Of auxins, toxins and raging hormones: Does Biochar really work?

March 31, 2014 |


So, what about biochar? Is it just fantasy, a sideshow, or a vital future market that will power the carbon economics for hot ventures like Cool Planet?

And, er, what’s an auxin anyway — and why is that important?

Dwelling as we do from time to time in the land of manure, fertilizers and soil amendments, we run into a steady stream of what a visiting professor once described to me as “crap research”.  I never did figure out if he was referring to the field of study, or the quality of some of the work. Sigh.

One of the latest entries is a study out of the UK’s University of Southampton, with assist from researchers in Scotland and Italy, that delves into the pros and cons of the soil amendment known as biochar.

It’s a hot topic in the environmental world, where it’s been hailed because, as the Southampton researchers observed, “this carbon rich substance could potentially lock-up carbon and reduced greenhouse gas emissions. The global potential of biochar is considered to be large, with up to 12 percent of emissions reduced by biochar soil application.”


The major findings?

The researchers found that an application of 50 tons of biochar per hectare boosts the plant growth rate of thale cress and lettuce by 100%.

But they warn that “[We had] negative findings for a suite of genes that are known to determine the ability of a plant to withstand attack from pests and pathogens. These defence genes were consistently reduced following biochar application to the soil, for example jasmonic and salcyclic acid and ethylene, suggesting that crops grown on biochar may be more susceptible to attack by pests and pathogens.”

Remembering those saccharine-loaded rats

Which all sounds highly interesting and relevant until you begin to count the number of farmers who, in the real world, would apply 50 tons of a soil amendment to a hectare of land.

Even in the land of high-yield crops like strawberries, the fertilizer load generally tops out 200-500 kilos per hectare. So it begins to remind one of those saccharine studies that produced cancer in rats if you loaded them up on a dosage equivalent to hundreds of cans of diet soft drinks per day, for life.

The problem here is that someone has to pay for the biochar, in theory.

Maybe the carbon sequestration benefit at some time in the future will be so valuable that just shoveling biochar into the ground will be worth almost any price, but getting a farmer to pay, say, $100-$200 per ton of soil amendment and asking them to apply more than a couple of tons per acre is asking for trouble.

The embryonic biochar market

And that’s about where biochar is right now — undoubted and well-documented benefits, if applied in the right quantities and regions. But no consensus just yet on the right volumes, the exact regions, the prices, who pays for what.

Consequently, the International Biochar Initiative is reporting that 827 tonnes were sold last year at an average retail price of $2.48 per kilo. “Biochar has yet to make a substantial entry into large-scale agricultural operations,” the ICI notes.

All of this would be useful material for another day if the stunning news of Cool Planet’s ascent towards scale, and monstrous $100 million Series D investment round haul, hadn’t crossed the wires earlier this week.

You see, Cool Planet already has broken ground on its first commercial-scale plant, has two more on the drawing broard in Louisiana alone. Each producing, we understand, 10 million gallons of renewable gasoline blendstock — and an as-yet undisclosed fraction of biochar.

Even if the biochar fraction is, say, 20% by weight, that’s something like 25,000+ tons of biochar in the planning mix right now, from those three plants. Now, the fraction could be smaller, we’re not exactly sure. But we look at that 827 ton annual volume in small-market sales, and it’s pretty clear that Cool Planet is going to need to find an industrial market.

Biochar’s target crops?

Where will Cool Planet look first? Think strawberries, tomatoes, peppers and celery. These are examples of relatively high-value crops grown in wetter or warmer climates that often struggle with poor soils and nutrient leaching. Take, for example, strawberries, where yields are in the 25 tons per acre range and the prices in the $2000/ton range — or around $50,000 per acre. There’s real value opportunity in boosting yields there.

The acreages are small, in comparison to corn and soybeans. But not too small. In the case of strawberries, there’s just over 50,000 acres per year in cultivation, in the US. At 10 tons of biochar per acre, the addressable market would be around 500,000 tons. Even at one ton per acre, strawberries provide a meaningful opportunity.

Which is one reason why former Cobalt CEO Rick Wilson has been hard at work establishing this division of Cool Planet — branding the new product Cool Terra. And why it was big news last week when the company announced an MOU with Organic Waste Solutions, which designs and constructs low impact solutions to address water pollution from storm water runoff, and for water treatment and environmental remediation.

According to Wilson, “The OWS team is well known in low-impact water remediation. They have designed and deployed water remediation solutions across the United States and around the globe, including projects in China. In commercial deployment, Cool Planet’s technology solutions will span water pollution, low-carbon liquid fuels, increased food capacity, and address drought and climate change in a very practical manner.”

Which is to say that not every potential application of Cool Terra is going to be about soil amendments aimed at plant growth.

But let’s look at that Southampton study on plant growth for a moment, shall we? Because its most important aspect was identifying a mechanism by which biochar is doing its magic.

The how and why of biochar’s impact – raging hormones

Truth be told, we don’t really understand what makes biochar so active, though it was used by pre-Columbian Amazonians as long ago as 500BC in order to boost agricultural yields. They would make a fire up biomass in trenches, then cover it with soil and let it smolder. The result was a rich soil the Europeans called Terra Prete de Indio.

We know many things it can do. It’s better than compost, for one. It helps soil hold onto nutrients, it aids water retention and water quality, makes soils less acidic, reduce nitrous oxide and methane emissions from soil, reduce fertilizer and water needs and improve yields.

But we don’t really understand the mechanisms well — making it hard to improve.

In fact, biochar has been known to flip on researchers and start acting like a herbicide, instead of a plant growth enhancer. It happened in the initial stages with Cool Planet’s biochar.

As Cool Planet founder Mike Cheiky told the Digest back in 2012: “Biochar is usually not much more than a powerful herbicide, usually has too many hydrocarbons or hydrophobic elements that drive off water. Our biochar has a high surface area, high purity, and is devoid of tars. It’s unique in that we keep some of the original cellular structure, we partially open cell walls. So the BET is in the 600m2 per gram range, making it highly activated carbon.”(Note, activated carbon manufacturers generally seek ratios on the 500 m2 per gram range).

Professor Gail Taylor, Director of Research at the University of Southampton Centre for Biological Sciences with research colleagues in Italy and Scotland have provided an explanation why biochar has this impact, in an article just published in Global Change Biology Bioenergy. In their study of thale cress and lettuce, the response of more than 10,000 genes was followed simultaneously, which identified brassinosteroids and auxins and their signalling molecules as key to the growth stimulation observed in biochar.

Professor Taylor noted: “Our findings provide the very first insight into how biochar stimulates plant growth – we now know that cell expansion is stimulated in roots and leaves alike and this appears to be the consequence of a complex signalling network that is focussed around two plant growth hormones.”

So, think of it as a case of raging hormones — and just think upon what a case of raging testosterone and estrogen can have, say, on human fertility — and you get the basic idea.

More about auxins

Now, interestingly, we know of another case where auxins can flip and act like herbicides instead of plant growth stimulators — and that is in the case of IAA, (indole-3-acetic acid), the most common plant growth hormone. Two common herbicides on the market, 2,4-D and 2,4,5-T, are synthetic auxins — developed as analogs to IAA — and are used to defend grass and cereal crops against their broad-leafed (dicot) competitors.

Back to biochar

So, for the first time we have strong ideas about how it works — biochar, if made right, stimulates the plant growth hormonal activity — and may have some herbicidal qualities that limit competition for resources. Plus, some effectiveness in retaining nutrients and water in soil. All good.

Biochar in the Cool Planet value equation

In the case of corn ethanol production, co-products like distillers grains are valuable as animal feed and corn oil can be sold for biodiesel or potentially for other applications. And, they provide a material boost to the revenue stream of the processor — because the tonnage of DDGs is about the same as the tonnage of ethanol.

In the case of biochar, the fraction could be much smaller by weight — and most of the discussions around price we’ve seen — for industrial agriculture scale — have focused on the sub-$200 per tonne range. Given that a gasoline blendstock will wholesale at something like $900 per metric ton – and given that biochar might be 10-20% of the resulting product stream by weight: well, there’s every reason to think that 95% of the value of Cool Planet’s process is in the gasoline.

The Bottom Line — So, why bother?

Four reasons to care for companies like Cool Planet and their biochar options.

1. There might be a lot more biochar in their process than we have surmised, After all, they haven’t publicly disclosed.

2. If it helps crops, that’s meaningful in its own right. The planet can’t get enough soil productivity.

3. If it can’t be sold, it will have to be disposed or given away – expensively.

4. It makes the Cool Planet renewable gasoline blendstock a carbon negative fuel.

How does that play, economically? Well, consider gasoline in California — where refiners have to contend with the California Low Carbon Fuel Standard. A 20% blend of Cool Planet fuel would drop the carbon-intensity of gasoline aimed at that market by more than 20% — that’s huge. And, no infrastructure issues as with ethanol.

So, that increases the value of the blendstock with respect to the California market — and makes offtakers more interested, and possibly interested in paying premiums to avoid other more costly options.

Which is to say that the green attributes of biochar may well be more important than the price attributes, for now — and that’s something that the Low Carbon Fuel Standard was supposed to create — value on carbon. Which means that – given that so much of the revenue might be in the gasoline blendstock, there’s not a huge need for revenue out of Cool Planet’s biochar — because the value is in the sequestration. So it could help farmers, help consumers, and help on carbon — for far less than companies are proposing to inject carbon dioxide into underground storage.

So long as biochar works as a soil amendment, it’s economics as a co-product (as long as the other product is a monster) might well be a sideshow.

Making biochar not a sideshow at all. And that’s materially interesting.

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