University of Colorado at Boulder Department of Electrical, Computer, and Energy Engineering Energy...
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University of Colorado at Boulder Department of Electrical, Computer, and Energy Engineering Energy Storage Research Group Energy Storage and The Integration of Renewable Energy Into The Grid http://www.colorado.edu/engineering/ energystorage/ Frank S Barnes [email protected]303.492.8225
University of Colorado at Boulder Department of Electrical, Computer, and Energy Engineering Energy Storage Research Group Energy Storage and The Integration
University of Colorado at Boulder Department of Electrical,
Computer, and Energy Engineering Energy Storage Research Group
Energy Storage and The Integration of Renewable Energy Into The
Grid http://www.colorado.edu/engineering/energystorage/ Frank S
Barnes [email protected] 303.492.8225
Slide 2
Acknowledgements Jonah Levine Michelle Lim Mohit Chhabra Brad
Lutz Greg Martin Muhammad Awan Taha Harnesswala The work leading to
this talk was conducted by 2 Richard Moutoux Camelia Bouf Kimberly
Newman
Slide 3
3 Outline of Our Work 1. Potential Location of Pumped
Hydroelectric Storage in Colorado 2. Issues in Compressed Air
Storage at 1500m in Eastern Colorado 3. The use of battery storage
for frequency control and voltage regulation 4. Feed In Angle for
Solar Power 5. The Optimization of Energy Use in Water Systems. 6.
Detection of Power Theft 7. Optimization of Energy Use in Water
Systems
Slide 4
Obstacles to Integration of Wind and Solar Energy 1. The
Variability of Wind, Solar and Hydroelectric Power and Mismatch to
the Loads 2. The Integration and Control of a Large Number of
Distributed Sources in to the Grid 3. Lack of low cost convenient
energy storage systems 4
Slide 5
San Luis Valley Solar Data (09/11/2010) Good Day [1] 5
Slide 6
San Luis Valley Solar Data (09/12/2010) Bad Day [1] 6
Slide 7
Intermittent Wind Generation 7 7
Slide 8
Simplified System Model 8 Reference: [2]-[4] S base = 600 MVA
Network Electric System Steam Generator + Wind Generators + Energy
Storage System (ESS) + + Load - Gas Generator Load (4-hr) Value
(MWh) Winter~1500 Summer~1640
Slide 9
Input Data 9 S base = 600 MVA 11 th Jan 2011: 1 pm9 th June
2011: 1 pm
Slide 10
Frequency - Winter 10 No ESS ~0.35 ESS~0.20 ~32% wind
penetration
Slide 11
Frequency - Summer 11 No ESS ~0.61 ESS~0.15 ~29% wind
penetration
Slide 12
Power Spectrum [1] 12 278 hour s 27.8 hour s 2.78 hour s 16.7
min 100 sec 10 sec 2 sec small magnitude: turbine acts as low-pass
filter Turbine upper limit Energy Storage Short-term Short-term
Storage Time Scale : 10 sec 3 hrs
Slide 13
References [1] J. Apt, The spectrum of power from wind
turbines, Journal of Power Sources, v.169, March 2007 [2] G. Lalor,
A. Mullane, M. OMalley, "Frequency Control and Wind Turbine
Technologies, IEEE Transactions on Power Systems, v. 20, no.4,
November 2005 [3] R. Doherty et al, An Assessment of the Impact of
Wind Generation on System Frequency Control", IEEE Transactions on
Power Systems, v.25, no.11, February 2010 [4] P. Kundur, Power
System Stability & Control, McGraw-Hill, 1994 13
Slide 14
Matching Fossil Resources to the Net Loads In Colorado
Generation Resource Type Rated Capacity [MW] Ramp Up [MW/hr] Ramp
Down [MW/hr] Coal sub- total [i] [i] 2834322.58-630.27 Gas
sub-total77537.70-65.75 Ramp per (MW/hr)/MW avg. NA.0998-.1926
Total3609360.28-695.02 Extrapolated Total 7,884
MW786.82-1,518.30
Slide 15
Xcel PSCo Load Duration Curve and Net Load Duration Curves Min
Coal Generation 15
Slide 16
Case When Wind Energy Exceeds Capacity. Current Law Requires
use of Wind Energy The wind energy may exceed the amount of gas
fired energy that can be shut off and require the reduction of heat
rate to coal fired plants This reduces electric power generation
efficiency and increase emissions of SO 2, NO x and CO 2 for old
plants It is expected to up to double the costs of maintenance.
16
Slide 17
Example of Wind Event and Response 17
Slide 18
Resulting Increase in SO 2, NO x 18
Slide 19
Emissions for Start Up, Ramping and Partial Loads IEEE Power
systems Nov-Dec. 2013 19
Slide 20
Number of Ramps per Year 20
Slide 21
Cost of Increasing Wind Energy Penetration 21 Gas Cost Impact
of wind penetration with and without storage on Xcels electric grid
Cost Impact of increasing wind penetration on Xcels electric
grid
Slide 22
Lower Bound on Cycling Costs IEEE Power Systems Nov-DEC 2013
22
Slide 23
Increasing Cost with Penetration of Wind Power 1 23
Slide 24
Approaches to Solving the Variability Issues. 1. At low
penetration grid spinning reserves. 2. Gas fired generators 3.
Storage a. Batteries, super capacitors, fly wheels b. Pumped
Hydroelectric systems, CAES 4. Demand Response 5. Biomass,
geothermal 24
Slide 25
Energy Storage Systems 25
Slide 26
Comparison of efficiency of several energy storage technologies
NREL report 26
Slide 27
Pumped Hydro Raccoon Mountain 1 27
Slide 28
Pumped Hydro In Colorado 1 28
Slide 29
Potential Locations and Capacity for Pumped Hydro in Colorado 1
29
Slide 30
Pumped Hydro Storage in Colorado Wind Integration Study for
Public Service of Colorado Addendum Detailed Analysis of 20% Wind
Penetration
http://www.xcelenergy.com/SiteCollectionDocuments/docs/CRPWindInteg
rationStudy.pdf 30
Slide 31
Snapshot of Pumped Storage Globally Rick Miller HDR/DTA Pump
Storage Units in Operation (MW) by Country/Continent Pumped Storage
Projects Under Construction (MW)
Slide 32
Slide 33
ECEN 2060 Lecture 37 December 2, 2013 Compressed Air Energy
Storage CAES 33
Slide 34
Compressed Air Storage 34
Slide 35
Compressed Air Energy Storage CAES Questions of Interest 1.
Where can we locate CAES.? 2. Some Design Considerations 3. Value
of Storage 4. When is it Cost Effective? 35
Slide 36
Current and Planned CAES Systems 1. Huntorf Germany 1978 290 MW
for 2 to 3 hours per cycle 2. McIntosh, Alabama 110 MW,19 million
cubic feet and 26 hours per charge 3. Others that have been under
discussion for a long time A. Iowa Stored Energy Park B. Norton
Ohio (2700 MW) 4. Others? 36
Slide 37
37 Aerial view of Huntorf facility
Slide 38
38 McIntosh facility plant room
Slide 39
CAES Characteristics 1. It is a hybrid system with energy
stored in compressed air and need heat from another source as well.
2. Require 0.7 to 0.8 kWh off peak electrical energy and 4100 to
4500 Btu (1.2 -1.3 kWh) of natural gas for 1 kWh of dispatchable
electricity 3. This compares with ~ 11,000 Btu/kWh for conventional
gas fired turbine generators. 4. Efficiency of electrical energy
out to electrical plus natural gas energy in ~ 50% 39
Slide 40
CAES Characteristics Another way to calculate efficiency is
comparing to the normal low efficiency of natural gas turbines with
heat rate of 11000 Btu/kWh yielding 0.39 kWh of electricity and
adding 0.75 kWh off peak electricity to get 1.14 kWhs to get 1 kWh
of dispatchable electricity This gives an efficiency of 88% There
are two types of CAES systems o Underground CAES o Above ground
CAES 40
Slide 41
Underground CEAS Potential for large scale energy storage 100
to 300 MW for 10 20 hours. Effective in performing load management,
peak shaving, regulation and ramping duty. Less capital cost
compared to other large scale energy storage options. 41 Main
components of underground CAES
Slide 42
Challenges associated with Underground CAES Identification of
suitable site for setting up a underground facility. Optimizing the
compression process to reduce the compression work required.
Thermal management efficiently extracting, storing and reusing the
available heat of compression, thus improving the efficiency of the
system. Understanding the effect of cyclic loading and unloading on
the structural integrity of the underground cavern. 42
Slide 43
Deep CAES Deep compressed air energy storage is an underground
CAES facility where the cavern is formed at depths of >4000 ft.
as against 1000-2000 ft. in case of conventional facilities. The
main advantage of going deep are, o Maximum permissible operating
pressure of a cavern increases with depth. - A good approximation
will be 0. 75 to 1.13 psi/ft. based on the local geology. o Hence
going deep helps store air at higher pressures in much smaller
cavern volume, hence higher energy density. The possibility of
setting up a deep compressed air energy storage facility in Eastern
Colorado is being currently investigated by Energy Storage Research
group at CU, Boulder. 43
Slide 44
Challenges associated with Deep CAES Deep CAES brings in
additional challenges, which are Utilizing the high pressure
compressed air effectively. Most of the off-the-self gas turbines
operate in the range of 70- 100 bars, hence it is necessary to
design the system such that high pressures can be utilized.
Understanding the effect of high pressure & temperature on the
cavern structure. Identifying suitable equipment's / material to
operate at high pressure. Potential for leakage through faults.
44
Slide 45
Criteria for Site Selection 45 1. Tight Cavern 2. Adequate
natural gas 3. Ability to withstand 600 to 1200psi for conventional
& 2000 5000 psi for deep CAES. 4. Proximity to Wind or Load to
minimize transmission line losses. 5. Appropriate geology 6. A
report by Cohn et al. 1991 Applications of air saturation to
integrated coal gasification/CAES power plants. ASME 91-JPGC-GT-2
says that this can be found in 85% of the US.
Slide 46
Possible Geologies 1. Abandoned Natural Gas fields. 2. Old
Mines 3. Dome Aquifers 4. Porous Sandstone 4. Salt Domes 5. Bedded
Salt 46
Slide 47
Why Salt Beds / Domes? Salt beds are more desirable for setting
up new Caverns because of the following reasons, Easy to be
solution mined Salt has good Elasto-plastic properties resulting in
minimal risk of air leakage Salt deposits are widespread in many of
the subsurface basins of the continental US, including western
states (Colorado, West Texas, Utah, North Dakota, Kansas) 47
Slide 48
Salt Formations 48
Slide 49
Potential CAES Sites 49
Slide 50
Potential CAES In Colorado 50
Slide 51
Gas Well in The Denver Julesburg Basin 51
Slide 52
Neutron Porosity Log 52
Slide 53
Salt Beds In Pink 53
Slide 54
Salt Beds In Eastern Colorado 1. Salt beds from 4100 ft to
6,800 ft. 2.Thickness from 3 to 292 ft. 3. Required Operating
pressures in the range of 4000 to 7000 psi. 6 At about 6,000 psi we
need about 14,400 cubic meters per gigawatt hour energy storage or
a cavern of about 30 x22 x 22 meters 54
Slide 55
Need for thermal management When air is compressed - up to 85%
of the energy supplied is lost in the from of heat. 55 Even with
isothermal compression 50% of the energy may be lost as heat
Storing and re-using the heat of compression would result in
increasing the overall efficiency of the CAES system and result in
reduced or no fuel consumption. Figure showing the fraction of work
stored in compressed air Vs. the pressure. Rest dissipated as heat.
Polytrophic compression
Slide 56
Isothermal CAES 56 Another approach to keep the temperature
constant during compression is to slow down the pumping process (As
it results in efficient heat dissipation thus constant
temperature). Such a system can be used for small scale
applications. Isothermal CAES developed by SustainX The SustainX
system operates at 0 to 3000 Psi and provides 1 MW for 4 hours at
an expected efficiency of 70%.
Slide 57
Recent developments in AA - CAES 57 RWE group, Germany in
collaboration with GE are developing an AA-CAES project. (Started
2010) They propose no fuel operation with a target efficiency of
70% Findings: Feasibility study has shown that such high
efficiencies can be achieved by system optimization and suitable
equipment development. Challenges: R&D is being carried out to
develop Turbomachinary & Thermal energy storage to achieve the
above goals.
Slide 58
Lecture 38 ECEN 2060 December 4, 2013 58
Slide 59
Storing & Re-use of compression heat Heat of compression
can be stored in two ways o With the help of thermal energy storage
facility o By storing the heat in compressed air itself There are
two options for utilizing the stored energy o Using the stored heat
+ Fuel for preheating the air o Only utilizing the stored heat (No
Fuel) also called as Advanced Adiabatic CAES (AA-CAES). 59
Slide 60
Thermal Time Constants Thermal time constants vary with the
surface to volume ratio. For a Sphere For a Cylinder For a cube For
a rectangle 60
Slide 61
(Source: Geyer 1991) 61 Physical Properties of Sensible Storage
Materials
Slide 62
Major Cavern Design parameters Cavern geometry & volume
Depth of the cavern as the overburden pressure increases with depth
Cavern Minimum operating pressure as inside pressure of the cavern
acts as a static lining to the cavern contour Cavern maximum
operating pressure must be fixed to avoid gas infiltration and
cracking of the surrounding rock mass Cavern operation pattern
Distance between adjoining caverns 62
Slide 63
Cavern operating pressures Operating pressure of the cavern
depends on the, Depth of the cavern The in-situ stresses in the
surrounding rock formation. The maximum operating pressure of the
above ground equipment. 63
Slide 64
Effect of cyclic loading on cavern Increase in cavern inside
pressure causes increase in deviatoric stresses, this in turn
results in increase in creep rate. Its has been found by laboratory
experiments that the overall creep rate decreases in case of cyclic
loading, thus resulting in reduced convergence good for CAES. But
the stresses in the rock mass increases. Charging & discharging
of cavern is associated with rise and fall in temperature inside
the cavern as well as the rock surrounding it. Heating of rock salt
creates thermal induced compressive stresses, cooling of rock salt
creates thermal induced tensile stresses. *Results of experiments
conducted by University of Technology, Clausthal-Zellerfeld,
Germany 64
Slide 65
Effect of cyclic loading on cavern 65 Transient effect of
cyclic stresses on the salt cavern (cycle period 5 days) The graph
shows the reducing creep rate & increase in stress with time.
*Results of experiments conducted by University of Technology,
Clausthal-Zellerfeld, Germany
Slide 66
Effect of cyclic loading on Cavern 66 Change in contours of the
Huntorf Caverns between 1984 & 2001 Survey of the Huntorf
cavern contour conducted in 1984 & 2001 show negligible
convergence of the cavern in spite of continuous cyclic operation.
Visualization of thermally induced cracks in salt rock
Slide 67
Further work needed: Understanding the thermo-mechanical
effects (convergence & creep) on surround rock at high
pressures & temperature. Effect of different charging and
discharging periods / operation patterns Effect of having a deep
cavern at atmospheric pressure for maintenance work. 67 Effect of
cyclic loading on Cavern
Slide 68
System Integration 68 One of the suitable configurations to
utilize the maximum available pressure
Slide 69
Economics 1. Costs A. A little more than conventional gas fired
generators at $4oo to $500/kW B. CAES estimates at $600 to $700/kW
(Note these numbers could be low depending on the site etc) C. Low
Operating Costs 2. Value A. Smooth out wind fluctuations B. Match
to transmission line limits. C. Match to loads increasing capacity
factor. 69
Slide 70
Economics 2. Value D. Absorb Energy when the wind power exceeds
transmission or load. This is in contrast to gas fired generators
E. Arbitrage, buy wind or other energy low and sell high. F.
Ancillary services, frequency control, black start etc. G. Reduced
natural gas consumption by approximately two thirds. 70
Slide 71
Economics Factors effecting CAES capital cost o CAES site
selection Depth of Cavern Local geology Proximity to transmission
network Availability of Natural gas o Presence of Thermal energy
storage,TES. Factors effecting CAES Operating cost o Cost of off
peak energy and/or Wind energy generation cost. o Natural gas
requirement based on TES availability 71
Slide 72
Levelized Cost of Electricity CAES Options 72
Slide 73
LCOE as a function of depth 73
Slide 74
Batteries 1. Lead Acid 2. Metal Hydride 3. Li Ion 4. Na S 5.
Vanadium Redox Flow 74
Slide 75
Lead-acidNaSLi-ion Vanadium redox Chemistry Anode Cathode
Electrolyte Pb PbO 2 H 2 SO 4 Na S -alumina C LiCoO 2 Organic
solvent V 2+ V 3+ V 4+ V 5+ H 2 SO 4 Cell Voltage Open circuit
Operating 2.1 2.0-1.8 2.1 2.0-1.8 4.1 4.0-3.0 1.2 Specific Energy
& Energy density Wh/kg Wh/L 10-35 50-90 133-202 285-345 150 400
20-30 30 Discharge P rofile Flat Sloping Flat Specific Power W/kg
Moderate 35-50 High 36-60 Moderate 80-130 High 110 Cycle life,
cycles 200-7002500-45001000 12,000 Advantages Low cost, good high
rate Potential low cost, h igh cycle life, h igh energy and good
power density, h igh energy efficiency High specific energy and
energy density, low self discharge, long cycle life High Energy,
high efficiency, high charge rate, low replacement costs
Limitations Limited energy density, Hydrogen evolution Thermal
management, s afety, d urable seals, f reeze- thaw durability Lower
rate (compared to aqueous system) Cross mixing of the electrolytes
75
Slide 76
NaS Battery. 76 NaS Battery Cell Diagram of electron and ion
motion during discharge and charge cycles. (Courtesy of NGK)
Slide 77
NaS Batteries Twenty NaS Batteries installed in four enclosures
77
Slide 78
NaS Battery Costs Major cost components for an installed
NaS-based DESS 78
Slide 79
Vanadium Redox Battery 79
Slide 80
Vanadium Redox Flow Battery
Slide 81
Vanadium Redox Battery FB10/100 Fluid, thermal, safety system.
81 1.Fluid lines 2.Positive electrolyte pumps 3.Positive
electrolyte tank 4.Return lines 5.Negative electrolyte tank
6.Negative electrolyte pumps 7.Stacks (also called cell stacks or
modules) 8.Rebalance valve. Source : html://www.cellstrom.com
Slide 82
82 Capital Costs for Energy Storage
Slide 83
Life Cycle Costs of Storage
Slide 84
Mobile Battery and Supercapacitor Costs Capacity Price Energy
Density 1. Lead Acid $215/KWh 25 Wh/Kg 2. NiM $3500/KWh 43 Wh/Kg 3.
Li ion $1250/KWh 300 Wh/Kg 4. Supercapacitors 4 Wh/Kg 84
Slide 85
Energy Density for Batteries
Slide 86
When does Storage Pay ? 1. It depends on the details, however
estimates are in the range of 15% wind energy penetration 2.
Thermal Storage seems to pay almost always for large solar thermal
systems. 86
Slide 87
Power Plant Transformer Substation The Regional Grid Pumped
Hydro Transformer Substation Current Power Grid The Regional Grid
87
Slide 88
Transformer Substation The Regional Grid Pumped Hydro
Transformer Substation Future Power Grid Wind Farm Solar Farm
Communication & Control CAES Thermal Storage Power Plant The
Regional Grid Batteries Solar Cells 88