Driving Innovation

Saving for a “Rainy Day:” Energy Storage to Keep the Power Flowing

May 2, 2017
Aleksi Paaso, manager of grid strategy and analytics for ComEd.

Aleksi Paaso, manager of grid strategy and analytics for ComEd.

From the time our children are young, we teach them to save for a rainy day. “You never know when you might need it,” we tell them.

Saving something now, so it might be put to better use later, is the entire premise behind battery energy storage – an area of great interest for energy delivery companies like ComEd. From power reliability, to power quality, to avoided system investments, batteries have many potential uses in our energy system.

ComEd recently earned “Top 10” recognition by the Smart Electric Power Alliance (SEPA) in its first annual rankings of U.S. utilities based on the amount of energy storage on their system. Since 2014, ComEd has interconnected more than 110 megawatts of energy storage. SEPA is an educational nonprofit working to facilitate the utility industry’s transition to a clean energy future through education, research and collaboration.

Aleksi Paaso, manager of grid strategy and analytics for ComEd, provides an update on our thinking and work on energy storage.

Aleksi, who earned a doctorate in electrical engineering from the University of Kentucky in Lexington, Ky., served as a graduate teaching assistant at the university’s Power and Energy Institute prior to joining ComEd in 2014.


Q:  What is energy storage and what benefits does it offer ComEd customers? 

A: Energy storage is the capture of energy produced at one time for use at a later time. The challenge of course, stems from the fact that electricity is used as it is generated. Nonetheless, we’re working on several proof-of-concept projects testing different applications, and we’re excited about the progress we’re making and the potential positive impact that energy storage can have on system performance, reliability, resiliency and power quality.


Q:  What type of energy storage solutions is ComEd currently developing?

A: Along with our sister Exelon utilities, we’ve developed a 10-year Roadmap on Energy Storage Technologies. We’re using new simulation and design tools to assess battery energy storage systems as potential alternatives to traditional distribution solutions. For example, we have a demonstration project that will test Community Energy Storage using small-scale (25kW/25kWh) batteries to reduce the impact of power outages in residential areas where customers have experienced an above-normal number of interruptions. We are demonstrating this technology in the southern part of the region we serve in northern Illinois, which has a history of being in the pathway of severe storms.


Q: What kind of device will the community solution use? 

A: The community energy storage unit is a 25kW unit that measures about 40” x 40”. It’s partially buried underground, typically near a group of residential properties that it will serve. In the event of a power outage, the energy storage unit can automatically restore power and has enough capacity to supply power to a defined group of customers for the duration of most typical outages. We’ll be looking for a reduction of outage frequency and duration. Through this project, we are evaluating the technical feasibility of CES for addressing reliability issues in certain parts of the northern Illinois region we serve.


Q: Does energy storage also support the development of green energy?

A: Absolutely. Our team is also studying how large amounts of solar along with battery energy storage systems can be integrated with microgrid technology. A microgrid is a small energy grid that can disconnect from the main utility grid and continue providing power if the power from the main grid is interrupted. This work is being funded through a $4 million grant that the U.S. Department of Energy awarded to ComEd.

Energy storage has a potentially even bigger “green” role to play in Illinois in the years ahead, given the recent passage of the Future Energy Jobs Act, which provides funding for new wind power, large-scale solar power and rooftop and community solar. The sun doesn’t always shine and the wind doesn’t always blow. That’s why these renewable sources have variable and uncertain output, which leads to concerns regarding reliability. Energy storage offers a potential solution. It helps maintain adequate energy reserves needed to meet varying and often unpredictable levels of energy demand, and that’s key to integrating large amounts of renewables into the energy grid. On distribution systems, energy storage can also mitigate the voltage fluctuation on power lines that can be caused by integration of large amounts of solar generation.


Q: What other applications are you exploring for energy storage?

A: Besides reliability and integration of renewables, we are also evaluating the use of large-scale battery storage technology to reduce the need to make traditional investments in the distribution system. We continue to monitor the declining prices of storage and have recently identified several projects where storage can be a less expensive solution than our traditional approaches. As prices continue to decline, we expect even more projects will be viable. This would create savings that would be passed on to customers.

So we’re making progress. We combined the ComEd Distribution Planning and Smart Grid & Technology teams last year, which has enhanced our ability to collaborate and accelerate our innovation process. We’re also making new investments to understand the evolving needs and interests of our customers, and we know that reliability and clean energy solutions are high on their lists. Energy storage fits that bill.

See the video above about ComEd’s project to test Community Energy Storage in residential areas.