Ateneo Innovation Center fellow Dr. Joel Cuello is currently developing an accordion photobioreactor at the University of Arizona.

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UA Researcher Predicts Algae Biofuel at the Pump in 5 Years

By Alan Fischer - February 18, 2010, 1:26 pm

Research originally focused on growing algae to feed astronauts could within five years offer a readily available renewable source of fuel for our vehicles here on Earth, a University of Arizona professor believes.

In the 1960s NASA began looking at algae as a way to facilitate human habitation in space, said Joel Cuello, UA professor of agricultural and biosystems engineering. Potential space applications for algae included feeding space explorers as well as treating wastewater and regenerating carbon dioxide produced by astronauts, he said.

“Depending on the species, certain algae are rich in protein or fats or carbohydrates, so with the right mix of algae, theoretically, you could come up with a diet that is sufficient for human life,” Cuello said. “Unfortunately, astronauts did not want to eat algae.”

Cuello’s current work at the UA focuses on mass-producing algae for biofuels, so that instead of feeding astronauts the microscopic organisms can be used to produce renewable energy to power vehicles.

And using algae to produce biofuels is not taking food out of the mouths of people.

“If you use a food crop as an energy feed stock, like corn and soybeans, you are diverting them from being a food producer into being a fuel producer,” Cuello said. “When you use algae there is no conflict or competition between food and fuel, since most people don’t eat algae.”

Algae also offers more productive yield rates per area than most other feed stocks, and can be grown using treated wastewater rather than potable water needed for most other feed stocks, he said.

Different types of algae can be selected to produce a variety of biofuels. Cuello’s research team is growing and testing various types of algae to maximize hardiness, rapid growth and biofuel capabilities. Some species are up to 75 percent oil by dry weight, he said.

“In the lab we have algae species that can produce hydrocarbons that can be used for jet fuel production. There are species that accumulate fatty acids which can produce biodiesel,” he said. “Some accumulate starch which can be fermented to produce ethanol. And some species of algae directly produce hydrogen gas, which is another type of biofuel.”

While algae production is successful on a laboratory basis, the challenge today is making large-scale production of algae cheaper and commercially feasible, he said.

One of the largest costs for commercial algae production is the photobioreactor, a container where algae grows with the help of circulating nutrients and light.

Enter the UA’s Accordion, a photobioreactor that Cuello and his graduate student Joe Ley designed and which Cuello believes could be used to inexpensively produce the huge amounts of algae needed for an effective biofuel program. UA has been granted a provisional patent for the device, and is working for a full patent, Cuello said.

The device, named after the musical instrument because of a loose similarity in shape, flows water and nutrients through a vertical series of clear panels set at a variety of angles, allowing the mix to have a controlled flow and receive a steady dose of light needed for growth.

The key benefit is the modularity of the system, which lends itself to convenient scale up, Cuello said. Another benefit comes from the material: inexpensive polyethylene film is used rather than glass or other expensive materials to bring the cost down. The device is made from off-the-shelf items.

Ley, UA graduate student in agricultural and biosystems engineering, is working to refine a prototype Accordion located at the UA Campus Agricultural Center. He is using the Accordion to grow Botryococcus braunii, a strain of oil-rich algae with jet biofuel applications.

The mix of algae and liquid nutrients is pumped to the top of the device, where it flows down from section to section while bathed in soft fluorescent light. In a real world application, rows and columns of the Accordions could be arranged inside a greenhouse or even outdoors in open air where sunlight would be the principal source of light.

In addition to lower cost, Accordion offers other benefits, Ley said.

The polyethylene plates are transparent and relatively thin, so that the algae can obtain the greatest amount of light needed for growth.

The flow of nutrient solution is regulated to keep the microscopic algae in suspension, thus ensuring that all algae cells receive adequate nutrition and light.

And the device is mounted on a framework of PVC pipe, allowing the shape and configuration of the panels to be readily changed as needed to maximize production rates, Ley said. In a real-world setting the PVC for the framework would be replaced by a less expensive material.

The design is scalable, and sites featuring vertical towers of hundreds – or thousands – of Accordions could produce the vast amount of algae needed for high-output production of biofuels, Ley said.

“We could develop acres and acres of systems like this for the higher production needed to produce biofuels,” Ley said.

The liquid pumped through the Accordion starts clear, and 500 milliliters of algae are used to seed the process. The liquid turns green as algae grow exponentially until growth plateaus after seven to 10 days, Ley said, at which time algae growth remains steady and the material can be harvested.

In addition to improving the algae-growing technology, Cuello’s research team is working to make harvesting the algae for processing more efficient. Current methods require a centrifuge to separate the algae from the liquid nutrients, which is expensive and time consuming, Cuello said.

“We’re developing a novel harvesting mechanism that will be able to accomplish this task more economically,” he said, but declined to offer details until patents are in place to protect the new technology.

Cuello believes the day is not too far off when we will be able to fuel our vehicles with biofuels derived from algae. “I really believe we will be able to make use of algae-based biofuels, probably in two to three years,” he said. “We will have the right mix of technologies in place in two to three years, and it will be at the pump, I would say, in five years.”

In addition to biofuels, a growing number of other commercial applications exist for the UA’s algae research efforts, Cuello said.

A company in Norway, Biopharmia, is in discussions with UA to use the Accordion technology, initially to produce high-value chemicals such as human food supplements and high-end fish feed, Cuello said.

And Cuello’s lab is receiving funding from Phoenix-based Sonador Research Group to pursue research into production of algae-derived antitumor compounds that target various types of cancer.

Project Sage Special Report: Achieving Sustainability Through Agriculture

(Click to enlarge) Joel Cuello checks the flow rate of air bubbling through algae growth flasks in his University of Arizona lab.

(Click to enlarge) Takanori Hoshino checks on a sample of Chlamydonomas reinhardtii algae he is growing to study maximizing the production of hydrogen.

UA researchers believe that algae will be providing fuel to power vehicles within the next five years.

Swimming pool owners in the Southwest must be vigilant to prevent algae from becoming a pesky scourge that grows quickly during hot summer months.

University of Arizona researchers believe the microscopic organisms will be providing fuel to power vehicles within the next five years.

Joel Cuello, UA professor of agricultural and biosystems engineering, said algae has been proven as a renewable source of fuels like ethanol, biodiesel and hydrogen, and his research team is working on ways to make such algae biofuels cheaper and commercially feasible.

"I really believe we will be able to make use of algae-based biofuels, probably in two to three years," he said. "We will have the right mix of technologies in place in two to three years, and it will be at the pump, I would say, in five years."

Different types of algae - with different qualities and attributes - are grown in Cuello's lab in UA's Shantz Building. Some algae varieties produce fatty acids that can be converted to biodiesel, others produce starches that can be converted to bioethanol, and some types of algae directly produce hydrogen gas, he said.

Algae offers major advantages over other things grown as sources for renewable energy, he said.

Growing algae produces oxygen and takes carbon dioxide out of the environment. It grows more productively than other fast-growing energy crops while requiring less space. Non-potable and treated wastewater can be used for growing algae. And using algae for fuel production does not take food out of the mouths of people or animals, he said.

The process begins with selecting the algae species appropriate to produce the desired fuel. Species and strain selection also considers the quickest and most productive type of algae, he said.

Huge amounts of algae are needed for large-scale biofuel production. Mass production takes two forms: growing it in open ponds or more complex and costly closed photobioreactors.

Open ponds where nutrients flow along a racetrack-like circuit offer a simpler and less expensive way to produce algae, but must deal with fluctuations in temperature and solar radiation as well as potential contamination. Photobioreacators, which are large containers in which algae is grown, control the environmental parameters and ensure the best environment for algae growth, but are generally more costly, he said.

A new less expensive, more efficient design of photobioreactor has come out of Cuello's UA lab.

"It's called the Accordion because it is suggestive of the geometry or configuration of the musical instrument. It is a vertical series of flat plate reactors at different angles, and the algae and nutrient solution is circulated through those flat plates," Cuello said.

Unlike other photobioreactors, Accordion is made of inexpensive, flexible plastic to keep costs down, he said. The system is also modular and scalable for high-volume production in an economically feasible manner, he said.

After production the algae must be harvested.

"Harvesting is not easy. We are dealing with microalgae, which are microscopic. And they are floating around in water, so it is not so easy to separate them from the liquid nutrient solution in which they are suspended," he said.

Centrifuges are most commonly used to separate out the valuable algae, a process that is very energy intensive. "We are looking at developing new methods or approaches for accomplishing harvesting microalgae from liquid nutrient solutions," he said.

UA has received a provisional patent for Accordion, and is in negotiations with a Norwegian company interested in a licensing option or agreement to use the device commercially, Cuello said.

The next step is dewatering, or drying, the harvested algae. The Southwest, with its abundant sunshine and high temperatures, is an ideal area for drying the algae biomass, he said.

After drying, the oils are extracted or starch is separated to produce biodiesel or bioethanol, he said.

Cuello's research team consists of six UA students and Sara Kuwahara, who recently earned a doctorate in biosystems engineering from UA.

Kuwahara is studying how best to use wastewater to effectively produce algae. This saves valuable groundwater for other purposes, and actually cleans the wastewater during the process of growing the algae, she said.

The process also produces oxygen while removing carbon dioxide from the environment, she said.

"We hope to make it a zero impact growing process," Kuwahara said.

Cuello said that with some addition of nitrogen and phosphorus, wastewater grows algae as well as more expensive solutions designed specifically for that purpose.

Takanori Hoshino, a biosystems engineering graduate student, is investigating better ways to produce hydrogen gas from algae.

Hydrogen can be used to power vehicles. But now, 95 percent of hydrogen is produced from natural gas, a fossil fuel, he said.

He is working with Chlamydonomas reinhardtii, a type of algae, to produce more hydrogen gas from a given volume of algae.

Algae is not the only UA focus of research for biofuel sources.

Mark Riley, UA agricultural and biosystems engineering department head, said a project using arid lands to grow sweet sorghum for ethanol is close to commercialization.

Sweet sorghum grows quickly - up to 4 meters in four months - and is suited to Arizona because it is salt tolerant and can use reclaimed wastewater for irrigation, Riley said.

Sweet sorghum can be fermented directly into ethanol, and Riley said a Pinal Energy LLC plant near Maricopa, Ariz., is nearing commercialization of the first large-scale energy crop for the Southwest.