Researchers seek to fuel jets with animal fats, algae oil
Chicken grease, hog lard and algae oil. These fats might not sound like something that could propel an airplane thirty thousand feet into the air. But NC State Professor of Engineering Bill Roberts says that someday, they will. "What we're trying to do is make a fuel that looks just like the petroleum derived fuel we're trying to replace." Roberts isn't cooking up ethanol or even biodiesel - which would freeze long before it hit cruising altitude. Instead, Roberts and his colleagues are working on a multi-step catalytic process that mimics petroleum on the molecular level. It's called Centia and it's not as complicated as it sounds. It all starts with fat - something most Americans would be happy to have a little less of. It turns out that crude oil and fat are surprisingly similar. They're both made up of hydrocarbon chains that can be broken down and rearranged to form new molecules. Just like in petroleum refineries, heat, pressure, and chemicals can break down the hydrocarbon molecules in fats too - transforming them into right kind of molecules to power jet engines. Professor Roberts explains the three-step process. "These oils or fats or lipids have this structure where you have a central molecule and then hanging off it are these long chains and so we want to break these long chains off. At one end it's got a couple oxygens and so we take those off in a catalytic process. So then those long chains are hydrocarbons which are perfect molecules for reforming to make what every we want." There's a shiny stainless steel cylinder in Roberts' lab. It's called a stirred autoclave. This reactor can get up 930 degrees and weighs nearly 700 pounds. Deep inside, the fats are broken down and transformed into fuel. "In this reactor we''l be able to do all three steps. So we put it our reactants, we bring it up to temperature, we stir it, let it react, let it cool down, then drain the products and see what we get," Roberts says. The Centia process can be used to produce jet fuel, bio-gasoline, or heating fuel depending on which chemicals are added. And because the fats are rearranged on the molecular level, this biofuel doesn't require new pipelines, storage facilities, or even new engines. "The jet engine manufacturers have billions tied up in jet engines and they're saying, 'You're going to change your fuel to run in our engines. We're not going to change our engines to work with your fuel.'" Billy Glover, managing director of environmental strategy for Boeing, agrees. "The only way this is going to work is if the fuel is what we call "drop-in." That is, it meets all of the requirements to fit into the current infrastructure and be able to be used with the current airplanes and engines without modifications." Last week, Continental Airlines used a Boeing 737 airplane to test a bio jet fuel made from a mix of algea and jatropha oils. "We expect that there will be a variety of feedstocks and processes that can create sustainable biofuel for jet aircraft in the future and so we're looking to all corners of the earth to find those things," Glover says. The leafy jatropha plant grows all over the world, from India to Africa, but Roberts is looking a little closer to home for Centia's fuel source. "We're focusing on North Carolina specific feed stocks like hog lard, chicken grease, and waste vegetable oil," he says. A big white barrel of Tyson chicken grease sits in the corner of the lab, waiting to be tested. Chicken processing plants normally throw this kind of fat away or sell it to companies that produce cattle feed. Roberts says these low quality fats are ideal for his method of biofuel production. "With animal fats you're not competing directly with the food supply and they don't make good biodiesel because of the high free fatty acid content," Robert says. North Carolina's hog farms and chicken processing plants produce plenty of excess fat, but before airlines can put it to use, Roberts and his team need to find a way to scale up production. "We've demonstrated it at the teaspoon scale and once we demonstrate it at the factor of a hundred times then we want to go to another factor of a hundred. Then you start making usable quantities." All of this research requires money, but Roberts believes that once additional funding is found, Centia biofuel could be ready to power jet airplanes in as little as 24 months. Diversified Energy Corporation, an Arizona-based company that specializes in renewable energy projects, has licensed The Centia process from North Carolina State University.