GREEN, CLEAN EMISSIONS CONTROL

In Business, July-August, 2005, Vol. 27, No. 4, p. 17

“As long as the economic discussion is framed as 'industry vs. environment,' there is very little room for new thinking,” says the founder of GreenFuel Technologies Corp. “But when we show people that our system is a tool to profit by reducing waste, the wheels really start turning.”

Diane Greer

FROM A DISTANCE, the structure atop the power plant roof at the Massachusetts Institute of Technology (MIT) in Cambridge appears to be a piece of avant-garde art. Thirty, eight-foot tall triangles made of clear plastic tubing sit side by side, circulating a bubbling green liquid. Closer inspection reveals the tubes to be filled with water and the fastest growing plant on earth - algae.
This innovative mechanism, the brainchild of Dr. Isaac Berzin - the founder of GreenFuel Technologies Corporation - harnesses the algae's photosynthetic process to consume waste gases from the power plant, fueling the algae's growth and delivering cost-effective emissions control. Once a day, the algae is harvested and dried, generating a commercially valuable by-product, known as algae biomass, used to create products ranging from biofuels to animal feed. “Our system is essentially a tool that enables the industry to profit by reducing waste,” explains Berzin.

FUELING PHOTOSYNTHESIS WITH FLUE GASES
A single celled organism, algae, lies at the heart of the GreenFuel Technologies effort. During photosynthesis, algae utilize solar energy to consume carbon compounds, such as carbon dioxide (CO2). Berzin is leveraging this process to turn CO2, a greenhouse gas found in flue gases, into oxygen and food to fuel the algae's reproduction. Algae also break down another flue gas component, nitrogen oxides (NOx) - a precursor to smog - into nitrogen and oxygen. Nitrogen serves as a nutrient, promoting algae growth.
Algae are ideal for Berzin's application. The organisms reproduce rapidly, doubling in volume in a matter of hours. Algae thrive in extreme conditions, able to withstand high temperatures and live in water sources readily available near power plants, even untreated or brackish water. Algae biomass can be used to produce biodiesel, bioethanol and animal feed or burned to generate energy.
Exploiting algae to reduce waste gas emissions from power plants is not a new concept. From 1978 to 1996, the U.S. Department of Energy (DOE) Aquatic Species Program researched the production of biodiesel from algae. As part of the study, algae grown in large-scale ponds in Roswell, New Mexico, were fed exhaust gas from coal-fired power plants. By carefully controlling pH and physical conditions, researchers achieved a 90 percent utilization of the injected CO2 and high algae yields.
Unfortunately, cultivating large volumes of algae in open pond systems proved to be impractical and expensive. Algae production was adversely affected by the uneven distribution of sunlight throughout the pond, wind blown contaminants and fluctuating temperatures. Harvesting the algae was difficult and expensive. Biodiesel generated from the ponds was calculated to cost twice as much as petroleum-based diesel fuel.

INNOVATIVE DESIGN
“We are beneficiaries of research done by DOE and others in the area,” says Julianne Zimmerman, Director of Business Development at GreenFuel Technologies. “Isaac Berzin read about this work and came up with ways to improve efficiency and take an alternative approach to this technology. The result is the very simple and elegant triangular enclosed bioreactor.”
Polycarbonate plastic tubes fabricated into a right triangle form the backbone of GreenFuel's bioreactor. The vertical leg of the triangle stands eight feet tall with a horizontal leg extending six feet. Placement of the device, with the hypotenuse facing the sun, optimizes sunlight penetrating the system.
Flue gases pumped into the legs of the triangle circulate through the system once before being expelled through the top of the device. Since algae require solar energy to consume CO2, removal of it by the bioreactor depends upon the systems' exposure to sunlight. Removal of NOx is not dependent upon sunlight and occurs continuously.
Fluid and gas dynamics along with gravity control the circulation of algae and water within the device. Designing the system with different diameter legs and adjusting the volume of gases going into the bottom vertices creates a pressure gradient within the device. Changes in the local pressure gradient drive fluid flow through the bioreactor. “This configuration allows us to control the rate of rotation of the liquid in the bioreactor,” says Zimmerman. “Control of the flow is simple and efficient.”

OPTIMIZING ALGAE GROWTH
Sophisticated algae culture management and control systems constitute the other key components of the GreenFuel system. In 2001, when Berzin was a research fellow at MIT, he advised Payload Systems on the design of a research apparatus for NASA's International Space Station. “The apparatus was required to grow essentially any type of cell in anything between zero and earth gravity, with as little mass, volume and power as possible,” says Zimmerman who also worked on the project for Payload Systems.
Berzin licensed a variant of the technology from NASA for his emissions control system. The technology, called AlgaTech, allows Berzin to tailor algae cultures to the specific characteristics of a power plant. Parameters specific to each power plant include fuel usage, type of available water, emissions profile and the temperature of the flue gases.
“We essentially choose algae that are known to display an affinity for the general conditions of the power plant,” says Zimmerman. “We start an algae culture in lab conditions and then quickly condition the culture to thrive at the power plant conditions.” The cell culture system essentially accelerates the natural selection process, favoring algae performing best under the desired conditions.
At the power plant, a real-time command and control system monitors and changes the flow of flue gases to optimize the algae's environment. Critical factors controlled by the system include the rotation of the liquid, nutrient distribution, internal temperature and the algae's exposure to sunlight. “The amount of light is critical to the process,” says Zimmerman. “It is important to understand the timing of the photosynthetic process.”
Previous research on photosynthesis found cells go through three phases. In the first phase, the cell accepts light; during the second phase, the cell processes the light; and in the final phase the cell rests. Models developed by GreenFuel calculate liquid circulation rates to optimize light exposure of cells in the hypotenuse of the triangle versus the legs (which are shadowed by the hypotenuse) corresponding to the cell's photosynthetic phases.

MIT FIELD TRIAL
During the summer of 2004, GreenFuel installed its first beta site at MIT's 20 MW gas-fired cogeneration plant. To test the emission reduction potential of the system, a small fraction of the power plant's flue gases, called a slip-stream, was diverted via a sampling port on the smokestack into a bank of GreenFuel Technologies bioreactors.
An independent testing firm, CK Environmental, measured the bioreactor's emission reduction performance during a seven-day period in September of 2004. Gas composition was measured going into and out of the bioreactor. The testing firm reported an 85.9 percent reduction in NOx and found CO2 emissions reduced by 82.3 percent on sunny days and 50.1 percent on rainy/overcast days. “The principal goal was to demonstrate the viability of our system and operational protocol in real world conditions,” says Zimmerman. “The test was hugely successful, beyond our expectations.”
“This new technology is very promising,” says Peter Cooper, MIT Director of Utilities. “A lot of the technologies you hear about that deal with carbon dioxide are very expensive. Going after the problem using algae is very interesting.” Cooper and GreenFuel wish to expand the MIT system, but face real estate constraints. The power plant, located in an urban setting on MIT's campus in Cambridge, only has space available on the roof for the bioreactors. “There is not enough space to treat our entire gas stream,” says Cooper. “The next step is to put enough algae reactors on the roof to provide a barrel of biodiesel fuel each week.”

SCALING THE PROCESS AND HARVESTING ALGAE
Space constraints at MIT point to a key issue determining the suitability of a GreenFuel installation at a power plant. In order to take advantage of the system, a power generating entity must have sufficient land with exposure to sunlight. Based on the 2000 census, GreenFuel estimates about two-thirds of the power plants in operation in the U.S. have adequate land at or adjacent to the facility to support a commercial scale installation of their system.
The footprint of an installation depends upon the volume of the emission stream and emission reduction targets. A bank of 30 bioreactors treats the slip-stream at the MIT beta facility. Installation of a system for a moderately sized power plant could cover many acres.
At the MIT facility, the rapidly reproducing algae are harvested daily using a manual technique. “We harvest by draining out some portion of the algae and squeezing out the water,” says Zimmerman. Ninety percent of the water removed from the system during harvesting is recycled back into the system. Harvesting occurs on a rolling basis so that the entire system continues to operate.
Large commercial application would include automated harvesting systems, allowing for nearly continuous collection. Once harvested, waste heat from the power plant dries the algae biomass, creating a valuable by-product.
A number of processes utilize algae biomass as a raw material. Biodiesel can be produced from the oils in the algae. Fermentation of algae biomass generates products ranging from bioethanol to bioplastics. Dried algae burned in gasification applications or co-fired with coal produces power. Algae biomass can also be reformed into biohydrogen. Finally, the raw material can be employed as a nutrient supplement in animal and fish feed.

PROCESS ECONOMICS
Production of coproducts such as biofuels, chemicals and animal feeds offsets the acquisition and operational costs of the emission control system. In larger installations, sale of the by-products may increase the profitability of the power plant. “We are converting CO2 into a revenue generation opportunity,” says Zimmerman.
As a rough rule of thumb, the mass of the algae harvested is about half CO2 by weight. So two tons of algae remove one ton of CO2. Every ton of harvested algae produces about three barrels of biodiesel. Zimmerman is quick to point out that these are very rough numbers.
Zimmerman has more difficulty providing hard and fast rules for determining the size for a breakeven or profitable operation because algae productions and emission reductions will vary by power plant, depending upon fuel mix and solar conditions. “Using really gross numbers in the Northeast, which does not have ideal solar conditions, minimum payback size for an installation could be as little as 10 acres, depending on the size of the site, ” says Zimmerman. Larger installations take advantage of economies of scale. The cost per acre goes down and the capacity to generate biomass goes up.
Smaller installations might not generate a profit, but they may reduce the costs of their emission control system. In some cases, small power facilities produce enough biomass to pay back the investment incurred to purchase and install the equipment.
The company estimates their application costs 40-60 percent less than comparable capacity selected catalytic reduction (SCR) systems employed to reduce NOx emissions. “Commercially rewarding does not necessarily mean the system must provide payback based on CO2 reductions,” points out Zimmerman. “On some of the legacy systems, the prospect of installing SCR to control nitrogen oxide emissions is daunting and expensive. GreenFuel's system enables them to avoid that cost. The CO2 reduction is a bonus.”

NEXT STEPS
To date, the company's focus has been on proving the technology. The next step is to validate the economics. “We need to provide something that is both technologically and economically sound,” says Zimmerman. “No one is going to do this if this is going to be a charity,” agreed Berzin.
Efforts are underway to expand field trials to larger sites in an effort to substantiate the economics. A larger scale validation of the system is planned for installation in September, 2005 at an energy utility in the Southwest. The company hopes to install a 25-30 acre site at a commercial facility in the 2007-2008 timeframe.
In addition to rolling out field trials, the company continues its research on algae and work on enhancements to the biological control systems. Specific efforts involve assaying algae species to determine oil content and other constituent components along with continued development of mathematical models to control inputs into the bioreactor. Longer-term projects include incorporating system augmentations to handle additional exhaust gas constituents, such as ash, SOx, and heavy metals, as well as exploring other product applications for algae.
The ten-person company, founded in 2001, recently hired Cary Bullock, as President and CEO. The firm is seeking its second round of funding. Access Industries, a New York equity firm, supplied $2.1 million in the first round.

REFRAMING THE DEBATE
To date, the debate on the cost to combat atmospheric pollutants and greenhouse gas emissions from the nation's power plants has pitted industry interests versus the environment, with little room for compromise on either side. Environmentalists, pointing to the mounting evidence of the human health and environmental consequences of air pollutants and greenhouse gases, call for more stringent control measures and mandatory reductions in greenhouse gases at the nation's power plants. Critics cite the costs to the U.S. economy of these policies.
“As long as the economic discussion is framed as 'industry versus environment,' there is very little room for new thinking on either side,” says Berzin. “But when we show people that our system is essentially a tool that enables industry to profit by reducing waste, that conflict is eliminated and the wheels really start turning.”

Diane Greer is an environmental consultant and researcher, specializing in the area of green technologies.

Copyright 2007, The JG Press, Inc.