Case Studies

Case Studies

Download the brochureMaxwell ultracapacitors are ideally suited to meet the performance and lifetime demands of grid applications around the world. Today, ultracapacitor energy storage provides a wide range of benefits to independent energy generators and utilitie s alike, including traditional fuel energy generation and renewable generation such as solar and wind. These case studies are a few examples of our expertise in applying ultracapacitor energy storage systems for power grid applications worldwide. Additionally, combining the power of ultracapacitors with the energy of batteries provides superior performance, operating range and life.*


*Results may vary. Additional terms and conditions, including the limited warranty, apply at the time of purchase. See the warranty details and datasheet for applicable operating and requirements


Maxwell Ultracapacitors for Solar Integration and Stacked Services:
Duke Energy’s Rankin Substation

Issue

As an increased amount of intermittent solar and wind energy generation is being added to the grid, utilities are reporting overall power quality issues that require substantial utility T&D infrastructure upgrades and/or replacement of costly in-service distribution equipment. Further, optimal utilization of solar and wind power can be increased by storing excess energy when demand is low, and deploying when demand is high.

Solution

Maxwell ultracapacitors are currently in service in a hybrid battery-ultracapacitor energy storage system designed to simultaneously perform PV intermittency smoothing, peak shaving, energy shifting, and load following. The ultracapacitors rapidly respond to PV intermittency power fluctuations, and remove fast, repetitive cycling demands from the battery. The batteries provide energy shifting and load following, allowing for the optimal time use and "time shifting” of the solar energy generated. With rapidly growing amounts of renewable and intermittent renewable energy generation coming on to the grid, the use of a hybrid energy storage system delivering multiple power and energy services provides the utility with more useful stacked services, flexibility, and also enables deferral of costly infrastructure investments.

Results
  • System commissioned February 2016
  • 277 kW / 8.0 kWh Maxwell ultracapacitors
  • 50 kW / 300 kWh low-cost aqueous batteries
  • Estimated 10–15% CAPEX reduction (vs. battery only)
  • Estimated 30% OPEX savings (vs. battery only)



Maxwell Ultracapacitors for Power Stabilization: Yangshan Deep Water Port

Issue

Located near Shanghai, Yangshan Deep Water Port’s 23 quay cranes have enough power draw to cause significant voltage fluctuations on the local grid for 10 to 15 seconds at a time. The port is located at the end of a 20-mile bridge, and increasing the transmission line capacity was deemed too costly.

Solution

Maxwell ultracapacitors were selected for their high cycle and design life and employed in a 3 MW/17.2 kWh energy storage system with 20 seconds of reserve power that mitigates voltage sag caused by crane operation. The solution made it possible to avoid costs associated with installing a larger transmission line.

Results
  • Ultracapacitor energy storage system fully operational for two years
  • 38% reduction in peak demand grid energy
  • Estimated $2.9 million in energy savings over lifetime*
  • Estimated $41 million in savings over lifetime † related to improved efficiency and reduced maintenance on transmission lines

*Cost savings based upon economics of the particular case study and assumes operation for 1 million cycles, 8,000 hours, 10 years; actual results may vary, including, notably, due to varying economics of operation at different locations throughout the world as well as varying operating and use models for different projects

Maxwell Ultracapacitors for Wayside Energy Efficiency and Frequency Regulation : Southeastern Pennsylvania Transportation Authority Light Rail System

Issue

More than 80% of the nearly 500,000,000 kW consumed by the Southeastern Pennsylvania Transportation Authority (SEPTA) rail system is used as propulsion power for its rail lines. Recovery of braking energy otherwise lost as waste heat could lead to significantly lower electricity costs.

Solution

Maxwell ultracapacitors were employed in a hybrid ultracapacitor-battery energy storage system to accomplish two critical functions:

Brake Energy Recovery: The ultracapacitors capture excess braking energy from the trains by detecting a rise in the line voltage on an overhead catenary system. These braking events occur several thousand times a day and can last up to 15 to 20 seconds.

Load modulation to provide frequency regulation on the PJM energy market.An average of 90 minutes per day is spent on capturing train braking energy, and the balance of the time is spent providing this secondary function.

Results
  • Reduction in SEPTA rail vehicles’ consumption of grid-supplied electrical energy by 10-20%
  • 800 kW of fast response load modulation support to the grid operator. This is a paid service which can provide greater than $200,000 in annual revenues to SEPTA.


Maxwell Ultracapacitors for Solar Firming : California Energy Commission

Issue

As an increased amount of intermittent solar and wind renewable energy penetrates the grid, output becomes increasingly unstable. Utilities increase peak power reserves to handle increased intermittency, which leads to increased costs for the utility and/or the ratepayer. Fast-responding energy storage can decrease the need for more peak power infrastructure.

Solution

An ultracapacitor energy storage system was designed to demonstrate the capability of filling in short-term solar power intermittencies and providing ramp rate control for longer intermittencies.

Modeling Results

To stabilize solar output for five minutes of ramp rate grid regulation, only 20 to 30 seconds of energy storage is needed to ensure local power quality at solar penetration levels of 50%. Ultracapacitors are an ideal solution for this function. Given the fast response of ultracapacitors, the system can also deliver other power reliability and quality services.

Maxwell Ultracapacitors for Wayside Energy Efficiency and EV Charging: Ferrolinera

Issue

Administrator of Railway Infrastructures (ADIF) in Spain required a wayside energy recuperation system to improve overall energy efficiency. The regenerative braking of trains generates large quantities of energy in short periods of time. When the train reaches the railway station, the generated energy must be consumed or it will be lost.

Solution

Solutions provider Win Inertia developed an optimized UCAP-battery hybrid energy storage solution to harvest breaking energy. The railway infrastructure includes an EV charging station that uses this harvested energy and PV. A management and control system is needed for the operation of the whole system.

Results
  • The hybrid system has been in operation for over one year, with a projected battery life extension of 25%
  • 8-10% energy efficiency improvement