How Green Can Brown Coal Be? Thursday 19th April, 2012, 1.00pm with lunch in the Legislative Council Committee Room

Transcription

1 The Presiding Officers invite Parliamentarians and Staff to a Science Briefing on How Green Can Brown Coal Be? Thursday 19th April, 2012, 1.00pm with lunch in the Legislative Council Committee Room Brown coal has for many years provided a source of cheap power to Victoria s manufacturing industries. But this advantage is now threatened by unacceptably high emissions from the combustion of brown coal in conventional coal fired power stations. With the world s second largest brown coal resource and the potential to store many decades of CO2 emissions in the nearby Gippsland Basin, Victoria is in an ideal position to meet the challenge of lowering emissions while capitalizing in a responsible way on the world demand for coal. To secure this future, organisations such as Brown Coal Innovation Australia are investing heavily in the R&D and skills requirements for future, low emissions coal projects. BCIA is taking action on three fronts research to improve efficiency of energy generation, research to accelerate adoption of carbon capture technologies, and investment into skills to ensure that we can meet the workforce demands of future technology deployments. BCIA also invests in low emissions projects looking at alternate high value uses of coal. Monash University is Victoria s leading centre for brown coal research and development. The speakers will outline some of the challenges and potential solutions to a low emissions future for brown coal in research and development being conducted worldwide, and show why Victorian brown coal projects are attracting significant research and industry interest from regions such as Japan, China and the EU. The speakers will be: Assoc. Professor Sankar Bhattacharya Department of Chemical Engineering Monash University Dr Phil Gurney Chief Executive Officer Brown Coal Innovation Australia The meeting will be chaired by: Dr Glen Kile FTSE The Parliamentary science briefings are organised by the Academy of Technological Sciences and Engineering (ATSE) under the auspices of the Presiding Officers and with financial support from the Department of Business and Innovation Notes on the talks are available on the Parliamentary Intranet. For information or comments on future briefings contact Professor Kerry Pratt on or kerry.pratt@monash.edu

2 Lower Emission Technologies Using Coal Sankar Bhattacharya Associate Professor Department of Chemical Engineering ATSE Parliamentary Briefing, April 2012

3 MWe 1,800,000 1,600,000 1,400,000 1,200,000 1,000, , , , , ,146 Role of Coal in Power Generation Global Installed Capacity (MWe) Operational Coal-fired power plants 268, Years Years 275, Years 266, Years 229,408 45,384 >40 Years Unknown age 1,651,858 TOTAL Global Coal-fired power generation capacity ~ 1650 GWe at the end of 2010 Significant source for power generation in several countries % Share of coal-fired plants in power generation, Poland South Africa Australia PR China Kazakhstan India Serbia Czech Republic Greece USA Germany Denmark Bulgaria Indonesia Portugal UK Korea Chinese Taipei Spain Japan Turkey Russia World

4 Low-rank coals : a major resource ~ 45% of global coal reserves ~ 207 Giga (billion) tonne > Estimated resource Giga tonne A significant source for power generation in several countries Greece ~ 90% Germany ~ 75% Poland ~ 55% India ~ 50% Australia~ 25% Russia ~ 45% USA ~ 10% Czech R ~ 50% Source: IEA Statistics 2011 BP Energy Statistics 2009 Thielemann et al., 2007

5 Quality of lignites : moisture and ash content 70 mois sture content of raw coal, % Mj/kg Mj/kg 12 Mj/kg 16 Mj/kg Mj/kg ash content of raw coal, % High-ash and/or High-moisture containing coals (often termed as lignites) their location, and calorific values (LHV, Mj/kg); country labels as follows: 1: Australia; 2: Indonesia; 3: India; 4: USA (Texas, North Dakota); 5: Germany; 6: Greece; 7: Spain; 8: Poland; 9: Czech Republic; 10: China; 11: Turkey; 12: Romania Source: various; IEA, 2009

6 Impetus for Efficiency improvement major and immediate effect on reduction of CO 2 emission Current sub-critical state-of-the-art Current SC state-of-the-art Future USC state-of-the-art CO2 reduction, % % point efficiency gain > 2.5% point CO2 reduction Net, HHV, efficiency, % Source: various; IEA, 2009

7 Redudction of CO 2 emission - prospects Average worldwide ~28.4% ~1110 gco2/kwh ~36% ~880 gco2/kwh State-of-the art PC/IGCC ~42% ~740 gco2/kwh Advanced R&D ~48% ~665 gco2/kwh deeper cuts by CCS adapted from VGB 2007; efficiency HHV,net for hard coals For lignites: 2-4%-point lower <2020

8 Effect of moisture content in coal on boiler size High moisture brown coal - ~60% moisture Source: Durie, 1993

9 Effect of moisture content in coal on unit efficiency 45 Approximate Influence of Coal Moisture Only on Plant Efficiency 43 NCV (LHV) Basis t Efficiency % Unit GCV (HHV) Basis Fuel Moisture %ar Significant drop in efficiency with moisture content in coal Development of a less energy intensive drying system is important

10 Drying of high-moisture lignites : major in evaporative drying Steam fluidized bed drying major developments developed at Monash University, Australia developed, demonstrated at larger scale and being commercialized by RWE (WTA technology) finer coal-feed conducive to faster drying, but may make fluidization difficult Being demonstrated at Niederaussem K and other units in Germany Also at Hazelwood, Victoria Source: RWE Power

11 Drying of high-moisture lignites : major in evaporative drying Hot-air fluidized bed drying major developments fluidized with hot air, heated with hot water developed, demonstrated at larger scale and being commercialized by Great River Energy with support from the USDOE applied to lower moisture lignites to dry from about 38% to below 30% moisture Source: Great River Energy

12 Drying of high-moisture lignites : Other past and recent Developments Mechanical thermal expression if coal is heated to o C at saturation pressure to prevent evaporation, the water in coal can then be squeezed out by applying mechanical pressure developed at the University of Dortmund - development work in Germany and Victoria to 15 t/hr now stopped Coldry process Continuous hydro-thermal dewatering (CHTD) vertical autoclave that uses gravitational head pressure and a small amount of energy to transform the molecular structure of brown coal claimed to remove up to 80 percent of moisture content in coal Source: various - Chaffee, Exergen

13 Drying of high-moisture lignites : Outlook and major development needs most technologies are demonstrated at small to large pilot scale urgent need to demonstrate at commercial scale, using waste heat or low-grade steam test the technologies integrated with full-scale power plant, and establish the economics fundamental research: drying kinetics for coal particles of varying size wastewater treatment for technologies based on nonevaporative drying

14 Advanced power generation : supercritical and ultra supercritical and ultra- supercritical pf-fired fired technology SC : Main steam pressure and temperature > 221bar, and < 600 C USC : Main steam pressure and temperature > 221bar, and > 600 C Proportion of SC or USC units in the coal-fleet of some coal-using countries Size of coal-fired fleet in major coal using countries A small proportion (~10%) of the recent built SC units use low-grade coals!

15 Advanced power generation : supercritical and ultra supercritical and ultra- supercritical pf-fired fired technology - outlook and major development needs the larger units to 1100 MWe size are progressively being built globally between 2004 and 2007, share of SC plants increased from 18% to 20% share of USC plants globally is about 1% of the coal-fired fleet USC units operating at 700 o C or higher steam temperature and >300 bar steam pressure are in the development phase supported by the EU (AD700) and DOE/EPRI (advanced materials) if successful, efficiency for new plants will reach 42% (HHV,net) with integrated pre-drying for high-moisture lignite-fired plants will have significant implications for CO2 capture as high efficiency is a necessary pre-requisite for CCS application on these plants

16 Advanced power generation : circulating fluidized bed combustion (CFBC) technology fluidized beds started with both bubbling and circulating beds almost all recent additions are, however, CFBC based can tolerate a wide variety of fuels including coal of different sizes and composition low NO x relative to pf-fired units due to lower operating temperature (<900 0 C) and air-staging easier sulfur capture, due to favorable operating temperature current CFB generation capacity MW and increasing all, except one, are sub-critical (steam pressures <226 bar) units Source: Utt, 2008

17 Air CFB and Oxy CFB - developments Air-fired CFB COMPOSTILLA Oxy-fired CFB CIUDEN 2015 Lagisza first supercritical air-cfb 4 x 550 MWe supercritical CFB for KOSPO and Huyndai 600 MWe supercritical CFB at Baima in China first Oxy-CFB development started in 1986! Compostilla Oxy-CFB - Adapted from Utt, 2008 Scientific R&D for Practical Solutions

18 CFBC technology technology : outlook and major development needs major barrier to wider adoption is the perception that CFB technology is relatively new and hence risky MW CFBC installation with significant operating experience size of CFBC fleet expected to grow with operating experience, and as coal quality worldwide gets inferior compatibility with oxy-firing and chemical looping combustion accelerated demonstration of larger supercritical units development of higher pressure and higher temperature resistant materials to improve steam conditions

19 Advanced power generation : Oxy Oxy-fuel technology Combustion air to the boiler is replaced with a mixture of furnace flue gas and oxygen from an ASU Plant Recycled flue gas/oxygen mixture burns fuel while allowing for uniform heat transfer through out the boiler Flue gas becomes inherently CO 2 rich without needing CO 2 separation process Plant stack gas can be simply condensed to produce a highly concentrated stream of CO 2 Can be designed to operate in conventional air of Oxy-fuel mode

20 Oxy-fuel technology : Outlook and major development needs Two major pilot projects Queensland (30 MWe) and Germany(30 MW th ) German (Vattenfall) units using lignite Several projects proposed up to 400 MWe scale none progressed though Experience from the two pilot projects to influence the progress of the technology for both pf-fired and CFBC technology Identification of optimum oxygen excess and oxygen fraction in the firing Burn-out behaviour of coals in atmospheres consisting of CO2, H2O and O2 Formation mechanisms of pollutants as NOx, SOx and CO Reliable mixture of oxygen with recycled flue gas Effect of flue gas composition on heat transfer, especially by radiation Potential for low temperature flue gas heat utilisation at boiler exit to improve overall efficiency Optimum temperature level for flue gas recirculation Fouling and corrosion under oxyfuel environment Minimisation of auxiliary power by integration of key elements

21 Advanced power generation : Chemical looping N 2 /O 2 CO 2 /H 2 O Fuel Reactor: Air Reactor M y O x Fuel Reactor (2n+m) M y O x + C n H 2m Air Reactor: (2n+m) M y O x-1 + mh 2 O + nco 2 M y O x-1 M y O x-1 + ½ O 2 M y O x Air Fossil Fuel Oxygen for gasification/combustion supplied by oxygen carriers rather than air separation plants

22 Advanced power generation : Chemical looping C 11 H 10 O (coal) + Fe 2 O 3 CO 2 + H 2 O + Fe + FeO : CO 2 production Fe + FeO + H 2 O (steam) H 2 + Fe 3 O 4 : H 2 generation Fe 3 O 4 + O 2 (air) Fe 2 O 3 : regeneration of iron oxide Key research needs: Modeling of oxygen transfer from oxygen carriers to fuel Interaction between fuel minerals and the oxygen carrier Control of the two reactors working in tandem

23 Advanced power generation technology Gasification systems Ash C h a r a c t e r Dry ash Sintered ash Slag Temperature

24 Advanced power generation technology Gasification systems for power generation Entrained flow gasifier (high temperature, slagging) dry feeding of coal Shell, Prenflo, Siemens, Mitsubishi, TPRI (China) slurry feeding GE, ConocoPhillips all except Mitsubishi are oxygen-blown temperature > 1200C for lignites Fluidized bed gasifier (low temperature, non-slagging) dry feeding High temperature Winkler (HTW), U-Gas (GTI) temperature ~ 900C Transport gasifier (Southern Company) temperature ~ 900C solids velocity ~10m/s Rocketdyne (Pratt and Whitney) much smaller gasifier under development

25 Advanced power generation technology Gasification systems for power generation issues for low-rank coals low-ash, high-moisture coals need to be pre-dried before being used in all dry-fed entrained flow gasifiers all types likely to provide almost-complete C-conversion ash-content of high-ash lignites need to be reduced (~10% or below) before being accepted in entrained flow gasifiers low-ash or high-ash coals can be gasified in fluidized or transport reactor C-conversion likely to be limited to around 90% friable lignites lose their carbon through elutriation of fines for hard lignites, fluidized bed or transport gasifier temperatures may not be high enough for full C-conversion new or modified designs necessary for full C-conversion Source: Bhattacharya, 2007

26 Advanced power generation : outlook and development needs for lignite-based IGCC systems none of the current IGCC plants are designed for low-rank coals for IGCC, large scale demonstration required for all types of low-rank coals fluidized bed or transport gasifiers will require separate combustors to convert the carbon from bed discharge demonstration of quench gasifier for lignites containing high-alkali levels investigation of ash-related problems in gasifiers the extent of problems depend on type of lignite and type of gasifiers being used characterisation of solid wastes discharged from the gasifiers development of a reliable system for feeding lignites to pressurised gasifiers

27 Even lower emissions? Research on newer and longer-term technologies has a strong role to play Some have been identified by Mr Phil Gurney Direct Carbon Fuel Cell (DCFC) in small distributed scale generation developed by CSIRO - Monash involvement Reuse of emitted CO 2 (in part) for chemicals and fuels production

28 Outlook : ongoing development in coal ongoing development in coal-fired power generation Average worldwide ~28.4% ~1110 gco2/kwh ~36% ~880 gco2/kwh State-of-the art PC/IGCC ~42% Advanced R&D deeper cuts by ~740 gco2/kwh CCS enabled technologies ~48% ~665 gco2/kwh ~ 600 g CO2/kWh or lower DCFC Efficiency HHV,net for hard coals Efficiency for high-moisture coals: 2-4%-point lower <2020