8 Ways around the Big, Bad Oxygen Problem in the Advanced Bioeconomy

October 12, 2015 |

arc-reactorIn the terrestrial world, oxygen is colorless, odorless, and try to get through an hour without some.

In the Bioeconomy Cinematic Universe, oxygen is harder than steel, heavier than a black hole, and higher than the Himalayas. Here’s the why and what’s being done about it.

At some stage during any conference on energy transportation, someone will mention Project Apollo and the moon landings, calling for a “moon-shot” effort to change the way we source and use energy. Usually lamenting the death of the “can-do” spirit that NASA exemplified.

Which usually brings on a ragged cheer from the audience.

On the other hand, consider that we have a perfectly good moon-shot technology, the Saturn V, which has been sitting on the ground for 40 years doing nothing, even during years when the United States can’t lift a feather up to the International Space Station.

Reminding us that, once the technology demonstration is completed, the “can-do” spirit converts swiftly into a “can’t afford”, and it all comes down to the costs and benefits.

The United States wouldn’t be going to the moon based on Saturn V economics, roughly $20 million per pound of payload retrieved (in 1972 dollars), even if it turned out the Moon was composed of solid gold.

When Obadiah Stane discounts “arc reactor” technology in Iron Man, saying, “we built that to shut the hippies up…it was never cost-effective,” we step out of the movies and into a million boardrooms, where there always seems to be an Obie making that remark. Every advanced technology has its Big Bad Barrier, even in the Marvel Cinematic Universe.

In the advanced bioeconomy, the Big, Bad Barrier is the Oxygen Problem. That is, 56% of a sugar molecule, by weight, consists of oxygen — and in the world of making hydrocarbons from sugar, the oxygen in the molecule poses as daunting a challenge as the absence of oxygen posed for the moon-shot science team. It turns out there really can be “too much of a good thing”.

Stripping Away the Os

Either you can’t afford to move it (raw biomass, which also contains oxygen in the form of water, to compound the felony), or you can’t afford the molecule after you’ve stripped away the Os.

If it costs $312 for a metric ton of sugar (the value that edible sugar is traded at this morning on NYMEX), then you need to spend $834 to get a ton of hydrocarbons if you have a process that gets 85% of the theoretical yield.

That equates to a feedstock cost of $2.38 per gallon (if you are making renewable gasoline) when the fossil-fuel variety is wholesaling at $1.42 — well, “Houston, we have a problem”.

So, what do you do? There are 8 routes which biofuels producers pursue, typically in combination. Let’s look at those individually.

I. What this country needs is a good five-cent sugar.

When table sugar is unaffordable, we start to hear about wood sugars or plant sugars, a/k/a/ “the cellulosic solution”.  In the municipal solid waste department, the organic fraction of around 30 percent can be acquired, in today’s market, for free or even with a tipping fee (a negative cost), because of the avoided social and economic costs of opening up new landfills.

Woods are supposed to be available starting as low as $20/ton — but in the DOE’s Billion Ton Study and related work, the costs keep creeping up, and are now estimated at an average of $115 per ton or so, delivered to the factory gate. That’s 5 cents per pound — but then we have the problem that woods and plants have lignin, which is a tough-to-work-with component, and most technologies just burn it to provide process heat.

With lignin at around 30% by weight, you end up with a potential cost of $164/ton for the cellulosic feedstock. That’s around $1.25 per gallon, much better than table sugar, but no matter how cheap the opex and capex, it’s not a fuel-grade solution in today’s market.

So, you look for sweetheart deals and tie-ups with feedstock providers — typically, like Renmatix has with UPM, where they invest in the technology, and provide access to, say, wood sugars at vastly cheaper prices. If there ever really is a $20/ton wood out there, delivered to a factory gate — well, then you have a $0.22 per gallon starting point. And you might really be in business.

Bottom line, anything much above $50/ton as a feedstock cost just isn’t cutting it in today’s fuel market.

II. We don’t need no stinkin’ sugar.

For those who can’t swing a sweetheart deal in feedstock acquisition, there’s bypassing sugar altogether and making fuels from feedstocks like CO2, water, carbon monoxide and the like.

The bottom line is that the yields are lower but the feedstock can be ultra-cheap. The low yields? When you make a hydrocarbon from CO2 and water, you get only a theoretical yield of 22% — so you have an even bigger oxygen problem. But, if you are paying nothing for the CO2 and $4/ton for water, you’re starting with a $1.16 per ton feedstock cost, or 0.3 cents per gallon. So, you have no issues there at all. It becomes completely a function of process yield, capex and opex — and whether you have a microorganism that can make a hydrocarbon at all.

With economics like this, it’s not completely surprising that Joule Unlimited is still on the fuels warpath and talking up fuels “competitive with $50 oil”.

III. Juicin’ the process yields and slashin’ that ol’ production cost

Another way around the problem is high process yields.

The most striking recent example is Amyris, which announced this week that they achieved a record low manufacturing cost of $1.75 per liter for farnesene in September 2015.

Most cellulosic technologies check in at around 80 gallons of ethanol per ton of biomass. And, there are technologies like ZeaChem’s which — because they have a hybrid approach with gasification and straight liquid fermentation — are targeting yields as high as 135 gallons per ton. Combine that with a sweetheart feedstock partner deal and some high-performing poplar, and ZeaChem checks in at something north of 2000 gallons of ethanol per acre of land.

Compare that to a typical biomass-to-ethanol venture that is getting something like 160 gallons per acre (two tons of corn stover per acre, and 80 gallons per ton of stover). So, that’s why ZeaChem is exciting. So why isn’t the world building ZeaChem plants everywhere? That’s where capex becomes a factor — the two-step ZeaChem process is costly and we have heard projections as high as $400 million for a first commercial plant.

IV. O2 give me a home where the customers roam

The most typical solution to the oxygen problem is to find a fuel or chemical that contains oxygen — and that’s where alcohol fuels like ethanol come in, and the organic acids like malic acid, glucaric acid, levulinic acid and the like. Basically, anything with an -nol or an -ic at the end.

There is some “fortunately” and “unfortunately” in this pathway.

Fortunately, two of the oxygen atoms end up in the fuel, so the waste factor drops and the process efficiency rises to 51%. Same cost, just more biomass in the fuel.

Unfortunately, there’s a sharp loss in energy density, an ethanol molecule has 66% of the energy contained in a gasoline-range molecule.

Fortunately, it’s a proven process, capex is low, plus feedstocks like corn come at a very low-cost and contain merchant by-products such as carbon dioxide, distillers grains and corn oil.

Unfortunately, US vehicles made before 2001 tolerate around 10% ethanol, and made since 2001 there’s a cap at 15%. So, there’s a point at which the US fleet reaches E10 saturation. Whether that forms a “blend wall” depends on which side of the fight you are on.

fortunately, fuel producers and the EPA say cars made after 2001 tolerate 15% ethanol blends, and fuel producers are fighting for higher basic blend volumes. They point to the fact that, in Brazil, the basic blend rate is around 25%.

Unfortunately, manufacturers say that only vehicles after 2012 are generally E15-tolerant; oil companies are fighting ethanol every step of the way, and the EPA has been timid about pushing beyond E10.

Fortunately, there are the higher alcohol fuels. A molecule such as butanol has near-to-gasoline energy density, but accesses the same feedstocks and basic equipment as corn ethanol fermentation. It can blend at 16 percent  in every US car, and up to 24 percent in newer models. It’s a different production organism and there are some unique processing challenges in keeping the yield sup in continuous fermentation, controlling side reactions and separating the butanol out of the broth — but that’s why companies like Butamax and Gevo.

Unfortunately, high alcohol fuels are made, to date, in limited quantities.

Fortunately, methanol fuel is another option, as a blendstock, and companies like Enerkem can make that, and Israel and China are very focused on that fuel. More about that here.

In tomorrow’s Digest, we’ll look at doors 5 through 8.


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