Page 58 - North American Clean Energy November December 2015

energy storage

Safe Energy Storage Systems:

A matter of chemistry and design

by Ron Van Dell

AS GREATER AMOUNTS OF RENEWABLE ENERGY begin to penetrate the electrical grid and technology like lithium-ion is not well suited for the demands of many stationary storage
utilities grapple with the issues of power quality and peak generation capacity, energy applications because it is inherently unstable. In fact, lithium-ion batteries are prone to
storage will become a key component of our energy future. As energy storage technologies thermal runaway, causing them to catch ire or explode – making them unsuitable for any

proliferate, commercial and industrial operations, and utilities will need to examine which demanding applications. Combating this requires added system costs beyond the battery
technologies to utilize and in which locations they should be deployed.
cells for precise cell equalization, ire suppression, and climate control. But, a zinc-iron low
he fact is, more value comes out of an energy storage asset when it is deployed near the battery uses plain water with which to mix the chemical elements of the electrolyte which
edge of the electricity grid. here are simply more services energy storage can provide at naturally dissipates heat during extended and punishing duty cycles.

the edge of the grid, particularly with distributed generation like rooftop PV. As a result
of being co-located with neighborhood communities where people live and work, a heavy Safety vs performance
emphasis needs to be placed on system safety.
he physical demands of stationary storage applications are another factor contributing
to safety issues. Heat generated from demanding charge and discharge cycles are a cause

Location dictates safety considerations
for irreversible capacity loss which is detrimental to most battery technologies and can
Safety determines where it is acceptable to site energy storage and what precautions must lead to catastrophic failures, including thermal runaway. Take, for example, a community
be taken to ensure health and environmental safety which can constrain deployment microgrid which integrates solar generation with battery storage. his scenario would

lexibility. A utility-scale application, for example, may need to be deployed at a substation require a morning discharge before the sun rises. his would deplete the battery, leaving
where lammable or explosive materials pose obvious risks to human life or the integrity of it at a low state of charge (SOC). he PV system would begin to provide energy, charging
power infrastructure. In microgrid applications, on the other hand, storage is often located the battery as sunlight begins to become available. During this PV ramping, however,
near distributed loads within communities. In those cases, safety is, again, of paramount many large utilities like PJM and ERCOT require the battery provides frequency regulation

importance because certain conditions can cause structural failure, allowing hazardous services to allow for smooth solar energy output. his process requires rapid switching
materials to leech into the surrounding soil, inding their way into the local water source.
between charge and discharge. Rapid cycling of this nature is well outside the capacity of
Two main factors determine the safety of energy storage systems: chemistry and design. lithium-ion batteries when they are at a high or low SOC (typically above 80% or below
Batteries with an acidic or otherwise caustic chemical makeup can cause immediate
30%). As a result, many battery storage manufacturers must impose further constraints

harm if the chemical electrolyte comes in contact with the skin (as anyone who might
on the operating parameters of their systems in order to ensure safety, further limiting
have accidentally picked up a leaky car battery will attest) or if it is ingested. If elements their capacity and capabilities. Battery storage technologies that can’t perform these tasks
and chemical compounds like vanadium, bromine, or sulfuric acid are released in highly without ensuring safe operation aren’t suitable for widespread deployment.
populated areas or in environmentally sensitive zones, they can cause long-term damage he safety of battery storage technologies is what will determine which ones will

to people, crops, water sources, and wildlife. Hazardous materials also pose a logistical proliferate. As we move toward an era when abundant and reliable energy will mean greater
challenge due to safety concerns whether the goal is to deploy energy storage in populated integration with renewable resources, we will see more and more need for energy storage to
areas or in remote locations. hese safety concerns add to the risks and the costs of make it work. After all, what good is clean energy without clean energy storage?
transporting hazardous materials or replacement battery cells to storage sites.

Ron Van Dell is the CEO of ViZn Energy Systems.
Safety in chemistry
One battery chemistry, in particular, has proven to be intrinsically safe: zinc-iron. Used as ViZn Energy Systems | www.viznenergy.com
part of the right battery system, zinc-iron has also proven to be quite good at both power

and energy applications. he components of this chemistry are inherently safe because
they are food-grade additives, similar to what may be found in any number of of-the-shelf
items at the local supermarket. In addition to being non-toxic they are globally abundant,
conlict-free products.

All batteries have a chemical metabolism that is afected by temperature, state of
charge (SOC), high power, and cycling which the design of an energy storage system
must take into account to meet the application demands for which it is intended. A

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