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By Donnelle Eller, Des Moines Register

April 18, 2023

Gross-Wen Technologies, a rural Iowa company that uses algae to clean wastewater, is partnering with what one of the company’s founders says is a “global energy company” to make sustainable aviation fuel from its nutrient-eating biomass.

Headquartered in the south Story County town of Slater, it’s also investing in a new downtown Des Moines office in the Financial Center and a research and operations facility outside of Boone.

Martin Gross, who founded Gross-Wen Technologies with Zhiyou Wen, said the company, a startup that emerged from Iowa State University nearly a decade ago, is receiving a large investment from the energy company. He said he’s unable to provide the company’s name and other details about the deal until later this year.

The company’s system uses vertical conveyor belts, about 6 feet tall and 3 feet wide, that move in a continual loop, cycling through the wastewater and air as multiple layers of algae grow on them.

“While the algae is growing, it’s cleaning the water, removing the nitrogen and phosphorus,” Gross said.

The company then harvests the algae like a crop, drying and pelletizing it so it can be used as a slow-release fertilizer, mostly on golf courses. Now it also will be used to make biofuel.

“Our algae that’s grown at the wastewater plants is a great feedstock to make” sustainable aviation fuel, Gross said, adding that it will be grown in a number of locations and likely transformed into fuel at an existing refinery.

Gross-Wen and its partner are still developing the process, Gross said. One challenge is generating enough algae to meet market demand, he said. But that will be solved as large sewage treatment projects come online in Washington state and elsewhere.

President Joe Biden challenged U.S. companies nearly two years ago to develop by 2030 a sustainable aviation fuel that cuts greenhouse gas emissions 50% or more. Biden set a goal for the air transportation industry to be carbon neutral by 2050, which will require suppliers to make 35 billion gallons a year of sustainable fuel available by then to meet anticipated need.

The administration is offering $4.3 billion in tax credits, loan guarantees and other assistance to help companies meet that goal.

Gross-Wen’s new deal is helping to drive the company’s expansion. It’s leased about 2,000 square feet in the Financial Center in downtown Des Moines, making room for some of its workforce, which has doubled to 20 since the company started.

And Gross-Wen is moving its research and operations into a 7,000-square-foot facility outside of Boone, Gross said. Its headquarter will remain in Slater, where it refurbished a dilapidated Main Street business with the help of a state grant.

The company’s largest commercial operation is at the wastewater treatment facility for the town of 1,500.

The company developed its technology with the help of about $3 million in grants from the U.S. departments of energy and agriculture, Gross said. Over the years, Gross-Wen has attracted about $14 million from investors to expand the business.

The Doerfer Companies, a Waverly manufacturer with global operations, makes Gross-Wen’s wastewater treatment equipment. It’s also a large shareholder, Gross said.

Donnelle Eller covers agriculture, the environment and energy for the Register. Reach her at or 515-284-8457.

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