Economics and Innovation
As part of our survey of available technologies for grid storage, we required not only an assessment of “Technology Readiness Level” (TRL), but also an economically relevant way to compare performance. We selected "Levelized Cost of Energy" (LCOE) as our metric for this comparison.
The 2013 DOE Grid Energy Storage Report (Economics-01) states:
"The future for energy storage in the U.S. should address the following issues: energy storage technologies should be cost competitive (unsubsidized) with other technologies providing similar services; energy storage should be recognized for its value in providing multiple benefits simultaneously; and ultimately, storage technology should seamlessly integrate with existing systems and sub-systems leading to its ubiquitous deployment."
The method provided for comparing these solutions is described:
"Levelized power purchase agreements (PPAs) represent an actual contract for future prices that has been “locked-in” and includes the value of any federal and state incentives. The levelized cost of electricity (LCOE) represents an estimate of the per-megawatt- hour cost of building and operating an electric generating plant, taking into account the project’s capital costs, operating costs, and capacity factor, among other factors."
The DOE Energy Storage Roadmap lists $250/kWh LCOE as the short-term goal.
The same report cites the following with regards to chemical flow batteries, in general:
- Peak Shaving
- Time Shifting/Arbitrage
- Frequency regulation
- Power quality
- Ability to perform high number of discharge cycles
- Lower charge/discharge efficiencies
- Very long life
- Developing technology, not mature for commercial scale development
- Complicated design
- Lower energy density
It's well documented that even with recently announced innovations in Lithium Ion Battery materials
, this technology suffers from low endurance when in "deep cycle" discharge mode. In other words, when most of the stored electricity is used up, the number of cycles the battery will sustain before replacement, diminishes. This Solar-Electric article
provides useful detail on Lithium-Ion as well as alternative battery technologies.
Flow-Batteries, especially ours, which can function at lower temperatures, sustain performance over a much higher number of discharges.