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Adding storage to wind and solar power

The energy storage space continues to grow quickly, with numerous storage projects on the go. But in perhaps one of the most interesting recent projects, Invenergy added a 31.5-MW storage facility toan already completed wind farm and solar power facility

By Paul MacDonald

The growth numbers for U.S. energy storage are truly staggering.

According to market research firm IHS, the energy storage market is set to "explode" to an annual installation size of six gigawatts in 2017—and over 40 GW in 2022.

This is from an initial, relatively miniscule base of only 0.34 gigawatts installed in 2012 and 2013.

Energy companies are investing millions of dollars in energy storage, and those numbers are bound to grow in the years ahead.

Energy storage now has the full attention of many major players in the North American power market, including Invenergy, the largest independent wind power producer in the U.S. Chicago-based Invenergy has developed and placed into service 51 wind farms across the United States, Canada, and Europe, totaling over 4,400 MW. Another 1,300 MW of Invenergy wind projects are currently under contract or under construction.

One of the company's most interesting recent projects involved an already completed wind farm and solar power facility. Earlier this year, Invenergy started commercial operation of its 31.5-MW Grand Ridge Energy Storage project in La Salle County, Illinois.

The project is about 80 miles southwest of Chicago at Invenergy's Grand Ridge Energy Center, which is made up of a 210-MW wind farm, a 20-MW solar project, and an existing 1.5-MW energy storage unit.

When it was built in 2012, Grand Ridge Solar was the largest solar farm in the Midwest, producing enough energy to power approximately 2,900 homes. The project features advanced PV solar modules supplied by GE. The output from Grand Ridge Solar is purchased by ComEd through a long-term agreement.

In addition to providing its thin-film solar panels to the project, GE supplied packaged inverter skids that include Brilliance inverters, transformers, and re-combiners in addition to its SunIQ plant controls. The project consists of twenty, one-MW solar inverters and more than 155,000 photovoltaic modules. Racking for the project was from Schletter Inc.

White Construction Inc., selected by Invenergy to be the solar project's EPC, engineered, procured, and constructed the balance of system components and installed the solar inverters and PV modules. The balance of system components include site preparation, security fencing, rack foundations, racking, DC wiring systems, AC collection system, and the electrical switchyard.

The wind power portion of the Grand Ridge facility consists of four project phases, featuring 140 GE 1.5 turbines. The Boldt Company (Grand Ridge I) and Gemma Renewable Power (Grand Ridge II-IV) were the project contractors.


Grand Ridge Energy Storage provides fast-response regulation service to the massive PJM market, explained Kris Zadlo, senior vice president of Regulatory Affairs and Transmission at Invenergy. PJM is a regional transmission organization that coordinates the movement of wholesale electricity in 13 U.S states and the District of Columbia, a market of more than 61 million people.

"We believe that energy storage holds the potential to be a transformative force in the evolution of the electric grid," says Zadlo. "As we expand our storage project portfolio, the Grand Ridge project reflects our company's commitment to, and belief in, the future of this revolutionary technology."

Zadlo is very excited about the company's recent energy storage projects, but he explained that when the Grand Ridge wind project was being planned and built, energy storage was not in the cards.

"We really do consider the Grand Ridge project to be our energy showcase," he says. "It's a project that has grown over time. It was originally planned for 100 MW of wind power, and now we have over 210 MW of wind, with 20 MW of solar-and now we have 33 MW of energy storage."

He added the project is located in a state—Illinois—and a region of the state—La Salle County—that have been receptive to renewable energy. "It's a community that we have had a good relationship with, and the project is in a part of the country that is receptive to renewables.

"The Grand Ridge project has been the perfect nexus of things coming together," he added.

But it has taken a while to get here. Their first energy storage project at Grand Ridge, a 1.5-MW system from Xtreme Power, came online in 2012.

"It was a small pilot project, to see what energy storage is all about, what we can do with it, does it live up to the expectations," explained Zadlo.

"We were very happy with how it operated, and we could see the potential for further energy storage, so we ended up going out for another tender and essentially kicked off the permitting and construction process in 2014."

The pilot project was helpful, says Zadlo, in that it built the foundation for doing the much larger project.

"We did learn a lot from the procurement and construction side," he says. "But I think the biggest thing we learned along the way is that we've had a paradigm shift in thinking about energy storage.

The energy storage system Invenergy selected for the Grand Ridge project in Illinois features BYD's proprietary Lithium-ion Iron-Phosphate battery chemistry. The storage system is housed in 18 eight-foot high containers, 40 feet long, on the Grand Ridge site, which has over 210 MW of wind power and 20 MW of solar power. 

"When most people think of energy storage, they think of shifting energy from off-peak to on-peak, moving blocks of energy, such as with renewables. But we think it's that and much more—that it's a transformational technology, and we're just beginning to scratch the surface of what it can do."

Energy storage can also be all about providing unique and ancillary services to the power market, everything from frequency regulation to power quality, and more. Among other things, energy storage can help provide a more efficient and reliable power grid that is more resistant to disruptions.

"It has really opened our eyes that energy storage can do a whole lot of things—it's extremely versatile and can provide a whole suite of services. There is a lot of flexibility on how you can apply stored energy," says Zadlo.

Invenergy has developed and built a long list of wind, solar, and natural gas-fueled power generation projects, and that knowledge base certainly helped with the storage project. Zadlo says that Invenergy worked with EPC contractor Henkels & McCoy to develop that knowledge base further, to encompass energy storage.

"It was a learning process for both of us, but an interesting one. Henkels & McCoy appreciated the opportunity to branch out and do something new—and so did we.

"It does require a different knowledge base—you have to be comfortable with the chemistry of the type of energy storage project that you choose. In a lot of ways, the application dictates the chemistry of your batteries. Just as with wind and solar projects, where you need to know the wind regime and you need to know your solar site, you need to know what you are going to be applying batteries for.

"Then there is the technology of the inverters and the communication that is necessary between the different components of the storage system," he added.

With the Grand Ridge power storage project, there were no federal or state incentives involved. "What we did have, though, is a community that is very open to us," said Zadlo. "We've had a good relationship between the Grand Ridge project and the community, and because of that, we've had a lot of success developing these multiple projects on this Illinois site."


Part of the success of any renewable project, whether it be wind, solar, or energy storage, is community buy-in. "When we were working on developing plans for the energy storage project, we went to the county and explained what we wanted to do," says Zadlo. "They did not say, 'yes,' right away.

"They asked a lot of questions. It was a learning process. They had to get comfortable with the technology and the mechanics of what we were proposing with energy storage."

This was not surprising; although many local governments—especially in Illinois with its many renewable energy projects—may be familiar with wind and solar power, energy storage is new to them.

"Once the county was comfortable with what we wanted to do, they approved the project," says Zadlo.

He noted that compared to wind and solar projects that can have large footprints, and involve the transportation of huge components—such as 50 meter long wind turbine blades—energy storage components are more modest in size. The building blocks for the Grand Ridge project are identical in size and shape to the shipping containers people see on trucks every day on the highway, and they are relatively low impact.

"We're talking about eight-foot-high containers, 40 feet long, on a site that is about a quarter mile from the nearest road," says Zadlo.

"People really can't see the energy storage project-it's out there in the middle of a cornfield. In terms of visual impact, compared to a community that has been so accepting of large wind turbines and a large solar farm, the storage system is very low impact."

In fact, the energy storage containers will blend in further with the surrounding cornfields, as they are painted green.

There are a total of 19 containers, 18 from the most recent storage project, and one container from the pilot project. They are set up on the site for easy access and serviceability. "We had good access off the road, so it was easy for us to take them off the truck and set them on the foundations," says Zadlo.

The safety aspect was an area of interest to the county. "You are introducing these containers with multiple racks of battery cells, and there is concern what might happen in the very unlikely event of a fire. The county wants to know what the emergency plan is."


To address any concerns, Invenergy walked the county representatives—including their Fire Marshal—
through their emergency plan, including details on their fire suppression system.

The small piece of land where the energy storage system is located is part of the larger Grand Ridge site, and the electrical infrastructure that was already in place was part of the reason Grand Ridge was selected for the storage system.

"We had spare interconnection capacity in the substation that connects the wind and solar power facilities we already have there," explained Zadlo. "We're utilizing that spare capacity and located the storage facilities right next to the existing substation." Additional infrastructure was minimal. They worked off the access road system, which led to a county road that had previously been improved for the wind and solar projects.

Zadlo noted that if they had to install that electrical infrastructure, the cost of the project would have gone up considerably. "If we had gone for something greenfield, we would have been looking at a new substation and a new interconnect study. By co-mingling the storage facility with what was already there, we did not need to do that. Plus, we already have operating staff for the wind and solar projects, on site."

Aside from having to deal with a harsh Illinois winter during construction (temperatures below -20 degrees), the project was fairly straightforward, says Zadlo. "We just had to keep in mind the cold temperatures when we were pouring the footings and the foundations. We had flexibility in the construction schedule to be able to do that work."

The energy storage system they selected for the project features BYD's proprietary Lithium-ion Iron-Phosphate battery chemistry. BYD says the system has the first environmentally-friendly battery chemistry, which was an attractive feature.

There were other reasons Invenergy went with the BYD system, says Zadlo.

"They provided us with the battery and inverter performance characteristics we needed for the PJM regulation application."

Probably the most challenging part of the project was getting the internal communication system right, says Zadlo. "It really is a high-tech project; there is a lot of communication infrastructure so all of the equipment can talk with each other. We have 18 containers, each container with multiple inverters, and we had to get that all to work together."

With the Grand Ridge energy storage project completed and successfully operating, Invenergy has moved on to another energy storage project. Later this year, it will bring online the 31.5-MW Beech Ridge Energy Storage project in West Virginia, where it has an existing wind power project. It will also utilize BYD's containerized energy storage system.

The contractor on that project is M.J. Electric.

The approach of adding energy storage systems to existing facilities allows Invenergy to gain an additional business opportunity from their many wind and solar power facilities. "That's one part of it," says Zadlo, "but we're also looking at standalone energy projects, too. Today's energy storage is more than just shifting energy—it's providing services for the market. It has unique attributes and can provide reliability services that even classic thermal services can't provide in the market."