Low-GHG Liquid Fuels from Coal + Biomass

Transcription

1 Low-GHG Liquid Fuels from + Eric D. Larson Energy Systems Analysis Group Princeton Environmental Institute Princeton University elarson@princeton.edu Chewonki Carbon Capture and Storage Seminar Wiscasset, Maine 4 October Energy Systems Analysis Group ESAG has been a research at Princeton University since Problem-focused research aims to understand near-term technology options to facilitate longterm solutions to major energy-related problems of global climate change, urban pollution, energy insecurity, rural poverty in developing countries, and others. Hard-nosed engineering-based analysis, but interacting with experts in many disciplines to help understand socio-economic contexts and to help shape solutions. 1

2 -Based Fuels and/or Electricity Production Low value feedstocks Gas Cleanup High-Value Products Pet Coke Oil Residue Wastes Oxygen H O CO Storage CO, H, H S, H O, CO CO Removal WGS: CO + H O H + CO H S Removal SULFUR RECOVERY Combined Cycle Power Block Gas & Steam Turbines Clean Syngas (H + CO) Electricity Steam Catalytic Synthesis Marketable Byproducts: Fischer Tropsch (or variety of other fuels or chemicals) Sulfur Slag Synthesis of Liquid Fuels from Syngas (CO+H ) Fuel product (vapor) + unreacted syngas LIQUID-PHASE SYNTHESIS P = atm. T = o C Steam Disengagement zone CO + H -C H - + H O Catalyst powder slurried in oil CO + H CH OCH + CO CO + H CH OH Fischer-Tropsch liquids (FTL) Dimethyl ether (DME) Methanol (MeOH) Cooling water Synthesis gas (CO + H ) CO catalyst CH OCH CH OH H C n H n+ (depending on catalyst) 4

3 Fischer-Tropsch Fuels (straight-chain C n H n, C n H n+ ) F-T fuels of interest include high-cetane, low-aromatic, no-sulfur diesel or jet fuel substitute naphtha as chemical feedstock (upgradable to gasoline blendstock) F-T technology is commercially established F-T production from stranded natural gas: Mossgas (South Africa) started 199: 6k barrels per day Shell Bintulu (Malaysia) started 199: 1k barrels per day Additional plants under construction or planned (Qatar > 00K bpd) F-T projects: Sasol II & III in South Africa, 150k barrelsl (bpd) total capacity 0k bpd, Inner Mongolia (007) x 80k bpd, Sasol/China feasibility study 5k bpd demo, Gilberton, Pa (008) Several projects (10k-50k bpd proposed for U.S.) F-T development in Germany (Choren/Shell) 5 -to-liquids (CTL) Technology CTL = F-T liquids from coal. Intense commercial interest in CTL, esp. in U.S. and China. CTL can be made with existing technologies, in large quantities, for a long time, and at competitive costs when oil is ~$50/barrel or higher energy security. CTL greenhouse gas (GHG) emissions are about twice the emissions per of energy as with petroleum-derived fuels global warming. With CO capture and storage (CCS), GHG emissions can be reduced to same level as for petroleum fuels not good enough (especially for U.S.) to stabilize atmospheric CO concentration. 6

4 Making FT Liquids Using F-T liquids from biomass (BTL) with CO vented. F-T liquids from biomass with CCS (BTL w/ccs) The F-T process generates a pure CO stream accounting for ~ ½ of the carbon in the feedstock Low incremental cost for CCS (CO compression + transport + storage). goes from being carbon neutral to carbon-negative (due to underground storage of photosynthetic CO ). F-T liquids from biomass + coal w/ccs (CBTL w/ccs) offers same benefits as BTL w/ccs and in addition: Economies of scale of coal conversion to be exploited for biomass without massive quantities of biomass. (F-T technology costs are scale sensitive.) Relatively high cost biomass can be used, since much of the feedstock input would be low-cost coal. Prospectively large climate-friendly role for coal and more effective use of biomass than conventional biofuels (like ethanol). Is CBTL w/ccs feasible? 7 Carbon Capture and Storage (CCS) has no significant future without CCS in a carbonconstrained world If CCS works for coal, it will also work for biomass IPCC Special Report on CCS*: IPCC is positive on geological storage, not so positive on ocean storage or mineralization (carbonate rocks) Assigns high probability (66-90%) that worldwide geological storage capacity is at least 000 Gt CO. Fossil fuel emissions were 4 Gt CO in 00. Regarding security of geological storage: Very high probability (90-99%) that > 99% retained over 100 years High probability (66-90%) that > 99% retained over 1000 years CO pipeline risks are comparable to, or less than, risks with hydrocarbon pipelines operating today * Intergovernmental Panel on Climate Change, Special Report on Carbon Dioxide Capture and Storage,

5 Baard Energy CBTL Project 50,000 barrels CBTL plant at Wellsville, Ohio on Ohio River Builds on Buggenum C/B co-gasification experience: Shell gasifier Up to 0% biomass planned CCS planned CO for EOR (nearby oil field) or stored in deep saline formation GHG emission rate for FTL ~ ½ rate for crude oil-derived products displaced IF fired with 0% biomass and 85% of C not contained in products is captured as CO How real is this project? Ongoing $50 million FEED study (Amec Paragon with Uhde/Black & Veatch) expected to be finished mid-008 Some long-term biomass supply contracts secured Seeking federal incentives but intend to proceed even if not received Ohio Air Quality Development Authority has authorized raising state taxexempt bonds for debt financing Plant start-up targeted for Twin River CBTL Project, Wiscasset 9,000 b/d FTL MW electricity capacity Bituminous coal is bulk of the feedstock. Eventually 5% to 15% of input feedstock is woody biomass. Dry-feed gasifier (Shell?) simultaneously gasifying the two feedstocks CCS? 10 5

6 CBTL w/ccs Process Configurations H S, CO CO Storage Syngas Conversion SYNFUELS and/or PARALLEL GASIFIERS H S, CO CO Storage Syngas Conversion SYNFUELS and/or SINGLE GASIFIER CFBG H S, CO CO Storage Syngas Conversion SYNFUELS and/or SEQUENTIAL GASIFIERS 11 Two CBTL Options with Parallel Gasifiers Once-Through Synthesis H S, CO F T Synthesis Upgrading, Refining F-T FUELS Atmosphere H S + CO Storage unconverted + light gases GTCC Power Island CO EXPORT Stage H /CO =.75 Recycle Synthesis Stage O + steam ATR H S, CO H S + CO Storage F T Synthesis Steam Cycle Power Island Unconverted + light gases Upgrading, Refining CO EXPORT F-T FUELS Atmosphere 1 6

7 Net GHG Emissions, kgc/gj FTL LHV Net Fuel-Cycle GHG Emissions Gasoline Diesel OT Recycle OT Recycle OT (6% bio) R (4% bio) Petroleum Vent with CCS /CCS For C/B systems w/ccs using switchgrass biomass, zero net GHG emissions when biomass fraction of input is 6-4%. Net GHG emissions charged to FTL include: all upstream emissions associated with coal and biomass production + emissions at the FTL production facility + emissions from combustion of the FTL when used as fuel - credit for emissions associated with electricity. [Per kwh credit equal to emissions from stand-alone 1 coal-igcc w/o CCS (-Vent cases) and stand-alone coal-igcc w/ccs (all CCS cases).] CBTL for + Mixed Prie Grasses and Two Carbon Storage Mechanisms Mixed prie grasses farms biomass gasification gasification gas shift stage water gas shift H S, CO H S + CO F T synthesis storage Upgrading, refining unconverted + recovered gas process electricity GTCC power island F-T FUELS EXPORT carbon Soil and root C storage input to realize zero net GHG emissions for FTL could be reduced further if biomass is grown on carbon-depleted soils. Additional C storage if biomass is grown on C-depleted soils Up to 0.6 tc stored in soils/roots per tc in harvested mixed-native prie grasses over 0 year period in Minnesota (Tilman et al, Science, 14: , 006). Once mixed prie grasses (MPGs) have been established, only modest additional inputs (e.g., gasifier ash) needed with annual harvesting. Local biodiversity gain (vs. net biodiversity loss for monocultures). 14 7

8 COAL + MPGs TO F-T LIQUIDS +, WITH CCS C equiv balances to atmosphere for F-T liquids OUT: photosynthesis (MPGs, soil&root C), electricity credit (,85 t C ) IN: upstream emissions, vented at plant, fuels burned in vehicle,s (,85 t C ) prie grasses upstream emissions 8 t C 1,607 t C photosynthesis fuel for transportation 1,810 t C prie grasses 1,607 t C 668 MW LHV 1,0 MW LHV carbon vented 75 t C credit for e.e. t C electricity production 45 MW ee coal 5,8 t C,449 MW LHV coal upstream emissions 5 t C accumulation in soil and root 1,0 t C arrow widths are proportional to C fluxes polygeneration plant char 5 t C carbon storage 4,7 t C 15 GJ per GJ Liquid Fuel (LHV basis) Needed per GJ of Zero-GHG Liquid Fuel [coal] [coal] 0.00 CBTL Recycle with CBTL Recycle with CCS, 16 MPGs CCS, Switchgrass (with soil/root C credit) (no soil/root C) EthOH, vintage 000, 7 gallons/ton EthOH, vintage 015, 90 gallons/ton EthOH, vintage 00, 105 gallons/ton Low biomass input required for zero-ghg fuel from C/BTL w/ccs compared with pure biofuel implies more market power for farmer. 16 8

9 Preliminary findings of NETL CBTL study* (Courtesy of Michael Reed, NETL) 00 A1 (100% bituminous coal) g-co E/ MMBtu of Fuel (thousands) B1 (100% bituminous coal) D1 ( ~ 5% Corn Stover) E1 ( 1% Corn Stover) Standard Petroleum W/out CCS With CCS Standard Petroleum ULSD Baseline Corn Ethanol C1 ( 59% by energy Switch grass) F1 ( 48% Switch grass) G1 (50% Switch grass) % energy basis H1 (100% Switch grass) Cellulosic Ethanol 100 I1 (100% Switch grass) * Ongoing study that builds on Aug. 007 NETL/USAF study, Increasing Security and Reducing Carbon Emissions of the US Transportation Sector: a Transformational Role for with. Note 1 component of feed is Illinois #6 bituminous coal Note Information is preliminary and should not be cited Note Size of spheres indicates plant size. A1 50,000 bbl I1 5,000 bbl Note 4 input is 5000 dry tonnes in all cases. 17 Illinois Case Study for /MPG Facility Minemouth facility in Clinton County Would use high sulfur bituminous coal and MPGs from land now growing corn. Co-produces FT fuel and electricity. MPG fraction of input is set to give zero net lifecycle GHG emission liquid fuel. One million t/yr MPGs needed; assuming 10.4 dt/ha/yr yield* and 15% of land around plant grows MPGs, average transport from harvest is 7 miles. CO captured/piped miles to injection site in Fayette Co. (Mt. Simon aquifer). * Clarence Lehman, U. of Minnesota (private communication, April 007), estimates that MPG yield on average cropland would be 1.5 X hay yield on lower-grade local land growing hay, based on correlation of actual hays and general productivity models. 18 9

10 POSSIBLE AQUIFER STORAGE SITE Suggested region for aquifer CO storage near proposed CBTL plant offered by Hannes Leetaru, and map of Mt Simon Sandstone features provided by Chris Korose both of the Illinois State Geological Survey, private communication April Prospective Farmer Economics Consider first a CTL plant with CCS Site: coal mine-mouth plant in Southern Illinois (corn country) CO storage: 7500 ft underground, Mt. Simon aquifer ( miles away) Feedstock: high-s bituminous coal Assume GHG emissions price = $100/tC. This is minimum needed to make CCS economical for coal power. ($100/tC applied to gasoline is 5 /gallon.) Breakeven crude oil price is in the range $50 to $60 barrel Next consider coal/mpg CBTL plant w/ccs with MPG input level to give net zero GHG emission rate for FTL & assume: Estimated MPGs yields for lands now growing corn there Same outputs/product prices as for coal-only plant with CCS determines willingness of synfuel producer to pay for MPGs What is income to farmer if MPGs displace corn compared to income from corn? Income/ha/yr comparable to that for corn at mid-007 corn prices Farmer income falls more than 40% if 0 credit for soil C/root C buildup0 10

11 Q & A. Some References Tilman, D., Hill, J. and Lehman, C., 006 Carbon-Negative Biofuels from Low-Input High-Diversity Grassland, Science, 14, , 8 December. Williams, R.H., Larson, E.D. and Jin, H., 006. Synthetic Fuels in a World with High Oil and Carbon Prices, Proceedings of 8 th International Conference on Greenhouse Gas Control Technologies, Trondheim, Norway, 19- June. Larson, E.D., Jin, H., Liu, G., and Williams, R.H., 007. Zero-Carbon FT Liquids via of and with CCS, 6 th Annual Carbon Capture & Sequestration Conf., Pittsburgh, PA, 7-10 May. Williams, R.H., Consonni, S., Fiorese, G. and Larson, E.D., 007. Synthetic Gasoline and Diesel from and Mixed Prie Grasses for a Carbon-Constrained World, 6 th Annual Carbon Capture & Sequestration Conf., Pittsburgh, PA, 7-10 May. Larson, E.D., Consonni, S., Katofsky, R.E., Iisa, K. and Frederick, W.J., 006. A Cost-Benefit Assessment of -Based Biorefining in the Kraft Pulp and Paper Industry, Vol. 1: Main Report, final report to US Department of Energy and American Forest and Paper Association under DOE contract DE-FG6-04NT460, Princeton Environmental Institute, Princeton University, Princeton, NJ, 1 December. 1 11