Most of the renewable energy news we hear coming from Texas is that it has built the nation’s largest fleet of wind power – which is in large part by socializing the cost of power lines to bring that power to the state’s population centers.
And as a result of this, the economic viability of the state’s coal fleet is being stressed and shut down. Sometime soon – perhaps in 2018 – Texas may see more electricity generated from wind than coal.
Big hat and a respectfully-sized field of cattle.
But that is not all. The state is finally getting some Texas-sized energy storage – and it is being added to Texas’ largest solar power plant. In a powerpoint delivered by Vistra Energy on investor day, they referenced the upcoming energy storage project.
The AC-coupled facility will be a 10 MW / 42 MWh lithium ion battery. In its documentation, Vistra Energy notes that the solar power plant has a peak output of ‘nearly 200 MW,’ even though its interconnection application is only 180 MW.
Thus, the energy storage plant will be used to capture the power that is being clipped. The powerpoint also states that the batteries can be charged during lower priced periods overnight, and discharged in the morning, to arbitrage the difference in prices.
The presentation suggests the energy storage facility will be used to firm up the capacity being delivered by the solar power plant. In the above image, they present a case for ‘wider shoulders’ during peak solar power production, along with more consistent, predictable and slightly extended ramp-up and ramp-down periods.
The presentation also suggests that the project is eligible for the Investment Tax Credit and bonus depreciation. The IRS has already ruled that residential energy storage added in at a later time is eligible for these tax benefits.
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Hi John, in looking at the weather-exposed batteries in the accompanying photo, I was wondering if the day-time heat causes adverse impacts on the storage batteries, and if so, wouldn’t a solar canopy remove such adverse impacts?
The engineers already ran the numbers to determine the best solution and they went without. Pretty sure Tesla batteries actually have internal cooling via water or antifreeze type materials.
Hi John. Do you know if this battery system will be AC coupled or DC coupled?
If it’s catching clipped electricity, then DC coupled. Edit – just got an email back from the CEO of FlexGen, Josh Prueher, who stated that the Texas project is AC coupled.
I am sure the project is AC coupled to the grid, as Josh stated, but I expect the batteries are DC coupled to the solar array as John suggested.
Hi Lorin, The author checked with FlexGen and it turns out that the energy storage is AC coupled. He edited his comment above to reflect the update.
This is an evolving answer, and edits should be coming to the story. I do believe this is an AC coupled energy storage system, as per the conversation with FlexGen. And I think that means the system isn’t catching clipped electricity behind the solar inverter, but might be catching it after it goes to the AC side – but before it goes to the local powergrid transformer. This was suggested to me as being curtailment recapturing…but I’ve not heard the terminology used that way before.
My interpretation of the provided PDF might be applying broader energy storage benefits to this specific project…got a phone called scheduled.
Happy to answer any technical or commercial questions around this project with a quick call if helpful. Please send me a note at email@example.com to schedule. Note the image John used for this article and is not related to Vistra’s 10MW/42MWh project.
All the best,
John, you mention that the batteries from Tesla should be fine. But the article didn’t mention the supplier. Is it confirmed that these are sourced from tesla?
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