Eskom owned the Mineral Rights
• Land used for cattle farming, and Eskom owns the farm land
• Study showed that gas could be co-fired with coal at Majuba power station giving a direct use for the gas.
• Study also showed that gas could be used as a fuel for a modern, high efficiency IGCC power station.
Dolorite intrusions
Majuba 4100MW power station
Eskom UCG Program
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Majuba UCG
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Eskom UCG Development Plan
2002
Scoping Study
2003
Pre-feasibility
Study
2005
Site
Characterisation
20th January 2007
Commissioned
5000 Nm3/h pilot plant
on Majuba coalfield
Done
To do
Current
28th October 2010
Commissioned
15000 Nm3/h co-firing into
Majuba power station
U2Comm
U3Comm
U4Comm
U5Comm
U6Comm
Commission
U1Comm
Apr 2009 Dec 2011 Sep 2015Mar 2015 Mar 2020 Sep 2022
ConstructionDesign
ConstructionDesign
Demonstration Plant
2100MW 1st Proof-of-Concept Plant
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UCG Project Progress
• UCG technology scan - April 2001
• Scoping study highlighted potential at Majuba colliery - Nov 2002
• Pre-feasibility study confirmed Majuba potential - Dec 2003
• Site characterisation study confirmed the potential - July 2005
• Commissioned a 3-5000 Nm3/h pilot plant - 20 Jan 2007
• First electricity generated from UCG gas at Majuba - 31 May 2007
Eskom flarestack – 20 Jan 2007
100 kW converted diesel gensetEskom has licenced UCG technology fromErgo Exergy Technologies Inc. (Canada)
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UCG Project Progress
Co-firing :
• Commissioned new co-firing gas treatment plant – Jun 2010
• Commissioned new 7km x 600mm NB pipeline to Majuba power station – Jun 2010
• Gas co-fired into Majuba U4 - 28 Oct 2010
UCG-OCGT demo plant :
• Design study underway for a demonstration plant comprising 250,000 Nm3/h gas production and a 100 – 140 MW gas turbine plant
15,000 Nm3/h gas
treatment plant
Gas Pipeline to Majuba
power station
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Eskom 100 – 140 MWUCG Demo Plant Layout
Water Wash Condensate
Removal
GasCompressor
Steam StrippingAmmonia Removal
Phenol Recovery
SulphurRemoval
Condensate
Gas H2S/NH3
Flue Gas
SCR NOX Abatement
Gas Turbine/
Generator
Raw Water
Phenols
Particulates and Oils
Sulphur
Pipeline - TXField PipingWells & Drilling
UCGTechnology
GeoSciences
Compressors
Air
Balanceof Plant
Electricity
Electricity
Water
Water
Emergency Flarestack
MajubaCo-fire
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UCG Phased Development
This figure explains UCG modularity, and the technology roll-out
Pilot Demo 1st Proof-of-Concept Plant
5-15,000 Nm3/h
250,000 Nm3/h
3,800,000 Nm3/h
100-140 MW OCGT Approx 250-350 MW CCGT per unit X multiple units = approx. 2100 MW
+ +
2012/02/28 2145,000 ha ??
1000 ha ?
Eskom UCG Expansion
5 ha ?
Gas Production Rate
& Investment :
Coal Resource Requirement :
The Demonstration and 1st Proof-of-Concept Plant will have a design life of 35 years. The Mineral Rights of both are required before
investing in the Demonstration Plant
The Demonstration and 1st Proof-of-Concept plant are extensions of the research initiated by
the Pilot Plant
Demo(250,000 Nm3/h)
Pilot(15,000 Nm3/h)
1st Proof-of-Concept
Plant(3,800,000 Nm3/h)
Environmental Impacts
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Environmental Impacts : Water
• Baseline water sampling performed of aquifers, including coal seam
• Water from surrounding aquifers monitored from shallow and deep boreholes, in concentric rings surrounding the process
• UCG is monitored extensively with piezometers (for measuring pressure & temperature)
• No UCG contamination evident
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Environmental Impacts : Air
• Baseline air quality tests done prior to UCG
• Permanent meteorological station on the UCG site monitors wind speed/direction, ambient temperature, barometric pressure
• Eskom’s continuous ambient emission monitoring stations monitor meteorological parameters, SO2, NO2, O3, PM10 etc.
• Additional comprehensive audit completed for : meteorological parameters, CO, CO2, SO2, H2S, NO, NO2, BTX, NH3, PM10 , PM2.5etc.
• Permanent monitoring site to be established
• UCG-IGCC promises a reduction in greenhouse gas emissions, compared to conventional power stations
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Environmental Impacts : Land
• Comprehensive plan in place with management and rehabilitation procedures. Regular audits done.
• Baseline flora & fauna survey and soil tests done prior to UCG starting up
• Majuba site shows natural vegetation re-establishes rapidly after drilling disruption
• Surface impact minimal post-gasification
• Subsidence is being monitored at Majuba using devices for conventional underground monitoring. The potential strata collapse has also been modelled.
• No subsidence observed yet.
Risk Status
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Risk Status – Feb 2011
Risk Rank Mitigation
Environmental HighMonitoring, design,engagement
Permitting &Licences
High Engagement
Cost Creep &Financial
Medium Project management
Resources &Skills
Medium Recruitment & training
ScheduleCreep
Medium Project management
UCG Performance
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Coal Seams
Majuba Seam Detail
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Eskom’s UCG Production Data
Operating Data - 20 Jan 2007 to 20 Jan 2011 :
• Total coal consumed/gasified = 34 663 tons
• Total gas produced = 131 719 400 m3
• A representative CV of the gas was 4.2 MJ/Nm3
• The average efficiency is 72 % (coal @ 20 GJ/ton)
• Current gas production rate = 11500 m3/hr (6768 cfm)
• Average well exit temperature = 168 ºC (344 ºF)
• Maximum well exit temp (normally temporary) = 430 ºC (806ºF)
• Average water consumption = 0.58 litre per kg of coal.
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UCG Gas Composition
• Gas composition varies with the lifetime of the production well, and between production wells.
• Gas composition depends on the operating parameters such as P and flow, and also on the design of the underground gasifier.
• Incorrect gasifier design or operation can result in the gasifier running in combustion mode.
• The final volume of gas is a blended average from several production wells.
UCG Gas - major components only
Composition (% by vol)
Hydrogen H2 15 - 19
Oxygen O2 0.2
Water Vapour H2O 5
Atm. Nitrogen N2 47 - 55
Carbon Monoxide CO 7 - 12
Carbon Dioxide CO2 17 - 19
Methane CH4 3 - 5
Calorific Value LHV MJ/Nm3 3.5 - 5.1
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Lessons Learnt
• UCG is not trivial. It requires a methodical implementation strategy, and extensive investment in skills to plan & execute, and capital.
• Eskom therefore licensed the UCG technology from Ergo Exergy Technologies Inc. (Canada)
• Base-level geological and hydrogeological data is essential, so a comprehensive prospecting program is required.
• Have several alternative sites to select from.
• Mining legislation in South Africa did not consider UCG when it was drafted, specifically whether it is legislated as gas extraction or coal mining.
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Lessons Learnt
• The quality of in-seam water is important, as this water comes to surface with the UCG gas, eg. the presence of chlorides can cause corrosion.
• The merging of mining, petrochemical and electricity industries requires a combination of laws (eg. MHSA and OHSA)
• Eskom adopted a phased investment approach, which has :
• Advantages : reduced investment risk, simultaneous learning process during development (both staff and stakeholders), technology optimisation
• Disadvantages : delayed implementation & delayed ROI
Conclusions
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Conclusions
• UCG is a promising clean coal option which allows the effective extraction and use of previously unminable RSA coal resources
• UCG has a role to play in the reduction of greenhouse gases and has possible potential for carbon capture and storage
• The Eskom UCG pilot has been operating reliably since Jan 2007 – 49 months and counting !!
• No environmental concerns have been noted to date
• Eskom has embarked on the phased research, development and demonstration of the technology, culminating in the 1st Proof-of-Concept Plant comprising approximately 2100 MW
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THANK YOU
Eskom UCG website URL :
http://www.eskom.co.za/c/14/underground-coal-gasification/