An Air Compressor That Can Improve Wind Turbines?

A few more startups out of ARPA-E

More than 300 companies presented at this year’s ARPA-E Summit. Many were familiar names, including CodexisCree and FloDesign.  But many were less familiar. In addition to Echogen, three companies stood out.

Algaeventure Systems (AVS): Based in Ohio, AVS seeks to develop and commercialize a new method for dewatering algae. In 2009, ARPA-E awarded AVS a $6 million grant to pursue development of its mechanical-electrical harvesting, dewatering and drying (HDD) system. This week, AVS will close a friends and family fundraising round.

AVS is tackling a significant barrier to industrial-scale production of algal biofuels. Today, centrifugation is the most efficient technique for turning dilute algal cultures into a concentrated sludge from which lipids can be extracted. But using centrifugal forces to separate solids and liquids is an energy-inefficient process that consumes 30 percent to 50 percent of the total cost of cultivating algae.

“Dewatering, drying the algae, and separating the oils from the biomass are issues that a lot of algae companies have not considered. They have considered the front end, engineering the organisms. But the separation and dewatering step uses incredible amounts of energy, specifically in centrifuges. That high-energy usage is a limiting step in creating cost-effective algae,” said Josh Green, a General Partner of Mohr Davidow Ventures.

AVS claims its system will significantly reduce the energy costs associated with the dewatering process.

“With less than 90 percent of the energy that would be used for a centrifuge that spins the entire water mass, we are able to separate micro-solids from water,” said David Coho, Algaeventure’s Vice President of Sales and Marketing.

To see AVS’ system at work, watch the videos available here and here.

AVS’ system uses two belts moving in opposite directions. The diluted algal solution is poured onto the top belt, which moves in one direction.  Directly underneath is the bottom belt, a wet capillary belt, which moves in the opposite direction. Liquid adhesion draws the water through the top belt to the bottom belt, dewatering the algae.

“First, we break the meniscus of the water. Then, with our capillary belt, using a wicking action, we pull the chain of water molecules…through the film,” said Coho.  “What we have [then] is material that completely flakes off or can be easily removed in a wet mass with just a fraction of the energy cost of incumbent technologies like the centrifuge.”

AVS’ initial application is for algal dewatering. Future applications for its HDD system include food processing. To date, AVS has sold 10 small-scale, collaborative units to institutions, including Old Dominion University and Ohio University. In mid-2011, it hopes to have three larger, commercial-scale demonstration units out in the field.

Caitin (an outgrowth of Pax Streamline): The ARPA-E awarded this Khosla Ventures-backed California startup $3 million for the development of a new blade for wind turbines and $2 million for research into more efficient air conditioning. The company’s wind technology efforts were on display at the ARPA-E Summit.

Applying active circulation control to turbines, Caitin is developing “blown wing” technology.  A blower system in front of each turbine compresses and blows air into the inside of the turbine. The air is subsequently released over each turbine blade’s trailing edge. By dynamically redirecting airflow, Caitin aims to change turbine aerodynamics — and enable a fundamental redesign of turbine blades.

“Flowing air over the trailing edge of the blade…allows you to change the angle of the tack and increase lift,” said Leigh Zalusky, a mechanics engineer at Caitin.  “You are changing the shape of the airfoil to the wind.  [It is] similar to having mechanical flaps on airplane wings. […] In doing this, we can straight[en] the blade out…which has big implications in terms of manufacturing.”

“[We] can make the blades lighter, which translates into a lighter gearbox, main shaft, tower — all the way down to the entire design of the turbine,” continued Zalusky.

Caitin also claims that its technology will eliminate the need for pitch and breaking systems, a critical maintenance and cost challenge for existing turbines.  A key question, however, is how the company’s pitch-system-less turbines will handle emergencies.

In the coming weeks, Caitin will find out. Last week, the firm deployed a 100-kW prototype in the Altamont Pass.

Vorbeck Materials: The Maryland company is working to develop graphene anodes and cathodes for increased lithium-ion battery capacity and output and enhanced cycle life.

Vorbeck is but one of many startups working to improve battery anodes (think Amprius) or cathodes (think Envia).  It’s a tough way to break into the battery business — large manufacturers are skeptical about taking technology from startups — but if enough good ideas pop up, it might work. Graphene Energy is developing ultracapacitors using graphene. After a 2010 Nobel Prize in physics was awarded to investigators working in this area, graphene research is hot at universities worldwide. Why keep tabs on Vorbeck?

Because the 25-person company was the first — and to date, the only — firm to secure EPA approval for the commercial sale of a graphene product: its conductive inks for the printed electronics industries. Vorbeck claims that later this year, it will announce several large partners and bring its conductive inks to market, but the firm’s energy products are further from commercialization.

“Right now, we are beta-testing anode materials, composite materials of graphene and other metal oxides,” said Christy Martin of Vorbeck research and development. “We are operating at better performance and similar or lower cost. […] Anodes are further along in the development cycle than cathodes, which are still in R&D.”

To date, Vorbeck has raised more than $8 million from private investors including Stoneham Partners and Fairbridge Venture Partners.


Yoni Cohen is a JD-MBA student at the Yale Law School and the Wharton School of the University of Pennsylvania.  A former college basketball writer for Fox Sports, he tweets about greentech @Cohen_Yoni.


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