Back to the Future of Materials: Spero Renewables and the First Reverse Gear for Thermosets

I. PROLOGUE: Brooklyn, 1901 — The Day the Reverse Gear Refused to Reverse

If you had wandered down Milton Street in Brooklyn on April 9th, 1901, the air would have smelled of spring, hot metal, and the optimism of a century just waking up. At No. 59, in a cramped garage not far from the Eberhard Faber Pencil Company and a stone’s throw from the James C. Sparrow Renaissance Revival townhouses, Frederic Ball—tinkerer, seafarer, and quiet genius—was preparing to file a patent for something small in appearance and enormous in consequence: the spur planetary reverse gear.

Outside, boys in flat caps were arguing about Ban Johnson’s radical new American League, and whether the Baltimore Orioles’ John McGraw would bolt for the upstart circuit. Inside, Ball wiped his hands, leaned over his mechanism, and wondered if the world was ready for a car that could, for the first time, truly go backward. And at that exact, historically quiet moment, a shimmering distortion in spacetime deposited a man who absolutely did not belong there.

Sun-yellow jacket. Mirrored shades. Hair greased like a moral warning. Biff Tannen.

He swaggered into Ball’s workshop as if he were returning a rental carriage. “Hey buddy,” Biff announced, thumbing his lapels. “You’re working on my invention.”

Ball blinked. “Your… what?” Biff slapped a shiny chrome badge onto the half-assembled transmission: BIFF TANNEN TOURING CAR

The Car That Goes Backward to Go Forward

Ball looked at it the way one might regard a hallucination wearing spats.

“Relax, Fred,” Biff insisted. “I’m from the future. Reverse gear? Total gold mine. I patent it today, we own the market tomorrow. Ford cries. Oldsmobile begs. We’re rich enough to pave the whole neighborhood.” Ball reached for his carefully drafted patent filing. Biff reached faster. A lunge. A wrench knocked loose. A gear assembly teetered, pinged, and locked. Smoke hissed. The prototype seized. The first American reverse gear refused to reverse. The universe snapped the timeline back into place, as if to say: Not today, Biff.

History remained intact. Ball built his six one-off Tonneau Touring Cars in peace. Biff cursed, stomped, and shouted the eternal lament of all who encounter irreversibility: “Why can’t anything just GO BACK?!” And in that moment—Doc Brown would later call it destiny—the story of reversibility began.

Ball solved it for automobiles. It would take 124 years for someone to solve it for materials.

II. THE PROBLEM: The Dark Art of Irreversible Plastics

The world Ball helped create—one of motion, gears, and the ability to reverse course—never extended its grace to one critical class of materials. Thermosets. The epoxies in your laptop. The silicones in cosmetics. The polyesters in fashion. The vulcanized rubbers in your tires. The adhesives, sealants, composites, and structural resins that bind modern life together. They are the invisible skeleton of civilization. They “surround us and penetrate us,” as Obi-Wan might say, “binding the galaxy together.”

But once they cure, they stay cured. No reverse. No rewind. No undo.

The very strength that makes them indispensable—rigid crosslinked networks—makes them impossible to recycle without grinding, burning, or landfilling. This is why wind turbine blades pile up, why carbon fiber composites go unrecycled, why aerospace scrap becomes waste instead of feedstock. Thermosets have been stuck in Biff’s nightmare for a century:

You can go forward, but you can never go back.

III. THE REVEAL: Spero Renewables Installs the First Reverse Gear for Thermosets

Enter Spero Renewables and its improbable, elegant solution—a molecular reverse gear so simple and so powerful that it echoes Ball’s innovation in 1901. The heart of the system is SPERLU, a process that turns lignin—the overlooked, aromatic, industrial wallflower of biomass—into renewable biophenols.

Lignin is everywhere: a waste product of pulp mills or a byproduct of cellulosic ethanol: expensive to burn, hard to dispose of, the most abundant aromatic polymer on Earth. It has always been treated like industrial ballast. But Spero treats it like a treasure map.

SPERLU extracts high-value phenolic building blocks that behave like petrochemical phenols—but with sustainability baked in. From those biophenols comes SperoSET™, a patent-pending, fully recyclable thermoset system that introduces something polymer scientists have chased for decades: chemically reversible crosslinks. Heat them or solvate them—and the network unlinks. Cool them or reform them—and the network relinks, good as new.

This enables:

1. Reversibility. A thermoset that can be unmade.

2. Repairability. Cracks can be healed. Surfaces welded.

3. Full recyclability. Materials retain strength, thermal properties, and mechanical performance.

4. Circularity at industrial scale. Especially for high-value composites like CFRP.

No exotic catalysts. No rare metals. No petrochemical penalty.

Critically, this reversible-bond architecture sidesteps the complications that plagued earlier attempts at recyclable thermosets—systems that often required metal catalysts, auxiliary monomers, or multi-step curing chemistry. SperoSET™ achieves the same recyclability with far greater elegance: a simpler, cleaner, catalyst-free pathway that keeps performance high while keeping complexity low.

And a dramatically lower carbon footprint than conventional BPA-based epoxies. It’s Ball’s reverse gear—but molecular. It’s the reverse button on Netflix—except with polymers. It’s the DeLorean at 88 mph—except the energy is renewable. And it’s finally real.

IV. VALIDATION: Shell GameChanger Hits the Accelerator

In November 2025, the Shell GameChanger program selected Spero for its global accelerator—a rare signal that advanced materials work has crossed the threshold from academic cleverness to industrial promise.

The Shell collaboration builds on a concrete scaling milestone already secured. Earlier in 2025, the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) awarded Spero Renewables $1.6 million specifically to scale up and commercialize the SPERLU™ production process. That funding accelerated pilot development, validated the core chemistry, and established a clear technical runway—giving Shell a strong signal that SPERLU™ was not just clever science, but scalable science. Shell sees what others were beginning to suspect:

SPERLU might be scalable. SperoSET, manufacturable. Reversible thermosets solve a zillion-dollar design flaw in modern materials. And lignin valorization is the next frontier of circular chemistry. For a solution that transforms a waste problem into a premium industrial feedstock, it’s the perfect accelerant.

As CEO Mahdi Abu-Omar has said, this partnership will help Spero understand where a reversible-force thermoset system can do the most good—across wind blades, automotive composites, sporting goods, structural aerospace, and electronics. Wherever things break, crack, delaminate, or eventually die… they don’t have to anymore.

V. APPLICATIONS: The Future of “Rewindable” Materials

SperoSET™ is particularly suited to fiber-reinforced polymers, where irreversibility has always been the curse: Carbon fiber composites in EVs and aircraft. Wind turbine blades that currently pile up in landfills. High-performance sporting goods. Electronics housings and insulation. Structural adhesives and sealants. Reversible thermosets could turn every high-performance part into a circular component:

• repair on site
• recycle at end-of-life
• recover fibers
• recapture resin
• relock strength with minimal energy

That’s not recycling. It’s reincarnation.

VI. EPILOGUE: From Brooklyn to the Bioeconomy

On that spring afternoon in 1901, Biff Tannen in his mythic-epic time traveling apparently learned a lesson the hard way: you can’t bully an irreversible system into reversibility. Ball figured it out. The automobile learned to go backward. And because it learned to go backward, it could go forward. Today, Spero Renewables is doing the same for materials. A century after Ball gave automobiles their reverse gear, Spero is giving thermosets theirs. Not metaphorically—chemically. And for a world trying to decarbonize, lighten, recycle, repair, and reuse, the ability to “go back” may be the superpower that finally moves us forward.