skip to Main Content
Long Duration Energy Storage

It’s estimated that energy storage distribution in 2018 was triple the amount of 2017. As deployment of energy storage has expanded on both sides of the meter, there is the need for greater technology with long duration energy storage.

The use of energy storage in grid planning and energy management is now commonplace. It’s being driven by advances in technology, lower costs, and the benefits it presents. Energy storage has become more widespread and it’s now common to see it used in the large capacity of megawatts. Even though most of the storage we see in the United States is pumped hydro, which has large capacities, and is fairly inexpensive, the rest of the energy storage is almost entirely in lithium-ion batteries.

The deployment of lithium-ion batteries has increased greatly over the past few years as costs have decreased, however, developers of renewable energy projects are still reluctant to use them in long duration energy storage. The shorter cycle lives of lithium-ion batteries, aren’t always an economical choice when compared with flow batteries and their levelized cost of storage (LCOS).

The owners of renewable energy projects and developers are also learning which of the applications of long duration energy storage will be the best to satisfy their energy requirements and ROI.

Uses For Long Duration Energy Storage

It’s becoming more and more important in grid service areas for long duration energy storage to deliver value. Long duration energy storage can benefit areas with a large volume of renewable energy. Also in communities that are tied to the grid, or even have microgrids, storage can work with the renewables to offer resilience and self consumption. Long duration energy storage can help demand management with peak shaving and time of use programs. Lastly, in remote areas energy storage can help save money, and give security and stability.

Energy Storage Technologies

Pumped hydro is one of the more popular forms of energy storage. It is the least expensive per MWh, has unlimited storage potential, and a long life cycle. However it has environmental impact since it needs to use two reservoirs at different levels and is difficult to permit and build.

There is a alternative type of pumped hydro being used. Excess electricity pumps water into shale rock in old oil and gas wells. This creates pressure that can be utilized to run machines and generate the power all over again. This kind of system is being tested and could be promising.

Thermal energy storage is also called “sensible storage”. It can be paired with larger solar plants. Sensible heat systems incorporate cooling or heating material to contain either heating or cooling potential. This can be done using water to store energy. Other material can be used such as including rock, molten salt, glycol, concrete, and rock.

Liquid Air Energy Storage (LAES) is another excellent product for long duration storage. It can expand to hundreds of MWhs. Ambient air is super cooled into a frozen liquid, then stored in a tank and changed back into a gas, that can power a turbine. LAES uses basic parts that last a long time. These types of systems are similar to pumped hydro and can utilize low-grade waste heat/waste cold from co-located processes used in manufacturing.

Compressed air energy storage (CAES) is a technology that stores ambient air underground. When the energy is needed, the pressurized air is heated and expanded in a turbine which gives energy production. CAES has a long life, and a good LCOS, but also has geological and permit/construction issues.

A Popular Energy Storage Solution

An excellent solution for long-duration grid-scale storage is flow batteries. There are various types and flow batteries that have been developed and used. This includes those based on zinc bromine, iron-chromium, vanadium, and all-iron. These technologies are very flexible in their ability to utilize power applications. Flow batteries afford a secure, cost effective way to store energy at grid scale levels. lower maintenance, and lower LCOS. Most offer more than a 20-year cycle life with capacity levels staying strong, and many flow batteries are safe, clean, and non corrosive.

Long Term Benefits of Energy Storage

Choosing a long duration storage solution depends on the application(s) to the grid, life span of the technology, LCOS, and, if necessary, geological conditions and availability of real estate.

Long duration energy storage can balance the output of solar and wind energy. It helps with transmission and distribution costs. It is replacing old peaker plants in states like California. Long duration energy storage is the future. It can assist in wind and solar output, and lowers costs of transmission and distribution.