I was trolling through the latest ISO New England data for FCA 13 and noticed that some Battery Energy Storage Systems (BESS) were awarded a Capacity Supply Obligation (CSO). One project in particular peaked my interest, the Madison Maine BESS. Â The website describes this project as follows:
New England’s first fully integrated front-of-the-meter grid tied battery energy storage system. The Madison project is a 5 MW / 10 MWh lithium-ion battery energy storage system that will participate in ISO-New England’s day-ahead energy market, real-time energy market, operating reserve market, frequency reserve market, and is expected to have a capacity supply obligation resulting from a successful offer in FCA #13. The Madison BESS is under construction and is expected to be commercial in Q2 of 2019.
I’m a little perplexed by the ISO New England classification of this resource, as non-intermittent:
This started me wondering about the definition of intermittent and non-intermittent resources, so I looked at the one place I knew for sure would have the answer, NERC. Interesting, there are no definitions available for intermittent or non-intermittent resources from NERC.Looking at the operating data for the Madison BESS, it shows a nameplate power rating of 5 MW and only 10 MWh of Energy (two hours of runtime at full power output). This makes me wonder, what exactly is a non-intermittent resource if a two-hour runtime qualifies? Should a non-intermittent resource have a minimum amount of energy output, i.e. 1 MW/hour for 24 hours, i.e. 24 MWh? I did find a definition for intermittent resource in the CAISO tariff “Generating Unit that is powered by one of the following sources, except for a de minimis amount of Energy from other sources: 1) wind, 2) solar energy, or 3) hydroelectric potential derived from small conduit water distribution facilities that do not have storage capability”. Does this mean that a 40 MW solar farm equipped with a 2 MWh battery in the CAISO control area is considered a non-intermittent resource?
ISO New England classifies all batteries as non-intermittent resources in the Forward Capacity Market.
I'm interested in what you think: Should batteries be classified as intermittent or non-intermittent?