One of the continent's largest energystorageshows hit San Diego, Calif. last week to good crowds and an increased momentum in the market. I emceed for a number of presenters in this year's Storage in Action series, seeking to highlight actual working energy-storage projects out in the world -- not pilots, but real, value-creating energy-storage projects. Here's a brief look at a few of the presenters. More to come.
S&C Electric and SWER lines
Troy Miller, S&C Electric Company's director of grid solutions, described a storage deployment in the Australian outback where twenty 25-kilowatt/4-hour systems are being deployed for voltage support in a single-wire earth-return (SWER) system architecture used to power rural and remote sites.
"SWER lines are an effective method of economically electrifying remote areas; however, the inherent electrical properties of these lines make them highly susceptible to power-quality problems, mostly around voltage," said Miller.
With SWER lines, "there's one wire that runs across 200, 300, 400 miles" with power returned through the ground, he explained. "It causes all kinds of power-quality issues, and they had very little information about what was actually going on at these particular locations. Farmers would wake up in the morning, try to cook their toast, and turn on the teakettle, and none of it would work. All the farmers were trying to turn on their toasters and teakettles at the same time."
Miller did point out, "One thing that farmers discovered was that if they were able to make the ground wet near the pole, they could basically increase the conductivity around the pole and get better voltage" and use their appliances. S&C offered a different solution.
"As the residents ask for more power, the voltage goes down. The people who used to [have trouble using] their teakettles now use milking machines and extra motors and plasma TVs, and everybody is [creating] an increase in load. The problem with these SWER lines, because they're so highly resistant, is that they can't be corrected using traditional types of VAR compensation (basically putting in some caps), because it's so highly resistant, we actually need real power."
"Why was this such a problem?" he continued. "They either have 11-kilovolt or 19-kilovolt lines. That one wire that runs across the outback, it's highly resistive because they wanted to put in as few poles as possible. They wanted to double the distance between the poles. So they used this highly resistive cable which was basically like fencing wire. What happens then is as the power goes up, the voltage starts to crash. You have a step-down transformer, so we're actually putting that energy storage out at the end of the line on the 240-volt system."
"So where do we get real and reactive power from? A battery and an inverter. The red line on the chart demonstrates how the correct combination of real and reactive power injection dramatically improves the voltage profile of the line. By employing a sophisticated, SWER-specific control algorithm, a four-quadrant inverter can produce or absorb real and reactive power at the same time. In addition to controlling the voltage on the line, such a system can be used to address other power-quality issues on the line, such as power factor and assisting with the integration of renewables," Miller said. "Once you start to knock the peak off, then you can pull that voltage up, you're able to selectively put in energy storage in the proper locations and not have to reconduct the whole system."
Last year, S&C won a tender to supply Ergon Energy with 20 Grid Utility Support Systems (GUSS) for connection to their SWER lines. "The systems will be installed on Ergon’s worst-performing SWER lines. In some instances, multiple GUSS units will be installed on one line. After extensive testing at an Australian university, the majority of the units have been shipped to Australia and will be installed on SWER lines between now and Christmas," according to Miller.
JuiceBox Energy behind the meter
Neil Maguire, the CEO of JuiceBox Energy, spoke about his recently formed behind-the-meter, lithium-ion battery energy storage company. "Our focus right now is residential energy storage," he said.
Maguire claimed, "This is the first system in California, and potentially in the United States, that is interconnected and permitted for peak shifting, backup power, load shaving, and exporting to the grid. With this AC-coupled system, the customer already had solar with a SolarEdge grid-tied inverter. We added a JuiceBox there (the big white box). We have very deep integration with a Schneider inverter. As the JuiceBox gets installed, you're splitting off critical loads in the house, and you have an AC disconnect as well."
"As the JuiceBox gets deployed, you install the enclosure and load the battery modules and the control system, and we have a cell modem on each. With that cell modem, we're communicating right away to go to an Amazon web services repository, and the user now has a web interface."
"Maguire described a DC-coupled system that was installed as part of a community center grid-resiliency project in San Jose. "Here the solar is going into a 600-volt charge controller, and from there into the Schneider XW+ converter, and the JuiceBox is in there as well. There's AC and DC coupling, so if you have microinverters, you're going to do the AC coupling; you already have AC coming in from the roof."
"We're shipping and installing these systems, in both AC- and DC-coupling," said Maguire. "We're really focused on the two guys and a van going around and doing rooftop solar. They get a pallet, they pick it up, they load it, install each battery module and the wire harnesses. There's a little blue button down on the bottom, and when you press that blue button, it's looking at the voltages and temperatures of each of the battery modules. If everything's okay, it closes an automotive-grade relay and powers up the inverter. Nobody has to become an off-grid battery specialist. They just press a button and it starts right up when we set up that inverter. That's what makes it very quick and very scalable for solar installers."
Maguire added, "On the services side, we believe we really have to do the last mile of energy storage. Getting systems successfully deployed in a repeatable manner, so that installers can properly put a quote together for a customer and everybody comes out OK. We bring installers in for batteries 101, battery pack design, how to permit, interconnect and how to install a JuiceBox. We've trained over 50 installers, and these people are now our sales force and our installation force. We started shipping systems over the summer, and now there are systems in Hawaii, New York, and Northern and Southern California."
"We're permitted in San Diego county now. If an application goes in for interconnecting, the County of San Diego [employees] know who we are and say, 'OK, that's a JuiceBox, good.' That's really the key right now -- to make it so that you can just have no hurdles as you're doing the installation," he said.
NRStor's technology offers ~5,200 full depth-of-discharge cycles in the first year
Alexander McIsaac is manager of business development for Ontario's NRStor, a "technology-agnostic energy storage developer" that has partnerships with Temporal Power, manufacturer of the flywheels highlighted in his project. The company has also partnered with the merger of General Compression and SustainX for isothermal compressed-air energy storage technology, and with Tesla to deploy the Powerwall in Canada.
McIsaac described the company's flywheel installation, a 2-megawatt facility located about two hours' north of Toronto: "It provides regulation service to the independent electricity system operator in Ontario." It's under a contract won for alternative sources of regulation service. "That RFP occurred in 2012. We started building it in 2013. We commissioned it in 2014."
"The flywheels are about 20 feet below the ground in concrete reinforced vaults. There's a lot of concrete. You can see us lowering one of the concrete molds in this December 2013 picture. We built a building around it. It gets down to negative 40 degrees. The building also has a crane that allows us to do maintenance on any of the 10 flywheels, which is good if we need to do a retrofit -- we can pick one up at a time. The whole facility doesn't have to go down," McIsaac said.
NRStor is the developer and put in 100 percent of the equity into the flywheel project special-purpose vehicle. McIsaac noted that Temporal Power performs ongoing maintenance for the flywheels. The Business Development Bank of Canada provided $3 million in project finance.
The system has "vacuum pumps that maintain vacuum pressure in the flywheels, which spin between 7,000 and 11,500 RPMs," said McIsaac, "so the outside of the actual flywheel itself is spinning faster than the speed of sound in that vacuum."
The facility performed approximately 5,200 full depth-of-discharge cycles in its first year operation. "That's a big number, and we're really proud of that. That's why we believe flywheels, in this case Temporal Power flywheels, are really the best solution for a regulation service out there. [The independent system operator] has been very happy with our performance. The ISO, NRStor and Temporal Power continue to learn from this facility being the first commercial one, [having] the only flywheels operating in Ontario, and [being] one of two commercial resource projects operating in Ontario."
"We hope to build many more of these and really take over the energy-storage regulation service market in Ontario, across Canada, into other markets. They're incredibly low in terms of ongoing operating costs to the ISO. They've been very impressed with the operating costs of the facility," said McIsaac.
"The other factor is that costs for flywheels are coming down," he continued. "I won't speak on behalf of Temporal Power, but they have made significant improvements to the technology, the way they work, and the various configurations in relation to the drives or the inverters. So costs are coming down on the flywheel side as well. Basically, just looking at each project holistically, over the length of contract, will make differences."
"We provide day-ahead forecasting to the ISO. We have a 1.8 percent forecast error. The availability factor of that time our facility is providing some level of service is 99 percent," according to McIsaac.
"In terms of network latency -- that's the time it takes the signal to propagate from our ISO to our facility -- we're working on various algorithms to lower that from 5 seconds to less than 1 second. In terms of response of accuracy, it's very, very small, 0.05 megawatts, but we believe there are actually things we can do to make that even [smaller]. In terms of state of charge limited, that's 94 percent, so it's a 15-minute duration facility."
As for the actual regulation service being provided, "You can see the black line [in the chart below] is the AGC signal. The IESO sends us a signal every 4 seconds. The purple line is the flywheel following that signal. The blue line is the state of charge. We do this 24/7/365."
"In terms of performance, a lot of people wonder how this project has been performing for the ISO. This is actually the first time we're talking publicly about our performance. In terms of overall performance...they're very happy with our facility. The number here at the end [shows that] in our first year of operation...we've done 5,200 full discharge cycles. You have to remember, when flywheels are compared to lithium-ion batteries, there's no degradation over time. This is designed to be a 20-year asset," McIsaac said.