Dr Holger Wolfschmidt from Siemens Energy explains why
without the right quantity and energy storage mix in place, we won’t be
able to stabilise the grid, decarbonise power generation, secure energy
supply and make sector coupling possible.
Today, major organisations demand a massive rapid rollout of energy
storage solutions, including setting clear targets for energy storage.
For instance, the European Association for Storage of Energy (EASE) states
that energy storage targets “are a necessary complement to existing EU
climate targets and will allow Europe to foster a local, sustainable
green energy system independent of external energy imports. The EU
urgently needs to adopt an Energy Storage Target and strategy to
accelerate the necessary storage deployment today.”
Simply put: When it comes to our energy future, nothing will work without energy storage.
However, such statements from EASE and other organisations concerning
energy storage still don’t get the public attention they deserve.
Today, increasing the share of renewables, mainly solar and wind,
seems to be on everybody’s mind, along with the urgency of phasing out
fossil fuels to reduce CO2 emissions and secure energy supply.
However, without energy storage to balance energy supply and demand,
further expanding the share of renewables would not be possible, thus
ultimately putting energy supply at risk.
Aiming for 600GW energy storage capacity by 2050 in the EU
Also, power generation is becoming more and more decentralised while
energy demand rises – and that also requires flexible energy storage.
Finally, sector coupling – transferring energy to other economic
sectors – depends on expanding energy storage. All that explains why
this topic deserves greater public attention.
Currently, we have around 60GW in energy storage capacity within the EU, mainly in the form of pumped hydro storage.
According to EASE’s estimates, at least 187GW by 2030 and 600GW by
2050 would be needed to enable electrification of various economic
sectors while securing energy supply.
Moreover, it will ensure grid stability with the removal of inertia from the grid during fossil power phase-out.
No major technological hurdles
This means that the EU faces a formidable challenge: instead of 0.8GW
installed in battery storage in 2020, 14GW of storage needs to be
installed each year throughout 2030.
Without this, it’s possible that EU countries will have to curtail
renewable energy generation and further rely on fossil power for
dispatchable energy supply.
While these targets may seem to be a tall order, the good news is
that the political will is there for creating a flexible decarbonised
energy system on transmission as well as a distribution level.
And while R&D for various storage technologies will continue well
into the future, there are currently no major technological hurdles
standing in the way of implementing realistic measures now and reaching
these goals sooner rather than later.
Energy storage solutions as varied as their applications
In fact, all the different energy storage solutions available can be
seen as a kind of Swiss Army knife, offering a great variety of
solutions for different applications.
Some, such as supercapacitors, store electric charges with high-power
density, and can thus deliver high energy within milliseconds, which
greatly helps with grid fluctuations.
By comparison, batteries support grid stability as well as deliver
dispatchable energy by discharging energy from milliseconds to hours to
days.
Then there are mid-term mechanical solutions, such as compressed air
storage that store energy for days or weeks, which can help balance the
grid.
Finally, we have seasonal and even longer-term solutions, such as
hydrogen, which enable shifting energy from the energy sectors to other
parts of the economy, such as industry or mobility.
Batteries: flexible, mature, and multi-purpose
Let’s take a closer look at the classic solution for short-term
energy storage: batteries, particularly lithium-ion batteries. As a
flexible and mature solution, they serve a wide range of purposes.
ost importantly, they provide grid services, such as frequency
regulation, serve in capacity markets, and can counter the volatility of
renewable energy sources by storing energy whenever abundantly
available, and provide it during shortages.
That’s particularly important for solar-dominated systems that require daily flexibility due to the day/night cycle.
Batteries have two additional benefits.
First, they help power producers or grid operators prevent a mostly
involuntary reduction of energy output, also known as ‘curtailment’.
Second, they make energy arbitrage feasible. This means that
producers can store energy when it’s cheap and sell it when prices are
high.
When combined with renewables, such as wind farms, battery storage
also helps manage power depending on current needs. They’re also well
suited for black-start capabilities or as backup solutions.
For example, the Marsh Landing Generating Station, a gas-fired power
plant close to Antioch, California, recently replaced its diesel engines
for black starts with a battery solution.
Finally, microgrids for data centres and industry grids also need storage systems to enable flexible power usage.
Cancelling out battery shortcomings
As important as batteries are, they do have their shortcomings. On
the one hand, rare elements are being used for their production, which
raises environmental issues as well as concerns over the dependency on
countries that supply them.
However, with continued research and development, rare elements could soon become less important.
Equally imperative is finding sustainable ways to either reuse or
recycle batteries. We also need to develop new battery concepts.
For example, we need better solutions to help us be less dependent on
and eventually replace lithium systems. One such concept is metal-free
flow batteries, which may achieve longer discharge periods.
Overall, batteries are a great option, but not the only one. Other technologies can provide capacities they currently lack.
Mid- to long-term solutions for energy storage
When it comes to wind-dominated systems or those that can face
‘dunkelflaute’ (a period in which little to no energy can be generated
due to insufficient wind and solar power), mid- to long-term storage
solutions are vital. Capable of storing energy for days, weeks or
months, they deliver energy when necessary.
Moreover, long-duration storage provides a great variety in terms of
mechanical, thermal as well as thermal-mechanical solutions. One classic
example of a mechanical solution is pumped hydro, which has been used
for millennia and makes up over 90% of today’s global total energy
storage.
By comparison, thermal energy storage adds another essential building
block for any future energy system. It makes use of heat produced by
renewable energy or captured from waste heat or exhaust gas, ranging in
discharge duration and mid-term to long-term storage.
Various heat storage mediums are available in the form of liquids,
such as molten salt and pressurised water, or solids, such as steel,
concrete, or sand. These storage mediums enable the distribution of
thermal energy across sectors back into various processes, including
heating as well as cooling applications for buildings or industrial
processes.
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