Green Economy Journal Issue 56

ENERGY
ENERGY
Lux Research
Long-duration
As we endeavour to reach a carbon-neutral economy, electricity will become the core of the
energy system. To ensure security of electricity supply, the resilience of networks needs to be
strengthened with the implementation of long-duration, utility-scale storage technologies for
discharge durations of four hours and beyond.
BY LUX RESEARCH*
According to the International Energy Agency, China and the
US had the largest utility-scale storage capacity in 2020,
with 1.9GW and 2.7GW, respectively; of this capacity, Li-ion
technology accounts for almost 90% but does not offer long-duration
energy storage capabilities. In this technology landscape insight, we
will categorise the options for long-duration energy storage (LDES),
excluding pumped hydro and hydrogen.
By region
Long-duration energy storage players.
ENERGY STORAGE
Flow batteries are getting more attention among the different
technologies; emerging interest is concentrated in the development
of nonvanadium batteries, due to the high cost of vanadium and
incentives to develop this technology using more sustainable
materials, particularly in EMEA. In contrast to SMEs, for large and
midsized corporations, chemical energy storage shows higher activity
than mechanical energy storage.
Organisation count by technology and entity type
Historically, there has been more demand and R&D opportunities
in electrochemical forms of energy storage. None of the large corporations
active in this space have energy storage as their core business;
therefore, most of the developments in this business tier come from
legacy electrochemical research. Across all organisation types, the
technology development landscape is fragmented, indicating that
there is no one-size-fits-all solution for LDES.
Chemical energy storage, primarily flow batteries, is the most active
technology in terms of number of developers. A vast majority of the
active SMEs are concentrating on flow batteries, although the market
already has big, mature players like Sumitomo Electric Industries,
Honeywell and Lockheed Martin. Nevertheless, there also is significant
activity from research institutes, which are currently working on new
materials, components and stacks to reduce the cost.
On the other end of the LDES technology spectrum, gravitational
energy storage shows the lowest activity. Higher capital costs involved
with the development of this technology and vast spatial requirements
make it less attractive for SMEs and ultimately corporates.
There is no one-size-fits-all solution
for long-duration energy storage.
CHEMICAL ENERGY STORAGE
Flow batteries. Flow batteries have efficiencies ranging from 60% to
75% and an expected cycle life of 20 000 to 30 000 cycles. The technology
is preferred for applications where it’s beneficial to decouple energy
and power and is particularly well-suited for microgrid support.
Vanadium redox flow batteries (VRFB) are the most mature technology,
but the high cost of vanadium pentoxide and security of supply have
driven development in other electrolyte chemistries.
Organic electrolytes are the least mature flow battery chemistry,
but companies like JenaBatteries are pursuing the technology due to
its low cost and use of sustainable materials.
Metal-air batteries. These batteries (MABs) have efficiencies between
50% and 75% and – depending on the chemistry – have an expected
cycle life of 100 to 1 000 cycles, but they can discharge for more than
100 hours. The technology is preferred for applications when renewables
need a backup for long periods (16 hours or more) and is particularly
well-suited for microgrid support to replace diesel generators.
Low efficiencies due to slow reactions at the cathode and to anode
The NAS battery is a megawatt-level energy storage system that uses
sodium and sulphur.
degradation because of dendrite formation are two major issues
currently bedevilling MABs. The development of low-cost air cathodes
is a major challenge for MABs, mainly thanks to the high cost of the
catalyst material (made from precious metals like platinum and gold).
In the midterm, MABs will find the best market fit in applications that
require a low-cost battery that can discharge for long durations, as in
commercial backup.
MECHANICAL ENERGY STORAGE
Gravitational energy storage. These technologies offer a round-trip
efficiency of almost 90%, with cyclability limited mainly by wear-andtear
on the machinery, which has an expected lifetime of between 30
and 50 years. Developers of this technology claim continuous power
discharge for eight to 16 hours. The energy output of the system
depends on the lifting height and mass of the blocks used. High capital
costs and vast space requirements that translate into extremely low
power density hinder the deployment of this technology.
NGK INSULATORS
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