Hiding A 15 MWh Battery In Plain Sight

Can you find the 15MWh battery hiding in this picture?

Stones Throw in East Stroudsburg, PA - Home of one of of the world's largest grid-scale batteries

Driving through the quiet town of East Stroudsburg, PA you wouldn’t expect it to be a hub of innovation–but you’d be wrong. That’s because the radical innovation developed there is hidden in plain sight–in the heating systems of peoples’ homes.

Back in the 1980’s when utilities were building nuclear power plants like Three Mile Island, the concern was that there would be so much electricity available, they couldn’t use it all. So Pennsylvania Power and Light (now PPL) convinced approximately 20,000 homeowners to install Electric Thermal Storage (ETS) heating systems in their homes. These systems “time shift” electric consumption by storing energy–in the form of heat–in dense ceramic bricks or tanks of water. The huge energy storage capacity of these systems means that these systems can procure all the energy required to heat a home in about 4 hours, usually during the middle of the night when wholesale energy prices are low and electric grid capacity is plentiful. They gradually release the stored energy during the day as heat as required to meet the home’s thermostat setting.

Over time, ETS fell out of favor with homeowners as price supports for heating electricity were removed and cheap natural gas lured homeowners away. Today, about 6,000 homeowners in PPL territory still have ETS systems, attracted by the low maintenance and the even, clean heat that they provide. Little did these homeowners know that they’d have a huge role to play in the development of one of the world’s largest energy storage systems, a key component of electric grid modernization.

VCharge, recognizing the energy storage potential of ETS, developed electronic controls for these heating systems that allow individual heaters or electric boilers to be switched on or off rapidly (within seconds) of the receipt of a control signal by VCharge’s Network Operations Center from the area’s grid operator, PJM Interconnect. The innovation started in the tidy development of Stones Throw in East Stroudsburg, where developers had installed identical ETS units in the 1980’s and ’90s, making it a perfect place to pilot VCharge’s technology. Now, over 60 Stones Throw homeowners, and nearly another 140 in the surrounding area, have installed free controls on their ETS heaters to participate in this radical experiment in grid storage and energy management–and to get a 25% discount on their home heating bills.

What’s radical about the aggregated energy storage asset is that by itself, any individual heating system is relatively unremarkable. But together, the 200 homes in VCharge’s Aggregated Transactive Load Asset (ATLAS) create a huge resource for grid balancing–specifically providing ancillary services like fast frequency response through the markets run by PJM. This reservoir of capacity, both to cut load on the system (effectively generating negawatts) and to absorb rapid influxes of energy (for example from a sudden surge from a solar or wind farm) means that grid operators have a powerful new tool in their belts to deal with the coming demands of a shifting energy mix.

How do you hide a 15MWh battery in plain sight? Spread it across 200 homes in eastern PA:


At our projected capacity, the VCharge PA ATLAS will offer 25MW of load control with 127 MWh of storage. And it holds its own relative to other large batteries today being assembled at far higher costs like the Duke Energy/Xtreme Power Notrees Wind Farm battery. Note that if all 6,000 people who were eligible for VCharge controls were to upgrade, the PA ATLAS battery would be 90,000 kW/450MWh. We’re pretty proud of the progress that we’ve made to date, and thank the people of Stones Throw for their willingness to work with us on launching this project.

If you’re one of the 5,800 homeowners in PPL territory without VCharge’s controls on your heating system, you can contact us here for more information.




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