Breaking Extrusion Rules: How We Made The Impossible Helix
After leaving v2food, I became obsessed with a single question: could we grow algae as cheaply as crude oil? Traditional photobioreactors can cost $100,000 to produce just one tonne of algae annually. At that rate, you're dead before you start.
The breakthrough insight: if algae flowed down transparent channels just millimeters thick, they could grow at high densities without shadowing themselves. But how do you manufacture hundreds of these channels cost-effectively, stacked in layers? The answer was a helix - a continuous, spiraling channel manufactured as one piece using plastic extrusion. Except making a dimensionally perfect 1-meter diameter helical photobioreactor? That's apparently impossible.
The Expert Consensus: Impossible
The expert consensus was clear: there's a reason most plastic extrusions are made in straight lines. After talking to countless extrusion companies, most explained (or mansplained, with varying levels of politeness) why this simply couldn't be done.
But sometimes the most important breakthroughs happen when you ignore expert consensus. Powered by equal parts naivety and hubris, I found a company willing to take on the challenge: Fenske, in Nowra, south of Sydney. After all, I’d made pasta spirals on an extruder. Couldn’t be that hard!
The Spectacular Failure That Changed Everything
Of course it didn't work. The experts were right about conventional extrusion rules. Making a large helix is not the same as making a twistie. But I saw something while we were trying that gave me an idea.
We had to break some fundamental assumptions about extrusion die design. We reimagined how plastic could flow through complex geometries. This resulted in our second patent - not just the concept, but the engineering breakthrough that made it executable.
We built a new die from scratch and organised another trial. What spiralled out of the extruder was a definite helix. Jubilation! Even our extrusion partner couldn't believe it. OK, so it looked more like modern art than a photobioreactor, but all we had to do was engineer it a bit and it could work. And if we could get it right we knew that the cheapest way to make plastic shapes was to extrude them - we could solve the cost problem of photobioreactors.
“This is not a Fruit Bowl”
I was so excited I showed everyone, including my venture capital friends, thinking they would now jump at the chance to invest. But what I saw as proof of concept, they saw a rather wonky plastic fruit bowl (which, in truth, it resembled) and politely declined to invest.
It wasn’t obvious to them that this was a breakthrough, the ability to make a complex photobioreactor essentially out of one cheap piece of plastic and some leds. For me this was the key to growing low cost algae. I did some maths: reactor costs could drop from $100,000 per tonne of annual capacity to around $2,000. And this could get 1$/kg algae within reach. We could be as cheap as crude oil.
But I needed to find an engineer help me take our fruit bowl and turn it into a photobioreactor.
Finding the Right Co-conspirator
Fortunately, I'd met John Martin, a Stanford engineer passionate about solving the algae problem. On a 3-hour electric car journey to our extrusion partners, Fenske (including stopping to reload my rather small battery), I convinced him to join me. June 22, 2024. I think John uses this as his PIN number now.
Extrusion is part art, part science, especially for complex geometries. I'd learned this developing products for Mars and PepsiCo, where every tooling change cost tens of thousands with no success guarantee. But conventional expertise couldn't help us here. No one had made helical extrusions before.
We learned from first principles, imagining plastic flows creating complex helical geometry. As our toolmaker Erich said, "this is doing our head in," but we made rapid progress every trial we did.
From Theory to Working Technology
After four tooling iterations and lots of early morning drives down to Nowra, we had our breakthrough: a working helix that could channel water in precise thin layers while distributing light efficiently. We'd solved the fundamental manufacturing challenge.
With our helical channel proven, we built our first complete photobioreactor. LED ribbons, optical physics, repurposed reflective particles, 3D-printed components, and lots of Bunnings runs. John with some help from Claude, engineered the control system and glued it all together.
We switched it on. Water flowed perfectly in a thin layer around the helix. We introduced Chlorella, a common algal species, from UTS and started growing algae. The fruit bowl had become a working biomanufacturing platform. Milestone 1: November 2024.
Why This Breakthrough Changes Everything
What looked initially like modern art was foundation technology for replacing fossil feedstocks across industries. The helical photobioreactor was the manufacturing innovation that could make algae economics competitive with crude oil.
If you can manufacture photobioreactors cheaply enough and grow algae productively enough, you can replace petroleum-based plastics, fuels, and chemicals with products made from CO2 and renewable energy.
Breaking extrusion rules wasn't about solving a technical curiosity. It was proving that biomanufacturing could scale economically. Sometimes the most important breakthroughs look like fruit bowls before they look like world-changing technology.