Science Never Sleeps, Green Hydrogen & Biochar Edition

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Hydrogen is the grease that turns the wheels of the modern industrial economy, but it has a supply chain problem. Almost all of the global hydrogen supply comes from natural gas or gassified coal. That is slowly beginning to change as more sustainable “green hydrogen” sources emerge. In an interesting twist, biochar could be in play.

What Is Biochar, Anyways?

The US Department of Agriculture offers a handy explainer about biochar, a carbon-rich material that is results from the partial, oxygen-limited combustion of organic waste or biomass.

USDA notes that biochar enjoys a solid reputation around the world as a beneficial soil enhancement. The material’s carbon sequestering talents have also crossed the CleanTechnica radar.

“A common attribute among all types of biochar is the primary ingredient: a recalcitrant carbon that can persist in soils for years or decades, and even millennia,” USDA explains.

“Biochar can be used as a soil amendment by itself, or it can be blended with other soil amendments to address a wide range of environmental, agricultural, and forestry challenges,” USDA adds. “Applications of biochar include improving soil health, raising soil pH, remediating polluted soils, sequestering carbon, lowering greenhouse gas emissions, and improving soil moisture.”

Sparks Fly When Biochar Meets Green Hydrogen

Aside from studying the application of biochar to soil, the research community has begun to deploy it for other purposes, including green hydrogen.

Green hydrogen refers to hydrogen pushed from water with an electrical current, assisted by a catalyst. In terms of carbon emissions and overall sustainability, that idea was a non-starter back when fossil fuels dominated the power generation industry. Now that renewable energy is widely available, water electrolysis makes more sense from a carbon-reducing point of view. In particular, electrolysis systems can provide a place for excess clean kilowatts to go whenever the grid is over-saturated with wind or solar power.

Renewable energy or not, the cost of green hydrogen remains high compared to its fossil-sourced cousin. However, technology improvements are bringing costs down.

Back in 2020, a research team based at the Israeli research institution Technion tackled the cost issue from the perspective of reducing energy consumption, leveraging the properties of biochar.

More recently, in 2023, a team from the University of Shanghai for Science and Technology in China also explored the potential for using biochar to reduce the cost of green hydrogen.

“Biochar-assisted water electrolysis (BAWE) for hydrogen production is employed to reduce energy consumption by replacing the oxygen evolution reaction (OER) with thermodynamically more favorable biochar oxidation reaction (BOR),” the team explained.

Solar-Powered Green Hydrogen Is Coming

As the University of Shanghai researchers note, the key element in biochar-assisted electrolysis is an electrolyte, a conductive solution that dissolves the biochar.  They also indicate that that their study could be a stepping stone for other researchers to continue fine-tuning the process.

Sure enough, earlier this week the University of Illinois – Chicago reported the results of a study published in the journal Cell Reports Physical Science, under the title, “Sub-volt conversion of activated biochar and water for H2 production near equilibrium via biochar-assisted water electrolysis.”

The short version, as condensed by the school’s media office, is that the research team reduced the energy needed to run the process by 600%.

“The energy requirements were low enough that the researchers could power the reaction with one standard silicon solar cell generating roughly 15 milliamps of current at 0.5 volt. That’s less than the amount of power produced by an AA battery,” the school noted.

The team tested different types of biochar slurry treated with sulfuric acid. Among the test materials, biochar sourced from cow manure performed the best and reached the 0.5 volt mark. The other materials — including sugarcane husks, hemp waste, and paper waste — performed less efficiently, but they saved energy, too.

In a press statement, study co-author Rohit Chauhan explained that the process is “very efficient, with almost 35% conversion of the biochar and solar energy into hydrogen.”

“These are world record numbers; it’s the highest anyone has demonstrated,” Chauhan added.

“We are the first group to show that you can produce hydrogen utilizing biomass at a fraction of a volt,” affirmed UIC associate professor Meenesh Singh, who led the multi-institutional study. Stanford University, Texas Tech University, Indian Institute of Technology Roorkee, and Korea University also contributed to the research, which was sponsored by the global firm Orochem Technologies Inc.

“This is a transformative technology,” Singh emphasized.

What About The Carbon That Gets Away?

There being no such thing as a free lunch, the UIC team also takes note of the carbon emissions angle. Biochar is made by burning stuff, which means that greenhouse gas emissions factor in somewhere along the line. If the biochar is used as a soil amendment, its carbon sequestering powers can soak up those emissions over time. According to a growing body of research, biochar can even attain carbon-negative status — when used as a soil amendment, that is.

Other use cases present a carbon challenge. Singh suggests that carbon capture technology could be deployed with a biochar-enabled green hydrogen system, though he does not appear to be a fan of underground sequestration. Instead, he suggests putting the captured carbon to use in making synthetic fuels or plastics.

That’s not a perfect solution either, but a co-lead author of the study, Nishithan Kani, takes note of the benefits to farmers. “This cheap way of making hydrogen could allow farmers to become self-sustainable for their energy needs or create new streams of revenue,” he explains. “It not only diversifies the utilization of biowaste but enables the clean production of different chemicals beyond hydrogen.”

More & Cheaper Green Hydrogen

The idea of leveraging green hydrogen to support energy independence for farmers could gain traction in the US, where the Department of Energy has been steadfastly trying to get more farmers to install distributed wind turbines on their property.

A distributed wind turbine can be any size, from a few hundred kilowatts up to the megawatt scale. The determining factor is the deployment of the clean kilowatts on site, or for use in a local distribution grid.

The idea would be to produce green hydrogen at night, when electricity demand is lower but wind speeds are optimal. The hydrogen could be stored for use in a fuel cell, deployed to produce green fertilizer, or sold as a revenue stream.

Last year, the Energy Department ran the numbers on the distributed wind market and noted that the smaller and larger ends of the wind turbine scale have sparked the most activity, with relatively little interest in mid-sized turbines.

“With the passage of the IRA and associated long-term incentives for distributed wind, the outlook for future distributed wind deployment looks much improved,” the Energy Department explained, while also taking note of other federal grant programs for renewable energy on farms.

Depending on the incentives, and on measures to streamline the permitting process, the Energy Department came up with a 10-year scenario that culminates in a total of 1.7 terawatts for behind-the-meter applications and more than 4 terawatts for front-of-the- meter.

Whether any of those clean kilowatts go to produce green hydrogen remains to be seen. If you have any thoughts about that, drop us a note in the comment thread.

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Photo (cropped): “Biochar permanently sequesters carbon and returns nutrients to the soil to bolster soil microbial activity (credit: Tracy Robillard, NRCS Oregon).