A sustainable, affordable diesel oxygenate

November 3, 2014 |

xF pilot plant smA bolt-on technology for ethanol plants, costing less than $2 per installed gallon, producing a cellulosic biofuel additive that oxygenates diesel fuel at competitive prices?

It’s early stage, but what’s not to like?

The Digest looks at xF Technologies.

Before we look today at an exciting new market for biomass and ethanol, let’s go back to school for four paragraphs on “oxygenates”.

What are they: As the EIA explains: “Oxygenates are hydrocarbons that contain one or more oxygen atoms. The primary oxygenates are alcohols and ethers, including: fuel ethanol, methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE), and tertiary amyl methyl ether (TAME).”

Why are they: Again, from the EIA: “Oxygenates are added to motor vehicle fuels to make them burn more cleanly, thereby reducing toxic tailpipe pollution, particularly carbon monoxide. Oxygenates are favored not only for their vehicle emission benefits but also their blending properties in motor gasoline (e.g., octane).”

Why did they become controversial: as Berkeley’s Hannah Breetz outlined in her recent review of the history of the Renewable Fuel Standard:

“Environmental concerns about MTBE also gave a huge push to ethanol. MTBE had been widely used to boost gasoline octane and meet federal oxygenate requirements for reformulated gasoline. In the late 1990s, it was discovered that MTBE, leaking from underground storage tanks, had contaminated groundwater in California and elsewhere.

“California announced in 1999 that it would phase out MTBE by 2003, and ultimately sixteen other states follows suit. In 2000, the EPA recommended a national MTBE phase out (which became part of the bargaining in the original 2005 RFS). As MTBE was phased out, demand grew for ethanol as a substitute fuel additive.”

But that’s the gasoline side. Lately, gasoline demand worldwide has been decreasing and diesel demand is increasing. What about oxygenates and diesel?

Turns out, as a US Army review noted, “Several exhaust emissions studies have shown that using oxygen-containing fuels such as methanol and dimethyl ether as diesel fuels substantially reduce PM exhaust emissions. A number of other studies report that blending oxygenates into diesel fuel will also significantly reduce PM emissions in diesel exhaust.”

The list of candidates for a diesel oxygenate is long. Here’s a sample of molecules that have been tested in hopes of finding that magic oxygenating molecule:


Turning to xF

One of the most promising molecules under development at the moment is the family of alkyl furoates, a tongue-twister we’ll describe from this point on as “xF”.

Why promising? They can cost under $2.00 per gallon, are an economical route to using cellulosic biomass, and can reduce particulate matter emissions (PM) from diesel by as much as 50 percent with just a 5 percent blend. And can add much needed lubricity to diesel engines that have needed it since sulfur was taken out and ULSD was introduced — and ULSD was once described by a mechanic as “sand in your engine”.

It’s the cost that’s most intriguing. Biodiesel, of course, replaces lost lubricity and elegantly reduces particulate matter emissions. But it costs $975 per metric ton, wholesale — that’s more than $3 per gallon. Small price to pay for reduced engine wear-and-tear and a better environment, but some consumers and distributors balk at anything that hints at higher cost at the pump.

These days, the leading biobased xF developer is named, unsurprisingly, xF Technologies and is based in Albuquerque.

Looking at xF Technologies

“Our xF is derived from methanol or ethanol, and biomass,” CEO Len Rand tells the Digest. “We use acid hydrolysis then organic catalysis. It’s a reliable process that gets the unsubsidized cost below $2.”

Here’s a diagram of the process, as presented at NREL this fall:

xF production process

The secret advantage as a production process? As you might have surmised from the reliance on an alcohol fuel and cellulosic biomass as feedstock, it is a bolt-on-technology for ethanol plants. In this case, the technology works with biomass sugars derived from corn starch or corn stover. In the case of stover, the economics are even stronger, especially on the opex side.

How can that be? Aren’t all cellulosic technologies generally costing in the $6-$10 gallon range (capex) and equal-or-higher on opex? Well, that’s perception, not reality — but generally speaking cellulosic technologies have capex north of $5 per installed gallon, even if their opex is competitive with corn ethanol (and not all technologies are).

xF economics

So, when a sub-$2 capex and sub-$2 opex bolt-on cellulosic product appears — and it has set its sights on the (as yet unsaturated) diesel market — instead of the (E10-saturated) ethanol market: well, you can see why there are good reasons to take notice. Much of the logistics of feedstock is already getting worked out, the end market is sound, and the only questions are whether the economics and technology work out as advertised.

xF ethanol integration

Couple of Q’s here you might be asking, and the A’s

How far along? The technology has reached pilot stage in Albuquerque — and is now embarked on a $20M capital raise to go to demonstration-scale. Here’s a photo of the pilot-scale plant.

xF pilot plant

Can you get advanced biofuel RINs out of this? Yes.

Any protected IP in here? 1 issued and 4 pending patents, here.


Are automakers expressing love or disdain? “I was talking with vice chairman of one of the Auto OEMs,” said Rand. “This person was really excited about reduction of after treatment and emissions controls. There’s a lot of resonance with auto OEMs, they’re supportive, although we can’t say names at this stage. We can say that more than one is interested enough to be testing in their own labs with both diesel and gasoline.”

Does this process use both the C5 and C6 sugars? Ah, good question. It uses C6 only. The process produces humic acid described by Wikipedia as “a principal component of humic substances, which are the major organic constituents of soil (humus), peat, coal, many upland streams, dystrophic lakes, and ocean water.” It’s not much like biochar, but it can be used in field applications. According to Rand, “the University of Iowa ran a study that valued humic acid at $100 per ton when used on field in lieu of stover.” And, as the above-mentioned IP inventory suggests, there’s an oilfield application in drilling muds. It’s that co-product value that helps bring down the opex of the cellulosic product below corn starch.

Temperature and pressure? How intense a process is this, anyway? There are two stages — stage one is under 100C and 100 PSI, stage 2 is room temperature and pressure.

How soon could xF be approved the market? Not next week, for sure. For diesel and heating oil, think 2.5 to 3 years for EPA and ASTM approval. On the gasoline oxygenate side, think (US market) in terms of 5+ years, for EPA and ASTM approval.

The company’s pitch? “It’s an entirely new market – non threatening to the ag lobby and potential ethanol partners, focused first on diesel applications and opening up a new market for biomass and ethanol. And, an economic route to cellulosic fuels and a good pathway to the fuel market for sugarcane bagasse, switchgrass, and blends of corn and stover.”

The bottom line

We’ve seen corn ethanol plants get into the diesel market with corn oil extraction which is sold to biodiesel producers, generally. They like it. They may well like this just as much, if not better.

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