Does continuous harvest, and direct production from CO2 and water, offer a transformative, no-kill way to improve the carbon and dollar economics of biofuels? Can the dairy model work?

Two years ago, in an essay titled “Drop In, Tune Out, Turn On,” the Digest profiled the rise of a new generation of “drop-in” fuels, made from non-food biomass, that promised to move the debate over developing biofuels at scale beyond the 2008-09 debates over food-vs-fuel and the infrastructure challenges (e.g. tanks, engines, pumps, pipelines) associated with biodiesel and ethanol.

That was the “drop in, tune out” part of the story. In the latter part of the essay, we introduced an even newer set of technologies – not always well understood, that held the promise of continuous harvest.

Continuous harvest

Here at the Digest we use a lot of farming analogies. In this example, contrast the nature of beef operations with the dairy farm, or grain production with fruit and nut growing. In beef and grain, the whole organism is harvested. In dairy and fruit, an output from the organism is harvested and the organism carries on. The organism carrying on – that’s continuous harvest.

Grasses have this quality. You plant the lawn, and then you mow it, and mow it, and mow it. Canes have the same quality too. True, with grasses, we lop off a lot of low-value material when harvesting the high-value material. A lot of tough-to-handle lignin, cellulose or bagasse comes off the field along with the high-value sugars. But, you get the idea.

Aside from the ethical willies that attend to, say, consuming organisms for food, fiber, or fuel (ethical protections which generally have a limit – not many vegetarians swear off, for example, cereals and breads) – there are good economic reasons why continuous harvest makes sense.

The productivity advantage is that the organic pool is never depleted, and the ecosystem has to expend less energy on making new organisms. Organisms that consume a lot of energy in the making of cell walls, defense systems, DNA skeletal material, and so on.

One advantage is lower nutrient loading of vital materials such as nitrogen, phosphorus and potassium. Also, you don’t see as many fallow seasons at the fruit orchard. Finally, there’s less moving around of low-value biomass – for example, when harvesting algae, you not only expend energy on getting the high-value lipids out of the water – you expend energy getting low-value cellular material out of the water, too.

Naturally Scientific

Back in 2009, we profiled Naturally Scientific as an example of what we believed was a wave of production based on continuous harvest.

Naturally Scientific uses waste CO2 to bio-manufacture fermentable sugars and pure vegetable oil (PVO) from plant cell cultures to provide truly sustainable feedstock for bio-diesel, ethanol and ‘drop-in’synthetic fuel producers.

In the first stage waste CO2, water (either fresh or salt) and light are combined in a photosynthetic reaction to produce sugars (Sucrose and Glucose). This natural sugar can be sold in either crystalline or syrup form, or alternatively used in the second stage of the Naturally Scientific process. This stage converts these sugars to produce pure vegetable oils (PVO) and their derivatives.

Naturally Scientific has constructed a demonstration plant in Nottingham, UK, that is fully operational, producing both sugars and oils. The company is also exploring the development of production at scale in China.

Algenol

Another case in point is Algenol, the Florida-based developer of algae that continuously secrete ethanol.

Now, most algal companies harvest the whole organism and fraction it into lipids, carbs and protein for further upgrading into fuels, chemicals and other products of interest. So, Algenol is an outlier, and not widely understood.

Basically, Paul Woods and his team in Naples, Florida have developed a set of algae strains that sweat profusely. Instead of sweating a saline solution like humans do, they sweat ethanol. Forming a condensate (with water) on the top wall of the algal photobioreactors, the condensate runs off and the ethanol is separated from the water. Voila, renewable fuels.

Solazyme, LS9 and other advanced sugar fermentation strategies

Another company that has continuous harvest is Solazyme. In this case, the company feeds sugar to its proprietary algal strains. As happens with human organisms when they eat too many Big Macs or sweets, the algae get fat. In this case, though – and wouldn’t this be a breakthrough for Jenny Craig – the lipids are secreted rather than conventionally harvested by capturing, concentrating and fractioning the algae.

That’s something that comes with fermentation technology – the organism operates on a given bit of biomass, converting it from a low-value material to a big-value one. Whether it is yeast fermenting corn starch into ethanol (or isobutanol), or an exotic form of e.coli converting sugars to fuels and chemicals, as is the case with LS9.

But there’s a catch. Even though the organism can survive (if you get the alcohol or the organism out of the broth fast enough – as anyone knows from first aid, put enough alcohol into the mix and you kill off the organism), the underlying biomass had to come from something. That’s usually something – whether it is corn starch, cane syrup or cellulose – that was harvested in the old manner (like beef cattle, not “milked” like dairy), and fractioned.

But that’s today. There’s no reason why, for example, Solazyme’s process can’t utilize Naturally Scientific’s no-kill low-cost sugars. Proterro is working on a synthetic approach to low-cost sugar as well. LS9’s magic bug is also being readied to work with these new sugars.

Joule Unlimited

Over at Joule, its a wildly different approach, but no less interesting, and there’s nothing wild about the premise. The company has engineered a system in which modified cyanobacteria, using CO2, water and sunlight, fix the underlying molecules into a hydrocarbon. Ethanol, renewable diesel, renewable jet fuel – all possible. Unlike many of the other advanced fermentation systems, there’s no need for an underlying biomass to work on. As long as there are sufficient feedstocks, Joule’s system — which is modular, flat and small (not unlike conventional solar panels) — could operate atop non-arable land just as well as atop arable land. The target fuels are continuously harvested, like a dairy operation.

OpenAlgae’s continuous harvest research

Recently at the Algal Biomass Summit in Minneapolis, a team of researchers from the University of Texas and the algal harvesting company OpenAlgae published a poster on “Non-Lethal Oil Recovery Suitable for Biocatalytic Algal Platforms”. The hypothesis: that a single pass of an emulsion of water, algae and oil, through an OpenAlgae oil recovery membrane, could harvest up to 95 percent of the available oils without inhibiting cell growth or viability. The experiments proved that the concept is feasible. Future studies may extend the use of the OpenAlgae techniques to other (non-algal) biocatalysts making drop-in molecules.

The Bottom Line

Even better for the environment than no-till farming, a generation of companies practicing no-kill farming is emerging.

The reduced cost of nutrients, the focus of the system on the production of energy as opposed to the production of systems that protect the cell itself, and the reduced cost of harvest – these are advantages that reduce both the operational cost and capital cost of advanced biofuels.

And, at the end of the day, there is the promise of making biofuels within systems that, in utilizing light, CO2 and water (and using low loadings of other nutrients, because the organism survives), do not require arable land in any aspect of their production.

Deserts for fuels, crops lands for foods. Using waste CO2 and saline water. That’s one model that would bring a smile to even the bitterest critic of biofuels over at Greenpeace. Not to mention the financiers of fuel production at scale, who see not only the happy world, but the happy margins within.