RICHLAND The most comprehensive analysis yet of the worldwide potential of biochar -- a charcoal-like substance -- shows it could offset up to 1.8 billion metric tons annually of the world's human-caused greenhouse gas emissions, according to a new study.
Biochar also can be used to improve poor soil and help it hold water, which can boost production of food crops, according to the study, which was co-authored by a Richland-based scientist.
And the process used to make it -- pyrolysis -- yields energy and bio-oil that can be used as fuel.
Biochar can be produced on scales large or small -- at industrial facilities or in a small farming operation. But its largest potential is as a tool to stabilize carbon from common sources, such as plants and wood or animal waste, and store it in the soil for decades, according to the study published this week in the journal Nature Communications.
"This is the most complete bottoms-up study of biochar and how it can combat climate change to date," said Jim Amonette, a soil chemist at Pacific Northwest National Laboratory and study co-author.
Amonette, who has studied biochar extensively for six years, joined scientists from Cornell University, Wales and Australia in the study, Sustainable Biochar to Mitigate Global Climate Change.
The study was funded by the Department of Energy, the Department of Agriculture, a New York state agency, the National Environmental Research Council in the United Kingdom and VenEarth Group LLC.
Biochar is produced when biomass is burned in the absence of or under low oxygen conditions so it doesn't combust.
The process, called pyrolysis, thermally decomposes the waste into biochar or bio-oil, depending on whether the pyrolysis is fast or slow.
The process isn't new. Researchers have found areas in the Amazon basin where people centuries ago deposited charcoal, leaving behind areas with rich soils and lush plant growth.
Amonette said biochar presents "one of the few ways we can create power while decreasing carbon dioxide levels in the atmosphere. And it improves food production in the world's poorest regions by increasing soil fertility."
Since 2000, researchers said carbon dioxide emissions have risen by more than 3 percent annually, "putting Earth's ecosystems on a trajectory toward rapid climate change that is both dangerous and irreversible."
Scientists looked at biomass sources that aren't being used for food -- such as corn stalks, rice husks, livestock waste and more -- and calculated how much reasonably could be used to produce biochar.
Then, they developed mathematical models that included different scenarios for creating biochar.
Amonette said researchers found under a maximum scenario that up to 1.8 billion metric tons annually of greenhouse gas emissions -- including such gases as carbon dioxide, methane and nitrous oxide -- could be offset by creating biochar.
The study found the maximum total offset amounts to 12 percent of the current 15.4 billion metric tons of greenhouse gas emissions that human activity adds to the atmosphere each year.
Researchers also calculated that about 1 billion metric tons could be sequestered annually worldwide under a minimal scenario.
Amonette said the study confirms biochar shows real promise.
"Now it's a matter of whether society gets serious about mitigating climate change," Amonette said. "This is one of the tools that can be used."
The study is at www.nature.com/ncomms/journal/v1/n5/full/ncomms1053.html.