Yet the condition you claim will give rise to widespread adoption of energy storage already exist in Hawaii: fossil fuels have to be imported making it expensive, and daytime energy prices regularly go negative due to widespread solar adopt. These conditions have existed for years. Yet people aren't storing and reselling this energy. Why not? If hydrogen storage really costs only $1/KWh then a company can reclaim their investment cost in less than a week of operation, with an average price of $0.30/KWh in the state. It's basically free money.
The reality is that hydrogen storage costs nowhere near $1/KWh. People making predictions about what a technology will cost and actually building it are two totally different things.
That storage cost is in salt formations, a technology that is already widely used to store megatons of natural gas. A single salt formation in Delta, Utah could store enough hydrogen to supply the entire US average grid power for 30 hours (and efforts to exploit this formation for hydrogen storage are ongoing). Salt formations exist in ample supply in Germany and Europe, but there are none in Hawaii, which is entirely volcanic.
The same excess of energy during peak renewable production exists in California, and parts of Europe. So this problem is more than just Hawaii's geology. There are costs in electrolysis, compressions, decompression, and conversion back to electricity that are just being hand-waved away.
Can you point me to a developer that's actually offering to build hydrogen electric grid storage at $1/KWh? As in, if I give them $1 million they will build 1 GWh of hydrogen electric storage for me. Are there any enterprises actually willing to provide grid storage at this cost? If so, please point them my way. I'll make a massive amount of money. But I doubt I'll have anyone taking this offer.
The storage costs your citing are absolutely incredible. As in, I genuinely do not believe them. You're claiming that the entirety of the US's grid storage (which cost billions of dollars to build, mostly in the form of hydroelectric storage) can be matched by only $20 million in hydrogen storage. This is a cost estimate totally disconnected from reality. Until enterprises are actually building hydrogen electric grid storage for $1/KWh then this figure is meaningless.
If not then what's your explanation as to why people are missing out on the opportunity to become billionaires or trillionaires by construction hydrogen electric storage? Bill Gates alone could build enough storage for 24 hours of the USA's electricity consumption with only 10% of his net worth. This would be a rounding error on the national budget.
The reality is that hydrogen storage costs nowhere near $1/KWh. People making predictions about what a technology will cost and actually building it are two totally different things.