A high-resolution model allowing for the comparison of different energy storage technologies in a... more A high-resolution model allowing for the comparison of different energy storage technologies in a variety of realistic microgrid settings has been developed. The Energy Systems Model (ESM) is similar to the popular microgrid software HOMER, but improves upon the battery models used in that program. ESM adds several important aspects of battery modeling, including temperature effects, rate-based variable efficiency, and operational modeling of capacity fade and we demonstrate that addition of these factors can significantly alter optimal system design, levelized cost of electricity (LCOE), and other factors. ESM is then used to compare the Aqueous Hybrid Ion (AHI) battery chemistry to lead acid (PbA) batteries in standalone microgrids. The model suggests that AHI-based diesel generator/photovoltaic (PV)/battery systems are often more cost-effective than PbA-based systems by an average of around 10%, even though the capital cost of AHI technology is higher. The difference in LCOE is greatest in scenarios that have lower discount rates, increased PV utilization, higher temperature, and more expensive diesel fuel. AHI appears to be a better complement to solar PV, and scenarios that favor the use of solar PV (low PV prices, low discount rates, and high diesel prices) tend to improve the LCOE advantage of AHI. However, scenarios that do not require constant cycling of the batteries strongly favor PbA. AHI is not a drop-in replacement for PbA. To minimize LCOE, microgrids using AHI batteries should be designed and operated differently than PbA microgrids.
We examine the potential economic implications of using vehicle batteries to store grid electrici... more We examine the potential economic implications of using vehicle batteries to store grid electricity generated at off-peak hours for off-vehicle use during peak hours. Ancillary services such as frequency regulation are not considered here because only a small number of vehicles will saturate that market. Hourly electricity prices in three U.S. cities were used to arrive at daily profit values, while the economic losses associated with battery degradation were calculated based on data collected from A123 Systems LiFePO4/Graphite cells tested under combined driving and off-vehicle electricity utilization. For a 16 kWh (57.6 MJ) vehicle battery pack, the maximum annual profit with perfect market information and no battery degradation cost ranged from ~$140 to $250 in the three cities. If the measured battery degradation is applied, however, the maximum annual profit (if battery pack replacement costs fall to $5,000 for a 16 kWh battery) decreases to ~$10-$120. It appears unlikely that these profits alone will provide sufficient incentive to the vehicle owner to use the battery pack for electricity storage and later off-vehicle use. We also estimate grid net social welfare benefits from avoiding the construction and use of peaking generators that may accrue to the owner, finding that these are similar in magnitude to the energy arbitrage profit.
ABSTRACT Flexible biodegradable electronics have the potential to serve as the centerpiece for te... more ABSTRACT Flexible biodegradable electronics have the potential to serve as the centerpiece for temporary electronically active medical implants. Biodegradable electronics may exhibit many advantages over traditional chronic implants. Two important long-term goals for biodegradable electronics are (1) supplying sufficient power and (2) reducing the invasiveness of device deployment. Edible electronic devices are capable of addressing both challenges. Here, we introduce electrochemical electronic power sources that are compatible with non-invasive deployment strategies and are composed entirely of edible materials and naturally occurring precursors that are consumed in common diets. The current sources developed herein are powered by onboard sodium ion electrochemical cells. Potentials up to 0.6 V and currents in the range of 5–20 μA can be generated routinely. These devices could serve as an enabling platform technology for edible electronics used in non-invasive sensing and stimulation of tissues within the human body.
Integrated microbatteries are currently being developed to help provide localized current capacit... more Integrated microbatteries are currently being developed to help provide localized current capacities or embedded power supplies at the chip level, for space exploration. This paper presents a design approach for charging and discharging such microbatteries. The microbatteries are charged using these complementary algorithms based on constant current, constant voltage and pulsed current. A unique experimental setup is developed to implement
2009 IEEE International Symposium on Industrial Electronics, 2009
Abstract Integrated microbatteries are being currently developed to act as a ldquomicropowerrdquo... more Abstract Integrated microbatteries are being currently developed to act as a ldquomicropowerrdquo source in microsatellites. They help provide localized current capacities or embedded power supplies at the chip level, for space exploration. These ...
2006 IEEE International Symposium on Industrial Electronics, 2006
Integrated microbatteries are being currently developed to act as a "micropo... more Integrated microbatteries are being currently developed to act as a "micropower" source in microsatellites. They help provide localized current capacities or embedded power supplies at the chip level, for space exploration. The microbatteries are charged using these complementary algorithms based on constant current, constant voltage and pulsed current. The charging current is in the range of nano-amperes. A unique experimental
ABSTRACT Interplanetary missions require rechargeable batteries with unique performance character... more ABSTRACT Interplanetary missions require rechargeable batteries with unique performance characteristics: high specific energy, wide operating temperatures, demonstrated reliability, and safety. Li-ion batteries are fast becoming the most common energy storage solution for these missions, as they are able to meet the more demanding technical specifications without being excessively massive. At JPL, we have undertaken materials development studies on both cathodes and electrolytes with the goal of further enhancing battery specific energy, discharge and charge capability, and functional temperature range. Results of these studies are described below.
ABSTRACT Crystalline solid solutions of 1:1 Li3PO4/Li4SiO4 were synthesized and tested electroche... more ABSTRACT Crystalline solid solutions of 1:1 Li3PO4/Li4SiO4 were synthesized and tested electrochemically using thin film physical vapor deposited electrodes. After cathode deposition, the electrolyte/cathode structures were annealed at 700 °C for 2 h—a process that resulted in cathode crystallization without encouraging deleterious interfacial reactions. Results indicate that the electrolyte functioned well in this configuration. Test cells were taken through multiple charge/discharge cycles at different rates and temperatures and demonstrated a marked enhancement in performance parameters in comparison to previous reports. It is suggested that this material could function well in Li batteries fabricated using proper form factors.
The effects of combined driving and vehicle-to-grid (V2G) usage on the lifetime performance of re... more The effects of combined driving and vehicle-to-grid (V2G) usage on the lifetime performance of relevant commercial Li-ion cells were studied. We derived a nominal realistic driving schedule based on aggregating driving survey data and the Urban Dynamometer Driving Schedule, and used a vehicle physics model to create a daily battery duty cycle. Different degrees of continuous discharge were imposed on the cells to mimic afternoon V2G use to displace grid electricity. The loss of battery capacity was quantified as a function of driving days as well as a function of integrated capacity and energy processed by the cells. The cells tested showed promising capacity fade performance: more than 95% of the original cell capacity remains after thousands of driving days worth of use. Statistical analyses indicate that rapid vehicle motive cycling degraded the cells more than slower, V2G galvanostatic cycling. These data are intended to inform an economic model.
A high-resolution model allowing for the comparison of different energy storage technologies in a... more A high-resolution model allowing for the comparison of different energy storage technologies in a variety of realistic microgrid settings has been developed. The Energy Systems Model (ESM) is similar to the popular microgrid software HOMER, but improves upon the battery models used in that program. ESM adds several important aspects of battery modeling, including temperature effects, rate-based variable efficiency, and operational modeling of capacity fade and we demonstrate that addition of these factors can significantly alter optimal system design, levelized cost of electricity (LCOE), and other factors. ESM is then used to compare the Aqueous Hybrid Ion (AHI) battery chemistry to lead acid (PbA) batteries in standalone microgrids. The model suggests that AHI-based diesel generator/photovoltaic (PV)/battery systems are often more cost-effective than PbA-based systems by an average of around 10%, even though the capital cost of AHI technology is higher. The difference in LCOE is greatest in scenarios that have lower discount rates, increased PV utilization, higher temperature, and more expensive diesel fuel. AHI appears to be a better complement to solar PV, and scenarios that favor the use of solar PV (low PV prices, low discount rates, and high diesel prices) tend to improve the LCOE advantage of AHI. However, scenarios that do not require constant cycling of the batteries strongly favor PbA. AHI is not a drop-in replacement for PbA. To minimize LCOE, microgrids using AHI batteries should be designed and operated differently than PbA microgrids.
We examine the potential economic implications of using vehicle batteries to store grid electrici... more We examine the potential economic implications of using vehicle batteries to store grid electricity generated at off-peak hours for off-vehicle use during peak hours. Ancillary services such as frequency regulation are not considered here because only a small number of vehicles will saturate that market. Hourly electricity prices in three U.S. cities were used to arrive at daily profit values, while the economic losses associated with battery degradation were calculated based on data collected from A123 Systems LiFePO4/Graphite cells tested under combined driving and off-vehicle electricity utilization. For a 16 kWh (57.6 MJ) vehicle battery pack, the maximum annual profit with perfect market information and no battery degradation cost ranged from ~$140 to $250 in the three cities. If the measured battery degradation is applied, however, the maximum annual profit (if battery pack replacement costs fall to $5,000 for a 16 kWh battery) decreases to ~$10-$120. It appears unlikely that these profits alone will provide sufficient incentive to the vehicle owner to use the battery pack for electricity storage and later off-vehicle use. We also estimate grid net social welfare benefits from avoiding the construction and use of peaking generators that may accrue to the owner, finding that these are similar in magnitude to the energy arbitrage profit.
ABSTRACT Flexible biodegradable electronics have the potential to serve as the centerpiece for te... more ABSTRACT Flexible biodegradable electronics have the potential to serve as the centerpiece for temporary electronically active medical implants. Biodegradable electronics may exhibit many advantages over traditional chronic implants. Two important long-term goals for biodegradable electronics are (1) supplying sufficient power and (2) reducing the invasiveness of device deployment. Edible electronic devices are capable of addressing both challenges. Here, we introduce electrochemical electronic power sources that are compatible with non-invasive deployment strategies and are composed entirely of edible materials and naturally occurring precursors that are consumed in common diets. The current sources developed herein are powered by onboard sodium ion electrochemical cells. Potentials up to 0.6 V and currents in the range of 5–20 μA can be generated routinely. These devices could serve as an enabling platform technology for edible electronics used in non-invasive sensing and stimulation of tissues within the human body.
Integrated microbatteries are currently being developed to help provide localized current capacit... more Integrated microbatteries are currently being developed to help provide localized current capacities or embedded power supplies at the chip level, for space exploration. This paper presents a design approach for charging and discharging such microbatteries. The microbatteries are charged using these complementary algorithms based on constant current, constant voltage and pulsed current. A unique experimental setup is developed to implement
2009 IEEE International Symposium on Industrial Electronics, 2009
Abstract Integrated microbatteries are being currently developed to act as a ldquomicropowerrdquo... more Abstract Integrated microbatteries are being currently developed to act as a ldquomicropowerrdquo source in microsatellites. They help provide localized current capacities or embedded power supplies at the chip level, for space exploration. These ...
2006 IEEE International Symposium on Industrial Electronics, 2006
Integrated microbatteries are being currently developed to act as a "micropo... more Integrated microbatteries are being currently developed to act as a "micropower" source in microsatellites. They help provide localized current capacities or embedded power supplies at the chip level, for space exploration. The microbatteries are charged using these complementary algorithms based on constant current, constant voltage and pulsed current. The charging current is in the range of nano-amperes. A unique experimental
ABSTRACT Interplanetary missions require rechargeable batteries with unique performance character... more ABSTRACT Interplanetary missions require rechargeable batteries with unique performance characteristics: high specific energy, wide operating temperatures, demonstrated reliability, and safety. Li-ion batteries are fast becoming the most common energy storage solution for these missions, as they are able to meet the more demanding technical specifications without being excessively massive. At JPL, we have undertaken materials development studies on both cathodes and electrolytes with the goal of further enhancing battery specific energy, discharge and charge capability, and functional temperature range. Results of these studies are described below.
ABSTRACT Crystalline solid solutions of 1:1 Li3PO4/Li4SiO4 were synthesized and tested electroche... more ABSTRACT Crystalline solid solutions of 1:1 Li3PO4/Li4SiO4 were synthesized and tested electrochemically using thin film physical vapor deposited electrodes. After cathode deposition, the electrolyte/cathode structures were annealed at 700 °C for 2 h—a process that resulted in cathode crystallization without encouraging deleterious interfacial reactions. Results indicate that the electrolyte functioned well in this configuration. Test cells were taken through multiple charge/discharge cycles at different rates and temperatures and demonstrated a marked enhancement in performance parameters in comparison to previous reports. It is suggested that this material could function well in Li batteries fabricated using proper form factors.
The effects of combined driving and vehicle-to-grid (V2G) usage on the lifetime performance of re... more The effects of combined driving and vehicle-to-grid (V2G) usage on the lifetime performance of relevant commercial Li-ion cells were studied. We derived a nominal realistic driving schedule based on aggregating driving survey data and the Urban Dynamometer Driving Schedule, and used a vehicle physics model to create a daily battery duty cycle. Different degrees of continuous discharge were imposed on the cells to mimic afternoon V2G use to displace grid electricity. The loss of battery capacity was quantified as a function of driving days as well as a function of integrated capacity and energy processed by the cells. The cells tested showed promising capacity fade performance: more than 95% of the original cell capacity remains after thousands of driving days worth of use. Statistical analyses indicate that rapid vehicle motive cycling degraded the cells more than slower, V2G galvanostatic cycling. These data are intended to inform an economic model.
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Papers by Jay Whitacre