Industry Market Trends

Cellulosic Ethanol Could Be a Game Changer

Feb 21, 2013

Improvements in cellulosic ethanol production would allow companies to utilize switchgrass and other plants that have little use or economic value. Credit: Margaret Broeren. Improvements in cellulosic ethanol production would allow biofuel makers to utilize switchgrass and other plants that have little or no economic value. Credit: Margaret Broeren.

A recent study at Michigan State University found that biofuels grown on "marginal lands" from perennial crops like wild grasses and flowers can provide roughly the same amount of biofuel per year as food crops, while eliminating twice as much CO2 at the same time.

This is consistent with the findings of the Land Institute, where research is being conducted on the development of food crops from "herbaceous, perennial, vegetative polycultures," following the remarkably resilient example of wild prairie. If this could be done practically at commercial scale, it would be far more efficient and sustainable than today's chemically dependent monocultures.

The Michigan study authors claim that this type of approach could represent our best chance to develop sustainable biofuels. "When biofuel is produced from such vegetation, the overall climatic impact is very positive," said study author Ilya Gelfand. The study can be seen as part of a growing concern over conflicts between biofuel and food crops.

The concern may not be entirely misplaced but might be a bit overblown, according to Bob Dineen, president of the Renewable Fuels Association (RFA). Dineen points out the improvements both in terms of crop yields, which have grown from 80 to 160 bushels per acre, and per-bushel extraction rates, which have increased from 2.2 to 2.8 gallons per bushel. At the same time nitrogen use has decreased 20 percent and direct energy fallen by 50 percent.  This year's domestic harvest, despite the drought, was only down 11 percent, still the eighth largest in history. Additional plantings in places like Canada, Mexico, and Argentina, driven by the higher corn prices, contributed to a global harvest that was only 2 percent below last year's.

The Michigan study acknowledges that corn had the highest biomass yield of all the plants studied, but much of that carbon benefit was squandered by plowing, tilling, replanting and other activities associated with annual crops.

A focal point of concern for many is the Renewable Fuel Standard (RFS), a federal mandate that requires that bio-fuels contribute an increasing share to our national fuel supply, eventually rising to 36 billion gallons by 2022. Given their current impact on food prices, how much worse will this make things?

What many people don't realize is that the RFS caps the amount of ethanol that can be derived from corn at 15 billion gallons. Considering that 14 billion gallons were already supplied last year, we won't need to bear much more of an increase.

But that leaves a 21 billion gallon gap of that needs to be filled, clearly opening the door for the kind of alternative biofuels described in the Michigan State study. But these kinds of plant materials, stalks and stems, grasses and leaves, which are called lignocellulose have been far more difficult to convert to sugars than the starches that have formed the bulk of first-generation biofuels.

This is where the biotech innovation of enzymatic conversion of lignocellulose into sugar really steps into the spotlight. This is the key for Fiberight's waste to fuel success story and it also opens the door to a vast potential of cellulosic ethanol, the surface of which has barely been scratched.

"If you look at the biomass resources in the U.S., there's over 60 billion gallons that can be made just from the sustainable biomass resources," said Adam Monroe, president of Novozymes North America, one of several suppliers of such enzymes along with ZeaChem, Genencor, Abengoa Bioenergy, and Qteros. "Just taking in 17 percent from crop residue alone, which is well under the amount that's considered sustainable, that's 16 billion gallons right there. So the 21 billion number is, in many ways, a conservative number."

New enzymes can help produce cellulosic ethanol at commercial rates. Credit: Novozymes. New enzymes can help produce cellulosic ethanol at commercial rates. Credit: Novozymes.

That's not counting forestry wastes and other sources. The 17 percent Monroe described as sustainable refers to the portion that scientists have determined can be safely removed from fields, generally the top portion of the plants, without adversely impacting soil conditions. A certain portion needs to be left on the ground to nurture and protect the soil.

Lignocellulose happens to be the most abundant organic material on Earth. But its transformation into a cellulosic ethanol industry has fallen behind the schedule that was originally promised. Can this technology deliver the goods?

Monroe said, "There are a number of things that people don't see, like this fantastic wave of innovation that has made possible other feedstock options, new pathways to get to cellulosic. That's a lot for the EPA to consider. This wave of innovation has overwhelmed the agencies. So, from my perspective, for a brand new industry, just launched in 2007 and we're on the cusp of commercialization -- that's pretty impressive if you ask me. And the RFS is absolutely the linchpin policy."

Still, the RFS has its detractors. One of them, Mark Rohr, chief executive officer and chairman of Celanese, suggests that an inflexible, obsolete RFS is harming the world economy. He said, "World Bank researchers -- among many others -- have blamed the depletion of corn from our food supply for soaring global food and feed costs." Instead of simply doing away with the ethanol requirement, "policymakers should revise the RFS to promote new alternatives for ethanol production, using technologies that were unavailable in 2007."

Why would Celanese be interested in the RFS? Well, it turns out that Celanese has developed a new technology that the company is touting as a lower cost alternative to biofuel. Its new TCX Technology synthesizes ethanol directly from hydrocarbon sources such as coal or natural gas. It is barred from using this product to satisfy the RFS mandate since it is not of animal or plant origin.

It would be hard to make the case that any fuel made from coal or natural gas is renewable or in any way consistent with what the RFS is trying to achieve, save one: which is to increase domestic production of liquid transportation fuels.

In my estimation, the true potential of biofuels lies in the synergies that no one is even talking about yet. Consider a corn operation, where the Dent corn is used to feed a first-generation biofuel process, while appropriate amounts of crop waste are fed simultaneously into a parallel, second-generation line producing cellulosic ethanol. Suddenly we are getting more fuel from the same amount of land, water, fertilizer, etc. This effectively increases the energy yield per acre which can significantly reduce the pressure on the food system.

Similar synergies exist between algae-based fuels, which were newly reclassified as second-generation biofuels and first-generation corn ethanol. First of all, according to Scott Poor, corporate counsel for Omaha, Neb.-based Green Plains Renewable Energy, "The algae can utilize the carbon dioxide, water and heat from the ethanol plant, so some of the key inputs for algae production are already available." Then, the algae's residual carbohydrate content can then be fermented into ethanol.

Biofuels may well be on the brink of a major transformation. But being new businesses, there are both risks and the need for investment.

As Novozymes' Monroe said, "The innovation that the RFS stirred has really given everybody a new set of binoculars as to the possibilities that are out there."