November 01, 2021

Let’s Turn Ag States Into Carbon Sinks

Posted on November 1, 2021 by Chuck Becker

One of my favorite movies is The Graduate. There is a scene in that 1968 film where Ben (Dustin Hoffman) is getting advice about his future from Mr. McGuire. Mr. McGuire takes Ben aside and says, in a conspiratorial tone, “I just want to say one word to you—PLASTICS.” It’s a great scene made tragic by the fact that it was prescient (plastic generation in the United States went from 2.9 million tons in 1970 to over 35.7 million tons in 2018).

If the scene were shot today, Mr. McGuire would say: “I just want to say one word to  you—BIOCHAR.”

Biomass-derived charcoal, or “biochar,” is charcoal that is made when biomass is heated in the absence of oxygen – a process called pyrolysis.  Another way of saying it is that biochar is produced when wood chips, manure, sludges, compost and green waste are burned under controlled conditions. The big difference between charcoal (like what is produced in a forest fire) and biochar, is that almost all of the CO2 of the biomass gets bound up in the biochar.  Thus, biochar effectively sequesters carbon in the biomass (as long as the biochar is not burned). A significant side benefit, however, is that it is a soil amendment that produces healthier soil, bigger yields, lower acidity and better water retention.  The resulting charcoal can cut greenhouse emissions from waste and boost soil fertility.  It has the added benefit of reducing the need for chemical and manure fertilizers as well as absorbing heavy metals and agricultural chemicals.  It is easily applied to farmland and can endure in the soil for thousands of years.

I know what you’re saying – “Chuck, where can I get me some of this miracle product?” Well, of course, there’s the rub.  Like so many ideas that are good for the environment, cost is the killer.  Although the technology to create biochar is not new, it isn’t cheap.  There are experimental examples that have been operational for several years and the fine tuning continues.  But there is reason for optimism.

Why? Allow me to digress for a moment.  Municipal solid waste (MSW) continues to be a significant problem, particularly in the United States, and disposal costs real money. We produce waste at the rate of 4.9 pounds of trash per person, per day – higher per capita than any other country. Of that amount, about half is landfilled, one-third is recycled and the remainder is burned for energy recovery.  In the United States, the waste stream consists of: food residue – 15%; wood waste – 6%; paper – 27% yard trimmings – 14%; rubber, leather, textiles – 9% plastics – 13%, metals – 9%; glass – 4%; and other – 3%. That means just about 70% of the MSW stream could be used to produce biochar. 

So what happens when the two are combined?  Specifically, what if we can reduce the volume of MSW and provide a source for the biochar ingredients at the same time? Imagine you want to make a widget. What if the cost of the raw materials to make the widget was zero?  Better yet, what if people would actually pay you to take the raw materials you need from them and even deliver the materials to you free of charge?  This could work with biochar.  In its simplest form, a city might pay a biochar company a dollar amount per ton of municipal waste delivered to the company rather than the city paying a tipping fee at a landfill. This almost eliminates the waste stream to the landfill (a small percentage of the pyrolysis process ends up at the landfill) and provides the company with its raw materials at a negative cost. Indeed, under the right circumstance, cities could “mine” their Mount Trashmores and send the materials to the company for processing into biochar. The biochar would then be sold to farmers as a soil amendment that would not only improve yields, but would sequester the carbon in, potentially, millions of acres of farmland.

Obviously this isn’t meant to be a deep dive into biochar. Rather, think of it as Mr. McGuire whispering in your ear.  Any product that sequesters carbon, replaces fertilizer, improves soils and reduces landfill usage is worth a hard look.