At a 100 year old building on the St. Paul campus of the University of Minnesota, an ambitious project is underway, to turn algae into diesel fuel. The work is taking place in three separate labs.
In the basement, algae is growing in racks of aquariums. It's an experiment with different types of lighting, to see which makes the algae grow faster.
In a small lab on the second floor, algae is growing inside plastic tubing that's coiled around three fluorescent light fixtures. Workers here are trying out different types of algae to see which contains the most oil.
And in another room, they feed algae through what they call a photo bio-reactor. It extracts the oil from the algae. Little jars of oil sit on shelves in the lab.
Roger Ruan, who directs the university's Center for BioRefining, has been working for years to try to figure out how to turn algae into diesel, economically. There's no question it can be done. Some people are already producing algae oil, growing the algae in open ponds, he says, and using it in pharmaceuticals, food supplements, and cosmetics.
"Right now, based on an open pond system, per acre per year you can easily get 5,000 gallons of oil," he says. "Soybeans would probably give you 50. That's a 100 times difference."
Algae can be far more efficient at producing diesel than soybeans.
In the quest to make algae competitive with petroleum diesel, Ruan has also been experimenting with various techniques to get more out of the algae. He's developed special ways to refine it. Just as with petroleum refineries, Ruan says we can produce not just fuel but other useful things when we refine algae.
"Because algae also at the same time contains a lot of other components like proteins and starch," he says. "So if you go to the bio-refining approach to utilizing these algaes, then it could be economical because there are components there that could have very high value."
The real challenge is to figure out how to do it on a big enough scale to meet our energy needs.
But that's where Ruan's research partner comes in, the Metropolitan Council's sewage treatment plant on the Mississippi River in St. Paul.
The basement of the plant's solids handling building is a brightly lit space filled with a network of steel pipes, valves and tanks. Centrifuges separate solids from liquid material so the solids can be burned.
Off to the side, Ruan's team is setting up a rack of aquariums just like he has in his lab on campus. When everything is ready, some of the partially-treated waste will be diverted into the tanks, where it will feed the algae.
The waste is still full of stuff that's bad for the Mississippi River, but good for algae.
The partially-treated waste has "a fair amount of phosphorus, and some ammonia nitrogen that the algae are going to need," says Bob Polta, manager of research and development at the treatment plant.
It's easy to see why Polta likes this idea: every day the facility takes four tons of phosphorus and more than 16 tons of nitrogen from Twin Cities' waste. It has to be removed before it's discharged into the Mississippi River.
The algae experiment, if it works, will allow them to do some of that removal in a more cost-effective way.
And this could be the answer to Ruan's problem of trying to create enough algae to make enough oil to compete with petroleum diesel.
There's a big potential for cities around the state and the country, both for cleaning wastewater and for producing energy in the same place, Polta says.
"All the wastewater treatment ponds in the small communities around the state are essentially using algae to treat wastewater, it's just that they're not being harvested," Polta says. "It's just that we're getting two goals together here -- one is essentially taking algae and harvesting the oil and making biodiesel, and the other is using algae as a treatment scheme -- and to see if we can make this thing really fit."
Polta expects by the end of the year he'll know more about whether this is a practical idea.
The U of M's Roger Ruan says within six-to-10 years someone, somewhere will be producing diesel from algae on a commercial scale.