Long-duration ENERGY STORAGE

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

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

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 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.

Of late, interest has revived in rail-based gravity energy storage systems, which could find a fit in applications with fewer restrictions on energy density.

Compressed and liquid air energy storage. Compressed air energy storage (CAES) and liquid air energy storage (LAES) technologies offer round-trip efficiencies between 50% and 90%, with cyclability limited mainly by machinery wear and tear. Such systems have an expected lifetime between 20 and 60 years and provide continuous power discharge for one to 24 hours. Over the past five years, approximately $500-million has been invested in CAES/LAES technologies; 63% of the investment has been raised by Hydrostor in 2022, which plans to develop a 500MW/4 000MW power plant in California, expected to be in service by 2026.

Lux Take

The future power grid will require a combination of these LDES technologies, depending on regional energy mixes. There will be no dominant long-duration technology, but within each application fit there will be clear winners.

Mechanical energy storage technologies use mature physical concepts and integrate system components from other industries. However, the implementation of these technologies is targeted at large-scale projects that require hefty capital investment in a market that isn’t yet equipped to optimise those assets.

Chemical energy storage technologies have a wide range of technology readiness, but among them, flow batteries are an active area of development with the most mature chemistry of VRFB. The development of chemical energy storage will be driven by the implementation of low-cost and sustainable materials.

Clients interested in LDES integration should consider engaging with companies that have a mostly developed technology but struggle to find deployment opportunities, like zinc-air developers or CAES companies. Clients interested in early-stage innovation should first evaluate what strengths they can offer to immature technologies; chemical energy storage companies would benefit from materials development, while mechanical energy storage companies would benefit from engineering optimisation.

THOUGHT [ECO]NOMY greeneconomy/report recycle

BATTERIES FOR STATIONARY ENERGY STORAGE 2023-2033 | IDTechEx | [November 2022]

Global Cumulative Stationary BESS Capacity to Exceed 2TWh by 2033

Battery demand for stationary energy storage is set to grow in line with an increasing number of renewable energy resources being added to electricity grids globally, alongside pressure from governments and states to reach targets pertaining to renewable energy generation and energy storage.

Various factors are driving the Battery Energy Storage System (BESS) market. Firstly, the necessity for higher levels of renewable energy integration into electricity grids will require higher volumes of BESS to help stabilise electricity grids while providing energy security and supply. As well as this, energy and battery storage targets and clear policy frameworks are helping to expedite BESS deployments in the regions where these drivers have been announced. This is apparent in countries such as the US, China and Australia.

The US and China will be responsible for most of the global cumulative BESS capacity in 2033 while rivalling each other for total deployments. Without question, these countries’ storage targets, clear market regulations, and profitable business models play a key role in the volume of successful project installations, especially on the front-of-the-meter (FTM) side.

Annual FTM installations will take a larger share of global annual BESS installations, by GWh, than behind-the-meter (BTM) installations in the next decade. Moreover, the means for these large battery systems to produce revenues for their owners are becoming more apparent through mechanisms such as revenue stacking. As business models continue to mature, investor confidence in large BESS profitability will grow, thus facilitating reduced future project costs and increased installation volumes. Order a copy of the report here