Here's the backstory: Part of the mission of Ecology's Waste 2 Resources program is supporting recycling in the state. That's not just bottles and cans and newspapers, it's also food and grass clippings and other organic material. That's what composting is all about – recycling organics.
A lesser-known part of that organics recycling work is what's called "waste to fuels." Anaerobic digesters are one example of this – digesters capture the methane from decomposing cow manure plus other organic material like food and green waste, and repurpose it as natural gas, either for heating or generating electricity.
|Producing biochar. Photo - Photo - Wilson Biochar, wilsonbiochar.com.|
Another example is biochar. And here's where we get back to saving the planet.
Biochar sounds sort of mysterious, but you might have a bag of it already out by the grill.
"This term 'biochar' is a new term – we used to call it 'charcoal,'" said Mark Fuchs, a hydrogeologist with Ecology's Eastern Regional Office in Spokane.
"It's pretty cool stuff that we're looking at," said John Cleary, an Ecology engineer also working on waste to fuels. "We're trying to find new ways to look at waste."
Charcoal (and biochar) is produced when you partially burn woody debris, removing moisture and volatile compounds. To produce biochar efficiently, you use a process called pyrolysis, where the wood is heated in the absence of oxygen – meaning that you do as little actual "burning" as possible. After all the volatiles cook off, you're left with a block of what is mostly carbon.
More than searing a steak
It turns out that you can do a lot more with charcoal than simply searing a steak. If you take a bunch of biochar and mix it in with compost or soil, you produce soil that's more fertile and better at holding water.
This isn't a new innovation. People have been putting their charcoal and ashes into soil for thousands of years. Native Americans in the Great Plains used to burn off the prairie each year in order to promote grass regrowth and prevent forests from encroaching.
What is new, however, is our understanding of the potential for biochar and carbon in soils to act as a carbon sink. Usually when we talk about carbon reduction, we're talking about prevention – improving fuel economy, upping energy efficiency, or switching away from carbon-intensive fuels like coal.Adding biochar to the soil is a different game.
Studies, including some by Fuchs working with researchers at Washington State University, and many others across the globe, show that biochar can lock away a potentially massive amount of carbon for a really long time – potentially storing hundreds of tons per acre for hundreds to thousands of years.
|Biochar under a scanning electron microscope. Photo - Washington State University|
When you start thinking about the millions of acres devoted to agriculture in the United States, you can really dream big. Biochar has real potential to help us address global warming. Even better, you're not just locking away carbon – you're improving the soil in the bargain by increasing its fertility and water-holding capacity.
"The biggest challenge for us for the next thousand years is carbon dioxide in the atmosphere," Fuchs said. "We've got to find ways to get it down."
Even better, the same pyrolysis process that produces biochar also produces bio-oil and biogas, which can be used to keep the process running, or captured and used for energy or heating.
Sounds amazing, doesn't it?
Well, it could be. But making enough biochar and making the economics work does get tricky. Air quality concerns, transportation costs and scientific questions are all barriers that stand in the way of large-scale implementation of biochar as a carbon reduction tool. The research that Fuchs and others at Ecology are supporting aims to answer those questions. (The Clean Air Rule Ecology adopted in 2016 caps carbon pollution in the state from major emitters, but focuses on reducing emissions instead of removing carbon from the atmosphere through means such as biochar.)
Fuchs sees too much potential in biochar to give up, though.
"The soil is a huge reservoir to place carbon in," Fuchs said. "We just need to understand how to get there – and we're starting to."
- Learn more about biochar at www.ubetbiochar.blogspot.com.
- Watch a 50-minute video on producing biochar at https://www.youtube.com/watch?v=c-tzu0P9hzI&feature=youtu.be.
By Andrew Wineke, Waste 2 Resources