Sumario de estudio comparativo de tecnologías de almacenamiento de energía. 2009

1. Grandes sistemas estáticos
de almacenamiento de
energía
Prospectiva tecnológica y
análisis comparativo
Comparativa tecnologías
de almacenamiento de
energía a gran escala.
Sumario Julio 2009

2. Energy Storage Facility Load Profile
Multiple Value Streams

3. Pumped Hydro 1
Availability 95% efficiency around 70%. 200 plus MW scale

4. Pumped Hydro 3
Capex = $3000/kW. Siting permit issues.
40 year life
Opex = $0.015/kWh

5. Pumped Hydro 4 – response rates

6. Pumped Hydro 2

7. Fuel cells
• PEM - low
temperature 120 º C
• Phosphoric Acid
(PAFC) and Molten
Carbonate (MCFC) –
medium temperature
• Solid Oxide (SOFC) -
high temperature
1000ºC

8. Limitations of Fuel Cells
• They reduce emissions, but do not reduce GHG unless hydrogen
fuel is derived using electrochemical processes from solar or wind
powered converters. This is highly inefficient
• They suffer from poisoning of noble metal catalysts by CO/CO2
• Energy efficiencies are approximately 60% less than for the VRB-
ESS
• High costs $3000- 4500/kW*
• Short cycle life – 1500cycles
* MTU and UTC 2007

9. Compressed Air Energy Storage
1. Excess electricity is 4. The electricity produced is
used to compress delivered back onto the
air grid
Exhaust
Waste heat
Air
2. Air is pumped
underground and stored 3. When electricity is needed,
for later use the stored air is used to run
a gas-fired turbine-
Compressed
generator
Air
Ridge energy
General compression in wind towers. Or in caverns salt LLC
domes etc.
Costs claimed around $1.8m/MW. HR= 4700btu/kWh
Ramp rates around 15seconds per 50MW
Requires natural gas supply
60MW or larger although tank compression on surface in smaller sizes proposed

10. Thermal Energy storage
• Hot water resistive heating - district
heating – proven - low efficiency
• Molten Salt energy storage - solar
concentrators –proven Expensive used in
PV concentrators
• Graphite block – ex nuclear industry
technology - research
• Ice storage – DSM approach - proven

11. Renewable
Electricity Transport
Source
Energy Consumer
by electrons
100%
90%
by hydrogen
electrolyze
fuel cell
renewable AC
r
transported
packaged
transferre
hydrogen
electricity
electricity
25%
store
20%
gas
DC
D
C
C
A
d
gaseous hydrogen d
liquid hydrogen
Ulf Bossel – October 2005

12. Lead Acid Battery The de-facto standard
There are two types of Lead
Acid Battery
- Flooded or vented
- Sealed: valve regulated lead
acid (VRLA) and Gel types
- AGM (Absorbed Glass Mat) –
advantages over Gel and
similar cost
-Costs for UPS shallow cycle
china lead acids $150/kWh
-Cost for deep cycle PV – EU -
$500/kWh
-China $280/kWh

13. Problems with Lead Acid Batteries
? Cannot leave battery in a charged state for long periods due to
sulphation
? If VRLA battery is not gassing when charged then there is a danger of:
- Stratification of electrolyte
- Reduction in battery life
- Gell damage is voltage incorrect on charge Despite these problems
? Gassing when charging results in they are the standard
and there is a great body
- loss of electrolyte VRLA of knowledge
- Explosive hydrogen formation
? Needs to be oversized for maximum cycle life
? SOC of battery hard to measure
? Charge to discharge ratio usually long – 5 to 1 : C-rates

14. Depth of discharge impacts on ALL non FLOW
batteries – reduces life and severely limits their
suitability for wind power smoothing
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15. Sodium Sulphur – NAS battery
• High Temperature – 350ºC Molten sodium and
sulphur
• 65 to 70% roundtrip efficiency (AC-AC) Small
footprint
• Received large Japanese subsidies over 15
years of development –strong balance sheet
• Don’t handle partial cycling e.g. wind –
integration for SOC
2MW 7.5 hour NAS in Japan
• SOC must be calculated/ averaged so periodic
off line measurements required
• Overcharging is dangerous
• Requires parasitic heating to maintain
temperatures
• 3500 cycles
• Maturing product, 250MW installed

19. This means that in an average wind application, where about 200 to 600 partial cycles (average power
swings of 50% (+-25%) occur per day averaging 0.3hours, the NAS battery with 6 usable hours of storage
will experience an equivalent of 3 to 5% of full rating in partial discharges. From the energy throughput life
curve below, the NAS battery will last around 100,000 cycles or about 1,000 days so 3 to 4 years. BY
overrating the battery this can be extended. A VRB-ESS has NO such limitation nor overrating requirement.
19

20. Equivalent VRB with no life limit for this
NOTE: Required for Charge and application is 50% the power rating and 35%
Discharge the storage (hours) and thus 20% the cost
20

21. NAS versus VRB-ESS cost comparison for
equivalent performance with wind
• NAS is modular MW x 6 hours. Cost with PCS and
controls and storage thus China and EDF around $550
to 650/kWh or US$4million
• VRB-ESS can have any number of hours. IT requires
50% MW rating for same NAS and storage of only 2
hours for wind for every 6hours of NAS – because we
know SOC accurately and have no cycle reduction due
to deep cycles. Thus an equivalent VRB-ESS will cost
US$2million
• VRB-ESS will last 3 times as long and then only costs
$500k to extend life another 10 years. NAS would cost
3.5Million to replace. Life cycle cost thus VRB-ESS=
$2.5million versus NAS $7.5million or 3 TIMES less.

22. Nickel Cadmium (Ni-Cd)
• Longer life than lead acid
• Suffer from problems of memory effect
• Disposal problems
• Shortage of Cadmium
• Expensive
• The Golden Valley installation in Alaska 40MW for 15minutes – 4 x VRB-ESS size.
10x cost. Has perfumed well over 5 years
Nickel Metal Hydride (Ni-MH)
• Similar to Ni-Cd but negative electrode uses metal alloy which absorbs hydrogen
• Hydride electrode has higher energy density than Ni-Cd so higher capacity for
same size
• More environmentally friendly than Ni-Cad – no Cadmium
• Suffers memory effect
• Expensive

23. Lithium Ion (Li Ion)
• Cathode is Lithiated metal oxide
• High Efficiency
• High energy density – 130Wh/kg
• 2000 cycles at 88% DOD
• Problem in Large sizes is that
special packaging for overcharge
control – ($1050/kWh) is required
• Battery life exhibits logarithmic
improvement with respect to
both average depth-of-discharge
and temperature
Lithium Titanate (A123), LI Phosphate (Valence), Lithium thionyl (Li-SOCl2)
AMR, BYD (China)

24. Lithium Ion (Li Ion) continued
? Li-ion is often misused as a battery type by misinformed OEM customers.
While the layman term is what is most commonly referenced when talking
about lithium batteries, it is really the true chemical compounds of the
anode, the cathode and the separator that make up a cell. Cobalt Oxide,
Iron Phosphate and Manganese Oxide are the most commonly used
cathode materials. "Poly" or lithium-ion polymer batteries are often
seen as a specific type of cell while in reality the term polymer in the name
describes the separator structure. Poly cells with Cobalt Oxide or Iron
Phosphate cathodes are used in cells today. No matter the makeup, each
of the lithium ion cell variants require careful tuning of their key
parameters to maximize cycle life.
? Signifcant cost challenges faced. Supply limited to three regions – ay
acceptable cost. These gave limited capacity for major markets of cars.
Tibet, Bolivia, (Brines) USA and Australia (Greenbushes)

25. A123 Lithium

26. The Zebra - Battery
• High Temperature battery – 270ºC 42kWh unit
• Developed by Anglo American and Daimler Benz
and now a Swiss company
• Sodium Chloride and Nickel
• Expensive but energy density high
• Liquid sodium not sulphur as with NAS
Metal-Air
•Zinc Air
•Aluminum Air
High Energy Density and low cost BUT Difficult to recharge_
several groups proceeding with this Siemens and in the USA

27. Zinc Bromine Batteries – ZBB and Premium Power
and Redflow (Australia) NetPower (China)
• 2000 cycles – zinc is plated on
the negative electrode during
each cycle
• Energy Density 33Wh/kg
practical Power density 50 to
80W/kg
• Bromine – environmental issues
• Hard to scale
• Must be deep cycled and
discharged weekly to maintain
life. Cannot do deep cycles on a
repeated basis. Cannot handle
wind balancing

28. Zinc Bromine 2
• ZBB sell 3.5hour 45kW systems at
$1000/kWh – have many systems in
field 20 to 30 or so
• Premium Power have claims of
$300/kWh – have had several
disasters
• Net Power claim they will achieve
$50/kWh – have no products yet (PCS
costs are nearly $70/kWh right now!!)

29. Flow Batteries
Regenesys - Polysulphide Bromine – cross contamination of electrolytes,
expensive recombination process control – targeted at very large systems due to
complexity. Low cost electrolyte
• Deeya – Iron-Chrome small 5 year life low cost low efficiency 1.2V couple
• Vanadium Bromine – experimental Australia and UK
• Squirrel (Selenium) series flow VRB prototype–
• Plurion – Cerium Zinc

30. Squirrel series VRB Cellenium Thaliand
• Reduces shunt current losses since series flow
• Reduces chance of dry cell and gas evaluation due to blockages
• Patent issues with Prudent
• Voltage issues in series systems, expensive and pressure issues

31. Plurion - UK
Prototype - Cerum Zinc: 10 year history – serious problems. Uses MSA so
environmentally acceptable, higher cell voltage than VRB-ESS, crossover
problems, membrane issues. Balancing problems.

32. Cellstrom VRB - Austria
• 10kW 100kWh – comprises 10 x 1kW cells
• Footprint larger than Prudent by 30%
• Patent issues with Prudent .
• Cost around 2 x Prudent

33. Competing technologies
First time
Life cycles > AC _AC
Capital cost Environmental Use with
Year 2009 50% depth of Roundtrip Pros/Cons
$/kWh to Risk wind
discharge efficiency
customer
Deep Cycle Gel Medium
recharge rate
LEAD ACID 3500 45% 1300 -1800 clean up heavy NO
slow
metals
Sodium Sulphur
Small
Company NGK SOC derived
3500 68% $675 Very High footprint/charge
double sizing
control issues
Zinc Bromine
Company ZBB needs
Compact / two
Premium Power, 2500 60% $1,000 High rebalancing
species
Redpower, every week
NetPower
Iron Chromium
Company Deeya limited life 5
Energy. Originated 1800 55% $1,200 High no membrane years small
systems
by SEI
Lithium Ion very compact/
storage hours
Companies A123, 2000 85% $6,000 High charge control
limited
AES challenge
Vanadium REDOX
Medium larger
Company Prudent Excellent
>100,000 times 65 - 75% $500 - $850 indefinite life footprint/SOC
Energy ideal
electrolyte always known
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