Making Algae Obese: Synthetic Genomics, ExxonMobil breakthrough brings algae fuels clearer, closer

June 20, 2017 |

In California at the annual BIO convention, ExxonMobil and Synthetic Genomics announced a breakthrough in joint research into advanced biofuels involving the improvement of the Nannochloropsis gaditana algae strain.

Currently at proof of concept scale, at the productivity rates seen under lab conditions, the strain could produce up to 1600 gallons per acre per year of lipids suitable for low-carbon fuels. The breakthrough was reported in the current issue of Nature Biotechnology by lead authors Imad Ajjawi and Eric Moellering of Synthetic Genomics. This is ten times greater than the oil-production rates of any known terrestrial plant that has seen widespread adoption, and double the productivity of the N. gaditana wild-type strain.

The reaction around the world has been a resounding Wow, Cool Tech. This article from Wired provides a smartly-written example of the type.

Here’s the rock-star of biofuels feedstocks, algae, and it’s getting fatter, and when movie stars become obese that’s tabloid fodder. So, understood — it’s cool science with the weird green slime factor rolled in.

But let’s move beyond the cool and towards the fuel. Do we have a path to algae biofuels here — or do we have another technology that’s going to get diverted eventually, via investor exhaustion, to something lovely but much higher up the price curve, such as nutraceuticals?

The algae problem

For decades, researchers have known that the best way to get algae to produce more lipids is to starve them of nitrogen. Goes the theory, proteins contain nitrogen and lipids do not — so when you limit the available nitrogen, algae make more fats, thereby storing up carbon energy “for another day”, So far, so good.

But here’s the problem. Algae use nitrogen to make enzymes, and they use proteins and enzymes to make fats, and they use nitrogen to make the chlorophyll that allows them to capture the sun’s energy in the first place.

So, nitrogen starvation results in more lipids but less algae growth — in research we’ve see the gain in lipid share but a loss of productivity. Improvements have been modest in overall oil yield.

But what if…?

Tunable algae? In this diagram, we see the difference between wild type algae and SGI’s new and improved strain with doubled oil content.

So, enter ExxonMobil and Synthetic Genomics. The two high-visibility organizations partnered in 2009 for algae R&D — amidst a tremendous series of algae-oriented television ads that seemed to dominate golf broadcasts for some time.  A key objective of the collaboration has been to increase the lipid content of algae while decreasing the starch and protein components — without inhibiting the algae’s growth.

The algal lipid trigger

In certain circles, the controlling hypothesis is that there may be an algal lipid trigger out there — so goes the theory, just at that point of nitrogen-starvation where lipid productivity takes off, you study the algae to see what they are up to, find the processes that up-regulate lipid production, and then enhance those. When the algae start the lipid dance, make them dance like crazy.

The interesting result

But, what if the mechanism that shunts carbon either to protein or lipid production turns out to be genetically subtle and tunable? What if we could find a way to divert the carbon down the lipid-producing pathway, without impacting the delivery of nitrogen for those other critical growth-supporting activities? Steering carbon rather than starving nitrogen?

Turns out, that’s a big part of the SGI / Exxon story.

The technique the researchers used was RNA interference, or RNAi.

In biologyese: In this technique, we target what are known as mRNA molecules, using RBA molecules, and we inhibit gene expression or translation.

In English: If you’ve ever been at a dance with a very good-looking prospective partner and suddenly found yourself completely lost for words — that’s not the same biological process but it’s the same result, the algae lose the ability to do something they really want to do.

What’s great about RNAi is that it works a little bit more like a tunable dial than the knock-in/knock-out techniques used in most applications of CRISPR-Cas9 gene editing.

What do you get?

In the results reported in Nature Biotechnology — you get double the lipid production without a loss of overall productivity, compared to the wild type. It’s not quite the level of lipid production that we’ve seen with Nanno under extreme nitrogen-starvation conditions (55% lipid content has been reported), but the key here is preserving the overall algae growth rate.

Wild type algae on the left, starved of nitrogen on the right, and SGI’s breakthrough in the center; the grey blob marked LD represents the lipids. Image: SGI

So, the researchers are reporting 5 grams of lipids per square meter per day, and that’s double the wild type, and now translate that into some street value.

The value target

In a techno-economic analysis you can read in glorious detail here, an NREL team found that an algae farm would need to support a minimum selling price of $491 per dry ton of biomass to provide a 10 percent ROI, based on algae productivity of 37 tons per acre. Putting that together, that’s an income goal of $18.167 per acre.

The addressable value

Can we get to algae biofuels, or even close? Right now, algae as a cellulosic fuels commands a values of up to $4.43 per gallon* in the California market, and keep in mind that carbohydrates and protein are also still produced by the organism and are available at harvest.

(*The value is $1.41 for a gallon of any diesel fuel, $2.51 for the cellulosic waiver credit and $0.51 for the California Low Carbon Fuel Standard based on a $52/ton carbon price and a CI index of 29).

At 5 grams per day of lipids (worth $1227 per ton, if you do the cellulosic fuel math), if you could keep the strain producing at this level (which in the field it usually does not) throughout the year (which you won’t be able to), the potential value creation of the improved strain could be as high as $13,323 per acre for the lipid fraction.

So, let’s think more in terms of real-world operation. If we assume that a system could get to 85 percent of this theoretical production rate, and stay open for 80 percent of the year, the value would be on the order of $9060 per acre, for the lipid fraction. (And yes, there’s further bioconversion to turn an algae lipid into a fuel — it’s not entirely “all about the feedstock”.)

And, the venture will need to generate $9,107 per acre off the carbohydrate and protein fractions. We have 7.5 grams per day of those, or 11 tons per acre per year. So, we’d need to see $818 per ton for that biomass.  It’s not out of this world to see these kind of numbers — fish meal sells above this price, and fish eat algae.

The Bottom Line

So, let’s be cautiously optimistic. R&D will continue, algae farm CAPEX prices will come down with innovation, yields may well improve from the levels we see here with SGI and Exxon’s work.

Bottom line, we don’t have a production organism here but we are beginning to see the kind of productivities with a defensible strain that support price-competitive algae biofuels at scale, even with the crushingly low oil prices we’re seeing. Rock your world tomorrow? No. In the ballpark of technology that is deployable? Sure.


Reaction from the stakeholders

“This key milestone in our advanced biofuels program confirms our belief that algae can be incredibly productive as a renewable energy source with a corresponding positive contribution to our environment,” said Vijay Swarup, vice president for research and development at ExxonMobil Research and Engineering Company. “Our work with Synthetic Genomics continues to be an important part of our broader research into lower-emission technologies to reduce the risk of climate change.”

“Advancements as potentially important as this require significant time and effort, as is the case with any research and development project,” Swarup said. “Each phase of our algae research, or any other similar project in the area of advanced biofuels, requires testing and analysis to confirm that we’re proceeding down a path toward scale and commercial viability.”

“The major inputs for phototropic algae production are sunlight and carbon dioxide, two resources that are abundant, sustainable and free,” said Oliver Fetzer, Ph.D., chief executive officer at Synthetic Genomics. “Discoveries made through our partnership with ExxonMobil demonstrate how advanced cell engineering capabilities at Synthetic Genomics can unlock biology to optimize how we use these resources and create solutions for many of today’s sustainability challenges – from renewable energy to nutrition and human health.”

“The SGI-ExxonMobil science teams have made significant advances over the last several years in efforts to optimize lipid production in algae. This important publication today is evidence of this work, and we remain convinced that synthetic biology holds crucial answers to unlocking the potential of algae as a renewable energy source,” said J. Craig Venter, Ph.D., SGI co-founder and chairman. “We look forward to continued work with ExxonMobil so that eventually we will indeed have a viable alternative energy source.”

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