The Development Roadmap  
of Large-scale Energy  
Storage Technology  
( B r i e f
 
V
e r s i o n )  
Global Energy Interconnection  
Development and Cooperation Organization  
(GEIDCO)  
The Development Roadmap of Large-scale Energy Storage Technology  
PREFACE  
Energy is closely related to the overall situation of the sustainable  
development of human beings. To achieve sustainable human  
development, it is a major and urgent task to address a series of severe  
challenges such as shortage of resources, climate change,  
environmental pollution and energy poverty currently facing the  
world, the root cause of which lies in the large consumption and  
heavy dependence on fossil energy. Fundamentally, the core of  
sustainable development is clean energy development, and the key is  
to promote transformation and transition of energy production and  
consumption. The Global Energy Interconnection (GEI) is a modern  
energy system that is built jointly and shared by all mankind and  
interconnected with predominately clean energy and electricity at its  
center. it is a platform for the development, transmission and use of  
renewable energy in large scales around the world to promote the  
global energy transition characterized by cleanness, electrification  
and interconnection.  
In order to accelerate the construction of the global energy  
interconnection and promote sustainable human development, The  
Global Energy Interconnection Development and Cooperation  
Organization (GEIDCO) has conducted extensive and in-depth  
research on key technologies such as energy storage.  
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The Development Roadmap of Large-scale Energy Storage Technology  
Dependent on natural resources, wind and solar power generation has  
the characteristics of randomness, variability and uncontrollability  
and is difficult to provide stable power supply for the system, and  
even more so to adjust its output to meet demand. The requirement of  
a system for energy storage (ES) essentially depends on the degree of  
imbalance between energy production and consumption, and in  
electrical power system, this is determined by the characteristics of  
net load. With the continuous development of large-scale renewable  
energy bases and distributed energy, power systems with high  
proportion of renewable energy(RE) have gradually taken shape with  
net system load fluctuation increasing, as a result, the power system  
demand for energy storage is on the rise. Energy storage, which plays  
an important role in improving the flexibility, economics and safety  
of power systems, will find wide applications in all aspects of the  
global energy interconnection.  
In this report, three important technical and strategic questions are  
addressed, namely, what kind of energy storage is needed, how much  
and how to apply and evaluate energy storage during renewable  
energy transition, which points out the direction for the development  
of energy storage technology and the improvement of economic  
indicators, as well as depicts a grand blueprint for technological  
progress and industry development. The report firstly reviewed the  
current development of energy storage technology, studied their  
requirements under different application scenarios, leading to the  
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The Development Roadmap of Large-scale Energy Storage Technology  
development of quantitative ES technology matching indicators and  
carried out research on matching and configuration methods of  
energy storage technology in various applications. Secondly, based  
on the comprehensive cost optimization model, the report put forward  
a calculation method to estimate total demand and allocation of large-  
scale energy storage during the energy transition. The global demand  
for energy storage demand in 2050 is obtained with main factors  
affecting the quantity, technology, cost and allocation analyzed. The  
report put forward the technology and economic development goals  
of energy storage that support the renewable energy transition. In  
addition, the report identified key technology pinch points from the  
aspects of energy storage unit, system integration, and operation and  
control, and developed a phased R&D program and prioritized action  
plan in 2035 and 2050, resulting in the formulation of a roadmap for  
key technology development of large-scale energy storage under the  
Global Energy Interconnection (GEI) application scenarios. Finally,  
an energy storage system with a high proportion or even 100% of  
renewable energy was prospected from the aspects of energy storage  
system structure, construction process and generalized energy storage.  
This report took a year to complete, during which we have cooperated  
with domestic and foreign research institutes in power system  
planning and operation, energy storage research and application, and  
listened extensively to the opinions and suggestions of experts inside  
and outside the industry. It is hoped that it will provide a valuable  
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The Development Roadmap of Large-scale Energy Storage Technology  
reference for relevant personnel of government departments,  
international organizations, energy enterprises and research  
institutions in their policy formulation, strategic research, project  
development and technological innovation. Due to the limited time  
and availability of data, it is inevitable that some deficiencies may be  
present in the report despite our best endeavors. Readers are welcome  
to send us any criticism or opinions.  
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The Development Roadmap of Large-scale Energy Storage Technology  
CONTENTS  
1. Roles and Evolution of Energy Storage...........................................2  
1.1 Roles of Energy Storage..............................................................2  
1.2 Evolution of Energy Storage.......................................................2  
2. Current Technology and Application..................................................4  
2.1 Current Applications ...................................................................4  
2.2 Current Technology.....................................................................4  
3. Requirements and Deployment of Energy Storage .........................14  
3.1 Methodology .............................................................................14  
3.2 Main Application Scenario .......................................................15  
3.3 Total Demand Optimization......................................................18  
3.4 Techno-economic Goals............................................................21  
4. Development Roadmap ......................................................................23  
4.1 Storage Device Technology ......................................................23  
4.2 Supporting Technology .............................................................28  
5. Development Prospect ........................................................................32  
5.1 System Structure .......................................................................32  
5.2 Construction Process.................................................................35  
5.3 Comprehensive Benefits ...........................................................36  
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The Development Roadmap of Large-scale Energy Storage Technology  
1. Roles and Evolution of Energy Storage  
1.1 Roles of Energy Storage  
For power systems, the function of energy storage is to  
directly or indirectly provide regulation capabilities,  
eliminate the difference between power supply and demand,  
and ensure system flexibility. In traditional power systems,  
primary energy such as fossil energy, hydropower, and nuclear  
energy are tangible entities that are easy to store. Energy storage  
is manifested primarily in the form of primary energy storage,  
such as coal yards, oil tanks, and reservoirs. Generators rely on  
these facilities to provide regulating capacity for the system,  
which regulating capacity is about 60% – 70% of the peak load  
in power and regulating capacity about 3% – 5% of the annual  
electricity consumption in energy.  
1.2 Evolution of Energy Storage  
In the traditionally fossil fuel dominated energy systems, the  
fossil fuels such as coal, oil and natural gas have the advantages  
of high energy density, solid and easy preservation, and are  
currently the best energy carriers for storage selected by nature.  
Therefore, the energy storage facilities of the traditional power  
system are mainly configured in the primary energy area, such as  
coal yard, oil depot, natural gas storage tank, etc.  
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The Development Roadmap of Large-scale Energy Storage Technology  
With the deepening of clean energy transformation, the  
proportion of RE power generation such as wind power and solar  
continues to increase, and conventional regulation capabilities are  
gradually reduced. New energy storage needs to be introduced as  
a source of regulation capabilities. Electrical energy storage will  
become an important form of energy storage in energy systems  
with a high proportion of clean energy, as shown in Fig. 1.1.  
图 1.1 Schematic Diagram of Energy Storage Transformation  
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The Development Roadmap of Large-scale Energy Storage Technology  
2. Current Technology and Application  
2.1 Current Applications  
Pumped hydro storage is still the most widely used mature  
energy storage technology, and the development of electro-  
chemical energy storage has accelerated in recent years. By  
the end of 2019, total installed capacity of global energy storage  
is about 184.6 million kW, of which 92.6% is pumped hydro  
storage, followed by electro-chemical energy storage and molten  
salt thermal storage, accounting for 5.2% and 1.7% respectively.  
In 2019, about 4.6 million kW of new energy storage capacity was  
added in the world, of which 2.9 million kW was electro-chemical  
energy storage, taking up the largest share with an annual growth  
rate of about 43.7%, as shown in Fig. 2.1.  
Fig. 2.1 Global Energy Storage Installation Capacity in 2019  
2.2 Current Technology  
There are many types of energy storage technologies, each  
with advantages and disadvantages. According to the methods  
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The Development Roadmap of Large-scale Energy Storage Technology  
of energy storage, it is mainly divided into mechanical, electro-  
chemical energy storage, electromagnetic, chemical energy  
storage, and thermal storage. Different types of energy storage  
technologies have different principles and techno-economic  
characteristics. There are also obvious differences in their  
applications in power systems.  
Mechanical storage: Pumped hydro storage technology is  
mature with a long service life (more than 50 years), high cycle  
efficiency (about 75%) and installed capacity up to GW level. Its  
continuous discharge time is generally 6 – 12 hours, but the site  
selection requirements are high and the construction period is  
long. The power cost is around 700 – 900 USD/kW.  
Fig. 2.2 Schematic Diagram of Working Principle of Pumped Hydro  
Storage Power Station  
Traditional compressed-air energy storage technology is  
mature and has a long service life (30 years), but low conversion  
efficiency(about 50%). The power cost is 900 – 1500 USD/kW.  
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The Development Roadmap of Large-scale Energy Storage Technology  
The storage capacity can be up to tens of hours for those utilizing  
natural underground caverns to store pressurized air although the  
site selection requirements are high; the new compressed air  
energy storage using gas storage tanks is more flexible in site  
selection, but it is still in the experimental or demonstration stage.  
Fig. 2.3 Schematic Diagram of Compressed-air Energy Storage  
Flywheel energy storage has the characteristics of high power  
density (5 kW/kg), small equipment size, and high conversion  
efficiency (over 90%), but its continuous discharge time is short  
(minutes), which is a typical power-type energy storage  
technology. Its cost is 15000 – 18000 USD/kWh.  
Fig. 2.4 Schematic Diagram of Internal Structure of Flywheel Energy  
Storage  
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The Development Roadmap of Large-scale Energy Storage Technology  
In recent years, due to the fact that mechanical energy storage is  
reliable and simple in principle, many organizations have begun  
to explore new solid material energy storage such as concrete  
blocks.  
Fig. 2.5 Schematic Diagram of IIASA Mountain Gravity Energy Storage  
Project  
Electro-chemical energy storage: lithium-ion batteries have  
high energy density and high conversion efficiency (90% – 95%),  
but its cycle life (about 4000 times) still needs to be improved,  
and there exist hidden fire safety hazards. The energy cost is 300  
– 400 USD/kWh.  
Fig. 2.6 Schematic Diagram of Lithium-ion Battery  
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The Development Roadmap of Large-scale Energy Storage Technology  
Lead batteries are safe and reliable, but have low energy density,  
limited cycle times (1000 to 2000 times), and limited service life  
(3 – 5 years). Energy costs are 100 – 250 USD/kWh.  
Fig. 2.7 Schematic Diagram of Lead-carbon Battery  
The flow battery is safe and reliable with the number of cycles  
reaching nearly 10000 times and the electrolyte recyclable.  
However, its energy density is low with large footprint and low  
conversion efficiency (about 70%). The energy cost is 500 – 550  
USD/kWh.  
Fig. 2.8 Working Principle of Flow Battery  
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The Development Roadmap of Large-scale Energy Storage Technology  
The performance of NaS battery is similar to that of lithium-ion  
batteries. It can be made from a wide range of raw materials  
although process requirements are extremely high. Furthermore,  
it operates at about 300℃, a potential safety hazard. Its energy  
costs is 400 – 450 USD/kWh.  
Fig. 2.9 Schematic Diagram of NaS Battery Reaction  
In recent years, scientific research institutions and technology  
manufacturers have been continuously exploring new materials  
and systems of electro-chemical battery technologies, mainly  
including lithium-sulfur batteries, sodium-ion batteries, liquid-  
metal batteries, and various metal-air batteries, in order to  
develop new batteries with high energy density, good safety, easy  
access to raw materials and long cycle life.  
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The Development Roadmap of Large-scale Energy Storage Technology  
Fig. 2.10 Schematic Diagram of Lithium-air Battery Reaction  
Electromagnetic storage: super-capacitors have a high power  
density (7 – 10 kW/kg) and large cycles (100000 times), but the  
unit capacity is small and the continuous discharge time is short  
(seconds). It is a typical power-type storage technology, power  
cost is 7 – 10 USD/kW.  
Fig. 2.11 Schematic Diagram of Double Layer Capacitor  
Superconducting magnetic energy storage has a very high  
power density and fast response speed, but its continuous  
discharge time is also very short (seconds) and requirements for  
auxiliary equipment is very strict. It is basically in the  
experimental R&D and demonstration stage, the power cost  
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The Development Roadmap of Large-scale Energy Storage Technology  
exceeds 1000 USD/kW.  
Fig. 2.12 Schematic Diagram of Superconducting Magnetic Energy  
Storage Device  
Thermal storage: it can be divided into sensible thermal storage,  
latent (phase change) thermal storage and chemical thermal  
storage etc. Among them, the sensible thermal storage technology  
is the most mature, with the advantages of low cost, long life, and  
easy expansion. Molten salt is  
currently the  
preferred  
material for high-temperature thermal storage, with  
a
thermal density of 150 kWh/m3, an efficiency of about 90%, and  
an energy cost of 25 – 40 USD/kWh.  
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The Development Roadmap of Large-scale Energy Storage Technology  
Fig. 2.13 Schematic Diagram of Relationship between Common Energy  
Forms  
Chemical energy storage: electrical energy is used to convert  
low-energy materials into high- energy materials that can be  
stored. At present, common chemical energy storage mainly  
includes hydrogen and synthetic fuel (methane, methanol, etc.).  
Among them, hydrogen energy storage uses electrolyzed water  
to produce hydrogen and stores energy in the form of hydrogen,  
which is easy to achieve large-scale energy storage, but the  
disadvantage is that the conversion efficiency of the whole  
process from electricity to hydrogen to electricity is low (about  
40%). Power cost is 2000 – 3000 USD/kW, energy cost is 20 –  
30 USD/kWh. In recent years, some countries have begun  
demonstration on the use of electricity to produce synthetic gas  
(methane) for storage, reducing carbon emissions, but the current  
cost is high (about 1.5 USD/m3), and the cycle efficiency of  
electricity-methane-electricity is low (about 25%).  
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The Development Roadmap of Large-scale Energy Storage Technology  
Fig. 2.14 Schematic Diagram of Hydrogen Storage  
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The Development Roadmap of Large-scale Energy Storage Technology  
3. Requirements and Deployment of Energy Storage  
3.1 Methodology  
With the increase of the penetration rate of renewable energy, how  
much and what kind of energy storage is needed in the power  
system in order to ensure sufficient flexibility and reduce the  
LCOE are questions that must be answered in the energy  
transition process.  
In order to analyze system’s demand for energy storage and their  
optimal configurations it is necessary to define system  
development goals. From the perspective of promoting clean  
energy transition, the development goals of the system mainly  
include two aspects: increasing the proportion of renewable  
energy and decreasing its LCOE. A set of quantitative analysis  
model method was established in the report to answer how much  
and what kind of energy storage is needed for the system in order  
to ensure the LCOE continue to decline with the proportion of  
clean energy continue to rise. Put forward energy storage  
technology and economic development goals and paths that  
support energy transition needs.The specific analysis process is  
shown in Fig. 3.1.  
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The Development Roadmap of Large-scale Energy Storage Technology  
Fig. 3.1 Flow Chart of Energy Storage Demand and Deployment Analysis  
3.2 Main Application Scenario  
Energy storage is widely used in different application scenarios  
on the generation, grid and user sides. Different applications  
have different requirements for the continuous discharge duration,  
accordingly the time series analysis methods commonly used in  
power systems can be divided into ultra-short time, short time  
and long-term time scales, as shown in Fig. 3.2.  
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The Development Roadmap of Large-scale Energy Storage Technology  
Fig. 3.2 Applications of Energy Storage in Power Systems  
On the generation side, applications such as smoothing the  
fluctuation of renewable energy output and frequency regulation  
belong to ultra-short and short-time scale ones, while  
applications such as seasonal load following belong to long-time  
scale ones. On the grid side, providing system reserve and  
mitigating congestion of the power transmission and  
transformation equipment are all short-time scale applications.  
On the user side, improving power quality and frequency  
regulation belong to ultra-short and short time scale application,  
and participating in demand response are both short-time and  
long-time scales. Ultra-short time scale (second-level)  
applications places a higher requirement on energy storage for  
response speed, efficiency, cycle life, and lower power levels and  
continuous discharge duration. Short-time-scale (hourly)  
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The Development Roadmap of Large-scale Energy Storage Technology  
application scenarios requires frequent charging and discharging  
and thus has higher requirements for power and cycle life, but  
lower requirements for response time. Long-term (several  
weeks to months) application scenarios requires the power and  
capacity of energy storages can be achieved separately, which is  
characterized with large storage capacity, little cost increase with  
capacity, and high conversion efficiency. The requirement for  
response time and cycle life is low.  
Based on their characteristics, energy storage technology  
matching analysis were carried out for selection of suitable  
new energy storages under different application scenarios.  
According to the characteristics of different energy storage  
technologies and their requirements under different application  
scenarios, this report established a comprehensive evaluation  
model including 10 indicators, such as continuous discharge time,  
efficiency, response time, and cost, etc., from the aspects of  
technical level, safety, and economics. Analysis was carried out  
on matching degree between energy storage technology and  
application scenarios. Research shows that supercapacitors,  
flywheels, and lithium-ion batteries are suitable for ultra-short-  
term application scenarios; short-term energy storage is suitable  
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The Development Roadmap of Large-scale Energy Storage Technology  
for pumped hydro, compressed-air, and electro-chemical energy  
storages. Long-term energy storage includes hydrogen storage  
and (cavern) compressed air storage.  
Fig. 3.3 Radar Diagram of Fitness of Various Energy Storage  
Technologies in Different Application Scenarios  
3.3 Total Demand Optimization  
Whole system requirements for energy storages should  
be quantitatively analyzed, and energy storage should be  
included as a regulatory resource in the generation planning  
for overall optimization. As the amount of energy storage  
requirement is a complex combination of its power, continuous  
discharge time, and cost, etc., it is proposed to use annual hourly  
production simulation method to calculate the energy storage  
demand with different models of energy storages that have  
distinctive different functional capabilities such as short-time  
energy storage (providing power regulation capability) and long-  
time energy storage (providing energy regulation capability), and  
with renewable power and energy storage installation conditions  
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The Development Roadmap of Large-scale Energy Storage Technology  
relaxed. It is solved linear optimization algorithm. Based on the  
optimization results, development goals of energy storage  
technology and economics supporting the energy transformation  
is proposed.  
Fig. 3.4 Total Energy Storage Demand Analysis Process  
Based on the research results of the Global Energy  
Interconnection Plan, this report optimizes and analyzes  
overall energy storage requirements of power systems across  
all continents, with the objective to minimize overall electricity  
cost, taking into consideration cost trends of various types of  
power generation, and characteristics of wind and solar resources  
as well as load characteristics in different regions. It is estimated  
that the global energy storage demand in 2050 is 4.1 TW. Among  
them, because the fluctuation of net load shows seasonal long  
cycles, more long-time energy storage is needed in North  
America and Europe. The ratio of energy capacity to annual  
consumption is significantly higher than in other continents. In  
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The Development Roadmap of Large-scale Energy Storage Technology  
Africa and South America, the penetration of PV is relatively high,  
the fluctuation of net load shows a daily change, more short-time  
energy storage is needed to relief solar curtailment. Asia has a  
vast territory, the characteristic of different areas is distinct, the  
total demand for energy storage is the largest.  
Fig. 3.5 The global energy storage demand in 2050  
From the perspective of development path, with the increase  
of renewable energy penetration, the system’s total demand for  
energy storage increases, the demand for energy storage  
technology also becomes increasingly more complex.  
It is estimated that by 2025, the penetration rate of RE will  
reach 20%, and short-term energy storage is required to provide  
power regulation capability; by 2035, the penetration rate will  
exceed 40%, and the energy regulation capability of long-term  
energy storage is essential; After 2050, the penetration rate will  
further increase, while developing energy storage, it is necessary  
to apply generalized energy storage technologies such as  
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The Development Roadmap of Large-scale Energy Storage Technology  
“electricity to gas” to improve demand-side regulation capability.  
In addition to increasing energy storage, curtailment of wind and  
PV is also a flexible regulation measure. With the rapid decline  
of power generation costs, the reasonable level of curtailment rate  
will increase accordingly. The most reasonable scale of energy  
storage is an optimization that is a balance between these two  
measures.  
Fig.3.6 The relationship between energy storage demand and VRE  
penetration  
3.4 Techno-economic Goals  
Only energy storage technology continues to mature and  
costs continue to fall in accordance with expected goals, can  
the cost of electricity be reduced with increasing RE  
penetration, thereby promoting a deeper and cleaner energy  
transformation. Assuming the trend of different power  
generation costs, especially RE such as wind and solar, it is  
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The Development Roadmap of Large-scale Energy Storage Technology  
estimated by the quantitative model that by 2035, the short-term  
energy storage cost needs to be reduced to below 200 USD/kWh  
and that of long-term energy storage to less than 10 USD/kWh if  
the overall electricity cost was not to be increased, In addition,  
by 2050, the short-term energy storage cost needs to fall to less  
than 120 USD/kWh and that of long-term energy storage to less  
than 7 USD/kWh.  
Fig. 3.7 The economical goals for energy storage  
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The Development Roadmap of Large-scale Energy Storage Technology  
4. Development Roadmap  
4.1 Storage Device Technology  
In order to achieve the above-mentioned economic goals, the  
energy storage device technology requires a clear and  
practical research and development plan to improve  
performance and reduce costs. The energy storage technology  
will continue the trend of development in improving technical  
indicators such as cycle efficiency, safety, life, etc., and reducing  
equipment costs.  
1. Mechanical storage  
Pumped hydro storage will develop in the direction of high  
head, high rotation speed and large capacity, and explore new  
technologies such as seawater pumped hydro storage. By 2035,  
the pumped hydro storage efficiency will reach 80%, and the  
power cost will be about 750 – 950 USD/kW.  
The focus of research and development of compressed- air  
energy storage is to improve core components, optimize system  
design, develop new type of gas storage technologies and  
equipment, and realize equipment modularization and scale. By  
2050, the system efficiency will reach 70%, and the cost of  
compressed-air storage with caverns will drop to 5 – 7 USD/kWh.  
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The Development Roadmap of Large-scale Energy Storage Technology  
Fig. 4.1 Future Technology Development Pathway of Compressed-air  
Energy Storage  
Flywheel energy storage further improves the system power  
density, improves the performance of key mechanical  
components, optimizes the system structure design, and improves  
system safety and reliability. By 2050, the power density will be  
increased to 20 kW/kg, and the commercialization of megawatt-  
level high- performance flywheel systems will be realized.  
Fig. 4.2 Future Technology Development Pathway of Flywheel Energy  
Storage  
2. Electro-chemical energy storage  
For lithium-ion batteries, research will be carried on new  
lithium-ion batteries with ultra-high cycle life such as all-solid-  
state electrolytes based batteries, low-cost non-lithium-based  
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The Development Roadmap of Large-scale Energy Storage Technology  
electro-chemical batteries, and composite lithium anodes  
batteries to achieve significant enhancement in battery safety,  
cycle times and energy density. By 2050, the number of cycles  
will be increased to 10000 to 12000, and the cost will be reduced  
to 70–100 USD/kWh, it is expected to become the most important  
short-term energy storage technology.  
Fig. 4.3 Future Technology Development Pathway of Lithium-ion  
Battery  
Lead-carbon batteries can take full advantage in costs and could  
become transition products or useful supplements before large-  
scale application of lithium-ion batteries. It is estimated that by  
2035, the number of cycles will be increased to 5000 – 6000 times,  
and the system cost will fall to 100 – 150 USD/kWh.  
Fig. 4.4 Future Technology Development Pathway of Lead-carbon  
Battery  
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The Development Roadmap of Large-scale Energy Storage Technology  
Flow batteries need to improve conversion efficiency and reduce  
costs. Research and development should be focused on key  
components such as exchange membranes electrodes, etc,  
process improvement, system and structure optimization, and  
flow batteries of new systems such as zinc-based hybrid flow  
battery. By 2050, efficiency could increase to 85% and costs fall  
to less than 250 USD/kWh.  
Fig. 4.5 Future Technology Development Pathway of Flow Battery  
3. Electromagnetic storage  
Supercapacitors need to develop high-performance electrodes  
and new electrolyte materials, and further improve energy density  
and economics. By 2050, the power density will be increased to  
100 kW/kg, and the cost will be reduced to less than 50 USD/kW.  
Fig. 4.6 Future Technology Development Pathway of Supercapacitor  
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The Development Roadmap of Large-scale Energy Storage Technology  
4. Thermal Storage  
Priorities should be given to the research and development of  
700℃ molten salt thermal storage, 600℃ phase change thermal  
storage and 800℃ solid particle thermal storage technology. We  
will continuously increase the energy storage density of the  
thermal storage system, boost the system efficiency, and reduce  
the loss in the energy conversion process, wide the application  
range of thermal storage technology, explore the application of  
thermal storage technology to realize large-capacity system-level  
electricity-heat-electricity energy storage. Before 2050, the  
ceramic sensible thermal storage technology at 1000℃ will be  
developed, thus increasing the thermal storage density by 50%  
compared with the current system (molten salt thermal storage  
system), the electricity-heat-electricity conversion efficiency will  
reach 65% and the thermal storage cost be less than 10 USD/kWh.  
Fig. 4.7 Future Technology Development Pathway of Thermal Storage  
5. Chemical energy storage  
Hydrogen storage will become the focus of development.  
The key is to improve the efficiency of hydrogen production and  
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The Development Roadmap of Large-scale Energy Storage Technology  
consumption, increase the energy density in hydrogen storage and  
transmission, develop key equipment and materials such as high-  
temperature solid oxide reactors, and develop new hydrogen  
storage and transmission technology. By 2050, the production of  
hydrogen from high-temperature solid oxide reactors becomes  
mainstream, technologies such as organic liquids and metal  
hydrogen storage realizes practical application, and high-  
efficiency, low-cost fuel batteries are widely used. The cycle  
efficiency of electricity-hydrogen- electricity is close to 60%, and  
the cost will be reduced to 3 – 4 USD/kWh. Hydrogen storage is  
expected to become the most promising long-term energy storage  
technology.  
Fig. 4.8 Future Technology Development Pathway of Hydrogen Energy  
Storage  
4.2 Supporting Technology  
In terms of energy storage integration, planning, operation  
and control technologies as well as their evaluation and  
standards, it is necessary to continuously refine and improve  
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The Development Roadmap of Large-scale Energy Storage Technology  
safety and reliability considering a range of requirements  
such as large-scale and multi-scenario applications, and  
standardization. With regard to integration technology, the  
focus is on the development of general modules and system  
design, echelon utilization of power battery, and design and  
integration of different energy storage systems.  
Fig. 4.9 Future Technology Development Pathway of System  
Integration  
In terms of planning technology, research should be carried out  
on integrated energy storage and VE planning, optimal  
configuration across wide-area of large power grids, and  
requirement assessment methods of generalized energy storage  
and their optimal allocation.  
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The Development Roadmap of Large-scale Energy Storage Technology  
Fig. 4.10 Future Technology Development Pathway of Application  
Planning  
In terms of operation control technology, research should be  
focused on coordinated energy storage and RE operation and  
control, multi-time scale, multi-objective coordinated control of  
energy storages, aggregation strategy and efficient collaborative  
control of distributed energy storage such as electric vehicles.  
Fig. 4.11 Future Technology Development Pathway of Operation Control  
In terms of evaluation and standards, it is proposed to establish  
a standard system covering five major aspects to provide  
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The Development Roadmap of Large-scale Energy Storage Technology  
comprehensive support for large-scale applications of new type  
energy storage. They are storage technologies, equipment and  
factory testing, station design, construction and commissioning,  
grid connection and testing, and operation and maintenance.  
Fig. 4.12 Future Technology Development Pathway of System Evaluation  
and Standard  
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The Development Roadmap of Large-scale Energy Storage Technology  
5. Development Prospect  
5.1 System Structure  
In the future energy systems with high proportion of renewable  
energy, many energy storage equipment will form an overall  
energy storage system from different dimensions such as time  
scale, configuration links, application scenarios, etc. to provide  
regulating capability for the system.  
In terms of time scale, ultra-short-time energy storage will be  
mainly applied to mitigate the rapid, random fluctuation of  
renewable power generation or load, and sees the smallest of total  
ES demand and can be replaced by short-time energy storage in  
some applications. Short-time energy storage, as an important  
guarantee for system flexibility and a core force of future energy  
storage system, will mainly provide power regulation capability  
for the system. Long-time energy storage, as an essential part of  
energy transition from high proportion to ultra-high or even 100%  
of renewable energy as well as a cornerstone of future energy  
storage system, will mainly provide energy regulation capability  
for the system, as shown in Fig. 5.1.  
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The Development Roadmap of Large-scale Energy Storage Technology  
Fig. 5.1 Composition of Energy Storage System from the Perspective  
of Time Scale  
In term of configuration links, the user side will use a large  
number of electric vehicles as short- time energy storage and  
P2G-based hydrogen (methane) as long-time energy storage. It  
is estimated that ES power to reach 55%-65% and stored  
electrical energy 60%-70%, thus forming the basis of energy  
storage system. The power generation side will see development  
of a appropriate amount of CSP with regulating capability, short-  
time energy storage such as electro-chemical energy storage,  
and long-time energy storage such as compressed air and  
hydrogen energy storage. It is estimated that the power capacity  
of generation side energy storages will reach 25%-35% and  
energy capacity about 30%-40%. The grid side will see  
deployment of short-time energy storage such as electro-  
chemical and pumped hydro storage. The power capacity of these  
energy storages is estimated to be about 5%-10%, and that of  
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The Development Roadmap of Large-scale Energy Storage Technology  
energy capacity not more than 1%, as shown in Fig. 5.2.  
Fig. 5.2 Composition of Energy Storage System from the Perspective  
of Configuration Links  
For application scenarios such as seasonal load following, long-  
time demand response, etc., energy storage mainly provide  
energy regulation capability, with energy capacity accounting the  
largest proportion of total energy storage systems. That used for  
diurnal load following, transmission and transformation  
equipment congestion management, contingency reserve, etc  
mainly provide power regulation capability, with the installed  
capacity taking the largest proportion. Power and energy capacity  
for energy storages used in application scenarios such as primary  
frequency regulation, power quality improvement and renewable  
energy output smoothing will be small, thus applied to specific  
occasions where its functions can be replaced by other short-time  
energy storage, as shown in Fig. 5.3.  
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The Development Roadmap of Large-scale Energy Storage Technology  
Fig. 5.3 Composition of Energy Storage System from the Perspective  
of Application scenarios  
5.2 Construction Process  
The configuration of energy storage is closely related to the  
degree of clean energy transition, therefore, it is constantly  
evolving with clean energy transition. According to the report,  
under the current level of RE penetration (about 10%), the  
full use of hydropower (including pumped hydro storage)  
regulation capabilities, and improvement of some thermal power  
plant flexibility can meet the operating requirements, There is no  
urgent need for deployment of large-scale energy storage. By  
2035, more short- term energy storage needs to be deployed on  
the power generation side to stabilize the randomness and  
volatility of RE, such as integrated wind/solar/energy storage  
projects, CSP stations, and multi-energy complementary projects;  
on the user side, the virtual short-term energy storage such as  
electric vehicle V2G will play an increasingly important role in  
35  
 
The Development Roadmap of Large-scale Energy Storage Technology  
the system. By 2050, larger-scale energy storage is needed as a  
flexible resource, Total energy storage power will reach 30% –  
40% of the system maximum load. The seasonal energy  
regulation provided by long-term energy storage will become  
more and more significant. Total energy capacity reaches 0.5%  
– 2% of the annual electricity consumption. In order to realize the  
100% clean energy systems, it is necessary to rely on chemical  
energy storage technologies such as electricity-to-fuels to realize  
the interconnection of multiple energy systems, integrate and  
optimize the storage capacity dispersed in different systems, and  
realize the “generalized storage” across different energy types.  
Fig. 5.4 Construction Process of Energy Storage System  
5.3 Comprehensive Benefits  
The large-scale application of energy storage technology can  
36  
 
The Development Roadmap of Large-scale Energy Storage Technology  
effectively reduce cost of clean electricity and facilitate clean  
energy transition. At the same time, it promotes the  
development of basic science, applied science, and  
engineering technology, driving overall upgrading  
of  
manufacturing industry. It is estimated that by 2050, the large-  
scale development and utilization of clean energy will bring  
about 4.1 TW and 500 TWh of global energy storage demand.  
Compared with the scenario with no energy storage, large-scale  
application of energy storage will reduce wind power and solar  
installations by 37.3 TW and reduce wind and solar curtailment  
by 86000 TWh each year, the global average comprehensive  
electricity cost is reduced by 3 cents, laying a solid foundation  
for the smooth realization of a clean energy transition.  
At the same time, the market size of energy storage reaches 2.8  
trillion USD, which will effectively promote the progress and  
integration of many disciplines such as theoretical physics,  
mechanics, thermophysics, chemistry, materials science,  
mechanical engineering, metallurgical engineering, and electrical  
engineering, and drive optimization, consolidation and  
technological progress in various upstream and downstream  
industries such as mining, metallurgy, manufacturing, electric  
37  
The Development Roadmap of Large-scale Energy Storage Technology  
power, automation, chemical industry, transportation, etc.  
Fig. 5.5 Comprehensive Benefits of the development of energy storage  
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