Last summer, crude oil prices spiked between $60 and $70 per barrel. That translated into very high gasoline prices.

Since then, “oil prices haven't dropped much and the bigger issue is much of our petroleum is coming from the Middle East, a politically unstable area,” said Ed Clausen, a chemical engineer with the University of Arkansas.

Those two things — higher gas prices and the politics of oil — have piqued U.S. interest in bioenergy.

Clausen, who spoke at the Arkansas Rice Conference in Wynne, Ark., focused on how rice might fit into the bioenergy field. First, he began with a few facts:

  • In 2004, the United States imported 58 percent of its crude oil. That has now grown to more than 60 percent.
  • It is estimated it would take a combined 180 billion gallons of gasoline and diesel to make the United States energy independent.
  • Arkansas alone consumes 2 billion gallons of liquid fuel annually.

Why should Arkansans be concerned with biofuels?

“Well, the state is biomass rich, and we've got the potential to grow much more biomass than we currently do,” said Clausen, who has studied renewable energy since the 1970s. “We have substantial agriculture and forestlands and good soils. We have water and agronomic resources and a well-developed agriculture and forestry sector.

“What we're talking about in the future is to produce liquid fuels as well as value-added products, which can, in some cases, bring down feedstock costs in making liquid fuel.”

Near- and longer-term

Clausen likes to classify renewable liquid fuels in two categories: near-term and longer-term. The near-term list includes ethanol from corn. The longer-term fuel list includes ethanol from lignocellulosics (like switchgrass) and other fuels.

Another common near-term fuel is biodiesel.

“Biodiesels — also called methyl esters — are clean-burning and are produced from vegetable oils and/or animal fats by a process called transesterification. Biodiesel can be blended with petroleum diesel to make B5 (5 percent biodiesel in a petroleum blend) or B20 (20 percent biodiesel in a petroleum mix). This fuel can be used in diesel engines with little, or no, modifications.”

Currently, FutureFuel Chemical (formerly Eastman Chemical in Batesville, Ark.) and Stuttgart, Ark.-based Patriot BioFuels are producing about 30 million gallons of biodiesel annually from oils and fats. The construction of several other plants has been announced — among them, Delta American Fuels in Helena, Ark., and Pinnacle BioFuels in Crossett, Ark.

“And there are more fuel plants coming. … Put all these plants together and Arkansas could be producing as much as 200 million gallons (in 2007). That's a huge amount of biodiesel — more than we need in the state.”

One big issue is where the operations will get the feedstocks to make that much fuel. Might rice fit the feedstock criteria?

“Arkansas produced 544,000 tons of rice bran in 2005. Rice bran contains about 20 percent oil and could serve as a feedstock for biodiesel. In fact, the 544,000 tons could produce about 30 million gallons. The problem is much of that rice bran is being extracted to produce high-quality cooking oil that the Japanese love. So the bran may not be available as a biodiesel feedstock.”

Corn ethanol

In 2005, the United States produced 4.3 billion gallons of ethanol from corn.

“I believe the number is close to 6 billion gallons currently. There's potential to produce about 13 billion gallons of ethanol without negatively affecting the food supply.

“Ethanol has been used in gasoline. Many heard of gasohol — a 10 percent blend — during the last energy crisis in the 1970s. Automotive manufacturers are now promoting E85 (85 percent ethanol fuel) vehicles.”

Ethanol is made from corn starch. The starch is converted to sugars through hydrolysis and the sugars are fermented. The ethanol produced is then recovered and blended with gasoline to produce fuel.

A few ethanol facts:

  • A bushel of corn (56 pounds) will make about 2.7 gallons of ethanol and 18 pounds of animal feed.
  • In 2005, about 14 percent of the corn crop (1.6 billion bushels) went to ethanol.
  • A typical modern ethanol plant produces 50 million gallons annually.

Arkansas produces about 600,000 tons of corn yearly. That's enough to produce about 58 million gallons of ethanol.

“Corn isn't expected to be much of a feedstock for ethanol production in Arkansas, with one exception: plants that could secure corn (being transported) down the river.”

How about rice?

“Arkansas produced a bit over 3 million tons of head rice and 650,000 tons of brokens in 2005. That rice could generate 430 million gallons of ethanol annually.”

The problem is the cost.

“With corn, the price is $3 per bushel and growing closer to $4. The equivalent for rice would only be 6 cents per pound. That's less than the current value of brokens.”

Filling the gap

In order to fill the “big energy gap,” Clausen said, the country could turn to lignocellulosic feedstocks.

“Those include agricultural wastes like cornstalks, wheat straw and rice straw. There are also forestry wastes — what's left in the forest after removing logs going to the paper industry. We can also use garbage. Also there are energy crops like switchgrass and hybrid poplar.”

Again, how about rice?

In 2005, Arkansas produced nearly 11 million tons of rice straw and 1.1 million tons of rice hulls. Of the two, rice straw is a particularly attractive feedstock for making liquid fuels. The hulls aren't so attractive due to very high silica content.

“But these are a significant lignocellulosic resource if we can solve harvesting difficulties of the straw. You could get roughly 70 to 80 gallons of ethanol per ton of the straw. Multiply 11 million tons by 80 and you could produce millions of gallons of ethanol.”

However, making ethanol from lignocellulosics isn't easy and hasn't yet been commercialized. There are pilot plants working, but it hasn't become a commercial venture.

“People often tell me they want to start planting switchgrass. I tell them, ‘Well, you can plant it, but you aren't going to be able to do anything with it yet.’

“We can convert the biomass to sugars through a process called hydrolysis. And hydrolysis is the hard part. Once you have the sugar, it's just like (making ethanol with corn).

“Also, instead of making sugars, we can gasify it. For example, Riceland Foods gasifies its rice hulls — the technology is available. Gasification produces carbon monoxide and hydrogen. When burning biomass, carbon dioxide and water are produced.”

Gasification makes syngas that can be fermented to produce ethanol.

Here's the key: the ethanol yield from biomass is between 40 gallons and 100 gallons per ton. Why the large range? Because there are many technologies — again, none yet commercialized — for doing it and they produce wide yields.

“The people developing the technology say it will cost 60 cents and $1.20 per gallon. I think those numbers are low, but that's what they're saying. (Keeping prices low) depends on feedstocks. If garbage is the feedstock, people will pay you to take the garbage. If an energy crop is used, the farmer must make money, and it appears (they'll need) at least $50 per ton.”

Now or never?

To serve the renewable fuels industry, Clausen believes Arkansas will first plant “lots of different oilseed crops. There is a huge demand for biodiesel and that means soybeans, canola, and cottonseed oils. We also have a lot of in-forest residue, crop wastes, and energy crops like switchgrass that aren't being planted yet but will be (once the cellulose technologies are worked out). … Arkansas is very likely to become a big player in growing cellulosic crops.”

If the crops are grown in the state, “we want to make the fuel conversion here. The crops can't be transported a long distance or the economics will eat you alive. If the crops are grown here, the liquid fuels have to be made here.”

When will the bioenergy sector actually get going?

“I've been working in this area since 1974. When asked that question, we've always said ‘10 years.’

“The reality is there are significant obstacles to get over. Now, we're getting better at that, but we're still not there. I look at some of these things like gasification and wonder why we aren't doing them right now. We can do that right now. We aren't because no one is investing in it. Why aren't we doing the enzymatic hydrolysis? Because it costs too much.”

But if the renewable energy framework is to be built and function well, there's no time like the present.

“If such businesses are going to make it, they'll make it now when we have real issues with the cost of gasoline and diesel fuel.”

For more on Eastman's biofuel operation, see