Case Study : Underground Coal Gasification (UCG) Majuba Update Mark van der Riet Corporate Consultant Eskom Holdings Ltd South Africa
Introduction Eskom presently generates 88% of its electricity from coal. This predominance will decrease, with the introduction of alternative energy carriers. Sustainable options are required to mitigate the continued usage of coal. Eskom has run a comprehensive Clean Coal Technology research and development program for several decades, to explore, identify and demonstrate solutions.
Coal Roadmapping Technology demonstrations are essential Technology transfer is required No single technical solution fits all needs South Africa needs to reduce dependency on coal for primary energy Eskom s own Clean Coal Roadmap is closely aligned with international best practice South Africa is also embarking on a national coal roadmap (SANERI/FFF)
IEA CCC Clean Coal Roadmap for India and RSA to 2030 Source : IEA-CCC 152, C Henderson, SJ Mills, Sept 2009 IEA-CCC suggested targets : 90% CO 2 removal, 45% efficiency, near-zero NO x, SO x, particulates
Eskom s Clean Coal Programme Improved efficiencies on existing Sub Critical Pulverised Coal Supercritical Pulverised Coal Medupi & Kusile Ultra-Supercritical Pulverised Coal - scanning Fluidised Bed Combustion - pilot Conventional and advanced emissions control - FGD Surface gasifier - IGCC Carbon Capture and Storage Underground coal gasification IGCC IGCC = Integrated Gasification Combined Cycle
Surface Plant (incl. IGCC) commercially proven with other gases UCG-IGCC Basic Principles Gas out UCG is a process where air is injected into the cavity, water enters from surrounding strata, and partial combustion and gasification take place at the coal seam face after ignition. The resulting high-pressure gas stream is returned to the surface, where the gas is dried and then combusted in a high-efficiency power station to generate electricity. Air in Graphic Reference : Science & Technology Review, Lawrence Livermore National Lab, USA, April 2007 UCG commercially proven in Former Soviet Union (FSU) Eskom is demonstrating in RSA
UCG Current World Trends FSU Uzbekistan : Angren commercial plant refurbishing New Zealand : Solid Energy NZ starting site characterisation R&D. Eventual UCG-CCGT USA : Laurus Energy investigating a 2.3 bt resource in Wyoming CIRI developing a 100MW UCG-CCGT in Alaska LLNL investigating the potential of UCG + H 2 production + CO 2 sequestration Australia : Linc Energy Pilot plant recommissioned. Relocating to S. Australia Carbon Energy 100d pilot trial successful. 20MWe pilot with CCS announced Cougar Energy site characterisation successful, and 10,000 Nm3/h pilot under construction
UCG Current World Trends cont. UK : Being investigated for coal under the Firth of Forth Clean Coal investigating 5 North Sea coal resource sites VP Power drilling in the Kish Basin, Dublin Bay India : GAIL approved a feasibility study Abhijeet Group investigating UCG-CCGT Pakistan : approved a feasibility study for UCG-CCGT Vietnam : study underway with JV : Marubeni, Linc Energy and Vinacomin China : Historically 16 sites, typically small scale New initiatives underway for SNG and methanol, following a successful 1 month trial Southern Africa : Eskom & Sasol, with several other entrants emerging
Eskom Strategic Drivers for UCG-IGCC 1.Security of supply 2.Clean energy 3.Flexibility 4.Utilize Unminable Coal 5.Lower cost option Baseload option Lower C0 2 Emissions (25 % lower than super critical PF coal) Modularity, lead time Potentially 350GWe Better utilisation than conventional mining Competitive R/MWh
LCA Comparative Emissions CO2 kg/mwh net 1000 900 800 700 600 500 400 300 200 100 0 Conv PF Super PF Conv IGCC UCG-IGCC Nat Gas CC (Without FGD) (With S removal to suit GT) CO2 NOx SOx Particulates 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 NOx/SOx/Particulates kg/mwh net Data Reference : Australian ACARP Life Cycle Assessment (LCA) study, Case Study B20, June 2002 The only cleaner coal-based technology is the developing ultra-supercritical PF
Environmental Precautions Water : Surrounding aquifers monitored monthly concentric perimeters. No UCG contamination evident Air : Baseline air quality tests. Continuous ambient emission monitoring Land : Baseline flora & fauna survey & soil tests Comprehensive EMP & regular audits Majuba site shows natural vegetation re-establishes rapidly after drilling disruption Subsidence is being monitored at Majuba using devices for conventional underground monitoring. The potential strata collapse has also been modelled. Minimal subsidence observed Outer Water Sampling Zone Inner Water Sampling Zone Production Area UCG Water Monitoring Network Sungazer Lizard Preservation Ambient Monitoring Station
UCG Aquifer Philosophy The UCG cavity pressure always maintained < hydrostatic pressure flow is always inwards Production wells steel-lined & cemented down to coal seam protects the surrounding aquifers Ash left underground UCG temperature = + 1200 o C leaching tests underway Majuba seam capped by 180m of dolorite sills & segmented by dykes Lateral water flow is nil/low Australian pilot (1999-2003) had 3 rd party audit, approved by Austr. EPA Seam Diagram not in proportion In Majuba, coal seam is 3-5m thick, and 280m underground
Resource Utilisation Efficiency 20% of coal resource utilised Thermal Efficiency Beneficiation Mining 20 36% of coal resource utilised 50 0% Super-critical Power Station with Longwall Mine & Beneficiation 100% 66 Thermal Efficiency Chemical Efficiency Mining Efficiency 36 0% UCG-IGCC 100% 71 95 Thermal Efficiency 0.5% of resource utilised 1% Extraction Efficiency 50 0% CCGT with CBM 100%
UCG Coal Value Chain Reduction = Less Cost The shorter value chain translates to lower cost, confirmed with Eskom concept-level and international costing
Eskom s UCG Progress Scanning study - April 2001, Eskom noted UCG technology potential. Scoping study - Nov 2002, highlighted potential at Majuba colliery Pre-feasibility study - Dec 2003, confirmed Majuba potential Detailed site characterisation study - July 2005, confirmed the potential 20 th January 2007 Eskom commissioned a 3-5000 Nm 3 /h pilot plant on Majuba coalfield 31 st May 2007 first electricity generated from UCG gas at Majuba 7km x 600mm NB steel pipeline built to link UCG with Majuba U4 Mar 2010 cofiring UCG gas into Majuba Design underway for a 100-140 MW OCGT demo plant Engineering and EIA will commence thereafter for a new 2100 MW power station, based on UCG and Combined Cycle Gas Turbine-Steam Turbine Gas Pipeline Horseshoe construction 108 MWe Alstom GT11N2
Eskom s UCG Progress UCG Site
Eskom s UCG Progress Average Gas Quality (ex. Pilot plant, May 2009) : Min (% vol) Max Hydrogen H2 14.0 18.0 Oxygen O2 0.2 0.2 Water Vapour H2O 5.0 5.0 Atm. Nitrogen N2 44.3 52.0 Carbon Monoxide CO 7.0 11.0 Carbon Dioxide CO2 16.5 18.5 Methane CH4 2.8 4.5
Eskom UCG Indicative Development Done 2002 Scoping Study 2003 Pre-feasibility Study 2005 Site Characterisation 20th January 2007 Commissioned 5000 Nm3/h pilot plant on Majuba coalfield Apr 2009 Mar 2011 Jan 2014 Jun 2014 Mar 2018 Sep 2020 6MW Cofire DRA = Decision Release Approval = Design, Engineering & Costing To do 40MW Demonstration Plant Ph2 DRA ERA COD ERA = Execution Release Approval = Procure, Construct and Commission 2100MW Commercial Plant DRA ERA U1 COD U2 COD U3 COD U4 COD U5 COD U6 COD
UCG CCS Potential + UCG creates a cavity that could potentially sequester CO 2 + The remnant coal, char and ash would have a higher surface area for CO 2 sorption + Infrastructure and wells already in place Requires depth > 800m Interaction of CO 2 with remnant coal, char and ash must be proven There is much research to be done! UCG leaves behind a heat effect cavity, with unknown behaviour
UCG Conclusions UCG is a promising clean coal option which allows the effective extraction and use of RSA coal resources UCG has a role to play in the reduction of greenhouse gases and has possible potential for carbon capture and storage UCG is gaining momentum worldwide The Eskom UCG pilot has been operating reliably for 33+ months No environmental impacts have been noted to date Based on work to date, UCG appears to be a very promising, stable and viable primary energy (baseload) option with potential on multiple sites Eskom is embarking on commercialisation of the technology, with the first milestone being successful operation of a 40 MW demonstration plant
Thank You Majuba UCG E Class GT Eskom s Ankerlig OCGT