12 energy storage startups to watch in 2015

If you care about the world’s transition to clean power, then you should pay attention to the emerging market for energy storage. A lot of times when “grid-scale” energy storage is discussed, it’s usually meant to describe big battery farms, but it can also mean other forms of energy storage like thermal storage (using heating and cooling), and the next-generation of compressed air storage.

It’s been over a year since California set the country’s first ever mandate that says that the state’s utilities need to buy over a gigawatt of energy storage services by 2020. But you don’t have to live in California, to be interested in this new market because what’s happening in the Golden State will likely be emulated elsewhere down the road.


Wind and solar power plant owners can use energy storage systems to bank electricity and discharge it at any time when they need it. That helps utilities dispatch solar and wind energy to homes and businesses even when their solar power plants and wind farms aren’t able to generate electricity (like solar panels during the night). The ability to do so makes it possible for utilities to forgo building more fossil fuel power plants, which are able to produce electricity around the clock.

Some companies are selling energy storage services to businesses that can use electricity from battery banks — instead of the power grid — when utility rates are high. Homeowners typically can’t save as much money as businesses can because they don’t face the same special charges on their bills from utilities. These types of battery services will become more attractive to customers once battery system prices drop low enough to make them more affordable.

Here is a list of battery technology and energy storage service startups that have completed sizable demonstration projects or started to deploy their energy storage systems more widely:

1). Aquion Energy: This startup just scored a major customer in a private estate off Hawaii’s Kona Coast, where it will install a 1 megawatt-hour battery that will store electricity from a 176KW solar energy system. Aquion has figured out a novel cocktail of materials for creating the chemical reaction needed to charge and discharge energy. The Pennsylvania-based company uses manganese oxide and activate carbon for the electrodes, sodium sulfate for the electrolyte and a synthetic material with a structure similar to cotton.

Batteries ready to ship at Aquion Energy's factory. Image courtesy of Katie Fehrenbacher, Gigaom.

Batteries ready to ship at Aquion Energy’s factory. Image courtesy of Katie Fehrenbacher, Gigaom.

2). Stem: Software development is key to Stem’s growth. The California company assembles lithium-ion battery cells and power electronics made by other companies. But it creates the software to monitor and predict its customer’s energy demand, and manage the charging and discharging of the battery systems to help customers reduce the use of electricity from the grid when rates are high.

Stem recently added Total Energy Venture and Constellation Technology Ventures as investors and raised a $27 million series B round. Some of the money will be used to develop, license or buy software technology to boost its energy management service, Stem’s CEO, John Carrington, told me. The company has lined up 85 MW contract with Southern California Edison.

Stem battery storage

3). EnerVault: A flow battery is made up of two tanks containing energy-storing chemicals and liquid electrolyte, which flows through a cell to react with the electrodes inside for generating power. EnerVault celebrated the completion of a 1 megawatt-hour flow battery system, which has iron in one tank and chromium in the other for storing energy, at an almond farm in California’s Central Valley last year. It was an important project for the company to demonstrate its technology. The performance of the system will affect whether EnerVault will line up more customers and financing.

EnerVault's battery on an almond farm in Turlock, California.

EnerVault’s battery on an almond farm in Turlock, California.

4). Sunverge Energy: Raising a $15 million Series B last year and teaming up with SunPower are propelling Sunvege’s growth as a battery system designer and installer. Sunverge integrates lithium-ion battery cells and power electronics into a cabinet and develops software to run the system.

SunPower and Sunverge started a pilot project with KB Home last year to show how a SunPower’s solar energy system could work well with Sunverge’s battery setup. The two companies are now co-marketing that solar-and-battery combination for a commercial rollout this year. One of the Sunverge’s investors is Total Energy Ventures, the investment arm of French oil and gas giant, Total, which owns the majority stake in SunPower.

Photo by Katie Fehrenbacher/Gigaom

Photo by Katie Fehrenbacher/Gigaom

5). Ice Energy: Using electricity to make ice at night, when electric rates are lower, and melting it to provide cool air for the building during the day is what Ice Energy offers as an cheaper alternative to running air conditioning in the hot afternoon, when electric rates are high. Ice Energy’s ice-making system, called Ice Bear, is located near a building’s air conditioning system, which is modified to integrate Ice Bear. The company recently won its biggest deal with Southern California Edison, which wants 25.6 MW of service from Ice Energy systems across different locations.

Ice Energy

6). Advanced Microgrid Solutions: This company was quiet until it got publicity for being selected by Southern California Edison to provide 50 MW of services. Helmed by Susan Kennedy, a former member of California Public Utilities Commission and chief of staff of former California Gov. Schwarzenegger. Advanced Microgrid Solution appears to be a pure project developer which doesn’t do in-house hardware or software development.

A bank of lithium-ion batteries from BYD.

7). Coda Energy: This is not the Coda Energy that wanted to make electric cars, though it was part of that enterprise until a group of investors bought the energy storage business during a bankruptcy sale in 2013. Coda Energy installed several energy storage projects in 2014.

The company designs lithium-ion battery systems and develops the electronics and software to manage the systems. Its largest project, a 510KW system that could deliver 1.05 megawatt hours of energy, is a demonstration project at its headquarters that was co-funded by a state incentive program and the South Coast Air Quality Management District in southern California.

Codea Energy tower

8). Imergy Power Systems: Imergy is a flow battery developer that has developed a process to purify low-grade vanadium, such as those from the waste stream from mines and oil fields, to make the energy storing compound in the liquid electrolyte. The vanadium technology is newer for the company, which sold several dozen iron and chromium flow batteries for off-grid use by telecom firms in India before making the switch a few years back. Imergy has announced several demonstration projects over the past year, including a 100KW system that will deliver 400 kilowatt hours of energy at a microgrid project at a U.S. Navy site in Port Hueneme, Calif.

Imergy's battery, image courtesy of Imergy.

Imergy’s battery, image courtesy of Imergy.

9). GELI: The acronym stands for Growing Energy Labs, Inc., and this startup has developed an operating system to make sure the battery systems work well with other pieces of equipment, such as solar panels or heating and cooling systems. Developing good software to predict energy use of a building and store and dispatch energy from a battery system efficiently is a major pursuit and challenge of any energy storage developer and service provider. You can expect to see more startups in the battery software space as the market grows.

10). Green Charge Networks: When I caught up with Green Charge’s CEO, Vic Shao, about a year ago, he had lined up $10 million for financing projects that use Green Charge’s software to manage the lithium-ion battery systems designed by the company, using battery cells from suppliers such as Samsung. Like its competitors such a Stem, Green Charge also is going after business and industrial customers, such as 7-Eleven and Walgreens. It has also lined up customers in public agencies, including school and cities.

Green Charge Networks

11). Ambri: The liquid metal battery developer raised a $35 million series C round last year to bring its technology to market. Ambri’s battery, unlike common battery designs, uses liquid anode and cathode, along with a molten salt electrolyte. The company plans to install prototype systems this year, look for a location to build a larger factory and complete the sale of its technology’s commercial version in 2016, according to a Boston Globe article.

Manufacturing equipment at Ambri's prototype plant.

Manufacturing equipment at Ambri’s prototype plant.

12). Solar Grid Storage: The company is part of a growing number of project developers that sell and install a bundle of battery systems with solar panels and electric car charging equipment. When I spoke with Solar Grid’s CEO, Tom Leyden, over a year ago, he talked about the challenge of securing financing separately for the energy storage and solar portion of a project. The company’s projects are mostly on the East Coast.

Solar Grid Storage

My 14 favorite energy stories of 2014

While the rest of the tech world focuses on things like Apple’s upcoming gadgets, which retailer is the latest to get hacked, or the ongoing drama around Uber, I’ve spent much of the past year (the past seven years, actually) looking at what’s going on at the forefront of energy innovation. Progress with energy — making it cleaner, more efficient and more accessible — can come in a variety of places, from university labs, within Silicon Valley startups, at big corporations, and even via government programs.

In 2014, there seemed to be resurgence of startups and entrepreneurs taking risks and daring to tackle the difficult world of energy. Perhaps they were inspired by the successes of Tesla CEO and SolarCity Chairman Elon Musk, or the Opower founders, who saw their energy data startup go public this year. Or maybe there was just a little bit more funding available to these types of strategic thinkers, after a couple years of political backlash in the U.S. and a backpedaling from energy investing by venture capitalists.

Looking back at the year, I think it’s one of the brightest ones we’ve had in awhile when it comes to the changing face of energy, using new technologies and new business models. Here were my favorite 14 stories, in chronological order, that I covered this year:

1. What 60 Minutes got right and wrong in its story on cleantech: The year kicked off with one of the most high profile — and most negative stories — to appear about the whole cleantech phenomenon in the long form television show 60 Minutes. While a lot of my peers rejected the coverage out right, I thought the producers got some things right (the VC cleantech crash angle), and some things pretty wrong (the politics and missing the solar panel boom).

Vinod Khosla – Founder, Khosla Ventures

Vinod Khosla – Founder, Khosla Ventures

2. The Hoover Dam of solar is now live in the desert of California, and why it’s important: The huge solar thermal plant Ivanpah was finally finished and started distributing electricity in early 2014. The project was one that highlighted the difficulties it takes to get a project like this built — it faced many delays, criticism from environmental groups (over desert tortoises), and also changing economics, as the cost of solar panels dropped dramatically as it was getting built (it doesn’t use panels, but mirrors to concentrate the sun). But the project also showed how the Department of Energy’s support of Ivanpah was crucial for it to get built, how a startup like BrightSource can innovate, and how companies like NRG and Google are eager to invest in clean energy.

A look at the heliostats and 2 of the 3 towers of Ivanpah. Taken from the 6th floor of the Unit 1 tower.

A look at the heliostats and 2 of the 3 towers of Ivanpah. Taken from the 6th floor of the Unit 1 tower.

3. The sheer size of Tesla’s massive battery factory could be a game-changer in many ways: One of the most interesting things to happen in energy in 2014 was the unfolding of Tesla’s plans for its battery factory, which is now planned for a spot just outside of Reno, Nevada. This is the article where I first started to realize how disruptive and unusual the idea was.

A recently raised spot of land in the Tahoe-Reno Industrial Center.

A recently raised spot of land in the Tahoe-Reno Industrial Center.

4. It’s easy to miss the meaningful parts of the Valley, if you ignore them: I went on a bit of a kick in the spring of this year, fighting back on the notion that the Valley doesn’t create anything meaningful anymore. Anyone who has followed the rise and fall of cleantech or is interested in energy innovation knows this isn’t true. A lot of times these Valley innovators are working on less sexy problems (so the media ignores them), and their innovations are taking longer to come to fruition.

Bloom Energy fuel cells.

Bloom Energy fuel cells.

5. As KiOR Crashes, it’s another cautionary tale for energy innovation: KiOR has always been a symbolic company for me when I think about some of the more unusual strategies that cleantech venture capitalists have taken around energy over the years. The company, which was largely owned by Khosla Ventures as well as Vinod Khosla personally, went public in the summer of 2011 at $15 per share, making Khosla Ventures’ share worth about $830 million at the time. But at the beginning of 2014 it was starting to falter, and by the end of the year it had filed for bankruptcy. I covered these guys from launch (first I heard of them was 2007) to the end.

One of Kior's facilities. Image courtesy of Kior.

One of Kior’s facilities. Image courtesy of Kior.

6. With Opower’s IPO, founders show meaningful tech can pay off: I was pretty excited to see Opower IPO in the Summer of 2014, and see that the company’s founders still held considerable equity at the time. Now Opower’s founders and longtime friends Alex Laskey and Dan Yates are the poster children for the growing meaningful tech movement.

Opower executives at the New York Stock Exchange ringing the closing bell.

Opower executives at the New York Stock Exchange ringing the closing bell.

7. As solar panels boom, it was the simple business model that the big energy players missed: While this wasn’t a huge story, I liked it because it shows that even in the difficult energy space there are things that entrepreneurs and innovators can do that big companies miss. Both NRG and GE lamented that they didn’t get in earlier into the solar-as-a-service financing business for rooftops that SunEdison started and companies like SolarCity are now dominating.

solar panels

8. An almond farm and a “big ass battery” show the future of energy in California: I visited the site of this flow battery in the little city of Turlock in the Spring of 2014. It stuck out in my mind because it shows how a really small company like EnerVault can use a tiny grant, and a lot of strategic thinking, to get entirely new energy technology built in very specific places for specific use cases. In this case, the battery is installed on an almond farm, and it bottles up energy from solar panels that help power an irrigation pump that waters about 300 acres of the farm.

EnerVault's battery on an almond farm in Turlock, California.

EnerVault’s battery on an almond farm in Turlock, California.

9. We don’t need solar roadways, we need to help unleash current solar panels: This story makes me laugh because there was SO much attention on it: 204 comments, some pretty interesting, some total garbage. Most of my peers in the energy tech sector (or covering it) I think agreed with my assessment, but didn’t want to come out and say it directly. After this was published, there were a variety of take-down articles written. Most people interested in sustainability are pretty nice and don’t want to come down on someone else’s project.

But a lot of readers out there across America did NOT like or agree with my opinion of solar roadways. Only time will really tell with these things, so I guess I’ll just have to review where the solar roadways project is in the spring.

solar panel

10. Behind the scenes with Tom Siebel, C3 and its data engine for the power grid: C3 has gotten a lot of flack over the years because it pivoted substantially early on away from carbon software and to energy data analytics for utilities. But I don’t think anyone should count C3 or Tom Siebel out just because their product has been a long time coming. Siebel is one of the world’s best salesmen, he’s all in on energy data, and the company has secured a large amount of customers in a short time frame. While this wasn’t one of the most popular articles, I thought it was a fun one.

Power grid

11. The Elon Musk playbook for disrupting energy: vertical integration and huge factories: I think it’s fascinating that SolarCity and Tesla are looking to disrupt energy and cars using similar businesses models. In this article, I tried to compare and contrast these methods and help entrepreneurs realize how Elon Musk is trying to scale these disruptions.

SolarCity panels on a Walmart, courtesy of SolarCity.

SolarCity panels on a Walmart, courtesy of SolarCity.

12. Behind the scenes of Aquion Energy’s battery factory & the future of solar storage: It’s exciting when startups that have been talking about a technology for years finally get to the point of commercially making and shipping it. I got a chance to check out Aquion Energy’s battery factory outside of Pittsburgh over the summer. It was still small, but represents a big leap for startups building the next-generation of grid batteries.

Battery stacks and modules in Aquion Energy's factory. Image courtesy of Katie Fehrenbacher, Gigaom.

Battery stacks and modules in Aquion Energy’s factory. Image courtesy of Katie Fehrenbacher, Gigaom.

13. The changing face of Reno: Why the ‘world’s biggest little city’ is attracting Apple & Tesla: Before Tesla announced that it planned to build its battery factory just outside of Reno, I took a trip up there and checked out the rumored Tesla factory site, as well as Apple’s yet-to-be-built-out solar farm up there. I also met with a variety of Reno officials as well as geothermal industry execs, who were in town for a conference. Reno, which has long been a gambling backwater, is slowly transforming into a high tech manufacturing hub, and Tesla’s factory will only accelerate that.

The Tahoe Reno Industrial Center. Photo by Katie Fehrenbacher/Gigaom

The Tahoe Reno Industrial Center. Photo by Katie Fehrenbacher/Gigaom

14. Lithium, the Salton Sea and a startup that’s trying to change the game: The Salton Sea is such a bizarre and fascinating place that any company trying to build something new out there would be interesting. But Simbol Materials turns heads because the startup is looking to recover lithium from geothermal plants, and it’s backed by Silicon Valley investors. I drove down to the Salton Sea in September and took a tour of Simbol’s demonstration plant in Calipatria, California.

Simbol Materials' VP of Business Development Tracy Sizemore stands in front of Simbol's demo plant that neighbors EnergySource's geothermal plant just below the Salton Sea. Image courtesy of Katie Fehrenbacher, Gigaom.

Simbol Materials’ VP of Business Development Tracy Sizemore stands in front of Simbol’s demo plant that neighbors EnergySource’s geothermal plant just below the Salton Sea. Image courtesy of Katie Fehrenbacher, Gigaom.

13 biggest moments in cleantech in 2013

Here’s the 13 biggest things I paid attention to this year around next-generation energy, sustainability, and resource management. Oh heck, let’s just keep calling it cleantech.