I just wanted to make clear that BNEF is talking about batteries threatening fossil peakers that produce expensive electricity, while OP was wondering how inexpensive CCGT generation could be threatened by batteries. CCGT and peakers are distinct and have different costs even when they both burn natural gas.
Hawaii doesn't generate electricity from natural gas but it does consume a lot of petroleum-fueled electricity:
More recently, the Hawaiian Public Utilities Commission has approved 247 megawatts of new solar capacity backed by nearly a gigawatt-hour of battery storage:
"The price for each of these contracts was between eight and ten cents per kilowatt-hour. This is cheaper than both gas peaker plants and HEI’s current cost of fossil fuel generation, much of which is petroleum-based, which the company put at around 15 cents per kilowatt-hour."
Note that these prices are only $80-$100 per MWh, because most of the solar electricity is consumed immediately and doesn't need to be stored in a battery.
Hawaii doesn't generate electricity from natural gas but it does consume a lot of petroleum-fueled electricity:
https://www.eia.gov/state/?sid=HI#tabs-4
Here's a story about a Hawaiian island replacing diesel output with solar and batteries from a couple of years ago:
https://arstechnica.com/information-technology/2017/03/kauai...
More recently, the Hawaiian Public Utilities Commission has approved 247 megawatts of new solar capacity backed by nearly a gigawatt-hour of battery storage:
https://pv-magazine-usa.com/2019/03/28/hawaiis-new-reality-o...
"The price for each of these contracts was between eight and ten cents per kilowatt-hour. This is cheaper than both gas peaker plants and HEI’s current cost of fossil fuel generation, much of which is petroleum-based, which the company put at around 15 cents per kilowatt-hour."
Note that these prices are only $80-$100 per MWh, because most of the solar electricity is consumed immediately and doesn't need to be stored in a battery.