December 12, 2011

“Realizing that we’ve discovered something no one else knows about is neat,” said Page Case, a UMaine research student. UMaine courtesy photo

A University of Maine engineer, Clayton Wheeler, and his student research team have discovered a revolutionary new chemical process that can transform forest residues, along with other materials such as municipal solid waste, grasses, and construction wastes, into a hydrocarbon fuel oil. One day some cars could be running on it, houses heated by it, and businesses powered by it.

“The process is unique,” said Wheeler, associate professor of chemical and biological engineering. “No one else in the world is doing this. With this new biofuel we have the potential in Maine of replacing 25 percent of our kerosene, diesel, and heating oil, while providing all the steam and power needs of processing plants.”

Treetops and limbs deemed by the forest products industry as unusable and often left behind in the woods could now become the biofuel of the future. As Governor John Baldacci said in 2007, when promoting alternative ways like biofuels to combat Maine’s dependency on oil, “Maine is the Saudi Arabia of wood.”

Maine has around six million green tons of available biomass, according to a 2008 Maine Forest Service Assessment of Sustainable Biomass Availability.

The process, known as thermal deoxygenation (TDO), involves converting cellulose into organic acids, which are combined with calcium hydroxide to form a calcium salt. That salt is heated in a reactor, which creates a dark, amber-colored oil. TDO will work on the cellulose found in wood or other substances that contain cellulose or carbohydrates.

“We can take almost anything that’s cellulose and convert it to hydrocarbon oil. The process takes the air out of the oil,” said Page Case, an undergraduate working on the project.

That removal of nearly all of the oxygen from the oil is a key step that distinguishes TDO from other biofuel processes.

“Biomass has a lot of oxygen in it. All of that oxygen is dead weight and doesn’t provide any energy when you go to use that as a fuel,” said Wheeler. “If you’re going to make a hydrocarbon fuel, one of the things you have to do is remove oxygen from biomass. You can do it by using hydrogen, which is expensive and also decreases the energy efficiency of your process. So if there’s a way to remove the oxygen from the biomass chemically, then you’ve densified it significantly. Our oil has less than one percent oxygenates. No one else has done anything like this.”

In an early round of analysis, the UMaine oil was found to have boiling points that encompass those of jet fuel, diesel, and gasoline. Further refinement to meet emissions standards would be needed in order to use the UMaine oil in vehicles, but Wheeler believes the oil can be refined as simply as any other current oil at a standard refinery.

The new fuel has been determined to have a number of properties that make it better suited to serve as a “drop-in” fuel — which means it works easier in fuel tanks and pipelines — than many hydrocarbon fuels being currently researched and even those already on the market.

“We’ve even made a batch using grocery store waste with banana peels, cardboard boxes, and shelving,” said Case.

Using these unpurified, mixed carboxylates, proved that contaminated cellulose sources can be used in the process, which makes the oil more attractive — and more cost effective.

“You don’t need pure wood or pure cellulose,” said Wheeler. “Anytime you can use something without having to separate it, your costs go down. You wouldn’t need a major capital investment to commercialize it.”

Wheeler and his team already have the ability to produce several liters of the fuel per month in the laboratory. The process can be scaled up using equipment and chemicals commonly found in facilities, such as some pulp mills.

UMaine’s bioproduct research moved forward with about $4 million in federal funds from the Department of Energy four years ago, as well as a Maine Technology Institute grant.

“It’s our spin on chemistry used to make acetone back in the 1800s,” said Wheeler.