Page 24 - Industrial Plants

“The rising penetration of renewable batteries are currently the cheapest zero-emissions
energy will require not just increasing option for providing balancing services of less than 4
amounts of energy storage but also hours. LDES (with different emerging technologies),
developing long-duration storage can provide duration for days and even weeks, with
solutions resilience to an electric grid ready to distribute solar
and wind power on a large scale. This extension to
complementing direct electrification and helping to periods lasting days or weeks is the need of
address harder to abate sectors: let say that storage imbalanced RE output or potential outages caused
needs remain relatively low up to a share of around by transmission constraints. LDES technologies are a
80% renewables, but increase substantially toward promising zero-carbon solution for these long-
100% renewables, with a growing importance of duration flexibility needs, especially those lasting
long-term storage for seasonal balancing. several days.

The rising penetration of renewable energy will require Finally, the need for seasonal flexibility is due to the
not just increasing amounts of energy storage but natural variability of solar irradiation, wind speed,
long-duration storage depending on the country and temperature, and rainfall over weeks and months,
the characteristics of its energy market. and also to extreme weather events.
In order to accommodate large amounts of renewable
energy new flexibility challenges across different Some LDES overview and
timing are to be considered: the HYDROGEN solution
• “Medium” duration :4h-8h for intraday flexibility; One of the first LDES is flow-batteries.
• “Large duration: 12h-60h for multiday flexibility Flow-batteries are liquid -based batteries that use
• “Extra Large duration”: months for seasonal tanks of liquid electrolyte. The electrolyte runs through
flexibility electrodes to charge and then run in reverse to
discharge. The possibility of reaching long duration is
To date, much of the focus has been on short- mainly due to the fact that doubling the capacity is
duration batteries of up to four hours, on the contrary only to double the tank; the design is easily scalable,
more research and development and industrialization and has a long life cycle and effectively unlimited
design will be needed to support longer-duration capacity. However, flow batteries have lower energy
storage options. Practically there is the need to density than lithium-ion and are not currently cost
develop energy storage technologies that can be competitive, but they are the most consistent electro-
cost-effectively deployed for much longer durations chemical solution for LDES.
than lithium-ion batteries. Vanadium is currently the preferred electrolyte for flow
batteries due to its stability, although the metal faces
“Medium” duration generally involves providing grid supply issues which, may in turn, affect costs (Fig.
stability services and peak-shifting and Lithium-ion 16).

Hydrogen technology is often considered to have the
highest long-term potential for LDES, with great
flexibility also because can be the key of a storage
solution rather than a transportation solution. Many
countries are considering hydrogen as a key part of
their emission reduction pathway even if the
technology to convert power to hydrogen and back
to power has a round-trip efficiency only around 30%
.
However, while producing renewable hydrogen via
renewable energy-driven water electrolysis is globally
growing, it still represents a small fraction of total
global hydrogen production and is far away from
being cost competitive. Research and development
into hydrogen storage for use as energy storage is
also at relatively early stages, but some conclusions
are already available:
Sustainable production of hydrogen is a key element
Fig. 16 - Redox Vanadium Batteries basic scheme of the LDES energy transition agenda, especially for

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