This document provides an overview of carbon capture and storage (CCS) and enhanced geothermal systems (EGS). It discusses the different rock types and layers that make up the Earth's crust and subsurface. It then explains the various zones where CO2 can be stored underground, including oil and gas reservoirs, deep saline aquifers, and coal beds. The document outlines the different mechanisms by which CO2 can be trapped over time. It also discusses some of the technical and economic challenges to widespread adoption of CCS and commercialization of EGS.

1. An introduction to the geology behind Carbon
Capture & Storage and Enhanced Geothermal
Logan West
Beijing Energy Network
6 Jan. 2010

2.  Three types of rocks
◦ 1. Sedimentary – sandstone, limestone, shale
◦ 2. Igneous – granite, basalt
◦ 3. Metamorphic – marble, quartzite

3. The Earth’s Layers Plate Tectonics

4. Source: IPCC, 2005

5.  What do with the CO2?
◦ Not up
◦ Not in the oceans
◦ How about the subsurface

6.  So what does the subsurface look like?
?

7. Realistically, sometimes
Idealized Subsurface
complicated

8.  For the purposes of CCS, we are interested
sedimentary basins, depressions in the earth’s crust
into which sediments accumulate. They often have a
bowl shape.

9.  Three main zones for CO2 injection:
◦ Oil and Gas Reservoirs
◦ Deep Saline Aquifers
◦ Coal Beds
 CO2 is injected in a supercritical state (31.1° degrees C, >7.39MPa) so
C
it behaves like a gas but with a density of a liquid
◦ Doesn’t float away as quickly or easily

10.  Subsurface accumulations of oil and gas that are contained in
porous rock layers and trapped by an impermeable formation above
(caprock)
 Common Reservoir Rock: sandstone, limestone, and dolomite
 Common Caprock: shale, evaporite, or mudstone
 With respect to CCS, they can be used for Enhanced Oil Recovery
(EOR) and Enhanced Gas Recovery
Source: IPCC, 2005

11.  An aquifer is a body of permeable rock in which considerable amounts of
water can be stored and through which groundwater flows
 Geologically, it is essentially the same as an oil or gas reservoir. The greatest
difference is that the fluid contained in aquifers is majority water rather than
hydrocarbons.
 Shallow aquifers are often used for drinking, the depth and high salinity of
these aquifers make them undesirable for drinking, agriculture or industry
Source: CO2 capture project

12.  More unknown option
 Due to the nature of the coal, CO2 will typically adsorb onto external
pockets along coal deposits and overtime is absorbed into the coal
 A driving factor for Coal bed storage is the opportunity for Enhanced
Coal Bed Methane recovery (ECBM) in which CO2 replaces Methane
(CH4) on the

13.  1. Stratigraphic Trapping
◦ A good caprock should be:
 Laterally extensive
 Will prevent vertical migration (low permeability, high capillary entry pressure,
hydrocarbon trapping)
 Expectations that present faults and fractures will seal
 Adequate Rheological Properties
Info Source: WRI CCS Guidelines, 2008
Images Source: http://www.co2captureproject.org/

14.  Stratigraphic Trapping
 Structural Trapping
◦ Heterogeneities
◦ Not only caprock blocks CO2
Source: http://www.co2captureproject.org/(left);

15.  Stratigraphic Trapping
 Structural Trapping
 Residual Trapping
◦ Stuck in the pore space
Source: http://www.co2captureproject.org/

16.  Stratigraphic Trapping
 Structural Trapping
 Residual Trapping
 Solubility Trapping
◦ CO2 dissolves into water
◦ No longer buoyant
 Hydraulic Trapping
CO2 (g) + H20  H2CO3  HCO3- + H+  CO32- + 2H+
Source: http://www.co2captureproject.org

17.  Stratigraphic Trapping
 Structural Trapping
 Residual Trapping
 Solubility Trapping
 Mineralization
◦ Bicarbonate (HCO3) formation
◦ Once it’s in mineral (i.e. solid) form, it’s stuck for
millions of years
3  KAlSi3O8   2H 2O  2CO2  KAl2  OH 2  AlSi3O10   6SiO2  2K   2HCO3

3  NaAlSi3O8  +2H 2O+2CO2  NaAl2  OH 2  AlSi3O10  +6SiO2 + 2Na + + 2HCO3
-
3  CaAl2Si 2O8  +4H 2O+4CO2  CaAl4  OH 4  AlSi3O10 2 + 2Ca(HCO3 ) 2

18. Storage Mechanisms Storage Risks
Source: WRI, 2008

19.  Key Parameters:
◦ Capacity  Can it hold all the CO2?
 Factors: size of reservoir, volume of pore space, CO2 density
◦ Containment  Will it stay there?
 Factors: Caprock Integrity, effect of other storage mechanisms
◦ Injectivity  Can we pump it in as fast as it’s piped to the site?
 Factors:Permeability
 Basin Depth between 800–3000m – for supercritical state
◦ Behaves like a gas but dense like a fluid (keeps it from “floating” away
quickly)

20.  Economics
 Conflict of interest (minerals, petroleum, water)
 Protected areas
 Population
 Etc.
Image Source: The World Bank, The cost of pollution in China, 2007

21.  Thorough Site Selection and Characterization
 Monitoring plan
◦ Start prior to injection
◦ Continue decades after injection
 Reservoir Models
◦ Create as you learn about the geology
◦ Update with monitoring data
◦ Use to predict how CO2 will move overtime
 Risk Analysis
◦ Identify known storage risks
◦ Create plans for how to protect against them
◦ Be prepared with plans if leakage does occur Seismic Monitoring
Source: IPCC, 2005

22.  Similar anthropogenic projects or natural formations
◦ Acid gas (H2S) underground injection
◦ Liquid waste underground injection
◦ Natural CO2 reservoir
 Thus far proven in CO2 Storage demonstrations
In Salah, Algeria
Sleipner, Norway
Weyburn, Canada
 IPCC Quote: “Observations from engineered and natural analogues
as well as models suggest that the fraction retained
in appropriately selected and managed geological
reservoirs is very likely25 to exceed 99% over 100 years
and is likely20 to exceed 99% over 1,000 years.”
Source: IPCC, 2005

23.  CO2 in heavy concentrations (>7-10% air
composition can lead to human death)
◦ Is denser than air so can accumulate in low lying areas until
is dispersed by wind
 Forms carbonic acid in water
◦ Render water non-potable, bad for agriculture
◦ Can leach heavy metals
 Can lead to acidification of soil
◦ Bad for organisms
◦ Can leach heavy metals – worse for organisms
 There are means of remediation to plug leaks and
minimize impacts
Source: IPCC, 2005

24. Emissions for Storage
Storage Prospectivity
Regions
Source: APEC 2005

25.  NRDC:
Source: http://www.nrdc.org/international/chinaccs/default.asp
 PNNL: China may have 2,300 Gt (>100yr demand)
of onshore CO2 storage capacity:
• 2,290 Gt in deep saline formations
• 12 Gt in coal seams
• 4.6 Gt in oil fields
• 4.3 Gt in gas fields
Source: PNNL, Establishing China’s Potential for Large Scale, Cost Effective Deployment of
Carbon Dioxide Capture and Storage, October 2009, PNNL-SA-68786

26.  Storage in China faces several challenges
◦ Geological Complexity
◦ Local Capacity Issues for EOR
◦ Unmarked, poor quality wells – potential leakage sources
◦ Data Accessibility – overall lack of data, data that exists often proprietary to oil,
gas, and mining companies
Capacity
Envelope -
Data Geological Reservoir Pipeline Conflicts of
Volume and Containment Injectivity Well Integrity
Availability Complexity Availability Distance Interest
Reservoir
Quality
Dagang Oilfield Province
Shengli Oilfield Province
Huimin Sag Saline Formations
Kailuan Mining Area
Low risk
Medium risk
High risk
Image showing relative risk in possible storage fields in China’s Bohai Basin
Source: Espie, T. COACH WP4: Recommendations and Guidelines for Implementation
COACH-NZEC Conference, 28 Oct. 2009

27. • Further analysis doesn’t necessarily support theoretical estimates
 Storage capacity
◦ oil fields: from 10 to
500MtCO2
◦ Deep saline aquifers: ~
20GtCO2
◦ Coal mines: 500GtCO2
BUT availability and
injectivity questionned
due to extremely low
permeability
Source: Kalaydjian, F. Key findings from NZEC Phase I: COACH Overview
Presented at NZEC-COACH Conference, Oct. 28, 2009

28.  Continue In-depth investigation to achieve
more realistic capacity estimates and identify
exact storage sites
 Improve access to data
 Begin storage demonstration projects
 Continue to improve reservoir modeling and
characterization technology
 Define tools and best-practice for site
characterization and monitoring

29. ENHANCED GEOTHERMAL
SYSTEMS (EGS)

30. WHAT DOES GEOTHERMAL MEAN?
 The Earth’s core is ~5,500C.
 Convection, Conduction, and Radiation transport
heat to the crust
 Geothermal Gradient
 Average surface temperature is 15C
 Temperature increases with depth at a rate ranging
from 15 C/km to 50 C/km

31. HOW DO WE USE GEOTHERMAL ENERGY?
 Direct Use: Heat Pumps, Bathing, Space
Heating, etc
 2000  75,000+ GWh worldwide usage
 Electric Power Generation: via steam powered
turbines
 2003  56,000+ GWh worldwide usage
Source：Glitner US Geothermal Energy Market Report 2007

32. WHAT ARE ENHANCED GEOTHERMAL
SYSTEMS (EGS)?
 Hydrothermal Energy: natural hot springs
 Shallow: < 3km depth
 In situ, High Temp Water: > 150C
 Limited Resources
 Enhanced Geothermal
 Deep: 3 – 10km depth
 Hot Rocks: Temperatures ranging 150 to 400+C
 No Natural Reservoir: Reservoir must be created and
water pumped in
 Vast Resources

33. BEST EGS REGIONS
 Looking for High Heat Flow and/or High
Temperature Gradients
 Plate Boundaries – Geologically Active
 Sedimentary Basins

34. USA GEOTHERMAL RESOURCES
Source: MIT Future of Geothermal Energy, 2006

35. Simplified cartoon rendering of EGS plant (left) and schematic of Geothermal Binary Power Plant (right): http://www.geothermal-energy.org/geo/geoenergy.php

36. KEYS FOR SUCCESS
 Most important factor is Flow Rate
 Combination of permeability, volume of fractured
rock, surface area of fractured rock
 Need to have as little loss of water as possible

37. POTENTIAL FOR EGS
 USA Recoverable Resource : 1
 In the USA alone, 28.95 million Terrawatt hours
 Could power the world for 590 years at 2007
consumption levels
 Other countries beginning to do analyses
 Predicted USA Development of EGS through the
year 2050 (MWe) ： 2
2015 2025 2050
1,000 10,000 130,000
1: Values from MIT Future of Geothermal Energy (2006) and BP Statistical Review of World Energy 2007 2: NREL Geothermal Resources Estimates for the US 2006

38. ADVANTAGES OF EGS
 Renewable
 Energy Security
 Limits demand for fossil fuels
 Every Nation possesses some geothermal resource
 Baseload Power Source
 Constant, non-fluctuating energy
 Hydrothermal Plants operate at 95% capacity
 Economically competitive
 Cost currently estimated 8-14 cents/hr
 Tremendous incentive for natural technology growth
 Minimal Environmental Impact

39. ENVIRONMENTAL BENEFITS OF EGS
 Near Zero Emissions*
Environmental Carbon Dioxide Sulfur Dioxide (SO2) Nitrogen Oxide
Emissions for U.S. (CO2) (Lbs/MWh) (NOx)
Power Plants (Lbs/MWh) (Lbs/MWh)
New Coal Plant** 2068 3.6 2.96
Old Coal Plant 2191 10.39 4.31
New Natural Gas Plant 850 0.018 0.31
Geothermal Flash
60 .35*** 0
Plant
Geothermal Binary
0 0 0
Plant
 Limited Plant Surface Area*
 7x less than Nuclear; 35x less than Coal
 Induced Seismicity comparable to oil, gas, and
mining operations
* Data from NREL Geothermal Report
** New = Coal Plants built in 1990s; natural gas combined cycle plants built in 2002
*** This is indirectly

40. POTENTIAL PROBLEMS
 Induced Seismicity
 Hydrofracturing rocks by nature sets of micro-
earthquakes
 Recorded magnitude 3.2 earthquake in Basel,
Switzerland argued to be caused by local EGS plant
 There are over 130,000 Magnitude 3-3.9 earthquakes
in the world each year with minimal damage at most1
 A magnitude 4.9 (almost 100x greater than Basel)
occurred in Yunnan New Year’s Day 2010. It received
no press.
 Technological Difficulties
1: USGS

41. WHAT STAGE IS EGS DEVELOPMENT AT?
 Successes : 1
 Pilot projects can create reservoirs, generate power on the
scale of a few megawatts
 Power plants already capable of converting supercritical
water (temp of 400 C) into electricity
 Technological Obstacles:
 Better control of reservoir creation
 Drilling equipment withstand > 5km depth and 200C
environment
 Maintaining a commercially viable, production flow rate
 Economic Obstacles : 2
 Capital Intensive (drilling and plant construction)
 Overcoming initial “Valley of Death” investment (est.
US$3.5 million per MW)
1: Source – MIT Future of Geothermal Energy 2006 2: Glitner US Geothermal Energy Market Report 2007

42. GEOTHERMAL RESOURCES OF CHINA:
HEAT FLOW
Source: Hu et. al., 2001

43. GEOTHERMAL REGIONS OF CHINA
High Grade Medium to Low Grade
Source: Pang, 2009 http://english.iggcas.ac.cn/pangzhonghe/index.html

44. CHINA, GEOTHERMAL, & EGS
 China is the world leader in total Direct Use
geothermal energy 1
 China only utilizes 5% of hydrothermal resources it
deems economically exploitable 2
 Southwest China (Tibet, Sichuan, and Yunnan) and
the Southeast Pacific coast possess large high-grade
geothermal resources 2
 Sedimentary Basins (also a key source) cover 36% of
China 3
 Currently China has only one hydrothermal power
plant in operation at Yangbajain (28 MW) providing
½ of Lhasa’s electricity 2
 If China were to possess only 1/10th of the recoverable
resources of the USA, it could still meet its 2008
primary energy demand for 333 years 4
1: Glitnir US Geothermal Energy Market Report 2007; 2: Ministry of Land and Resources; 3: Pang, Z. 2009; 4: Calculations from Data of MIT & BP Reports

45. POTENTIAL NEXT STEPS FOR CHINA
 Conduct full Geothermal resource assessment
 Already has plans for new hydrothermal resource
assessment
 Promote investment of deep drilling technology
investment and other Geothermal Technologies
 Further develop its hydrothermal resources
 Plan for EGS pilot plants based on finding of
geothermal resource assessment

46. ACKNOWLEDGMENTS
 Tsinghua-BP Center
 World Resources Institute
 National Resources Defense Council
 Princeton In Asia
 Zhang Dongjie