ETA 2021 Strategic Plan - Flipbook - Page 21
Chemical Energy Storage
Thermal Energy Storage
Chemical energy storage includes hydrogen
and other hydrogen-rich chemical energy
carriers produced from diverse energy sources.
Chemical storage enables high energy density,
long-duration/seasonal storage, and the ability
to address not only the power sector but
industrial and transportation sectors as well.
For chemical storage to be competitive with
other storage technologies, cost reductions
are needed in the synthesis of hydrogen or
other hydrogen-rich carriers, as well as in the
chemical storage system components. Emerging
manufacturing technologies, such as roll-to-roll
manufacturing, additive manufacturing, and
increased modularity and automation of the cell
and stack assembly processes have the potential
to enable the higher production volumes
needed. ETA researchers recently developed
a unitized reversible fuel cell (URFC) that can
boost round-trip efficiencies by combining the
electrolyzer and fuel cell into a single device. The
unconventional configuration explored involved
both electrodes each participating in reacting
both hydrogen and oxygen, an approach verified
by laboratory experiments, techno-economic
analysis, and accelerated stress testing.
The thermal focus will explore new concepts and
technologies to push the boundaries of thermal
energy storage. New approaches to energy
storage that can provide flexibility are essential
for increasing the reliability and resiliency of
the energy systems. To meet this challenge,
researchers are exploring various routes to
optimize thermal energy storage materials and
designs, some of which are described here:
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• Developing dynamically tunable thermal
energy storage materials that could be
integrated with thermal switches for building
envelope applications. This new technology
has the potential to enable optimal thermal
routing in both space and time. Combining
the new thermal switches with dynamically
tunable thermal storage should enable:
thermal microgrids within a building
envelope, time shifting thermal loads (e.g.,
to exploit nighttime cooling the following
afternoon), and intelligent thermal isolation
among local hot/cold zones within a single
building. The dynamically tunable thermal
storage materials developed here can
modify their switching temperature or
characteristics to operate optimally in both
summer and winter. This will significantly
reduce the cost of thermal storage when
compared to that of existing thermal
storage materials. To enable flexibility, we
are developing thermal switches to control
directional heat transfer. The thermal
switches will be integrated with dynamically
tunable thermal storage to provide control
over the timing of charging or discharging.
Such devices would allow buildings and
industrial plants to deploy and time-shift
thermal storage technologies in new
ways and expand the potential for better
informatics-based energy management.
• Developing thermochemical materials (TCMs) that
undergo solid-gas reversible chemical reaction
with water vapor. These materials would enable
users to store and release energy with high
storage capacities (600 kWh/m3) and negligible
self-discharge, as energy is stored in chemical
bonds. This design makes them uniquely suited as
compact, stand-alone solutions for daily-seasonal
energy storage for residential, district-level, or large
commercial buildings. Researchers aim to address
the core technical challenges while also elucidating
the potential of TCM-based storage (at different
scales, from day-night to seasonal) to provide gridinteractive energy efficiency and flexibility in the
U.S. building sector.
• Using computer modeling techniques to determine
reactant mixtures that can boost the heat capacities
of thermal energy storage liquids by 30%. Such
mixtures are achieved by breaking or forming
reversible covalent bonds upon heating and
cooling and have been confirmed experimentally.
Computer modeling is also being used to identify
new solid thermal storage media that balances
high-temperature stability, electrical and thermal
conductivity, heat capacity, mechanical robustness
at high temperature, and cost. The thermal energy
storage solutions will need to identify cost-effective
and efficient approaches to convert the thermal
energy into electricity for grid applications.
• Developing a composite material capable of converting
excess electricity into heat and storing it. Large-scale
inexpensive energy storage could smooth out the
timing disparity between renewable energy overproduction and grid demand, enabling the switch
to a 100% renewables-powered grid. To provide
cost-competitive thermal energy storage solution,
researchers are developing a composite material
capable of converting excess electricity into heat
and storing it at temperatures in excess of 2,000°C,
from which it can be dispatched up to 100 hours
later when demand peaks. The high-grade thermal
energy can then be converted back into electricity
for the grid, or supplied directly as process heat to
industrial manufacturing processes (e.g., for making
steel or cement, which require temperatures >
1,500°C). Such applications otherwise rely on
burning fossil fuels to supply steady thermal
energy.
Berkeley Lab Energy
Storage Center
Building on decades of
scientific leadership in energy
storage research, Berkeley
Lab has established this new
center to harness, guide,
and galvanize the expertise,
capabilities, and innovation
across the entire lab to
accelerate real-world energy
storage solutions, enabling
the nation’s transition to
a clean, affordable, and
resilient energy future.
The center encompasses
a broad range of storage
technologies beyond simply
electrochemical, from
chemical and thermal to
mechanical and “virtual.”
It will drive coordination
internally and externally to
grow science-to-systems
collaborations, accelerating
impact for the grid, buildings,
transportation, and industrial
sectors. Early focus areas
include securing the lithium
supply chain, the science of
manufacturing for advanced
batteries, long-duration
storage, and hard-todecarbonize sectors.
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