Coal Based Energy Systems: Options for a Secure Sustainable Environment

Transcription

1 Coal Based Energy Systems: Options for a Secure Sustainable Environment Daniel J. Maloney Director Energy System Dynamics Division U.S. Department of Energy National Energy Technology Laboratory Presented at the 2007 Joint Services Environmental Management Conference Columbus, Ohio May 23, 2007

2 National Energy Technology Laboratory DOE s only national lab dedicated to fossil energy RD&D Government owned and operated Full operations office capabilities One lab, three R&D locations, five project management locations, one management structure 1,100 Federal and support-contractor employees Conducts research spanning basic science through technology demonstrations Significance - fossil energy supplies 85% of Nation s energy needs Pennsylvania Oregon West Virginia Alaska Oklahoma

3 NETL s Mission Implement research, development, and demonstration programs to resolve environmental, supply, and reliability constraints to producing and using fossil energy resources

4 How NETL Accomplishes Its Mission Shape, fund, and manage national extramural RD&D (OPM) Conduct hands-on intramural science and engineering research and development (ORD) Support energy policy development and implementation Expand the nation s options for utilizing fossil energy resources, thereby contributing to the Nation s economic and national security

5 The energy demand and supply situation Energy use is split in 3 categories, and growing. Conventional domestic supplies of gas/oil are tight Domestic NG production flat (leading to LNG imports). Domestic oil production strained, too (leading to imports). Biofuels expected to help.but not the total answer 1 billion tons/year goal = 30% of the total liquid transportation supply 1 Public debate on how to achieve the goal 2 Transportation 32% Natural Gas 21% Coal 36% Other 30% Electricity 39% Oil 43% US Energy use and supply (AEO 2004) [1] Breaking the Biological Barriers to Cellulosic Ethanol, DOE/SC-0095 (2006), pp. 10 [2] Overselling Ethanol, U. S. News and World Reports, Feb 12, 2007

6 U.S. Oil Situation: Past, Present and Projected Future M BPD Consumption 20.7M BPD 58.5% Total Imports 60% by 2025 Production 8.6M BPD (5.4 Crude/ 3.2 Other) M BPD (5.0 Crude/ 0.6 CTL/ 4.8 Other) 2025 Source: EIA (AEO 2006), Reference Case Scenario

7 Coal is a plentiful domestic source of clean energy Billion Barrels Oil Equivalent (BBOE) 2,500 2,000 1,500 1,000 Comparison of World Oil and Coal Reserves U.S.: 22 BBOE Oil Reserves U.S.: 535 BBOE Others Australia India China Russia USA Middle East Coal Reserves World oil demand will grow by 40% to 50% by 2030 Crude supplies concentrated in OPEC/ politically unstable geographies Coal offers opportunity to diversify worldwide fuel supplies Reference- Miller EIA 2007

8 Coal Reserves are Abundant Years Supply at Current Production Rates Provides over half the Nation s electricity Abundant domestic reserves Low cost stable supply Clean utilization technology available Western Eastern Coal Oil Gas Reference - BP Statistical Review, June 2004

9 Carbon Dioxide Management - Rapidly Becoming a Commercial Issue Some recent news articles: Deep in the Sahara BP tries to Put Dent in Global Warming (Subtitle: Too much Carbon for Perrier) Wall Street Journal Feb. 4, 2005 pp. A1 For German Firms, New Emissions Caps Roil Landscape Wall Street Journal Sept 11, 2006 pp. A1 Businesses Rethink Carbon Caps Wall Street Journal March 3, 2007 pp. A7 Recent Supreme Court ruling on Carbon Regulation

10 Technological Carbon Management Options Reduce Carbon Intensity Renewables Nuclear Fuel Switching Improve Efficiency Demand Side Supply Side Sequester Carbon Capture & Store Enhance Natural Sinks All options needed to: Affordably meet energy demand Address environmental objectives

11 Carbon Dioxide Sequestration Terrestrial Sinks CO2 Capture & Sequestration Ocean Sequestration Geologic Sequestration Ocean Unmineable Coal Beds Depleted Oil & Gas Reserves Enhanced Oil Recovery Deep Saline Formation Sources: Derived From NETL & IEA Illustrations

12 North America Geologic Storage Capacity (> 600 Year Storage Capacity for U.S. & Canada) 3,700 Capacity (Gigaton CO 2 ) Maximum Capacity Potential 20 ~ 6 Gigatons CO 2 0 Deep Saline Formations Coal Seams Depleted Gas Fields Depleted Oil Fields Storage Option Annual U.S. & Canada Emissions Source: Battelle, A CO2 Storage Supply Curve for North America, Descriptor September - include 2004, initials, PNWD-3471 /org#/date

13 Carbon Dioxide for Energy Production Carbon Dioxide is used for Enhanced Oil Recovery (EOR): 30+ years experience injecting CO 2 into marginal oil wells. (CO 2 source: natural deposit, NG clean-up) 34 Million tons CO 2 injected in (equivalent CO 2 emission of ~ ten 500 MW coal plants) miles of CO 2 pipeline exist in U.S. 2 Weyburn Project: CO 2 from North Dakota coal gasification plant for Canadian EOR. 3 How much/how long will the injected CO 2 stay underground is a research issue. 1. Final Report, Interstate Oil and Gas Compact Commission, pp. 27 DOE DE-FC26-03NT Ibid., pp Moberg, R., Stewart, D. B., Stachniak, D. (2003). Greenhouse Gas Control Technologies, Vol. 1, pp Pergamon Press.

14 Carbon Dioxide for Energy Production (cont.) Carbon Dioxide may be used for Enhanced Coal Bed Methane (ECBM): Coal bed methane is 8% of lower 48 natural gas production. 1 CO 2 is preferentially adsorbed onto coal versus methane. CO 2 injection increases methane production versus simple depressurization. Pilot since 1995 show CO 2 to methane production ratio of More methane out than the CO 2 in. Breakthrough after four years of injection. 2 Relevant to unmineable coal. How much/how long will the injected CO2 stay underground is a research issue. 1. Energy Information Agency, Annual Energy Outlook, 2004, DOE/EIA-0383(2004), Fig. 14, pp Oil and Gas Journal, Vol , mar 3, 2003, pp. 43. Marshall County, West Virginia ECBM Project

15 CO2 injection into saline formations Sleipner North Sea Project 1 M tons/year CO 2 sequestered since CO2 stripped from natural gas recovery. CO2 injection avoids carbon tax. Currently monitoring CO 2 migration. Similar projects elsewhere Wall Street Journal Feb. 4, 2005 pp. A1

16 Geologic Sequestration Options Deep Saline Formations Deep Coal Seams Enhanced Oil Recovery Fields Comment:* There are 140Mt of natural gas stored in the US each season, using: 38 saline formations depleted oil and gas reservoirs Other (LNG etc.) 80 years of experience! *Final Report, Interstate Oil and Gas Compact Commission, pp. 36 & 48 DOE DE-FC26-03NT41994

17 Sequestration Summary Geological Sequestration is already being practiced. Some benefit to oil and gas production via injected CO 2. Estimates of potential storage capacity exceed the need. But, what do we need to do to capture the CO 2 in coal based systems?

18 Pulverized Coal Flue Gas CO 2 Scrubbing Amine scrubbing: already in use for gas scrubbing, at smaller scale. Reversible chemical reaction with CO 2 releases CO 2 with heat addition. Air Coal 4,000 ton/day Steam Boiler Power Ash 27,000 lb/h ESP Low Press. Steam 1,215,000 lb/h FGD Limestone ID MEA CO 2 Capture CO 2 Comp. Flue Gas 3,440,000 lb/h CO 2 15 Psia Some amine applications for coal flue gas where CO 2 is needed for commercial products. Base w/capture Net power (MWe) CO2 capture load - 21 CO2 compression - 35 Efficiency (HHV) 40% 28% * Basis CO2 compressed to 1500 psi, 50 mile transport CO 2 10,000 ton/day 1,500 Psia *These numbers are specific to cases studied prior to 2005 by the NETL systems group. Updated cases, more detail in 2006, larger plant size, are not significantly different:: 39.1%base versus 27.2% w/capture. To appear on NETL web, 2007.

19 Emerging ideas/options Existing power cycles were developed before CO2 management was an issue A century back, producing CO 2 was a good thing! What would energy systems look like if we started all over?

20 Energy Systems to Capture CO 2 Flue gas scrubbing from Pulverized Coal Plants. Fuel gas scrubbing from Integrated Gasification Combined Cycle (IGCC). Advanced Concepts: Oxy-fuel Chemical looping SOFC fuel cell/turbine hybrids w/o anode air mix

21 FutureGen Objectives World s first near zero-emission, coal-based power plant to: Pioneer advanced hydrogen production from coal Emit virtually no air pollutants Capture and permanently sequester carbon dioxide Integrate operations at fullscale a key step to proving feasibility

22 FutureGen Concept Hydrogen Pipeline Oil Pipeline Refinery Electricity and / or Coal-Fired IGCC CO 2 Pipeline Enhanced Oil Recovery Geologic Sequestration

23 Keys Goals of FutureGen Verify effectiveness, safety & permanence of carbon sequestration Establish standardized technologies & protocols for CO 2 measurement, monitoring & verification Gain domestic and global acceptance for FutureGen concept Validate engineering, economic & environmental viability of coal-based, nearzero emission technologies that by 2020 will Produce electricity with < 10% increase in cost compared to non-sequestered systems Produce H 2 at $4/MMBtu wholesale price ($0.48 /gal gasoline eq.)

24 Why IGCC? R&D Pipeline Reducing Cost & Improving Efficiency Gasifier/refractory material Low-cost oxygen Gas separation membranes Environmentally superior Easily adapted for CO 2 sequestration High efficiency Fuel & product flexibility Promising coal to hydrogen option Producing concentrated stream of CO 2 at high pressure Improves sequestration economics Reduces efficiency penalty

25 Gasification - A Versatile Source of Fuels Oxygen Extreme Conditions: 1,000 psig or more 2,600 Deg F Corrosive slag and H2S gas Coal, Biomass, Pet Coke Water Products (syngas) CO (Carbon Monoxide) H2 (Hydrogen) [CO/H2 ratio can be adjusted] By-products H2S (Hydrogen Sulfide) CO2 (Carbon Dioxide) Slag (Minerals from Coal) Gas Clean-Up Before Product Use

26 Gasification and Gas Cleaning Products from Syngas Clean Syngas H 2, CO, CO 2 Clean Electricity Gas Turbine H 2 Stationary Fuel Cells Building Blocks for Chemical Industry CO + 3H 2 Methanation Methane (SNG) CH 4 + H 2 O Transportation Fuels Shift Reaction Separation of H 2 CO + H 2 O H 2 + CO 2 CO 2 Fischer- Tropsch or Methanol Synthesis 2nH 2 + nco CO + 2H 2 (- CH 2 -) n + nh 2 O CH 3 OH from CO 2 H 2 Fuel Cell Vehicle

27 Integrated Gasification Combined Cycle w/fuel Gas CO 2 Scrubbing Gasification creates CO + H 2 (syngas) from coal Shift reaction used: CO + H 2 O H 2 + CO 2 CO 2 removal possible with existing technology: Selexol may remove sulfur, too Physical absorption avoids thermal energy to regenerate amine scrubbing Coal 3,800 ton/day H 2 O 1,600 ton/day Gasifier 800 Psig O 2 3,160 ton/day Raw Syngas 677,350 lb/h H 2 30% CO 40% Steam CO 2 10% PM 3,500 ton/day Water Gas Removal Shift 12% Syngas Recycle Shifted Syngas 811,000 lb/h H 2 55% CO 1% CO 2 39% Syngas 2-Stage Cooling Selexol Unit Fuel Gas 105 o F 102,000 lb/h 700 Psia 70 o F 695 Psia Saturator Sulfur 104 ton/day CO 2 682,000 lb/h 70 o F 25 Psia Base w/capture Net power (MWe) CO 2 capture load - 9 CO 2 compression - 23 Efficiency (HHV) 43% 35% * 478 MW (387 MW Net) Combustion & Steam Turbine Island CO 2 Comp. Basis CO 2 compressed to 1500 psi, 50 mile transport Flue Gas 4,800,000 lb/h Air + Steam Recy. 4,300,650 lb/h CO o F 1,500 Psia *These numbers are specific to cases studied prior to 2005 by the NETL systems group. Updated cases, more detail in 2006, larger plant size, are not significantly different: 41.1 %base versus 32% w/capture for one type of gasifier. Other gasifiers have different capture penalties. To appear on NETL web, 2007.

28 Higher Efficiencies with Fuel Cell Integration For coal based systems or liquid hydrocarbon fuels Solid Oxide Fuel Cells are a good match Potential for good thermal integration and higher efficiency Separation of anode and cathode flows - easy CO2 separation The air supplied to the cathode must be heated (~700C example) The fuel cell operation rejects heat to the cathode exit air (~ 850C) Internal losses (ohmic, activation & others) Combustion of unused fuel (not described here) What can you do with that heat? Potential for very high system efficiency Reformed hydrocarbon (H 2, CO) electrolyte O 2- Air (O 2, N 2 ) O 2- H 2 O, CO 2 e - e - Electric Load

29 Comparing the bottoming cycles Higher efficiency (60+%) is produced by using the FC rejected heat at the full thermodynamic potential (hottest condition) 600C 20 C 700 C The heat engine peak temperature Is set by the steam cycle (600C supercritical) The availability of the 850C stream is reduced. The heat engine uses the cathode Heat from 850 C to 700 C to produce work; i.e., at the full availability 850 C = 1561F, easy turbine condition

30 Hybrid Turbine Fuel Cell Research Hybrid efficiency exceeds turbine & fuel cell efficiencies. Technical issues: How to manage energy split (FC vs. GT), load shed, compressor surge? Can fuel cell tolerate plant dynamics? NETL HYbrid PERformance (Hyper) facility: Evaluate control architecture to maximize efficiency. Validated models to predict large hybrid performance. Measure real loads expected in fuel cell operation. Pressure Compressor map of NETL engine Stall line Mass flow Efficiency curves High efficiency occurs near the stall line (red) Speed(rpm) Speed Set-Point Ramp 40.5 to 41krpm Sim Speed (rpm) Actual Speed (rpm) Sim Fuel Flow (g/s) Actual Fuel Flow (g/s) Time (sec) Set-point transients may reverse expected fuel cell flows Fuel Flow (g/s) NETL Hyper Facility simulates fuel cell dynamics in real turbine environment. Solid oxide fuel cell can be tested In situ after controlling dynamics

31 Another option: Oxy-Fuel Cycles The chief difficulty with CO 2 separation is the nitrogen in air - consider CH 2 (representative HC): CH 2 + 3/2 (O N 2 ) CO 2 + H 2 O + 5.7N 2 + energy But if you supply pure oxygen Lots of nitrogen to separate from CO 2 before storage. No! CH 2 + 3/2 O 2 CO 2 + H 2 O + energy In practice, need to dilute the Cooling the exhaust will condense water and leave just CO 2 - very easy! oxygen with cooled, recycled H 2 O or CO 2

32 Power cycles that produce CO 2 streams O2 C x H y 1450 C? combustor Air (Hot) CO 2 H 2 O CO 2 diluted oxy-fuel CO2 Chemical looping Metal oxide (MeO) Metal (Me) O2 CO2 H2O Air (Ambient) Fuel C x H y combustor 600 C? H 2 0 diluted oxy-fuel Liquid H2O H2O, CO2 Condenser SOFC fuel Cell without Anode/air combustion Reformed hydrocarbon (H 2, CO) electrolyte O 2- Air (O 2, N 2 ) O 2- H 2 O, CO 2 e - e - Electric Load

33 Operating oxy-fuel power plant. The photos show the Kimberlina Power Plant, located near Bakersfield, California. The plant was developed by Clean Energy Systems, Inc. The plant has been successfully connected to the electric power grid. Up to date details: Oxygen supplied from cryogenic sources

34 DOE Development Path to Establish a CTL Industry in the U.S.

35 Coal-to-Liquids Study CTL Development Plan requested by Congress in Dept of Defense FY06 appropriations law Plan considerations: 1. Technology needs & barriers 2. Economics & national security 3. Environment & CO 2 4. Financial incentives 5. Schedules / Milestones 6. Regional diversity Coordinated with DOD Liquids Utilization Plan

36 DOE CTL Development Study Three thrust plan: 1. Facilitate Limited Early Learning Commercial Experience Support Treasury in Implementation of EPACT 2005 Co-Fund Site Specific Design Studies Analyze Incentive Packages Directed at Promoting Early Commercial Experience 2. Focused R&D activities: IGCC integrated with F-T process Cost reduction Improve environmental performance Integrative analyses/modeling International coordination & information exchange 3. Fuels Formulation & Testing

37 Vision Provide a pathway by which 10% of the nation s liquid transportation fuel requirements (2 million BPD) can be met with CTL fuels by Government Role Creation of financial incentives, Site specific design studies and analyses, Direct support in focused R&D; Cost-sharing of plant construction and operation; CTL testing, verification, and certification. Basis DOE expertise and experience in liquids fuels.

38 Coal To Liquids Perspective Indirect CTL is a commercial technology SASOL in South Africa (150,000 bpd) Clean Fuels Clean-up accomplished during gasification FT process very flexible Designed to meet specific application (gasoline, diesel, jet fuel, etc.) Issues Coal has higher C/H ratio than natural gas or petroleum (bigger carbon footprint) Co-gasification of coal with Bio-mass offers potential for carbon management

39 Bio-Mass Addition for Carbon Management Biomass + coal +sequestration Negative CO 2 emissions Mixes good economics of coal w/variable feed bio/waste supplies Could make transportation fuel from coal (FT liquids) CO 2 Terrestrial Sinks Biomass Coal This idea has been described by the Princeton Environmental Institute, Energy Group. sites/pei Enhanced Oil Recovery Geologic Sequestration Unmineable Coal Beds Depleted Oil & Gas Reserves Deep Saline Formation Figure sources: Derived From NETL & IEA Illustrations See Williams, R. H. Larson, E., Jin, H. (2006). Synthetic fuels in a world with high oil and carbon prices, 8 th International Conference on Greenhouse Gas Control Technologies, Trondheim, Norway, June 2006.

40 Co-Gasification of Coal and Biomass (Switchgrass): An Alternate Approach to Making Diesel Fuel from Biomass MM BTUs/Ton: Bituminous coal (Pgh seam dry) 27 Switchgrass (over-dried) 14 1 GJ Input 0.05 GJ Biomass GJ Coal 0.48 GJ Output 0.15 GJ Electricity GJ F-T Liquids Net Carbon Emissions 1. All Coal plant: 28.3 kg C per GJ of F-T liquids 2. Coal + Biomass Plant: 25.0 kg C per GJ of F-T liquids Therefore, by co-feeding 5% biomass on an energy input basis, carbon emissions are reduced by about 12% F-T Liquids Production from Coal and Coal + Biomass with CO 2 Capture and Alternative Storage Options; R.H. Williams, et al; review draft 13 Jan 2006

41 Summary Coal is a major fuel resource. Carbon management is now commercially important. Carbon dioxide capture and sequestration could produce a sizeable dent in CO 2 emissions. Current and future options for efficient power systems with carbon dioxide management: IGCC Hydrogen with CO 2 Capture Oxy-fuel Systems Hybrid Fuel Cell Cycles Coal-Biomass To Liquids