Thus far, the structure and integrity of the grid have limited the deployment and effectiveness of intermittent alternative energies, such as solar photovoltaics (PV). The sun may not always shine enough to meet demand. Conversely, solar power may generate more than enough to meet current demand, but then the issue becomes adequately storing surplus energy for a rainy day. Solving that problem with smart power storage can make renewables more viable, and as alternative-energy supporters push the industry, electrical contractors can offer mutually beneficial solutions.
Grid energy storage comes of age
A battery energy storage system (BESS) can alleviate intermittency in renewable energy and reduce demand charges and load stress on transformers and other grid equipment. Specifically, these systems are useful to achieve balance and quality at the grid-operator level and can perform key functions that include frequency regulation, voltage support or control, smoothing renewable integration, spinning reserves, electric supply reserve capacity, and load following.
Pacific Data Electric Inc. (PDE) Total Energy Solutions, San Leandro, Calif., recently designed a custom BESS that is being tested for the Department of Defense in Southern California. The project integrates energy storage, advanced power electronics and controls into a microgrid or smart grid. Forbes Magazine listed the project as one of its “Top 12 Energy Projects to Watch in 2012.”
“The market and application for energy storage is developing. Energy storage integrated within a microgrid or coupled with renewable generation source(s) is a focus area for PDE,” said Shelley Keltner, LEED AP, PDE CEO. “Through demonstration projects and military installations, more energy storage projects will find their way into the mainstream. There is a big push in the Department of Defense to reduce energy consumption and develop commercially viable and DFAR military specific and deployable technologies to improve energy efficiency and energy surety.”
Keltner said one of the benefits of microgrids is the ability to provide consistent and reliable power in environments that are often unstable and rely on generators for a portion of their power. Commercial and medical facilities may eliminate or minimize their use of diesel generators and older technology lead-acid batteries for backup power.
Renewable-power sources can be optimized using new battery energy storage, such as GE’s Durathon battery with advanced controls. Integrating battery energy storage and renewable generation to electric vehicle charging stations will allow electric vehicles to charge with “green energy” and will mitigate or defer utility transmission and distribution upgrades that would have been needed due to the added electrical load.
According to a recent report from Pike Research, Boulder, Colo., “Energy Storage Systems for Ancillary Services,” the growing need to integrate intermittent renewable sources of energy, particularly solar and wind power, into the power grid will help drive significant growth in energy storage systems for ancillary services over the next decade. In the context of the power grid, ancillary services refer to auxiliary functions that are necessary to maintain the balance and quality of electricity on the grid.
“The potential market for ancillary services is vast and will continue to grow as global generation capacity increases, as a result of both new electrification and capacity additions to existing networks, and increased instability resulting from renewables integration,” said Anissa Dehamna, Pike Research analyst. Pike Research forecasts that revenues from energy storage technologies for grid services applications will rise from $412 million in 2011 to more than $3.2 billion by 2021.
Dehamna said that, initially, the energy storage systems for the grid services market will be limited to regions with suitable market structures, primarily deregulated electricity markets. The key regions will be North America, Europe and Asia-Pacific, particularly for frequency regulation, load following, spinning reserves, and short-duration renewables integration. The primary technologies for these energy storage services will include flywheels, pumped storage, compressed air energy storage, and battery technologies, such as lithium ion, sodium sulfur and advanced lead-acid batteries.
PDE’s Keltner said that each battery technology serves a specific purpose, so selecting a storage option is application-specific. There are many aspects to analyzing which battery technology will be the right fit for a project.
“There’s not one particular battery technology that is one-size-fits-all. It depends on the application, the load and other factors. In some cases, the old-fashioned 99 percent recyclable lead-acid battery may be the best technology for your application. You have to look at all the different battery technologies to make a decision,” Keltner said.
Functionality, efficiency and energy security
In 2011, PDE partnered with GE Global Research, GE Energy Storage and Dynapower Corp. to propose a 1 megawatt (MW), 576 kilowatt-hour (kWh) BESS at the Marine Corps Air Ground Combat Center (MCAGCC) located in Twentynine Palms, Calif.
The MCAGCC has one of the most extensive solar arrays on any U.S. military base. More than 4,500 solar panels are installed on the base’s two parking areas, an amphitheater and a recreational park. According to the installer, Baker Electric Solar, not only do the four separate arrays integrate into structures providing premium shading in the desert sun, but they add up to 464,000 square feet of PVs and provide 1.5 MW of generating capacity for the base.
The methodology used in this installation represents a paradigm shift in the production of power. The project directly linked energy surety with critical power needs by integrating distributed energy resources, such as solar, cogeneration and storage into an existing local electrical distribution service area—a microgrid.
According to Keltner, during microgrid operations, the combat center was not able to use the power generated by the PVs due to cogeneration facility ramp rate control restrictions.
“The BESS system will facilitate photovoltaic use during microgrid operation and improve the power factor and output of the cogeneration plant,” she said.
The installation offers local control of the microgrid resources, enabling smart grid functionality for demand response, such as shutting down high-energy-use equipment for brief periods when demand electricity is high. It was also designed to provide intelligent interconnection and integration of multiple distributed energy resources.
According to PDE vice president of operations Dan Cohee, this decentralized approach also introduced an enhanced “islanding” function, an integral part of the battery energy storage demonstration project that will keep the system operating when the grid goes down. The battery will be dispatched to help smooth the energy produced by the PV.
“The microgrid will island the energy being produced by the solar and keep generating energy for the base,” Cohee said.
The battery also will be dispatched to improve the power factor of the microgrid and enable full efficiency of the site’s co-generation plant using less fuel.
As the prime contractor for the project, PDE is coordinating all aspects, including medium-voltage 12.47-kilovolt (kV), 480-volt (V) and 120V power as well as design, procurement, integration, factory acceptance testing, installation, commissioning and ongoing testing and reporting services. The system components used in the project include the GE Durathon batteries, the battery management system, power electronics, controls and installation of a NEMA 3R cabinet. PDE also will provide GE Multilin software to integrate with the base’s existing SCADA system.
The installation will establish dispatch and control algorithms to demonstrate power factor improvement, peak shave functionality, firming renewables and grid-independent microgrid operation. PDE also will provide construction project management over the next two years through monitoring and reporting processes and providing adjustments.
Cohee, who will direct the project for PDE, said it is currently in the design-review stage. Construction and installation of the BESS system will be complete by late 2012. Cost and performance reporting will continue through 2013.
The benefit of PDE’s Twentynine Palms installation is transferable to other mission-critical facilities such as hospitals, long-term care facilities and data centers. Nonmission—critical facilities, such as commercial/industrial buildings and individual households, also will benefit eventually from this smart microgrid application.
MCCLUNG, owner of Woodland Communications, is a construction writer from Iowa. She can be reached at email@example.com.