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Long Duration Energy Storage: Are We There Yet?

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Diane Cherry's picture
Principal Diane Cherry Consulting, LLC

Diane Cherry is a woman owned small business providing clean energy consulting services for local government, clean energy companies, non-profits and educational institutions. Her projects and...

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  • Dec 27, 2022

Long duration energy storage (LDES) – defined by the U.S. Department of Energy (DOE) as a system that can store energy for more than 10 hours --  is the lynchpin for solving the intermittency issues with renewable energy production. While shorter-duration energy storage (SDES) (usually 1-4 hours) can support some renewable energy generation intermittency, as more and more renewables are added to the grid, LDES is needed to store energy to be dispatched during long stretches when solar or wind are not producing. This article explains top use cases for LDES and the most promising LDES technologies, as well as Leyline’s insights about the LDES sector moving forward.

Why Does Long Duration Energy Storage Matter?

A primary goal of LDES is to ensure that renewable energy can be stored when it is generated and deployed to meet sustained energy demand at a later time. In this way, LDES supports the increased penetration of clean energy technologies; it also gives grid operators added flexibility to balance supply and demand, enables grid resilience, and enables costly transmission and distribution infrastructure upgrades to be deferred. LDES will help the U.S. achieve a net-zero carbon grid – a target the Biden administration has set for 2050 – by dispatching low carbon power when needed and accelerating the retirement of gas peaker-plants. 

Development of an LDES market has received federal government support through ARPA-E, the research and investment arm of the Department of Energy (DOE). The DOE also launched the Long Duration Storage Shot in July 2021 to reduce LDES costs by 90 percent (for systems that deliver energy ten or more hours) by 2030. In addition to the DOE’s research and funding efforts, the Infrastructure Law is providing $505 million for energy storage demonstration projects, as well as more than $6 billion for activities related to battery material processing, manufacturing, and recycling. These additional resources will help LDES providers demonstrate the value and scale of LDES, hopefully advancing the sector closer to market viability. 

The federal government is not the only one getting into the LDES game - there is growing support from the private sector as well. Dozens of large companies such as Microsoft and Google are part of an organization called the Long Duration Energy Storage Council (“Council”) to push for LDES deployment with reports to encourage its adoption. 

Long Duration Energy Storage Technologies

LDES encompasses a group of conventional and new technologies that vary depending on level of maturity and commercialization potential. There has recently been a huge influx of private investment in the LDES sector. A few of these include announcements by FlexGen Power Systems, EnerVenue, Malta, and Form Energy. As of early this year, investment in the sector included more than 5 gigawatts (GW) and 65 gigawatt-hours (GWh) of LDES capacity announced or already operational. The table below from McKinsey & Co. shows the forecasted cumulative installed capacity and capex investment through 2040.

Table    Description automatically generated

LDES technologies can be divided into electrochemical energy storage, thermal energy storage, and chemical energy storage. Leading technologies include: 

Electrochemical LDES: Companies in this space are trying to find the sweet spot of lithium-ion batteries for long-duration energy storage. Earlier this year, an eight-hour duration lithium-ion battery project became the first long-duration energy storage resource selected by a group of non-profit energy suppliers in California. 

Flow Batteries: Flow batteries are a subcategory of electrochemical energy storage that operate on the idea of incorporating liquid electrolyte to function as a source of direct current electricity that runs through an inverter for conversion to alternating current power. Flow battery performance does not degrade, which is why there are fewer limitations on use cases. While this continual performance stands out compared to lithium-ion batteries, which exhibit greater performance degradation if they are cycled multiple times per day or used for different applications, the only current commercial flow batteries are based on vanadium and zinc.

Mechanical and Geochemical: These solutions include compressing air, gas, or water in natural caverns and combined with gravitational systems.

Thermal Storage: Thermal storage uses excess power to charge a thermal battery made of molten salt.

The chart below shows the market readiness for each LDES type:

Table    Description automatically generated


A Long Road Ahead for LDES 

Unfortunately, economically-viable LDES is not yet available because commercial production is years away for many technologies, and, perhaps more importantly, energy markets are currently focused on short-term applications. Short duration (4 hour) lithium-ion (li-ion) battery storage has dominated the market to date, driven to commercial-readiness by automotive companies racing to develop competitive batteries for electric vehicles. However, because the first hour of energy storage is more valuable than every additional hour, LDES must be even less expensive than the incumbent li-ion technology. 

Recently, the state of Arizona tried to address LDES’ needs through incentives for storage technologies with more than five hours of discharge. Outside of Arizona’s incentive program, only Texas and California have added enough renewable energy capacity to create substantial market value for energy storage in applications such as load shifting. In addition, the deregulated markets allow for the ability to create value with the asset owner, something that cannot be done in other regions of the country.

NREL recently compared costs and revenues with the most promising 14 LDES technologies. The researchers ranked the 2050 net cost results for two duration categories: 12 hours and 120 hours, and li-ion leads as the lowest-cost 12-hour technology. Today, these batteries only last about four hours, but the NREL report posits that the duration of lithium-ion batteries can reach 12 hours by 2050. Despite the wide number of LDES technologies currently under development, it’s possible that li-ion is the best technology to deliver LDES. 

In a recent LDES panel at the energy industry conference RE+, Kiran Kumaraswamy, VP Of Growth and Head of Commercial at large-scale energy storage provider Fluence, stated that the while there is no clear LDES favorite yet, the winner will ultimately target different value propositions that puts it in a different league than li-ion. Because li-ion has such a strong hold on the energy storage market, a leading LDES technology must demonstrate more than just a marginal benefit over li-ion. By targeting a niche application, LDES technology providers will more easily be able to demonstrate its distinct value to the market. 

It is important to support new developments that support the growth of renewable energy capacity across the country. It remains to be seen what and when the dominant LDES technology reveals itself. 



Billy Gogesch's picture
Billy Gogesch on Jan 3, 2023

Thank you for this thorough article!


I think there needs to be another parallel analysis with this. Clearly you are right in asserting that LDES is essential to filling the Gap left by wind and solar if we do not want to use carbon emitting energy sources for that job.


The glaring omission I see is that we are not discussing nuclear power. It meets all the criteria of clean energy, save but it's spent fuel, which many raise objections to. In reality there's a very small inventory of spent fuel when compared to the enormous amount of energy extracted from it. The fact that the US has tied itself in knots over a used fuel policy should not be an obstacle for moving forward with nuclear power. In fact, with the urgency that government policy expresses over anthropogenic climate change we should prioritize irrational used fuel policy.


Nuclear power already delivers most of our carbon-free energy. Proposals to shift dramatically to wind and solar demand massive changes to grid topology and delivery strategies which we are discovering are not trivial.


The grid is the beating heart of civilization. We had better be careful with the surgery we perform on it in the name of saving civilization.


It feels like we are rushing out the door with an incomplete solution by insisting on wind and solar as our primary energy inputs while at the same time insisting that nuclear power be retired.


If the preservation of life and health of the planet is our primary concern we may end up doing more harm than good with this strategy.

Diane Cherry's picture
Diane Cherry on Jan 4, 2023

So nuclear facilities (of which NC and SC have several) have extended their useful life from 60-80 years and there has been some push to extend it to even 100 years. The question to me is ok NRC is going to extend many that would have by now expired, can SMRs get successfully commercialized in that timeframe? If so, then we have a game changer. But without commercial operation now, I'm not sure where that leaves us except extension of assets to perhaps a time we should not. 

Michael Keller's picture
Michael Keller on Jan 9, 2023

To paraphrase Margret Thatcher, “Sooner or later the green energy movement is going to run out of other peoples money”. The movement sits on a rotten foundation that will inevitably collapse as reality becomes increasingly more difficult to ignore.

Our water planet’s climate is not controlled by man made CO2 emissions;  vastly more complicated than simply looking at a trace gas that involves a small spectrum of the sun’s energy.

peter snell's picture
peter snell on Jan 10, 2023

Sad to say, you are correct.

And we are relatively surrounded by folks profiting

from the decaying false foundation of Green Energy;

those folks are NOT eager to discuss the situation.

Audra Drazga's picture
Audra Drazga on Jan 10, 2023

Great article - this story makes me think of the war between Betamax and VHS.  I know that dates me. The question in LDES is which "type" will win out - and will it be the best choice?  Many argue in the Betamax vs. VHS battle that Betamax had higher resolution, the tapes were smaller, and they had higher recording capacity.

I look forward to reading more insights on this topic in the future! 

Matt Chester's picture
Matt Chester on Jan 10, 2023

With Betamax vs. VHS there was likely to be a single winner, but hopefully the variety of energy storage technologies can simply plug in at the best point in the grid where they are advantageous (different geographies, grid needs, customer needs etc. might make different batteries the 'right' choice in various circumstances). Why choose one solution when we can have many!

peter snell's picture
peter snell on Jan 10, 2023

Of the 'types' of LDES listed, there will be no winner. It's like determining the

finest Brand of Phlogiston .. to be chosen by an Emperor with no clothing. NONE

of those LDES mechanisms is likely to actually WORK.

Diane Cherry's picture
Diane Cherry on Jan 16, 2023


I wouldn't bet against LDES technology that could in fact be a game changer for intermittent resources. Check out the Speed and Scale book that was written in 2021. There are many folks investing in this technology in the clean tech venture world and ARPA-E as well. 



Andrew Blakers's picture
Andrew Blakers on Jan 16, 2023

Long duration energy storage is a solved problem. Pumped hydro energy storage is available off-the-shelf in unlimited quantities at low cost. There is 170 GW already operating. Most potential sites are closed loop (off-river) that require no new dams on rivers - 600,000 sites are shown in the global atlas including 34,000 in the USA, which is 200 times more than will ever be needed. Even Texas has a large pumped hydro potential to support its large-scale solar & wind, and so has Virginia.

Australia is far ahead of the USA in moving to solar & wind: 26% of electricity generation in 2022, tracking towards 75% in 2030. Australia (population 26M) has 15GW of pumped hydro announced by Government or under construction along with many GW of batteries and new transmission. 100% renewables isn't very difficult.

Michael Keller's picture
Michael Keller on Jan 17, 2023

Out here in fly-over country, the opportunities for pumped hydro are limited. Also the lack of water in parts of the West is problematic. The point is long-term energy storage is not solved.

In passing, nuclear energy provides one of the best long-term energy storage options. The energy stored in uranium atoms vastly exceeds all other methods.

Andrew Blakers's picture
Andrew Blakers on Jan 17, 2023

Water is not a significant issue for off-river (closed loop) pumped hydro. The same water goes up and down for 100 years. In dry areas, evaporation suppressors are available.

Australia is far ahead of the USA in moving quickly to solar/wind on a per capita basis because solar/wind are compellingly cheaper than coal, gas, nuclear. Australian experience shows that storage is a solved problem via pumped hydro, batteries, transmission and demand management. No need to argue about it - just look at facts on the ground in Australia.


Diane Cherry's picture
Thank Diane for the Post!
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