Frequency regulation is a key use case for utility-scale energy storage. [Engerati-Frequency Regulation and Energy Storage]
A recent study from the Global Smart Grid Federation found that its application in the PJM market in the US is one of two use cases that are currently cost effective businesses. [Engerati-Battery Energy Storage Is Economically Viable (In Some Cases)] No wonder that the PJM market accounted for the majority of utility-scale storage deployments in the US during 2015, as reported by GTM Research and the Energy Storage Association in their Energy Storage Monitor for the year.
KEPCO looks to battery storage
South Korea’s largest utility, Korea Electric Power Corporation (KEPCO), is also appreciating the potential of battery-based storage for frequency regulation with a project to instal 500MW by 2017.
The installation to date by South Korean battery storage provider Kokam Co. Ltd comprises 56MW with a 24MW/9MWh lithium nickel manganese cobalt (NMC) system – claimed to be the world’s largest of its type – and a 16MW/6MWh lithium NMC system alongside a 16MW/5MWh lithium titanate oxide (LTO) system that was deployed in August 2015. The two lithium NMC systems became operational in January 2016.
“Kokam’s 56MW of energy storage systems are making a major contribution to the stabilization of our grid,” commented Hwang Woohyun, KEPCO's senior vice president and head of the Innovative Energy Business division.
In addition to improving grid reliability, the energy storage systems will enable KEPCO to improve its operational efficiency by reducing its need for spinning power generation reserves. This will allow KEPCO to shift energy generation to lower cost, more efficient power plants. For example, the three systems are expected to deliver estimated annual savings of US$13 million in fuel costs, providing savings three times larger than the systems’ purchase price over their lifetimes. Further, with a reduction in the amount of fossil fuels burnt, KEPCO’s greenhouse gas emissions also will be reduced.
Battery storage for frequency regulation
KEPCO’s new 24MW and 16MW systems utilize Kokam’s ultra high power NMC battery technology, which is designed for high power storage applications, such as frequency regulation, wind or large solar power system ramp rate control, uninterrupted power supply (UPS) and voltage support. Features include 2.4MWh energy density and a 10,000 cycle lifetime.
The systems are installed in 12m containers with a direct cooling design that reduces the HVAC requirements.
Kokam has deployed approximately 95MW of energy storage system capacity in operation in South Korea, the US, Canada, Germany and Australia. Notably, the company’s batteries were also selected for the first Solar Impulse, which protoyped the potential for a plane to circle the earth using only solar power. As it is, it is the batteries that have delayed the current attempt to make the trip with Solar Impulse 2, after they were damaged by overheating, due to being packed in too much insulation, in the long leg from Japan to Hawaii last June/July. The flight is now expected to resume next month.
Batteries are particularly suitable for short‑term frequency control, due to their capability of changing output level and rapid switching from discharge to charge mode. But other technologies may also be suitable and Ontario’s Independent Electricity System Operator (IESO) is currently trialling for comparison purposes several different storage options. [Engerati-Ontario System Operator Procures 34MW Storage To Test In Grid Operation] The outcomes of this project is awaited with a good deal of interest.