The Future of Geothermal Energy -- Can it become a major supplier of primary energy in the U.S.?

Transcription

1 The Future of Geothermal Energy -- Can it become a major supplier of primary energy in the U.S.? Jeff Tester Croll Professor of Sustainable Energy Systems School of Chemical and Biomolecular Engineering Director of the Cornell Energy Institute and Associate Director for Energy Cornell Center for a Sustainable Future Cornell University jwt54@cornell.edu Geothermal energy today resources from hydrothermal systems to hot dry rock applications for direct heating/cooling and electricity An assessment of US potential Lessons learned in 30+ years of progress on EGS technology A pathway to universal heat mining with technology improvements

2 Utilization of Geothermal Energy 1. For Electricity -- As thermal energy for generating electricity 2. For Heating -- direct use of the thermal energy in district heating or in industrial processes 3. For Geothermal Heat Pumps as a source or sink of moderate temperature energy in heating and cooling applications

3 Looking to inner space for opportunities in the Earth s Geosphere Earth s Geosphere

4 Accessible Pressure Temperature Domain Earth s Geosphere Geothermal energy in use today

5 Geothermal systems common characteristics and limitations An accessible, sufficiently high temperature rock mass underground Connected well system with ability for water to circulate through the rock mass to extract energy Production of hot water or steam at a sufficient rate and for long enough period of time to justify financial investment Means of directly utilizing or converting the thermal energy to electricity Hydrothermal Reservoirs

6 Geothermal started producing electricity in Italy at Larderello in 1904 over 100 years ago

7 Geothermal has enabled Iceland s transformation In 50 years Iceland has transformed itself from a country 100% dependent on imported oil to a renewable energy supply based on geothermal and hydro >95% of all heating provided by geothermal district heating >20% of electricity from geothermal remainder from hydro 2 world scale aluminum plants powered by geothermal Currently evolving its transport system to hydrogen/hybrid/electric systems based on high efficiency geothermal electricity Condensers and cooling towers, The Geysers, being fitted with direct contact condensers developed at NREL The Blue Lagoon in Iceland

8 Today there are over 11,000 MWe on-line or under construction-- USA MWe up from 2544 MWe in 2005 How is Mexico doing? Total installed by December ,000 MWe A.S. Batchelor, 2005; Bertani,2008; and GEA, 2009

9 Luis C.A. Gutiérrez Negrín 1,3, Raúl Maya González 2 and José Luis Quijano León 3 1 Geocónsul, 2 Comisión Federal de Electricidad, 3 Mexican Geothermal Association. Mexico Session 5E: Country updates

10 Cerro Prieto 720 MW Las Tres Vírgenes 10 MW Total geothermal electric installed capacity (net): 958 MW Total electric generation in 2009: 6,793 GWh National average CF: 80.9% Fields and power units are owned and operated by CFE Cerritos Colorados (Potential: 75 MW) Los Azufres 188 MW Los Humeros 40 MW Mexican Volcanic Belt

11 Total: 51,718 MW

12 Geothermal energy today for heat and electricity From its beginning in the Larderello Field in Italy in 1904, over 11,000 MWe of on-line capacity worldwide today Additional capacity with direct use and geothermal heat pumps (e.g >100,000 MWt worldwide) Current costs /kwh Attractive technology for dispatchable, base load power for both developed and developing countries Condensers and cooling towers, The Geysers, being fitted with direct contact condensers developed at NREL But geothermal today is limited to high grade, high gradient sites with existing hydrothermal reservoirs!!

13 Enhanced/Engineered Geothermal Systems (EGS) could provide a pathway to universal heat mining EGS defined broadly as engineered reservoirs that have been stimulated to emulate the production properties of high grade commercial hydrothermal resources.

14 A range of resource types and grades within the geothermal continuum Average surface geothermal gradient from Blackwell and Richards, SMU (2006) Hydrothermal Conduction-dominated EGS Volcanic EGS Co-produced fluids Geopressured Three critical ingredients for successful heat mining 1. sufficient temperature at reasonable depth 2. sufficient permeability 3. sufficient hot water or steam 6

15 Environmental concerns and benefits Benefits Land use small footprint compared to alternatives Low emissions, carbon-free base load energy No storage or backup generation needed Adaptable for district heating and co-gen / CHP applications Concerns Induced seismicity must be monitored and managed Water use will require effective control and management, especially in arid regions The Future of Geothermal Energy

16 Water availability and proper water management are important in certain regions Ormat s 5 MWe organic binary plant in Nevada operates with no cooling water consumption!

17 The footprint of geothermal power developments is small Source - The Future of Geothermal Energy, MIT report (2006)

18 Billion Metric Tonnes of CO 2 per year Current 100 GW EGS Effect of Geothermal Deployment (EGS) on CO 2 Emissions from US Electricity Generation 1, EIA TWh Generation 1.0 TW e Capacity 200 GW EGS 300 GW EGS Current 100 GW EGS 2030 EIA Projection TWh Generation 1.2 TW e Capacity 200 GW EGS 300 GW EGS Current Constant Growth to 2100 Assuming 2030 Energy Mix TWh Generation 2.3 TW e Capacity 100 GW EGS 200 GW EGS 300 GW EGS 500 GW EGS Notes: 1. 95% capacity factor assumed for EGS 2. Assumes EGS offsets CO2 emissions from Coal and Natural Gas plants only 3. EIA Annual Energy Outlook

19 The Geothermal Option A undervalued opportunity for the US? Is there a feasible path from today s hydrothermal systems with 3000 MWe capacity to tomorrow s Enhanced Geothermal Systems (EGS) with 100,000 MWe or more capacity by 2050? Hydrothermal Average surface geothermal gradient from Blackwell and Richards, SMU (2006) EGS

20 The Future of Geothermal Energy Transitioning from Today s Hydrothermal Systems to Tomorrow s Engineered Geothermal Systems (EGS) -- Primary goal: to provide an independent and comprehensive evaluation of EGS as a major US primary energy supplier -- Secondary goal: to provide a framework for informing policy makers of what R&D support and policies are needed for EGS to have a major impact An MIT led study by an 18- member international panel Full report available at future_geothermal.html

21 A key motivation -- US electricity capacity is now at 1 TWe (1,000,000 MWe) and threatened 1. Retirements of old coal and nuclear units In the next 15 to 20 years 40 GWe of old coal-fired capacity will need to be retired or updated because of a failure to meet emissions standards In the next 25 years, over 40 GWe of existing nuclear capacity will be beyond even generous re-licensing procedures 2. Projected availability limitations and increasing prices for natural gas are not favorable for large increases in electric generation capacity for the foreseeable future 3. Public resistance to expanding nuclear power is not likely to change in the foreseeable future due to concerns about waste and proliferation. Other environmental concerns will limit hydropower growth as well 4. High costs of new clean coal plants as they have to meet tightening emission standards and may have to deal with carbon sequestration. 5. Infrastructure improvements needed for interruptible renewables including storage, inter-connections, and new T&D are large Geothermal provides base load, dispatchable power

22 Multidisciplinary EGS Assessment Team Panel Members Jefferson Tester, chair, Cornell & MIT, chemical engineer Brian Anderson, University of West Virginia, chemical engineer Anthony S. Batchelor, GeoScience, Ltd, rock mechanics and geotechical engineer David Blackwell, Southern Methodist University, geophysicist Ronald DiPippo, power conversion consultant, mechanical engineer Elisabeth Drake, MIT, energy systems specialist, chemical engineer John Garnish, physical chemist, EU Energy Commission (retired) Bill Livesay, Drilling engineer and consultant Michal Moore, University of Calgary, resource economist Kenneth Nichols, Barber-Nichols, CEO (retired), power conversion specialist Susan Petty, Black Mountain Technology, reservoir engineer Nafi Toksoz, MIT, seismologist Ralph Veatch, reservoir stimulation consultant, petroleum engineer Associate Panel Members Roy Baria, former Project Director of the EU EGS Soultz Project, geophysicist Enda Murphy and Chad Augustine, MIT chemical engineering research staff Maria Richards and Petru Negraru, geophysists, SMU Research Staff Support Staff Gwen Wilcox, MIT

23 Estimated Temperatures at Specific Depths The Future of Geothermal Energy 7

24 U.S. Geothermal resource is large and underutilized 1 EJ = J or about BTU Annual US energy consumption = 100 EJ

25 A key question -- how much could be captured and used? 1,000,000 EJ 10,000 x US use Estimated total geothermal resource base and recoverable resource given in EJ or Joules.

26 30+ Year History of EGS Research Cooper Basin (Australia) TBD Future US EGS Program EGS CORE KNOWLEDGE BASE Soultz (EU) Basel (Swiss) Fenton Hill (USA) Coso, Desert Peak (US) Hijiori & Ogachi (Japan) Landau (German) Rosemanowes (UK) The Future of Geothermal Energy

27 Developing stimulation methods to create a well-connected reservoir The critical challenge technically is how to engineer the system to emulate the productivity of a good hydrothermal reservoir Connectivity is achieved between injection and production wells by hydraulic pressurization and fracturing snap shot of microseismic events during hydraulic fracturing at Soultz from Roy Baria

28 Large stimulated reservoir volumes are created by hydraulic pressurization Mapped microseismic events plotted in plan view during hydraulic stimulation in the Cooper Basin In Australia Scale in meters

29 R&D focused on developing technology to create reservoirs That emulate high-grade, hydrothermal systems EGS Reservvoir at Soultz, France from Baria, et al. 30+ years of field testing at Fenton Hill, Los Alamos US project Rosemanowes, Cornwall, UK Project Hijori, et al, Japanese Project Soultz, France EU Project Cooper Basin, Australia Project, et al. has resulted in much progress and many lessons learned directional drilling to depths of 5+ km & 300+ o C diagnostics and models for characterizing size and thermal hydraulic behavior of EGS reservoirs hydraulically stimulate large >1km 3 regions of rock established injection/production well connectivity within a factor of 2 to 3 of commercial levels controlled/manageable water losses manageable induced seismic and subsidence effects net heat extraction achieved

30 Although much has been accomplished there are a few things left to do 1. Commercial level of fluid production with an acceptable flow impedance thru the reservoir 2. Establish modularity and repeatability of the technology over a range of US sites 3. Lower development costs for low grade EGS systems A robust research program in geoscience and engineering would contribute significantly to: better characterization of in situ stresses and fracture propagation mechanisms improved hydraulic stimulation procedures enhanced fracture mapping with improved reservoir connectivity better understanding of induced seimicity improved models of thermal hydraulic performance improved understanding of borehole breakout mechanisms and stability issues

31 And today the Australians are making progress Cooper Basin geothermal resource. One of the best sites in world for Hot Fractured Rock (HFR) geothermal electricity generation - potential for 1000 s MW generating capacity.

32 And the Australians are continuing to make progress in Wellhead flow rate 18 kg/s at 275 bar, o C

33 But the economics of EGS still need to be proven 100 Drilling and Reservoir Stimulation Power Plant 80 % of Total Cost High Grade Hydrothermal (<3 km) Mid-Grade EGS (3-6 km) Low Grade EGS (6-10 km) As EGS resource quality decreases, drilling and stimulation costs dominate

34 Factors controlling the economics of EGS Major impact with higher uncertainty and risk -- Flow rate per production well (20 to 80 kg/s ) Thermal drawdown rate / redrilling-rework periods (3% per year / 5-10 years) Resource grade defined by temperature or gradient = f(depth, location) Financial parameters Debt/Equity Ratio (70/30 to reflect industry practice) Debt rate of return ( %) Equity rate of return (17%) Drilling costs Lesser impact but still important -- Surface plant capital costs Exploration effectiveness and costs Well field configuration -- 5 production wells / 4 injection wells Flow impedance Stimulation costs Water losses Taxes and other policy treatments

35 Economics of EGS sensitivity analysis and supply curve projections Parametric analysis of capital and levelized electricity costs (LEC) : 1. Drilling depths: 3 km to 10 km 2. Average temperature gradients from 10 C per km to 100 C per km 3. Production well flow rates of 20, 40, 60, 80 and 100 kg/s. 4. Geofluid production temperatures : 100 C C 5. Six different drilling cost cases 6. Two electricity price scenarios Break-even Price ( /kwh) EGS supply curve MIT EGS model predictions with today s drilling and plant costs and mature reservoir technology at 80 kg/s per production well ,000 10, ,000 EGS Capacity Scenario (MW e )

36 Supply Curve for EGS Electricity High impact levels for EGS are estimated with a modest investment The Future of Geothermal Energy for research, development and deployment over a 15 year period DOE Workshop June 7, 2007

37 In simpler terms, with EGS working at depths to 6 km all of the US becomes a viable geothermal resource From Blackwell and Richards (June, 2007)

38 Opportunities exist in Mexico for high grade EGS geothermal resources suitable for electric power generation ACOCULCO 2 wells about 2 km deep where drilled by CFE Very high temperatures ( >300oC) But very low permeability requires stimulation

39 ACOCULCO Two deep wells finished in granite. Very high temperature but low permeability With EGS techniques it could be fractured to increase permeability in the nearby reservoir of both wells to produce some7 MW each Or to build a EGS by hydraulic fracturing to form adoublet. Inject water in one and recover steam in the other

40 Summary of major findings 1. Large, indigenous, accessible base load power resource 14,000,000 EJ of stored thermal energy accessible with today s technologies. Key point -- extractable amount of energy that could be recovered is not limited by resource size or availability 2. Fits portfolio of sustainable renewable energy options - EGS complements the existing portfolio and does not hamper the growth of solar, biomass, and wind in their most appropriate domains. 3. Scalable and environmentally friendly EGS plants have small foot prints and low emissions carbon free and their modularity makes them easily scalable from large size plants. 4. Technically feasible -- Major elements of the technology to capture and extract EGS are in place. Key remaining issue is to establish inter-well connectivity at commercial production rates only a factor of 2 to 3 greater than current levels. 5. Economic projections favorable for high grade areas now with a credible learning path to provide competitive energy from mid- and low-grade resources 6. Deployment costs modest -- an investment of $ million over 15 years would demonstrate EGS technology at a commercial scale at several US field sites to reduce risks for private investment and enable the development of 100,000 MWe. 7. Supporting research costs reasonable about $40 million/yr needed for 15 years -- low in comparison to what other large impact US alternative energy programs will need to have the same impact on supply. The Future of Geothermal Energy

41 Recommended path for enabling 100,000 MWe from EGS by 2050 Invest a total of $1000 million for deployment assistance and for research, development and demonstration over 10 years Support site specific resource assessment Support 3-5 field EGS demonstrations at commercialscale production rates Short term -- develop high grade EGS sites at the margins of hydrothermal reservoirs and in high gradient regions at depths of 3 to 6 km for power generation Longer term develop lower grade EGS sites requiring deeper heat mining at depths >6 km for co-generation Maintain vigorous R&D effort on subsurface science, geo-engineering, drilling, energy conversion, and systems analysis for EGS Less And, than provide the a price comparable of one clean amount coal of plant R&D! support for conventional hydrothermal The Future of Geothermal Energy

42 Advanced Geothermal Technologies 1. Expanding direct use and cogeneration with lower grade resources 2. Spallation drilling using hydrothermal flames and jets -- MIT/ETH/Cornell 3. Increasing efficiency by going deeper to supercritical conditions (Icelandic IDDP) 4. Ultra high grade geothermal energy from submarine hydrothermal vents (Mexico, Hiriart, et al)

43 Opportunities for direct use below 250 o C are substantial US Energy demand versus temperature Resid. Water Heating Comm. Water Heating Comm. Space Heating Industrial Process Steam Comm. AC Pools, etc. Resid. Space Heating Clothes Dryer Resid. Refrig. Cooking Resid. AC Fox, Sutter, Tester (2010) Represents about 35% of total US demand in 2008

44 Example 1 Advanced technology for continuous drilling using thermal spallation/fusion Low density oil-air flame drilling in open boreholes

45 Spallation drilling using hydrothermal jets Hydrothermal flames at high density using CH 4, H 2, CH 3 OH Flame jet spallation at atomspheric pressures

46 Our research is extending spallation/fusion drilling to deep well drilling using hydrothermal jets Visible combustion flames produced in a supercritical water environment ( P > 220 bar) Temperature at center of flame can reach over 3000 K, but subcritical water temps at walls T ~ 2500 K/cm) Hydrogen, methanol and methane fuels considered Research focus is on experimental and theoretical studies of hydrothermal flames and jets in supercritical water. Contributing researchers Chad Augustine and Hildigunnur Thorsteinsson and Prof. Philip von Rohr and colleagues at ETH in Zurich

47 Drilling Costs Actual and Predicted Actual oil and gas well costs JAS database Actual geothermal well costs MIT and Sandia databases Livesay WellCost Lite model EGS well predictions +/- 25% Advanced drilling technologies cases1-3 NB normalization to 2004 $ using MIT drilling cost index

48 30 Predicted Breakeven Electricity Prices(LEC) 5 km and 60 C/km - 25 LEC - this study kg/s Base Case Feasibility at 2050 High Case Feasibility at kg/s 80 kg/s 5 0 Wellcost Lite +25% Wellcost Lite Base Wellcost Lite -25% Case 1 Case 2 Case 3 Wellcost Lite +25% Wellcost Lite Base Wellcost Lite -25% Case 1 Case 2 Case 3 Wellcost Lite +25% Wellcost Lite Base Wellcost Lite -25% Case 1 Case 2 Case 3 LEC cents/kwh The Future of Geothermal Energy

49 Levelized energy costs vary with resource grade and reservoir productivity and drilling costs km depth Today's drilling technology with 20 kg/s flow rate 200 Today's drilling technology with 80 kg/s flow rate Advanced drilling technology with 80 kg/s flow rate LEC /kwh km depth km depth 4 km depth C/km 40 C/km 60 C/km 80 C/km Average Temperature Gradient The Future of Geothermal Energy

50 Accessible Pressure Temperature Domain Earth s Geosphere Geothermal energy in use today

51 High efficiency electric power at supercritical conditions

52 Iceland moves toward utilizing supercritical geothermal water Iceland s natural supercritical water region If IDDP is successful it will enable a new generation of ultra high efficiency geothermal power generation

53 Accessible Pressure Temperature Domain Earth s Geosphere

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55 What do we know now about Ocean Ridges There are 67,000 km of Ocean Ridges, representing 30% of all heat released by the earth 13,000 km have been already studied, representing 20% of the Ridges of the World 280 sites of geothermal vents have been discovered, representing 3,900 km of active vents 67,000 Km Ocean Ridges 13,000 Km Explored 3,900 Km With good vents 1 % usable 39 km! Baker has reported up to 100 km of uninterrupted vents. some of them with a thermal power of up to 6,000 MWt What if we use only 1% of the known vents to generate electricity?

56 Thermal power of an hydrothermal vent 10 cm T = 250 C T sink 10 C V = 1 m/s 1 m Q= 240x4187x1x0.1 =100 MW t /m

57 Schematic representation of a binary submarine generator 45% Carnot 90% Turbine η =10 % Total transformation efficiency (0.1x0.45x0.90) η = 4 % Specific Electric Power= 100 MW t x 0.04 = 4 MW/m Total Electrical Power in 39 km MW!!

58 Thank you for listening Please read our report at

59 Acknowledgements Acknowledge Support for the Project provided by the Geothermal Division and its Laboratories Idaho National Laboratory National Renewable Energy Laboratory Sandia National Laboratories We are especially grateful to the US DOE for its sponsorship and to many members of US and international geothermal community for their assistance, including Roy Mink, Allan Jelacic, Joel Renner,Jay Nathwani, Greg Mines, Gerry Nix, Martin Vorum, Chip Mansure, Steve Bauer, Doone Wyborn, Ann Robertson-Tait, Pete Rose, Colin Williams, Mike Wright, Roland Horne, Hidda Thorsteinsson and Valgardur Stefansson