Battery Energy Storage Systems (BESS)
“The Battery Energy Storage Systems (BESS) industry has been dominated by lithium-ion batteries, but the need for more long-duration storage, which cannot currently be done economically and safely with lithium, will open the door for promising non-lithium technologies”.
Dr. Matthias Simolka, product manager and part of Technical Solution Engineering at TWAICE, a cloud-based battery analytics software provider headquartered in Germany.
The following basic facts about BESS = Excerpt from “Technical Information Paper Series” of The Hartford
BACKGROUND
With the growth of renewable energy sources for commercial, residential,
and industrial applications over the past few decades, the battery energy
storage system is a relatively new technology finding its way into many
business operations to better support this planned and anticipated growth.
The US utility PV market is expected to increase capacity by over 400
gigawatts over the next 10 years, and energy storage is a key component
to supporting that level of capacity expansion.
The BESS is one of three general types of energy storage systems found
in use in the market today. These include Thermal Storage Systems,
Mechanical Systems and Battery Energy Storage Systems. The basic
premise on all three general categories of energy storage is a technology
which stores energy collected from a wide variety of sources and maintains
that energy until it is called upon or demanded from equipment or a service.
Each technology has unique equipment and operational characteristics
that intend to assure that energy is available at times of peak rates from
the utility grid, or at times of power loss due to major disruption, including
power blackouts or natural hazard disruption.
The current and future expected rapid growth of battery energy systems
can be explained by their cost of implementation, resilience, environmental
efficiency, smart energy consumption, smaller footprint of installation, and
their ability to quickly transfer from charge to discharge upon demand.
Despite their benefits, battery energy storage systems (BESS) do present
certain hazards to its continued operation, including fire risk associated
with the battery chemistries deployed.
TYPES OF BESS
BESS units are available in a variety of power (measured
in kW and MW) and energy ratings (measured in kWh
and MWh). The energy ratings describe how much
energy can be delivered by the BESS over an hour,
while the power ratings depict the maximum amount
that can be delivered, constrained by the inverter and
system design.
BESS units are available in a variety of capacities,
depending upon use. For example, small, residential-
sized BESS units typically have an energy rating of up
to 5 kW, while commercial and utility scale BESS can
range from the single digit MW comprising individual
containers up to hundred(s) MWh systems. There are
new projects being developed now that exceed 1 GWh
(gigawatt hours) in energy capacity.
BESS battery cells contained within modules on racks
can be interconnected to increase the energy capacity
and align with the expected demand for specific use
applications. These module arrays are typically contained
within a room or within an exterior container which can
vary in length, usually between 20 and 63 feet.
• Lithium-Ion (LMO, NMC, NCA, LFP)
• Lead Acid (Flooded)
• Nickel-Cadmium, Sodium-Sulfur
• Flow (Vanadium Redox)
The most common chemistry found in the BESS market
today is Lithium-Ion, followed by lead acid and flow
(vanadium-redox) battery chemistries. The popularity of
chemistries is influenced by the power density ratings
for each, rechargeable time requirements, duration of
energy discharge, and availability. However, the fire risk
of each chemistry is a factor that should be considered
when selecting a chemistry for a BESS implementation.
WHERE ARE BESS FOUND?
The number and uses of Battery Energy Storage Systems
are expanding to a wider variety of business operations
and applications than when they were first introduced o
the industry over a decade ago. Today, these applications
may be found providing support for grid peaking to
supply energy back to the utility grid when demand
is high, either at local power substations or at private
locations which use BESS to help offset peak grid rates.
They can also be found in remote locations where
renewable energy sources are plentiful to collect and
store renewable power for later use.
Increasingly, we are seeing BESS installations at
commercial occupancies, including retail centers,
warehouse and distribution centers, data centers, and
many others where renewable power in the form of
photovoltaic panels are being installed in yard areas or
on unused roof spaces. The BESS enables the operators
of the PV arrays to store energy collected via PV panel
cells and hold it for use at a time when utility power
is high due to demand, or at a time when increased
demand exists at the location. In many of these
installations, the operators have sell/buy contracts with
the local utility in which excess and unused but stored
power can be distributed to the local grid at higher
demand periods.
Today, we are also seeing smaller versions of an
industrial BESS installed within single- and multiple-
family homes, which collect and store energy from
smaller roof-mounted PV panels.