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By The Numbers: Grid Energy Storage gets Cheaper PUBLIC ACCESS

One of the drawbacks to renewable power is its intermittency. New battery technologies are coming on line to fill in the gaps.

Mechanical Engineering 140(04), 28-29 (Apr 01, 2018) (2 pages) Paper No: ME-18-APR1; doi: 10.1115/1.2018-APR-1

Abstract

This article discusses introduction of modern technologies to enhance electric grid storage. The New York investment firm Lazard released an analysis of energy storage technologies, based on the levelized cost. The analysis looked at two different common battery chemistries—lithium-ion and lead-acid—as well as flow batteries. Lazard analyzed the cost of ‘behind the meter’ applications, such as battery backups for residential solar systems or businesses trying to save demand at peak times. Lazard expects lithium-ion storage prices to continue dropping over the next 5 years. It is expected that the cost of storage may soon become cheap enough to make the spotty service of wind and solar power an annoyance, not a deal-breaker.

Article

A 31.5-MW lithium-ion battery system supports a wind farm in Marseilles, Ill. Image: Invenergy

Grahic Jump LocationA 31.5-MW lithium-ion battery system supports a wind farm in Marseilles, Ill. Image: Invenergy

Anyone who has dealt with renewable power skeptics can likely repeat the phrase "when the sun doesn't shine and the wind doesn't blow” in their sleep. To be sure, the variability of solar and wind power-minute-to-minute, day-to-day, and season-to-season-is a headache for grid operators, especially those who cut their teeth on more dependable baseload power. But there are ways of handling intermittency. Shedding demand or adding power from gas turbines are two of the most common.

Perhaps the ultimate way of meeting the intermittency challenge would be to store excess renewable power when it's made and tapping that cache when it's needed. That's why grid-scale energy storage is such a hot R&D topic today.

Recently, the New York investment firm Lazard released an analysis of energy storage technologies, based on the levelized cost. These costs include not only the money needed to finance the purchase, but also the operational costs, such as maintenance and the cost of the electricity that charges the system, and expenses like taxes and insurance. Lazard also focused on a subset of commercially available technologies capable of being deployed in a variety of settings, which ruled out pumped hydroelectric and compressed air storage due to their dependence on specific geologies.

Instead, the analysis looked at two different common battery chemistries-lithium-ion and lead-acid-as well as flow batteries. Flow batteries work a bit like fuel cells, but with a liquid electrolyte such as vanadium oxide undergoing a chemical change as it flows past a membrane; the charged electrolyte can be stored in large tanks for long periods of time, then discharged by returning the electrolyte to the membrane.

For grid-scale applications, Lazard found, no technology looked to be a clear winner. Lithium-ion batteries had a levelized cost of storage capacity of between $282 and $347 per MWh when replacing a peak power generating asset, and were slightly more expensive in microgrid applications. Flow batteries, both those using vanadium chemistry and those employing zinc, had a wider range of levelized costs-from $209 to $413 in replacing peak generation-which is function of the lower degree of commercialization for the technology.

Lazard also analyzed the cost of "behind the meter" applications, such as battery backups for residential solar systems or businesses trying to shave demand at peak times. These applications had much higher levelized costs-as much as $1,274 per MWh of storage capacity for residential lithium-ion battery banks-due to the higher unit cost of smaller systems. Lead-acid battery banks required about 40 percent less capital outlay than lithium-ion, but with operation and maintenance costs running three to four times as high, they are not competitive with the newer battery technology.

What's more, Lazard expects lithium-ion storage prices to continue dropping over the next five years. Soon, perhaps, storage may be cheap enough to make the spotty service of wind and solar power an annoyance, not a deal-breaker.

Copyright © 2018 by ASME
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