On the agenda for COP29 is the Global Energy Storage and Grids Pledge – a pledge which targets a sixfold increase in global energy storage capacity to 1.5 TW by 2030. As reported by the Global Renewables Alliance, the pledge has gained traction, already winning support from multiple countries. This is just the start – the Long Duration Energy Storage Council envisages that up to 8 TW of Long Duration Energy Storage (LDES) will be needed by 2040 to achieve net zero.
Energy storage plays a pivotal role in bridging the gap between energy generation and consumption. This capability is particularly important for renewable energy generation from inherently intermittent sources, such as solar and wind. Demand for energy is also volatile, illustrated starkly by the 2,800 MW spike in electricity demand in the UK following England’s penalty shoot-out loss against Germany during the Italia ‘90 football World Cup. Effective energy storage is therefore crucial in reducing strain on the grid, by mitigating lulls in supply and peaks in demand.
Long Duration Energy Storage (LDES), when paired with renewable energy, also plays a vital role in off-grid industrial decarbonisation, with the potential to reduce greenhouse gas emissions by nearly two-thirds. Beyond its environmental impact, LDES also presents a compelling business case, by enabling industries to tackle energy price volatility and enhance supply reliability.
Of course, these diverse demands call for equally diverse solutions. Each energy storage technology has its own application sweet spot, in terms of duration, power and cycling requirements. For example, the varying charge and discharge profiles of different technologies can be selected to meet real-time grid management needs or to address long-term and seasonal variations. The broad spectrum of innovation has in turn precipitated a steady increase in the generation of IP in this sector.
Understanding patent trends offers valuable insights into the likely future direction of energy storage developments and serves as a strategic lens for stakeholders in the sector. By analysing these trends, it is possible to gain a better understanding of the competitive landscape, assess freedom to operate, and refine IP filing, licensing, risk management, and enforcement strategies.
Sector and Sub-Sector Trends in Energy Storage Patents
A few years ago, we investigated global patent trends in energy storage. With innovation and demand accelerating rapidly in this field, this article examines the latest emerging trends, first in terms of overarching sector trends, and then delving into specific sub-sectors and technology areas.
The following analysis draws on data from the European Patent Office’s (EPO) recently published report on energy storage and other enabling technologies. In this report, the EPO broadly categorises energy storage technologies into three primary sectors – electrochemical (i.e., batteries and supercapacitors), thermal, and mechanical – and then looks at sub-sectors and technology areas within these sectors.
Sector Trends
The above chart highlights the dominant role of electrochemical battery technology (based on the total of the sub-sectors identified by the EPO) in the growth of energy storage patent publications, with a notable acceleration of publications over the past 2–3 years. This surge aligns with the booming demand for electric vehicle (EV) batteries and the rising need for energy storage systems integrated with renewable energy sources. Despite challenges in sourcing critical minerals and raw materials, the rapid growth of demand is set to sustain high levels of patent activity in this sector.
While smaller in volume, patent publications directed to mechanical and thermal energy storage (TES) solutions have also seen notable growth, particularly over the past five years.
TES patent activity, for instance, experienced a significant uptick around 2018, following increased funding and recognition of the need for diversity in storage technologies. TES systems have also found applications in hybrid systems paired with battery technologies, and in applications for decarbonising heating and cooling. Technological advancements associated with specific applications, such as Concentrated Solar Power (CSP) facilities, have also driven the surge in patent activity around this time, as will be discussed in further detail below.
Mechanical storage technologies saw their most significant growth in patent publications in 2022 and 2023. This growth has been driven by several factors, including supply chain constraints affecting electrochemical technologies, an increased emphasis on energy resilience at this time, government incentives, and notable technological advancements, discussed in further detail below.
Electrochemical storage technologies inevitably will remain at the forefront of energy storage patent filings, due to declining long-term costs, operational flexibility, and broad applicability. However, the growth in patent filings in thermal and mechanical storage technologies reflects their increasing appeal; with cheap or even free storage mediums, lower supply chain risks, lower environmental impacts, greater operational safety (e.g., no thermal runaway risk), and greater durability.
Sub-Sector Trends – Mechanical Energy Storage
In the realm of mechanical energy storage, it is clear that pumped hydroelectric (PSH), flywheel (FES), and compressed air energy storage (CAES) lead the way in patent publications.
Of these, pumped storage hydroelectricity (PSH) is the dominant sub-sector, reflecting its established position in the market. Indeed, PSH accounts for 96% of all utility-scale energy storage in the United States. In spite of its maturity, PSH continues to be a hotbed for innovation and patent activity, spurred by advancements in small-scale decentralised pumped storage, underwater and underground reservoirs (such as the StEnSea project), and high-density pumped storage (pioneered by British-Canadian company RheEnergise).
Compressed air energy storage (CAES) similarly has a long history, with its origins dating back to the Victorian era, when it was used in city-wide distributed networks to directly power heavy industry. While earlier implementations of CAES were inefficient, recent innovations have greatly enhanced its commercial viability. A prime example of this progress is the world’s largest grid-connected CAES plant, Hubei Yingchang, in China. Several sites are also being developed in the UK.
Flywheel energy storage (FES) has seen consistent growth in patent filings, driven by significant technological advancements. Innovations in high-strength materials have enabled higher rotational speeds, providing for increased storage capacities. Magnetic and superconducting bearings have enhanced efficiency and energy retention, while advancements in vacuum chambers have further minimised energy losses.
Although trailing in total filings, dry gravity energy storage (GES) patent activity is gaining traction in the past few years. This technology is, relatively speaking, in the early stages of large-scale commercial deployment, though promising projects, such as the Energy Vault facilities in China, Sardinia, Australia and the US, are beginning to come online. Dry gravity storage offers notable advantages, including independence from water (making it more resilient to climate change in water scarce regions), and generally lower installation costs compared to equivalent PSH systems. Looking ahead, it will be interesting to see whether modern advances in Linear Electric Machine Gravity Energy Storage, which uses consequent-pole linear Vernier hybrid machine topology to reduce loss inefficiencies due to friction, can translate into broader adoption of this technology in the coming years.
Unlike electrochemical storage technologies, mechanical storage facilities are often constructed using locally sourced materials and inputs, creating an economic “multiplier effect” akin to that seen in large-scale civil infrastructure projects, increasing their economic attractiveness to host nations. These favourable supply chain dynamics and economic benefits are likely to drive increased research and development in this field in the coming years.
Sub-Sector Trends – Thermal Energy Storage
Within the thermal storage sector, technology relating to heat storage in solar thermal power plants dominates the patent landscape. In these systems, holding tanks for heat transfer fluid or molten salts are located adjacent to Concentrated Solar Power (CSP) facilities. A notable and sustained uptick in patent publications within this sub-sector occurred around 2017. This coincides with a surge in CSP projects around the world, including Noor Ouarzazate in Morocco – the world’s largest CSP plant, as well as advancements in molten salt storage technologies for CSP applications.
Latent heat (phase change) energy storage has also gained traction around the same time, thanks to its higher storage density compared to other thermal storage methods, and the isothermal nature of the storage process. However, challenges remain, including asynchronous melting and the inherently low thermal conductivity of phase change materials, which hinder efficient charging and discharging. Of course, these drawbacks present an opportunity for innovation, paving the way for more efficient and practical solutions.
Sub-Sector Trends – Electrochemical Energy Storage
Turning to electrochemical battery technology, the EPO’s report indicates that innovation in the field has been spearheaded by lithium-ion (Li-ion) batteries, accounting for 45% of publications, compared with just 7.3% for other chemistries (with the remainder for manufacturing and engineering aspects). As Li-ion clearly dominates, the above chart focusses on the other chemistries.
A substantial share of patent activity relates to inorganic solid-state electrolyte innovations. This trend highlights the industry’s drive to leverage the enhanced safety and higher energy densities offered by solid-state electrolytes.
Sodium-ion batteries are emerging as a fast-growing electrochemical storage technology, a trend underscored by rapidly increasing patent filings. This growth is driven, in part, by the potential of sodium-ion batteries to mitigate challenges associated with lithium-ion batteries, such as thermal runaway (i.e., exothermic chain reactions) and dendrite formation, which can reduce battery lifespan. Additionally, sodium’s greater abundance and lower cost compared to lithium makes it an attractive alternative. Despite these advantages, lithium-ion batteries continue to hold the market standard, due to their superior energy density and the relatively nascent stage of sodium-ion technology.
Summary
While electrochemical batteries continue to lead in patent filings, mechanical and thermal energy storage technologies are rapidly gaining momentum. This growth is reflected in their increasing integration into energy grids and an increasing volume of patent filings, driven by advances in R&D, improving economic viability, and enhanced supply chain security. As patent applications are often filed well in advance of public deployment, the trends discussed here offer valuable insights into the likely future trajectory of energy storage developments in the years ahead.
At Carpmaels & Ransford, our multi-disciplinary Energy team brings extensive expertise across a broad range of energy storage technologies. We are uniquely positioned to assist innovators with securing commercially valuable protection for energy storage technologies, ensuring they are well-guarded in an increasingly competitive market.
