“Energy storage is no longer the technology of the future,” David Walls of Navigant Consulting and the moderator of a Wednesday morning conference session told the audience.
Some technologies are being used now, but significant work remains to be done on other energy storage technologies, Walls said.
Thomas Golden, technology development manager at Duke Energy Corp. (NYSE: DUK), who presented in the session, had a compelling message for electricity generators/suppliers.
“Energy storage will offer challenges and opportunities to power generators, and they must find a way to use energy storage to their benefit,” he said.
The 9:30 a.m. session, “Energy Storage Applications from a Generator’s Perspective,” drew a large crowd, and the presenters supported Wall’s opening remarks. Many different types of energy storage technologies are in development. Some have moved beyond the demonstration stage to full installation; others are in their infancy and still waiting to move to the demonstration stage; most are somewhere in between.
Golden explained why energy storage technology is so important to the industry, especially grid owners and operators.
The electricity industry is the only industry that does not have a place to store its inventory somewhere in its supply chain, Golden said. And as more renewable energy sources, which are highly intermittent, are added to the supply mix, storage will be key to ensuring electricity reliability.
Renewables and energy storage go hand-in-hand, Golden told the audience. Renewable energy sources—especially solar—are becoming more economically competitive with other sources of electricity. Grid owners and operators must figure out how to integrate these intermittent resources.
Duke Energy has tested six different types of batteries, Golden said. All have worked, and as the technology gets cheaper, batteries will be used for ancillary services, transmission infrastructure services, distribution infrastructure services, bulk energy services, and customer energy management services, he said.
In his conclusion, Golden emphasized that although energy storage will be an important technology going forward, it is only one of many solutions to the changing grid.
Compressed Air Energy Storage (CAES)
Jim Heid and Bobby Bailie of Dresser Rand spoke about their company’s involvement with Pathfinder Wind Project, a mammoth project in which wind energy from Wyoming will be transported via a 540 mile-long transmission line to salt caverns in Utah where the electricity will be used to compress air and store it in salt caverns. That compressed air will then be used to generate electricity that will be transmitted hundreds of miles over existing transmission lines to California.
The CAES generated electricity will be especially useful to grid operators in California that must offset the loss of large amounts of solar energy in early evening when demand for electricity often peaks, Heid said.
Bailie explained the technology that Dresser Rand is using to compress the air at night and then use it to generate electricity during peak times.
“It is like cutting a combustion turbine in half,” Bailie said. “Compression is on one side, and generation is on the other.”
He said Dresser Rand was selected to provide the compression and generation equipment because of its extensive experience with compressed air in the oil and gas industry.
Liquid Air Energy Storage
Song Wu of Mitsubishi Hitachi Power Systems America spoke about his company’s liquid air energy storage technology--ReFLECS™.
“Liquid air as a form of stored energy is not new,” Wu said. “In 1902, the liquid air car was introduced.”
Wu said a one-size solution does not fit all energy storage needs and explained the benefits of liquid air energy storage.
“Liquid air energy storage is designed to provide similar storage as pumped hydro and CAES, but without the restrictions on location,” Wu said. “There are no special site requirements. It can be built anywhere.”
ReFLECS can be used alone with air as the only fuel—pure energy storage—or it can be used in tandem with a combustion turbine to increase efficiency and reduce the fuel requirement. In either instance, the storage technology can store from 50 to 600 MW. In addition, its discharge rate can range from two to 12 hours, and the technology has a 30-year life.
Combined Heat and Power (CHP)
Oliver Deneux of EDF closed out the presentations by speaking about the economic benefits of using CHP plants as energy storage.
At times it can be beneficial to store the hot water from these plants and generate electricity when prices are high. This type of CHP operation provides another energy storage option, Deneux said.