Interra and the pursuit of soil magic via affordable biochar

May 14, 2017 |

Around this time of the year, driving southeast out of Palm Springs and the Coachella Valley towards the Mexican border is an exercise in slow pyrolysis — the temperature soars from time to time into the low 120s and breathing in the gaseous fire they use for breathing air, you start to feel the oxygen debt. Try and golf in this weather and by the 18th fairway you’ll feel like rubber and swinging anything heavier than a seven-iron isn’t in the cards. There are moments when you think that, if you don’t find a roadside oasis soon, you’ll become a neatly-piled up heap of desiccated dust.

Congratulations, you’ve become human biochar.

The world of feedstocks is watching biochar very carefully these days, and for good reason. Although it might feel quite a long ways upstream from the world of making and upgrading liquid fuels — affordable, sustainable feedstock is the pathway to biohappiness, and in a world where competition for waste feedstocks is rising, there’s more demand for calories and water aggregation is under stress — agricultural yields and water efficiency is under the microscope for everyone proposing to use biomass.

Meanwhile, we’d also like to reduce atmospheric carbon, in case you haven’t heard.

All of those factors are powering the whispering around biochar these days. Will it work? Is it affordable? Companies like Cool Planet are working hard on it.

In a perfect world, biochar checks off an awful lot of boxes. Sequesters carbon from the original biomass and packs it permanently into the soil. Improves, obviously, soil carbon. Depending on the configuration of the biochar particles, it can assist greatly with water and nutrient retention. Check check check.

The biochar story is a romantic one — usually the tale begins back in the ancient Amazon, where the tribes developed a soil-improving method of building up soil carbon through what is called terra preta. It has enough “Seven Wonders of the World” performance to it, that researchers have been scratching their heads for decades trying to exactly reproduce it. Most efforts are based in pyrolysis — since slow cooking of biomass is undoubtedly the approach these ancient Amazonians took.

In recent years, a number of players have popped up in the chase from biochar. Some comes from the energy side and have embraced biochar as a valuable first product with an enthusiastic supporter base. Others have come to biochar from the sustainable grower community.

Which brings us to Interra Energy and its Interra Preta product.

The CEC Grant round

In January 2015, a group of three companies received grants from the California Energy Commission towards the development of modular bioenergy systems for “forest/urban interface areas”, and biochar figured in one of the winning entries.

The CEC focus was improving the financial performance of small waste-to-energy systems that have to a great extent in the California market lived off tipping fees from accepting construction and yard waste and chipping and grinding them down for power gen — as an alternative to shoveling more waste into landfills.

But, why not biochar?

The winning technology in question is Interra Energy, which has developed a carbon-negative system and that is because of the focus on generating biochar — at affordable costs. Some 75 percent of the energy coming in to the project becomes system energy or syngas used for power gen — but the slow pyrolysis used by this technology has been supporting 23-28 percent biochar yields.

It’s the second grant for Interra from CEC. Another one came in during the 2013 round, for development of the initial pilot-scale reactor.

The goal for this modular system is a 4 ton per day commercial unit that would produce roughly 1 ton per day of biochar that could be commercially sold at around $800 per tom. That’s transformatively lower than the prices generally seen for biochar – even in the California market where water is scarce and crops such as grapes, strawberries and almonds have exotic revenues per acre.

“As long as biochar hits quality metrics, we are going to be able to manufacture at a price much lower  than competitors,” said Interra CFO Kenny Key, in an interview with The Digest. “At a commercial price of $600-800 per ton, there would be movement from the major agricultural players, Right now the larger ventures are selling at around $1200, and some over $1500 per ton, and it’s difficult for large-scale agriculture to get behind biochar at that price.”

The commercial-scale unit and business model

That 4-ton per day system —  which is the next step in Interra’s evolution as it transitions from a testing-size 2 ton per day system — would be enough for the company’s first commercial project to be cash positive, and that prospect has the company out in the market raising a financing round that could range from $2 to $4 million for equipment, site upgrading at the company’s proposed first commercial site in California’s Imperial Valley, and for working capital.

The range in this financing round stems from an opportunity to acquire an established chipping and grinding operation, which could be partly debt financed — and which would provide the front end for the project as well as the site for the first commercial project.

For the first three projects, the company is expecting that it will be in a build, own and operate business model — as the technology is proven to potential licensors — long-term, the expectation is to move towards the more capital light licensing model.

The technology story

It’s pressurized, slow pyrolysis. The reactor is pressurized and in the reactor test runs that were set up under the California Energy Commission grant, the reactor was run at 20, 35 and 45 psi.

The chipped material enters the reactor via what is commonly known as a knife gate among those who have worked in the pulp-and-paper industry — the biomass has been heat dried down from an initial 30 percent water content to something in the 10-15 percent range. Once running, the biomass provides all the system energy — and residence time is in the 45-60 minute range. So think in terms of a larger reactor than we would see in fast pyrolysis — as more than 250 pounds of material are going into the reactor, per batch.

We don’t see slow pyrolysis systems very often — they produce minimum bio-oil content and interest from the energy community has focused on the higher value and utility in the liquids. And we generally don’t see much of the screw-conveyor auger systems. So, Interra’s approach is a novelty — although there’s nothing particularly daunting about an auger screw conveyor to move material into a reactor, or the scientific world of slow pyrolysis, which in some ways isn’t completely different to braising a meal in a pressure cooker.

Recycling energy is a key feature however — capturing waste heat to drive the drying of biomass prior to entering the reactor — for example.

The final pressure that the system will run at — that awaits the data from all the configurations that were run under the CEC grant. Ultimately, the reactor design could support as much as 100 psi, but the current design iteration has seen just enough seal damage from running biomass through the knife gate that operation at above 75 psi is likely not feasible without a design revision.

Here come the claims

Here’s the basic Interra claim: “comparing to traditional gasification systems of similar scale (four tons/hour), Interra’s system is approximately 1/3 the capital to build and has the potential to produce 3 to 24x the operational profit.”

Well, it’s an early-stage company and has a ways to go to prove that out, but it gets your attention.

The rationale? Twofold.

  1. First. “Due to the technology’s patented (U.S. and International) design, Interra can increase the tons-per-day throughput, gas quality output, and biochar yield while decreasing the capital cost compared to existing technologies.”
  2. Second. “The technology produces two saleable products that do not require expensive upgrading equipment prior to their end use. Revenues from the dual co-products of biochar and bioenergy/biofuel are diversified and can cross-subsidize each other.”

The feedstocks

The CEC grant was specific to forest and urban woody waste — so, the 27 different configurations tested to date have featured that feedstock set. Ultimately, the system is designed to be more feedstock-agnostic than that and would support the use, for example, of manure resources at a large ag licensor — a little more drying there and costly in terms of the energy inputs, but feasible.

The bio-char

The mystery to some extent is in the biochar’s performance. Given that the focal point in this CEC grant-supported set of configurations has been validating the design and measuring yield, we are about two months from wrap-up in this round from having biochar over at an external lab to analyze and compare in terms of product quality. Following that analysis, next steps would be to take the top candidates into field testing to understand how it performs as a soil enhancer. So,. we’ll be standing by on that.

The Interra backstory

The company is the brainchild of founder Thomas Del Monte, who was the co-founder of the Journal of Climate & Energy Law while at University of Sam Diego, and was president of the Environmental Law Society there, stemming from a “strong interest in green construction practices and similar industries.”

He researched California energy law and policy as applied to manure management practices using anaerobic digesters to capture methane to create electricity. During his research, he stumbled upon an internet article about pyrolysis and biochar — as a carbon negative method of producing energy.

In May 2012, Interra launched its first line of biochar enriched soil products. The Interra Preta line currently features both a biochar enriched soil amendment and a biochar enriched potting soil.

But expansion of the company beyond terra preta enthusiasts is predicated on deployment of this commercial-scale system.

To that end, the “large, California-based agricultural partner” working with Interra is not disclosed at this time, but for sure Interra has been working with San Diego State, which has an Imperial  Valley campus at Brawley, which lies southeast of Palm Springs and the Salton Sea and is roughly 24 miles north of Calexico, which is the “north of the border” counterpart to Mexicali.

The Bottom Line

One more round of funding is probably enough at this stage to see if Interra can translate promise into “promise realized” — but progress has been made, that’s for sure. The financial upside and low “cash-to-breakeven” makes this a tempting target for those who find the allures of $800 biochar more compelling than $450 per ton biocrudes. We’ll be watching the results out of the lab to see if this venture can make a biochar that can unlock, through a combination of price and performance, the interest of larger-scale agricultural ventures in California.

Lower inputs mean more sustainable feedstock and more of it. And that’s good for all who find themselves downstream.


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