UA team converts algae into fuel

It will take a lot of algae and land to make a dent in the use of gasoline in the U.S., but researchers at the University of Arkansas have developed a process they say could be commercialized within 5 years.

A team of chemical engineers at the University of Arkansas has developed a method for converting common algae into butanol, a renewable fuel that can be used in existing combustible engines, according to a UA statement released Tuesday (Mar. 1).

The conversion of algae to butanol was developed from a process now being used to clean excess nitrogen and phosphorous — primarily from fertilizer use — from lakes, rivers and other bodies of water.

“We can make cars go,” said Jamie Hestekin, assistant professor and leader of the project, noted in the statement. “Our conversion process is efficient and inexpensive. Butanol has many advantages compared to ethanol, but the coolest thing about this process is that we’re actually making rivers and lakes healthier by growing and harvesting the raw material.”

Although the process has been developed, don’t expect to soon see algae-produced butanol at your neighborhood gas station.

“I think something like this could be commercialized in the timeframe of less than 5 years, but 5-10 years is probably the most realistic,” Hestekin said.

Hestekin told The City Wire that conversion costs aren’t yet certain.

“Right now, the conversion costs are still a little higher than we would like them to be but we are working hard to bring these costs down. I don’t think we can give you an exact number yet but would be able to do that in a month or less,” Hestekin explained.

Also, it’s not yet certain what system would be used to mass produce butanol. Hestekin said the team is looking at options. One option would be for small production areas that could be placed on or used by a family farm.

“Another would be a 1000 acre clean-up system to go with a major waterway,” according to Hestekin. “This system could produce greater than 1 million gallons of butanol per year. Even one 1,000 acre system would make an impact on water clean-up and fuel potential!”

Considering that 378 million gallons of gasoline a day was the average use in 2009, butanol may struggle to be a significant replacement based on the acreage required.

The UA research team grow algae on “raceways” that are typically 2 feet wide and range from 5-feet to 80-feet long, depending on the scale of the operation.

Algae survive on nitrogen, phosphorous, carbon dioxide and natural sunlight, so the researchers grow algae by running nitrogen- and phosphorous-rich creek water over the surface of the troughs. They enhance this growth by delivering high concentrations of carbon dioxide through hollow fiber membranes that look like long strands of spaghetti.

The algae is harvested every five to eight days by vacuuming or scraping it off the screens. After it dries, the material is ground into a fine powder from which carbohydrates are extracted. The starch from the carbs are treated with acid to break them into natural sugars.

“They then begin a unique, two-step fermentation process in which organisms turn the sugars into organic acids – butyric, lactic and acetic,” noted the UA statement.

Advantages of butanol compared to ethanol, according to the UA researchers, include:
• Butanol releases more energy per unit mass and can be mixed in higher concentrations than ethanol;
• It is less corrosive than ethanol and can be shipped through existing pipelines;
• Unlike corn, algae are not in demand by the food industry; and,
• The algae required to produce butanol can be grown virtually anywhere and does not require large tracts of valuable farmland.

Hestekin’s team is working with the New York City Department of Environmental Protection to create biofuel from algae grown at the Rockaway Wastewater Treatment Plant in Queens.

The UA statement also notes that municipal and state governments, primarily on the East Coast, have implemented large-scale processes similar to what the UA researchers are doing to address so-called “dead zones,” where excess nitrogen and phosphorous have killed fish and plants.

The students’ project will be featured on Planet Forward’s Earth Day special April 8 on PBS. The UA team produced this video to explain their research.