National Grid and PNNL explore a modern, battery-enhanced grid

by Scott Sowers

National Grid, a transmission company that services New York, Rhode Island and Massachusetts, has inked an agreement with the Department of Energy’s Pacific Northwest National Laboratory (PNNL) to partner up on modernizing the electric grid while adding resiliency.

The public-private agreement announced this week focuses on cyber security, distributed energy resources (DERs), advanced transmission network controls and grid scale energy storage that may include new generation redox flow batteries.

Secretary of Energy Rick Perry cheered the agreement saying, “Innovation partnerships with the private sector are critical to the groundbreaking work our National Labs undertake. DOE is committed to the modernization, reliability and resiliency of our grid and expanding energy storage research and this partnership is a great example of that commitment.”

To explore storage options, Richland, Washington-based PNNL has been researching redox flow batteries over the past few years.

Lawrence Thaller at NASA originally developed the technology for deep space missions in the early 1970s. Flow batteries store energy in two tanks filled with liquid electrolyte separated by a membrane. Pumps push the charged electrolyte back and forth to free electrons and produce electric current. Maria Skyllas-Kazacos at the university of New South Wales improved on the original design in the 1980s by adding the element vanadium to the electrolyte.

Flow batteries can be adjusted and scaled to the size needed by increasing the size of the tanks or changing the speed of the pumps. Flexibility is a key selling point when it comes to adding resiliency to an electric grid that is being impacted by natural disasters and DERs.

Lithium-ion batteries, the current state-of-the-art battery technology, have limitations for use on the grid due to the amount of batteries needed to back-up a generation plant and their relatively short lifespan.

Vince Sprenkle, Technical Group Manager and materials engineer at PNNL, said, “On the grid, you need something that’s highly flexible that will last more than a couple of hours a day. You need something that will last a utility-scale lifetime and they think in terms of 40 to 50 years. That’s still a stretch for flow batteries but we’ve seen systems that have lasted 18-20 years,” Sprenkle said in an interview with Daily Energy Insider.

The lab, in partnership with the Department of Energy, has advanced the design pioneered by Skyllas-Kazacos by adding chloride to the electrolyte, which allows the batteries to store more power in a smaller physical package and operate at a wider temperature range.
But getting the costs down to where it makes sense to deploy the batteries on a utility-sized scale depends on controlling the price of vanadium, which is used in steel production to increase the hardness level of stainless steel.

“We started looking at costs and vanadium was accounting for 55 percent of the cost of the system so we started engineering organic molecules that can be backwards compatible with today’s vanadium systems,” Sprenkle said. “We’re looking for something that’s not dependent on commodity metals pricing which will get another 50 percent price reduction and put us around $125 per kWh in costs.”

For comparison, the cost of lithium-ion batteries have been falling and have been as low as 140 kWh, as they have been adapted for use in everything from phones to cars.

Flow batteries do have disadvantages as compared to lithium ion. Flow batteries are physically larger, making them less energy dense, which means they will never fit in phones or cars. But they may prove to be a valuable key for utilities that are facing resiliency challenges or those who are looking for a solution to costly, rarely used peaker plants.

“If you’re building a new substation to be able to handle a peak load, you can put a storage system downstream and not have to upgrade that station for a number of years – those are pretty easy wins and I think peakers are probably next,” Sprenkle said.

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