Energy Storage Roadmap (ICEF Innovation Roadmaps)
The ICEF Innovation Roadmaps are created every year to seek opportunities for net-zero CO2 emissions in the future. The roadmaps are presented in draft form each year at the ICEF conference and then released at the annual Conference of Parties to the United Nations Framework Convention on Climate Change. In 2017, the ICEF Innovation Roadmap Project released two roadmaps. One is for CO2 utilization, the other is for energy storage. In this article, we introduce the ICEF Energy Storage roadmap.
ICEF Energy Storage Roadmap
Future low carbon energy systems would consist of large share of renewables in primary supply and power generation, high share of electricity and other low-carbon energy carries in transport. This scenario cannot be achieved without innovations in energy storage technology. Energy storage technology can enhance energy system flexibility, and fill the gap between energy supply and demand in terms of time and space.
In this roadmap, focus is placed on three technology categories: stationary power storage systems, mobility energy storage for transportation, and stationary thermal storage systems. Targets for technology development and their achievement schedules are illustrated in the roadmap. Market introduction schedules were established, considering the development status of each technology toward the realization of a net zero emissions society.
Energy Storage for power systems is one of the important technologies for large-share variable renewable power (VRP) and should be designed in the power system flexibility technology portfolio. Under large VRP shares, the volume of charging capacity has to be larger, discharge duration must be longer, and unit scale must also be larger. In addition, we have to prepare grid-stabilization options, including dispatchable power supply, curtailment of VRP output, demand side adjustment, transmission network enhancement, consolidation of balancing areas, and energy carrier conversion, depending on technology progress and regional power system design policies. Market and institution is essential to recover storage investments.
Pumped hydropower storage is mainly used in current power systems as a daily storage-discharge cycle, and it is the dominant option for large scale storage. Air energy storage, superconducting magnetic energy storage, flywheels, and supercapacitors are also utilized. Batteries are another candidate for backup power to prepare for sudden blackouts or renewable power output adjustments. Options such as lead acid, sodium sulfur, and redox flow have been tested. Lithium ion was developed for mobile use but can also be used as a stationary utilization.
Mobility Energy Storage is enabling technology for transportation electrification and can work as stationary storage via grid connection. However, there are many obstacles in transportation electrification such as high cost, driving range, heavy weight, and space utility. These factors are directly related to batteries. Secondary battery technology with low-carbon electricity would change the transportation system in that sense. Charging time is another concern. In order to diffuse fast-charging facilities, safety and other issues should also be resolved. Battery replacement and road electrification could be useful alternatives. Grid integration and stationary use of used mobile batteries is an attractive option for system cost reduction. Energy can be stored in hydrogen, especially for heavy duty vehicles.
Secondary batteries are crucial technology for electricity-driven vehicles. Nickel-metal hydride or lithium ion types are currently used in light duty vehicles for driving the motors, while all-solid-state or metal air type battery technologies are in the development stages for the next generation of electric energy storage for vehicles to overcome obstacles.
Heat Storage can store renewable-based or environmental heat for building use. Its market is different by region, because heat demand volume and space density are different by regional condition. Many types of thermal storage technologies have been proposed and research and development activities are now underway. However, considering the heat loss and power consumption needed to transmit heat, most technologies for low temperature heat utilization are not feasible in practice, because the running merits are too small to recover their initial investments. As a result, low temperature heat is not being recovered completely and is wasted in many cases.
Public support and institutions are required to grow the stationary energy storage market. Research and development, financial incentives, initial creation of service markets, and guidelines especially related to safety are just a few examples of what should be provided as generic measures for diffusion. Power storage mandates, zero emission vehicle policies, charging infrastructure and district heating promotions are other examples of sector-specific measures. There are many challenges for energy storage itself and its applications. Transparent approaches via roadmap sharing among global regions will bring huge benefits through good practices and capacity building of the society.