Sally M. Benson Director, Global Climate and Energy Project
Stanford University
OCTOBER 10, 2012
GLOBAL CHALLENGES – GLOBAL SOLUTIONS – GLOBAL OPPORTUNITIES
GCEP RESEARCH SYMPOSIUM 2012 | STANFORD, CA
May 15-16, 2013
Lynn Orr Stanford University
Research at Stanford University in:
Carbon Mitigation and Advanced Combustion
Global Exergy Stores
From Hermann, 2006: Quantifying Global Exergy Resources, Energy 31 (2006) 1349–1366
0
1
10
100
1000
10000
100000
Geothermal E
nergy*
Deuterium–trit
ium (from Li)
Uranium
Thorium
Coal
Gas Hydrates Oil
Gas
Yearly Human Consumption
Exer
gy (
ZJ)
Reducing CO2 Emissions from Fossil Fuel Use
• Improve combustion efficiency • Capture and store some of the CO2 in the
subsurface • Switch fuels to lower carbon content (coal to CH4
for electric power generation, for example)
Nuclear – 30% Coal – 30-40% Solar – 15% Natural Gas – 40-60% Wind – 50% Source: US EIA, http://www.eia.doe.gov/cneaf/electricity/epa/epata6.html
Average Conversion Efficiencies
0.1
1.0
10.0
100.0
1600 1700 1800 1900 2000 2100Time (Years A.D.)
Firs
t-Law
Effi
cien
cy (%
) .
Savery, Newcomen (<0.5%)Watt/Boulton Steam EnginesPost-Watt Steam EnginesLenoir, Hugon Coal-Gas EnginesOtto/Langen Coal-Gas EnginesAtkinson, Tangye Coal-Gas EnginesBanki Spirits EnginePriestman's Oil EngineDiesel's Oil EnginesAutomotive SI EnginesTruck Diesel EnginesLarge Bore DI DieselsSteam TurbinesGas Turbine/Steam TurbinePolymer Electrolyte Membrane FCPhosphoric Acid Fuel CellsSOFC/Gas Turbine
Conversion Efficiency of “Engines”
50%
Source: C. Edwards, GCEP
Advanced Coal Conversion - Supercritical Water Oxidation with CCS Reginald Mitchell and Chris Edwards, Stanford University
Analysis of full SCWO system shows overall efficiency of 37% and is a potential option for the efficient use of coal in electricity generation with zero emissions
to the atmosphere.
Enhanced Oil Recovery by CO2 Injection
• If pressure is high enough, oil is displaced very efficiently in the swept zone.
• Transfer of components between phases by phase equilibrium and chromatography is responsible.
Reservoir Displacement
• Heterogeneity and gravity strongly influence well-to-well flow of injected gas.
• Extremes of permeability dominate the flow. • Low viscosity CO2 will find the easy flow paths between wells. • Breakthrough of injected CO2 limits sweep efficiency and recovery. • Stanford has performed decades of research to delineate the
physical mechanisms and model accurately the fluid flows in heterogeneous subsurface reservoirs
Example: CO2 Storage in a Gas Reservoir containing Condensate
ln(k)
Gas
Sat
urat
ion
Tota
l Mob
ility
Wave Velocity (z/t)
13 component fluid description (35% H2S), pure CO2 injection
Heterogeneous permeability field, 30 × 90 × 5 = 13,500 grid blocks
Numerical dispersion prevents finite-difference methods from resolving the condensate bank, except at very high grid resolution, even in 1D.
Sgas after 2500 Days Injection
Sgas
Compositional Streamlines 24 seconds
Finite difference 38,991 seconds
CSLS approach is 1600 times faster than FD (and the speedup scales as the number of grid blocks squared).
For large-scale compositional simulations sensitive to numerical dispersion, CSLS is the only feasible approach.
ERE CCS Faculty: Benson, Brandt, Kovscek, Tchelepi, Wilcox
Substituting Natural Gas for Coal in Electric Power Generation
• Reduced SOx, NOx, particulate, Hg emissions
• Reduced mining impacts, ash disposal
• Reduced CO2 emissions per kWh generated: – 57% less CO2 per unit energy in
fuel for natural gas – Better power plant efficiency
• 32% old coal • 35% NG single cycle • 60% NG combined cycle
• CO2/kWh reductions: NG 48%, NGCC 70% (if no leakage of CH4)
Source: http://www.flickr.com/photos/davipt/164341428/sizes/l/in/photostream/
Source: http://www.sitheglobal.com/projects/goreway.cfm
14
Global Shale Plays
~22,600 TCF of Recoverable Reserves 6600 TCF from Shale (40%) Current use ~160 TCF/year
Major Reassessments Reported In England, Argentina and Bengal Province
Shale Gas Basins and Gas Pipelines, India & Pakistan
Source: US EIA, World Shale Gas Resources (ARI)
Shale Gas Research Questions
• Adsorption, diffusion, and flow in nanoporous shales
• Fracture properties, slow slip
• CO2 adsorption, possible CH4 stimulation
• Accurate long-term shale production modeling at field scale
• Gas firming of intermittent renewables
Faculty: Brandt Wilcox Zoback
Conclusions • Remaining fossil fuel resources are quite large: reducing
worldwide GHG emissions will require using them in very different ways in the future
• Substituting natural gas for coal in electric power generation reduces CO2 emissions and has many other benefits (air quality, health, mining, …)
• Shale gas: potential for significant additional supplies worldwide, many remaining research questions
• Capturing and storing CO2 in the subsurface can contribute significantly to emissions reductions. Enhanced oil recovery is the primary initial target for economic reasons