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Energy Storage Technology Briefing

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Since the discovery of electricity, we have sought effective methods to store energy for use on demand. Energy storage systems offer a solution to managing power supply in order to create more resilient energy infrastructure. Energy storage systems can be broken down into the energy storage unit and the power conditioning system. The energy storage unit determines how much energy can be stored, or the capacity, in kWh, while the power conditioning system is the interface between the grid and the energy storage unit, and controls charging and discharging. Thus, the power conditioning system is largely responsible for the power in kW of the energy storage system.

Storage technologies presented here include lead-acid (Xtreme Power), lithium-ion, flow (vanadium redox and zinc-bromine), nickel-based (nickel cadmium) batteries, flywheel, compressed air, and closed- and open-loop pumped hydro. Demonstration projects were removed from this analysis since many had unexplainably high costs.


Current Installations in Alaska

Energy storage systems are still new in Alaska, with a few exceptions. Thus, the dataset provided in the Alaska Energy Authority Renewable Energy Fund applications has been supplemented by data from the Department of Energy Global Energy Storage Database, which captures installations worldwide by data from Sandia National Laboratory’s energy storage reports (several editions) and by data collected through personal communication with energy storage developers and utilities.

Key Performance Metrics

Energy storage is hard to quantify in terms of performance, cost, and economic value. Costs and performance have been evolving sporadically, without any clear trend. The most significant trend in the data considered here is the increased variance in costs over time. Thus, there are now more options for energy storage systems with “low cost per kW”/“high costs per kWh” and vice versa, indicating a greater variety of specialized energy storage systems for targeted applications. Still, it is often difficult to justify energy storage based on fuel savings alone. There is certainly potential to look for additional cost savings, such as reduced fuel consumption and stress on a diesel generator by smoothing out the load. The data analyzed here do not show any difference in the cost of energy storage in Alaska compared with the rest of the nation or globally. Alaska has had relatively few energy storage technology failures, most due to operational errors.

Technology Trends

Recent material advances, especially in nanotechnology, have advanced the development of energy storage systems–such as low-cost electrodes and membranes for flow batteries, flywheel designs, and increased surface area supercapacitors and superconducting materials. New chemistries are also a focal point of research with regard to different oxidation-reduction reactions and electrolyte solutions for lower costs, higher performance, higher safety, and longer life for batteries and flow batteries. Inverters and converters have been improving in performance and coming down in price, with better power electronics and new topologies. The electric vehicle market is a major driver of energy storage system development, resulting in home and grid-connected battery development.

Technology Gaps & Barriers to Success

Lack of standardization and quantification of costs and benefits is the main barrier to implementing energy storage in Alaska. In addition, communities often wish to avoid energy storage systems that use hazardous materials, since disposal is especially difficult in rural Alaska.

Recommendations

Energy efficiency grants could be leveraged for energy storage systems. The development of standardized use case scenarios for the operation of energy storage systems would maximize their economic benefits in Alaska. These scenarios would ideally include quantifying economic savings, performance specifications for manufacturers, and comparison metrics. Guidance documents would be extremely helpful with regard to information on need, required specifications, and selection procedures for energy storage systems. These documents should include information on how to protect an investment from technical failures by agreeing on performance and lifetime guarantees as well as responsibility for failure.

Images
Left: A flywheel is one way to store kinetic energy. They are used in everything from trains to race cars to power plants. Photo by Wikimedia Commons. Center: Batteries use a chemical reaction to prouce electrical energy, the most common type of energy storage system today. Photo by Wikimedia Commons. Right: While energy storage technology is still relatively new in Alaska, advances in electric vehicles is driving R&D in this field. Photo Wikimedia Commons.