In the first quarter of 2017, the US energy storage market set a record.
The 234 MWH represents more than fifty-fold growth over the same period last year. The 71 MW capacity trails only the fourth quarters of 2015 and 2016.
Most of this growth comes from utility scale projects in Arizona, California, and Hawaii.
California rushed to build two renewable energy battery systems totaling 150 MWH because of a massive gas leak at the Alito Canyon Storage Facility. Nothing of similar scope will come online any time soon. Therefore, large increases in storage capacity will not continue at the same rate.
Nearly all this new capacity represents so-called front-of-the-meter storage. Behind-the-meter-storage, residential and commercial battery storage systems use Tesla’s Powerwall or comparable technology. This sector actually saw reduced deployment compared to this time last year as measured in MWH.
The amount of deployed energy storage remains tiny compared to the amount of electricity the leaked gas at Alito Canyon could have generated. Lithium ion batteries probably don’t represent the ultimate solution in solar power storage systems.
Still, energy storage is the wave of the future. Utilities use front-of-the-meter storage to control voltage and frequency. It enables them to integrate renewable energy into the grid without the dangerous fluctuations that have held it back. Residences can use battery storage systems to control how much electricity their roof-top solar panels return to the grid. That ability further helps grid operators.
How renewable energy causes problems for the grid
Utilities have some legitimate concerns about residential and commercial solar. And it’s not just the economics of net metering. Creation and use of electricity must balance. Demand fluctuates.
Therefore supply must fluctuate with it. Failure to do so can result in cascading problems such as blackouts. Plant operators plan for the day ahead, the hour ahead, and monitor real-time conditions.
They must maintain a frequency of 60 Hz. Since all utilities are interconnected, if one utility runs into trouble maintaining that frequency, it can jeopardize the operation of the entire grid.
If a utility generates all its electricity with fixed power plants, it can vary their output. Baseline plants run continuously. Other plants turn on and off to adjust to changing demand.
Adding intermittent renewables to the mix complicates the necessary calculations. Not only do solar panels not operate at night, they produce more or less electricity depending on cloud cover, which can change many times during the day.
A utility that deals with a high penetration of rooftop solar systems has more trouble than most to maintain the correct balance.
New developments in utility-scale energy storage
Environmentalists love to portray utilities as standing in the way of renewable energy. In fact, many are actively exploring how to integrate solar and wind energy into their systems. Power storage technology makes it possible. Here is a single example.
The University of Arizona and Tucson Electric Power (TEP) have been collaborating at the Solar Zone, part of the university’s Science and Technology Park.
One of their contractors, E.On, recently completed its Iron Horse, the first project of Solar Zone’s second phase. It is the third solar project the German E.On has built in partnership with TEP.
Iron Horse combines a 2-MW solar array with a 10-MW capacity lithium-ion battery facility. The university will soon call for projects for the rest of phase two, which will concentrate on distributed energy systems and microgrids, grid optimization, and embedded building-integrated photovoltaics.
The Science and Technology Park now hosts ten companies. Their combined solar installations have a generating capacity of 25 MW. That’s enough to power about 4,600 homes in the Tucson area. Electricity from the Iron Horse costs only 3¢ per KWH. The battery system adds about 1.5¢ per KWH to the cost. Just a few years ago, TEP had to pay 10-12¢ per KWH for renewable energy.
Iron Horse’s storage system will make the grid more reliable by providing ancillary services like frequency regulation and voltage control. Storing electricity to use when the sun goes down will require longer-duration systems, which TEP plans to buy in order to move away from fossil fuels.
New developments in residential energy storage
Dave Everson, a homebuilder in Arizona, explores ways to use new technology to address environmental issues.
For the past three years, his company has built “discovery homes.” That is, it designs and builds one home to apply technology in novel ways.
It then adds the most successful and viable innovations to every subsequent home it builds.
His newest discovery home aims to combine solar panels with a battery. It has just enough panels to keep the battery charged while the sun is out. Unlike most solar homes, therefore, it doesn’t feed excess power back to the grid.
At night, power from the grid keeps the battery charged. So the home runs off the battery, not the panels or the grid.
Even if the concept works as planned, Everson will not be able to incorporate it into regular production without some help from Arizona Public Service, the local utility. He plans to ask for some kind of subsidy or rebate.
Arizona has such a high penetration of roof-top solar that APS struggles more than most utilities to maintain its part of the grid. Therefore, it has reacted favorably to Everson’s concept. The home has not yet opened. APS and Everson will monitor it to determine how well it works.
If it proves to be reliable, safe, affordable, and cyber secure—and if APS decides to provide financial assistance—Everson will apply it to every home he builds in the future. It will make the utility’s ability to integrate solar power into its operation easier. Other builders elsewhere in the country will take note.
It would appear to me that if new homes can be built to run off a battery, it should be possible to retrofit existing homes to do the same when installing or upgrading a solar system. Back-of-the-meter storage represents only a small fraction of deployed energy storage systems. But it has great growth potential.
Renewable energy storage systems are in their infancy. They will have to become more reliable, more affordable, and more numerous before the grid can fully digest renewable energy. But battery systems for both utility-scale and residential-scale applications have made excellent progress in recent months.
Battery powered homes may be future of homebuilding / Max Efrein, The Daily Courier (Prescott, Arizona). June 6, 2017
Renewable energy intermittency explained: challenges, solutions, and opportunities / Robert Fares, Scientific American. March 11, 2015
Tucson Tech: UA Solar Zone enters second phase / David Wichner, Arizona Daily Star. June 3, 2017.
US energy storage market experiences largest quarter ever / Mike Munsell, Greentech Media. June 6, 2017
Portland lithium battery system. Some rights reserved by Portland General Electric
Vanadium flow battery. Photo by UniEnergy Technologies. Public domain from Wikimedia Commons
PowerWall installation. Some rights reserved by Bryan Alexander