OUC—The Reliable One is looking forward to combining two research projects to test and demonstrate the possibilities of energy storage technologies, including hydrogen storage, that could be used to smooth out intermittent power from solar resources.
Orlando, Florida-based public power utility OUC has a goal of reaching zero carbon dioxide (CO2) emissions by 2050, with interim goals of 50% by 2030 and 75% by 2040. There usually is abundant sunshine in Florida, but there is also a lot of cloud cover across the state that can be very sporadic and make solar output particularly erratic.
“Energy storage technologies with longer durations are important to us,” Sam Choi, manager of emerging technologies and renewables at OUC, said. That gives OUC a strong interest in alternatives to lithium ion batteries that have to date dominated the market for energy storage, he said.
OUC has two projects that are testing longer duration energy storage technologies. One is a nanogrid now in operation at the public power utility’s Gardenia operations center. This spring, OUC completed the installation of the equipment for its Gardenia nanogrid project, including doubling the existing solar panels, which float on a pond at the site, to 64 kilowatts (kW), two vanadium redox flow batteries with a total capacity of 20 kW, 80 kilowatt hours (kWh), and three electric vehicle charging stations, including one with vehicle-to-grid capability that the utility is getting ready for operation.
OUC chose flow batteries because they offer longer durations than lithium ion batteries and because, unlike li-ion batteries, the duration (energy) and capacity (power) of flow batteries can be scaled independently. “As we scale up the energy, we may not need as much power,” Choi said.
The eventual goal is to be able to “island” or separate the nanogrid from the surrounding grid in order to power the Gardenia operations center during a storm or an outage.
The other project is funded by a grant from the Department of Energy (DOE).
In August 2019, OUC and its partners won a $4 million grant under the DOE’s H2@Scale program, which explores the potential for wide-scale hydrogen production and utilization to enable resiliency in the power generation and transmission sectors.
OUC’s partners in the hydrogen grant are Giner ELX, OneH2 and the Florida Solar Energy Center at the University of Central Florida. After partner contributions are counted, the total value of the project is $9 million. Progress on the three-year grant was on hold for a few months when Giner was acquired by Plug Power over the summer. OUC, in June, received carbon fiber tanks to store hydrogen and expects to install the rest of the equipment by mid-2021
The remaining equipment includes a 510-kW electrolyzer that produces hydrogen and oxygen from water, two fuel cells, which use hydrogen to produce electricity, one stationary (600 kW), the other mobile (300-kW), a transformer and fuel cell vehicles.
The fuel cell vehicles, both light duty and larger vehicles, will be able to take advantage of the higher energy density of hydrogen compared with lithium-ion batteries for purposes of demonstrating the potential for electrification of the transportation sector, Choi said.
The electrolyzer will be sited near the pond with the solar panels so that their electrical output can be used to produce “green” hydrogen. The hydrogen project is on track to begin operation by late 2021, and the operations of the two projects, hydrogen production and storage and the nanogrid, could be combined as early as 2022.
When both projects come together, OUC will be able to produce solar power and either store it in the flow batteries or run it through the electrolyzer.
“One of the key research concepts of this project is the electrolyzer,” Choi said. When it is producing hydrogen, the electrolyzer can be ramped up or down to mitigate fluctuations in solar output, he said.
OUC will also be able to store hydrogen in tanks and, by combining tanks stored on a trailer with the mobile fuel cell, will have an emergency, backup generator that can deliver green energy where it is needed during storms and outages.
OUC is also in the process of procuring two flywheel energy storage devices. Flywheels have been most often used to store energy for short periods of time to inject bursts of energy into the grid for services such as frequency regulation. Once again, OUC is looking for a longer duration system, 8-kW flywheels with durations of up to four hours. “We are looking for solar smoothing, and flywheels have a very fast response time and no degradation,” Choi said.
OUC plans to use its Gardenia campus as a test bed that will be able to swap out and test different types of storage technologies. “We are looking to see what works and, especially with distributed resources, what potential there is for us as a utility,” Choi said.