Baking Soda As the Key to Renewable Energy Storage

PNNL scientists examine the promising properties of a typical, Earth-abundant salt.

In a world of repeatedly hotter temperatures, a rising consensus calls for that vitality sources have zero, or next-to-zero, carbon emissions. That means rising past coal, oil, and pure fuel by getting extra vitality from renewable sources.

One of probably the most promising renewable vitality carriers is clear hydrogen, which is produced with out fossil fuels.

It’s a promising thought as a result of probably the most considerable ingredient within the universe is hydrogen, present in 75 p.c of all matter. Moreover, a hydrogen molecule has two paired atoms—Gemini twins which are each non-toxic and extremely flamable.

Hydrogen’s combustive potential makes it a gorgeous topic for vitality researchers around the globe.

At Pacific Northwest National Laboratory (PNNL), a group is investigating hydrogen as a medium for storing and releasing vitality, largely by cracking its chemical bonds. Much of their work is linked to the Hydrogen Materials-Advanced Research Consortium (HyMARC) on the Department of Energy (DOE).

Hydrogen storage not but optimized

One PNNL analysis focus pertains to optimizing hydrogen storage, a cussed challenge. To date, there isn’t a fully secure, cost-effective, and energy-efficient option to retailer hydrogen at giant scales.

PNNL researchers not too long ago coauthored a paper that investigates a baking soda answer as a way of storing hydrogen. The examine has already been dubbed a “hot paper” by the journal itself, Green Chemistry, printed by the Royal Society of Chemistry. That signifies that it has had numerous clicks exhibiting curiosity.

Chemist Tom Autrey. Credit: Photo by Andrea Starr | Pacific Northwest National Laboratory

The hydrogen-based storage efforts at PNNL are funded by the DOE’s Hydrogen and Fuel Cell Technologies Office within the Office of Energy Efficiency and Renewable Energy (EERE). The analysis advances the DOE’s [email protected] initiative in addition to the company’s Hydrogen Shot.

The new paper’s two predominant authors are chemist and PNNL Laboratory Fellow Thomas Autrey and his colleague Oliver Gutiérrez, an knowledgeable in making chemical reactions speedy and cost-effective.

“You have to be a little creative,” mentioned Autrey, who’s amused at how widespread, low-cost, and gentle baking soda is as a possible reply to an enormous downside. “Not every chemical is going to be efficient at storing hydrogen. You have to work with what Mother Nature gives you.”

Clean hydrogen for long-term vitality wants

Autrey, Gutiérrez, and others at PNNL see long-duration vitality storage as the important thing to hydrogen’s future as a provider of renewable vitality.

Current battery expertise is designed for a number of hours of storage. In a renewable vitality grid, batteries can deal with about 80 p.c of storage wants.

But “the last 20 percent will take unique approaches,” mentioned Autrey. “We will want to store the excess energy to be prepared for Dunkelflaute.”

Chemical Engineer Oliver Gutiérrez. Credit: Photo by Andrea Starr | Pacific Northwest National Laboratory

That’s a German phrase describing circumstances with out sufficient photo voltaic and wind vitality potential. During the darkish, windless durations of Dunkelflaute, grids want a option to retailer vitality for extra than simply a number of hours.

Seasonal storage functionality like that is one in all hydrogen’s points of interest. So is the truth that hydrogen storage can occur anywhere-that it’s “geographically agnostic,” as consultants say. Hydropower, for instance, requires variations in elevation to retailer extra water to make energy. Hydrogen storage requires no particular circumstances associated to geography.

In addition, mentioned Autrey, as scales get bigger, hydrogen will get extra economical. It is cheaper to purchase just a few extra hydrogen storage tanks than to purchase numerous batteries.

Finding one of the best ways for hydrogen storage

Clean hydrogen has nice promise as an vitality supply. A course of referred to as electrolysis, for example, can cut up water into hydrogen and oxygen. In one of the best of worlds, the facility for electrolysis would come from renewable vitality sources, together with photo voltaic, wind, and geothermal.

However, there’s one cussed problem: to provide hydrogen extra cheaply.

To tackle that, in 2021 the DOE introduced its Energy Earthshots initiative, a sequence of six steps to underwrite breakthroughs in clean-energy expertise. Introduced first was the Hydrogen Shot, a quest to cut back the price of hydrogen to from $5 to $1 per kilogram in a decade-an 80 p.c discount.

Beyond getting clear hydrogen manufacturing prices down, “you have to figure out how to move and store it,” mentioned Autrey, that are steps that may ship costs again up.

But discovering the perfect medium for hydrogen storage has been elusive.

Hydrogen may be compressed right into a fuel, however that requires very excessive pressures—as much as 10,000 kilos per sq. inch. A secure storage tank would wish partitions of very thick metal or costly space-grade carbon fiber.

How about cryogenic liquid hydrogen? This is a confirmed storage medium however requires getting and preserving one thing so chilly (-471 F, or -279.four C) that peripheral vitality prices are vital.

What appears to carry probably the most promise are molecules which are liquids, optimized to retailer and launch hydrogen. Jamie Holladay, a sustainable vitality knowledgeable, not too long ago directed PNNL-led analysis on easier and extra environment friendly methods for liquefying hydrogen.

Using such liquids as a storage medium have the benefit of preserving present vitality infrastructure in place, together with pipelines, vehicles, trains, and taker ships, mentioned Gutierrez.

The bicarbonate-formate cycle

Want to bake cookies? Or retailer hydrogen vitality? Baking soda may very well be the ticket. This gentle, low-cost sodium salt of bicarbonate is non-toxic and Earth-abundant.

Not baking soda precisely. The PNNL group is investigating the hydrogen vitality storage properties of the long-studied bicarbonate-formate cycle. (Formate is a secure, gentle liquid natural molecule.)

Here’s the way it works: Solutions of formate ions (hydrogen and carbon dioxide) in water carry hydrogen based mostly on non-corrosive alkali metallic formate. The ions react with water within the presence of a catalyst. That response makes hydrogen and bicarbonates-the “baking soda” Autrey admires for its absence of environmental impacts.

With the precise gentle tweaks in strain, the bicarbonate-formate cycle may be reversed. That supplies an on-off change for an aqueous answer that may alternately retailer or launch hydrogen.

Before baking soda, the PNNL hydrogen storage group checked out ethanol as a liquid natural hydrogen provider, the trade’s blanket time period for storage and transport media. In tandem, they developed a catalyst that releases the hydrogen.

Catalysts are designer components that pace the processes used to make and break chemical bonds in an energy-efficient approach.

In May 2023, for a venture associated to the PNNL effort, EERE granted OCOchem of Richland, Washington, $2.5 million in funding over two years to develop an electrochemical course of that makes formate and formic acid from carbon dioxide. The process would bind carbon dioxide with the hydrogen located in water’s iconic chemical bond, H₂O.

In a partnership just starting, PNNL will develop ways to release hydrogen from the OCOchem products.

Hydrogen storage that ‘looks like water’

In the world of hydrogen storage research, the bicarbonate-formate cycle has created a buzz for quite some time. After all, it is based on materials that are abundant, non-flammable, and non-toxic.

The cycle is built on an aqueous storage solution so mild it “looks like water,” said Autrey. “You can put out a fire with it.”

But for formate-bicarbonate salts to become a viable means of storing hydrogen energy, researchers must still develop economically feasible scenarios. So far, the technology stores hydrogen at only 20 kilograms per cubic meter, compared to liquid hydrogen’s industry standard of 70.

More fundamentally, said Autrey, researchers need a systems-level understanding of the required electrochemistry and catalysis. In engineering terms, to date, the idea of a workable bicarbonate-formate cycle has a low technical readiness level.

“If we solve the catalysis problems,” he added, “we could get some real interest.”

‘An amazing shiny thing’

On the plus side, the salt solutions under consideration at PNNL release hydrogen upon reaction with water. They also operate at moderate temperatures and low pressures.

In theory, at least, as Autrey and Gutiérrez describe in their 2023 paper, the bicarbonate-formate cycle represents “a feasible green alternative for storing and transporting energy” from hydrogen.

The baking soda idea is also at the nexus of what the 2023 paper calls “several urgent scientific challenges.”

Among them are how to make a hydrogen storage media from captured excess carbon dioxide. And even to use the same media to store electrons, which offers the promise of direct formate fuel cells.

In addition, the PNNL work could provide insights for catalysis in the aqueous (water) phase. For now, the PNNL team is using palladium as their candidate catalyst. Their efforts include finding ways to make the rare metal more stable, reusable, and longer-lived.

In all, the baking soda idea “is this amazing shiny thing” for hydrogen storage, said Autrey. “What’s exciting are the possibilities.”

Reference: “Using earth abundant materials for long duration energy storage: electro-chemical and thermo-chemical cycling of bicarbonate/formate” by Oliver Y. Gutiérrez, Katarzyna Grubel, Jotheeswari Kothandaraman, Juan A. Lopez-Ruiz, Kriston P. Brooks, Mark E. Bowden and Tom Autrey, 29 March 2023, Green Chemistry.
DOI: 10.1039/D3GC00219E