One of the most innovative electric power projects in this country sits on Alcatraz Island, in the middle of San Francisco Bay. On The Rock, Princeton Power Systems coordinates a microgrid combining 307 kilowatts (kW) of solar panels, a 400 kW (two megawatt-hour - MWh) lead acid battery bank, two diesel generators and its own controllers and inverters to keep the island running 24 X 7.
Microgrids are small electrical grids that can either stand remotely (as in the case of Alcatraz, and in some island or remote northern communities) or be interconnected with the main power grid. In the latter instance, they can be severed from the main grid (‘islanded’) in times of distress to become independent.
Microgrids have come into vogue lately, and they cannot come too soon. Our U.S. electric grid is in pretty rough shape. Many of the components are older than this writer (by way of context – I cried when the Red Sox lost the World Series in 1967), and we are not doing enough to maintain the existing grid, let alone improve it. The American Society for Civil Engineers gives our grid a D+, and estimates that we are underinvesting to the tune of roughly $11 billion annually.
The manifestation of this is that on any given day, an average of half a million people are without electricity for two hours. The Eaton Annual Blackout Tracker reports that according to Dunn and Bradstreet, 59% of U.S. companies suffer a minimum of 1.6 hours of electric outage-related downtime per week. Eaton estimates average annual costs to be on the order of $46 million per company. A recently released White House report estimated total 2013 outage-related costs at between $18 and $33 billion.
Some of this problem can easily be rectified with more grid investments, but in many cases, the only way to truly harden one’s facility against outages caused by the likes of a severe and widespread weather event – or terrorism – is to invest in microgrids.
Back-up diesel generation can be helpful for a limited duration, but in long-term events, such as post-Katrina or Sandy, liquid fuels are likely to be unavailable. In such instances, one’s diesel generator becomes a reminder of a failure to plan for the worst, and a rather unsightly paperweight.
The military has become increasingly aware of this situation, which is why it has recently moved to develop microgrids to harden its facilities and is utilizing significant amounts of renewable energy to power the mix (though diesel gensets are often included as well).
States such as Connecticut – which suffered widespread damage in 2011 as a result of both Hurricane Irene and a freak October snowstorm – and New Jersey – which got pummeled by Hurricane Sandy – are also moving rapidly to establish microgrid capabilities.
One company which stands to benefit from this trend is Princeton Power Systems. Princeton Power is one of the first companies to have recognized both the need and the opportunity for microgrids, over a decade ago, and they have been helping to drive this trend ever since.
I recently spoke with Darren Hammell – Co-founder and CSO – to learn more about the company and its capabilities. It was clear from the outset of our conversation that the founders were visionary. Hammell noted that the company actually started in a dorm room at Princeton University as part of a senior project. With the help of a professor and an initial angel investor, the company initially focused on government research and development programs.
The first product we ever built – which was more of a prototype - we installed at a cogeneration plant in Princeton. Princeton University has its own microgrid set up. We installed a motor drive that runs one of the cooling towers.
Princeton Power Systems focused on the electronics, which continues to be the company’s focus today.
We started out developing electronics technology, at a commercial and industrial scale from 10 kW to 500kW. The first projects were mostly around the military – we developed a set of motor drives that ran air handlers on the Navy’s newest aircraft carrier. That allowed us to hone the technology.
Then, before most others saw it, the founders realized that renewables and energy storage might have a bigger role to play in the system, if they could be properly coordinated and integrated. Hammell commented,
We started working on distributed generation, mostly looking at solar arrays and energy storage, back around 2003. We looked at what we saw as the coming boom in solar, and thought we were going to need to have energy storage to make solar truly useful.
In the mid to late 2000’s, they found a few forward-looking electric utilities in a relatively quiet space.
At that time nobody wanted to pay for microgrids. We did some work with SDG&E. The Department of Energy SEGIS (Solar Energy Grid Integration Systems) R&D program was also very forward looking. The premise was, if we had really high penetration of solar on the grid, how could we manage that? Our concept was to provide power electronics incorporating batteries with solar and load control, and to be able to deal with intermittency, ramp rates, and back-up power.
Then in 2008, the Alcatraz project came along. The island has had a problem since a ship’s anchor ruptured the electric power lines nearly 50 years ago. Since that time, Alcatraz had been operating on expensive diesel, which was shipped across the Bay. As solar energy became more viable, the National Parks Service began to look at the concept of replacing diesel with solar and battery storage, and decided to make the leap.
Image: Princeton Power Systems
The Parks Service hired a general contractor, who in turn bought some converters from Princeton Power.
We got a call saying ‘hey this stuff isn’t working the way we expected it to,’ and we found they were trying to design and build a PV microgrid, but nobody had experience with microgrids or ownership in the design.
Princeton Power Systems ended up assuming responsibility for designing the systems, as well as monitoring the construction and project commissioning. Completed in 2012, the project is celebrating two years of operation.
Hammell noted that the challenge was to get the constituent elements to work together, including a controller that monitors and synchronizes all the pieces.
Solar generates power and that gets dumped into an AC microgrid. If there’s too much solar, the excess charges batteries. If there’s not enough, the batteries discharge. And if batteries get low enough, we turn on the diesel generators to operate at peak efficiency just long enough to charge the batteries. We turn on the diesel once every three or four days for a few hours and then shut it off.
The overall result is to reduce diesel fuel consumption by approximately 80%, resulting in a cost savings for the National Park Service.
In the ensuing twenty-four months since the Alcatraz project has been commissioned, Princeton Power Systems has developed projects at a number of locations. These include: the Brooklyn Army Terminal (100 kW of solar combined with a 720 kWh battery and a building management system); the EaglePicher Energy Storage System in Joplin, MO (one MW of energy storage combined with both wind and solar); Fort Bliss, Texas (a demonstration project with Lockheed which includes several 100 kW grid-tied inverters paired with advanced lead acid batteries providing 20 kWh of storage); and the San Diego Zoo (a 90 kW solar canopy tied to an electric vehicle charging station with a Princeton Power Systems inverter modified to allow for rapid EV charging).
The result of Alcatraz and these follow-on projects, according to Hammell, is that “We established ourselves as a technical leader in a market that didn’t exist quite yet."
Now that the market is taking off, the company is more actively moving into greater coordination with storage companies, which it sees as one of the next frontiers. Princeton Power Systems recently announced a relationship with Aquion – a manufacturer of aqueous hybrid ion batteries – and a demonstration project on-site at Aquion’s Pennsylvania headquarters. This project will highlight Princeton’s DRI-10 inverter with 14 of Aquion’s 270 kWh batteries in a fully functioning microgrid.
Like others in microgrids and storage, Princeton Power Systems is going to markets where avoided costs are high, and this means moving into the developing world where costly diesel is still a mainstay, or areas where reliability is critical.
In developing countries, it’s simply bringing electricity where none was before. A solar microgrid is often the cheapest way to do that – many places don’t even have a diesel distribution system.
As the immature marketplace evolves, Princeton Power Systems’ short-term operations-focused niche has emerged out of necessity, but the company foresees an evolution over time.
Our real piece is on the operations side – making sure the whole system runs reliably, that the power stays on, and none of the equipment fails. There is a layer on top with more customized software algorithms (that interact with power markets) for optimizing economics and market transactions. We in some cases stay involved as microgrid operator right now, since it’s a bit of an immature market and we are filling a gap. We could imagine ceding this role in the future to companies specializing in owning and operating microgrids, so we can focus on the power electronics and software that makes the microgrid work and train others to own and operate our systems.
Clearly, the microgrid trend is in its early days and there remains a good deal to be learned about the interaction of the parts, the economics, and the optimal configurations. Just as clearly, there is a growing need and market for microgrids both in the developing world and in the U.S. electric power grid. Politicians, power planners, and private companies are awakening to the value these systems can offer, even as the technologies mature and price points come down. As these markets grow in size, expect Princeton Power Systems to continue driving the conversation and to claim its fair share of the market.
