Fail-Safe Battery Energy Storage Behind the Meter

To understand what a VPP, or Virtual Power Plant, is, first you should understand what a Distributed Energy Resource, or DER is.  A DER is a device capable of interacting with the electric grid–either by producing energy (like the solar panels on your neighbor’s garage or a wind turbine at a family farm) or providing capacity (like a smart thermostat or electric vehicle charger able to turn on and off at certain times based grid conditions).

Firms are focused more than ever on understanding and controlling their energy usage, and are installing DERs of all sorts, in buildings one at a time, or across worldwide campuses.  Their goals are numerous: to gather data, produce more local energy, save on energy bills, generate revenue through VPP or Demand Response services, and measure and control the shift away from carbon intense generation, among others.  However, on an individual basis DERs tend to be too small to influence the available energy on the large, sprawling electric grid.

A Virtual Power Plant is a collection of DERs that can be remotely aggregated together and coordinated with grid operations.  If enough DERs can be controlled simultaneously, their ability to deliver controlled energy can rival traditional brick and mortar power plants.

Any firm looking to enroll its DER assets in VPP services to generate revenue should be focused on dispatchability.  As the grid adds new loads like EV charging and electrified heating, and new intermittent renewable generators like solar and wind, the swings in supply and demand will intensify throughout the day, week, and season.  This will create major opportunities for DERs to respond to this volatility, and supply grid firming services at a local level–as long as they can be called upon to do so quickly.  As great as DERs like rooftop solar and wind turbines are, they are not dispatchable.  At least, not without energy storage.

Energy storage is the holy grail of DER technology, offering the ability to store excess energy when it isn’t needed and deliver it later during times of peak demand.  And at a distributed scale, no technology matches the capabilities of Lithium-Ion Battery Energy Storage Systems.  Aggregating large numbers of distributed, remote-controllable batteries into VPP portfolios is big business.  But how do we create a world with sufficient, dispatchable battery storage, and what are the barriers that Lithium-Ion faces today?

Fail-Safe Option: Viridi Lithium-Ion BESS

Safe Deployment in and Around Occupied Spaces

Viridi’s fail-safe lithium-ion technology provides the ideal solution for behind-the-meter energy storage, allowing for safe deployment in and around occupied spaces. With high power (w/kg) and energy (wh/kg) densities, this technology enables any BTM application, including resiliency, peak shaving, and rate arbitrage. The fail-safe design of Viridi’s batteries passively stops thermal runaway at the cell level, eliminating the need for fire suppression equipment.

Legacy Option: Lead Acid

Limited Resilience with Poor Energy Density

Lead acid batteries, despite being widely used, have limitations when it comes to resiliency and energy density. With poor energy density (wh/kg), lead acid arrays only provide short bursts of resiliency, limiting practical discharge durations to 20-60 minutes. This makes them unsuitable for use cases like peak shaving and rate arbitrage. Additionally, lead acid batteries have a relatively short lifespan, requiring cell replacements every 3-5 years. While they offer low fire risk and allow for indoor installations, their heavy arrays require a significant amount of dedicated floor space.

Legacy Option: Lithium-Ion (No Thermal Management)

Improved Energy Density but with Critical Safety Concerns

Lithium-ion batteries, on the other hand, offer improved energy density, allowing for a greater range of applications, including resiliency, peak shaving, and rate arbitrage. With good lifespan (3,000 cycles @ 80% DOD), lithium-ion cells can be used regularly for approximately 10-15 years before replacement. However, their high fire risk limits deployments to dedicated outbuildings and requires extensive fire detection and suppression systems. The need for thermal/offgas alarms and liquid/foam sprinklers can significantly increase costs and insurance premiums.