Flow Batteries comes to mind
“1. Flow Batteries, just starting to come to market, can theoretically operate for 5,000 charge cycles or more. In some cases they can operate for 10,000 cycles or more. In addition, the electrolyte in a flow battery is a liquid that can be replaced, refurbishing the battery at a fraction of the cost of installing a new one.
2. Compressed Air Energy Storage, like LightSail Energy’s, uses physical components that are likewise rated for 10,000+ cycles of compression and decompression.”
The downside for the Vanadium Redox Flow Battery (“VRB”) is its bulkiness and relatively lower round-trip efficiency (measured by power out over power in) of 75% compared to 85% with lithium batteries.
Here is my exercise to calculate the cost of running a VRB:
redT energy plc claims at its website that its Gen2 VRB machine price starts at $490/kwh
I called redT last week. They currently have about a dozen customers with a total of 2,000 kwh of deployment and I obtained general pricing information and calculated the all-in cost of their product as follows:
Thus, the LCOE of VRB and lithium batteries are similar at 33 cents per kwh. (assuming the cost of a lithium battery at $300 per kwh, VRB has a higher initial cost but more charge cycles with longer battery life). The 33 cents per kwh is the cost of storage and does not include the input cost of electricity.
On-Grid VRB Application
33 cents per kwh is more than what redT quoted me, which was 24 cents per kwh.
However, even at 24 cents per kwh, with retail electricity rates around the US average of 12 cents per kwh, VRB for the on-grid market still has some way to go, other than for specific applications such as
– Replacing natural gas peakers.
The energy grid has to be built out to support peak use. Peaker plants are reserve natural gas plants. On average, they’re active far less than 10% of the time. They sit idle, fueled, and ready to come online to respond to peaking electricity demand. Even in this state, bringing a peaker online takes a few minutes.
– Arbitrage on Tiered Pricing
From the same 2015 article by Ramez Naam Why Energy Storage is About to Get Big – and Cheap: “In California, one can choose the standard tiered rate of 18.7 cents per kwh. Or one can choose the the time-of-use rate. In the latter, there’s a 19.2 cent per kwh difference in electricity rates between the minimum (9pm to 10am) and the peak (1pm – 7pm).
Batteries cheaper than 19 cents / kwh LCOE (including financing, installation, etc.) can be used to arbitrage this price difference. Software fills the battery up with cheap power at night. Software preferentially uses that cheap power from the battery during the peak of demand, instead of drawing it from the grid.”
– Storage of excess renewable electricity for use when needed
This can be useful for unstable grid with low availability factor or when the grid is charging above 34 cents per kwh.
My last vanadium article talked about the largest vanadium battery, which is 60 Mwh at Hokkaido Japan, and which went live in 2016. At the current rate of innovation and adoption, the cost of grid-level energy storage batteries may approach $100 to $200/kwh – equal to approximately 10 to 15 cents per kwh LCOE within 3 to 5 years. At that rate, I believe we will see mainstream adoption on-grid.