Chesapeake Quarterly
River of Opportunity
Innovation for a Cleaner Chesapeake

ERICA GOLDMAN

Along the banks of the Susquehanna, environmental engineer Patrick Kangas monitors rising levels on his oxygen meter. The water he measures, drawn from the river, has journeyed down a long raceway and passed over hundreds of thousands of filaments of algae. Now oxygen-rich and lean on nutrients, it returns to the river though a black rubber hose. Credit: Erica Goldman.

ON FARAWAY HILLSIDES in New York and Pennsylvania, water begins a downhill journey toward the longest river in the eastern United States. By the time that flow reaches the Conowingo Dam in Maryland, where the Susquehanna River's 18-million-acre watershed drains into the Chesapeake Bay, more than 40,000 cubic feet per second rush in at a single point of entry. At this neck of the funnel, at least half of the Bay's total load of nitrogen and phosphorus makes its entrance. It has come from farmland and urban pavement, septic tanks and the outfalls of sewage treatment plants. Once in the Bay, these nutrients feed the prolific growth of microscopic algae that has become the hallmark of a degraded Chesapeake.

Walter Adey sees this pollution chokepoint at the Susquehanna River in a unique light. For him, the neck of the funnel represents a golden opportunity to set things right for the Chesapeake. This veteran ecologist from the Smithsonian Institution has a bold idea, one more than 30 years in the making. His concept could rid Susquehanna River water of excess phosphorus and nitrogen before it enters the Bay and inject oxygen into bottom waters at the same time. He's calculated that his approach would cost a lot less than current estimates for cleaning up nutrients in the watershed. And he thinks that the time to try it has finally arrived.


On a bank high above the Susquehanna River perches the Muddy Run Pumped Storage Plant. Just up the road, horse-drawn buggies amble through the rolling green hills of dairy farms in Pennsylvania Amish country.

In sharp contrast with the surrounding landscape, the plant's scaffold towers string power lines across the water. An aluminum raceway — eighteen inches wide-by-300-feet long — sits propped off the ground by aluminum stilts. Reversing turbines rise in the distance. Each night these structures transport water up from the river to a reservoir. Susquehanna River water, rich in nutrients and low in dissolved oxygen, courses down the raceway, pulsing over a plastic mesh surface carpeted by long hair-like strands of algae.

Standing near the bottom of the raceway, Patrick Kangas pulls an oxygen probe from the water. Its black wand dangles from a wire on a handheld console. He jots the value in his notebook, adjusting his hard hat and repositioning his glasses so he can see the page clearly. He takes another measurement with a pH meter, waits for the probe to equilibrate, and writes down the number. Then he walks along the edge of the raceway and climbs a short flight of metal scaffold stairs to the water input area. Since this section is elevated, gravity carries the water downhill. He plunges the probes into the water again, first oxygen, then pH, and scribbles down a second set of numbers.

Since he took over for his graduate student earlier that morning, Kangas has been taking measurements every three hours. These measurements are part of a 24-hour series of oxygen and pH readings of water flowing over the algae-covered raceway.

This long contraption is called an Algal Turf Scrubber, the key to Walter Adey's visionary idea to capture nutrients from the river. Kangas, a professor of environmental engineering at the University of Maryland College Park, is working to implement a pilot project to test that vision. The goal of their project is ambitious: Harness the power of fast-growing, photosynthesizing algae to take up nutrients like nitrogen and phosphorus from polluted water. In turn, let the algae pump the water full of oxygen. Then vacuum up the algae and feed it to a reactor for making a biofuel — in this case, butanol. Clean the Bay, tap into an emerging market for alternative energy, and create a revenue stream to drive the clean-up effort — all in one fell swoop. Kangas is eager to test the promise of Adey's dream.

Harnessing Light from the Sun

Adey's idea for the Algal Turf Scrubber came from his studies of coral reef ecosystems back in the 1970s. Since 1964, Adey has served as a curator and research scientist for the Smithsonian Institution. Though speaking today from his book-filled office at the end of a long corridor off the National Museum of Natural History's archived fossil collection, he's spent nearly 20 years at sea in the Caribbean. There he studied algae in coral reefs and devised ways to continue his studies by bringing reefs into the lab — in microcosms and mesocosms, experimental enclosures that approximate natural conditions. He founded the Smithsonian Institution's Marine Systems Laboratory at the museum in D.C., a lab that specialized in developing such experimental ecosystems. From 1975 to 1999, he served as its director.

In his early studies of Caribbean coral reefs, Adey and his team of student researchers discovered that most of the reef's primary productivity occurred in lush algal turfs growing on dead coral. It seemed that these algal turfs were highly adapted for capturing energy from the sun. Adey's team discovered that by replicating the natural wave surge and current that algal turfs experience on coral reefs, they could reproduce the high levels of light capture and growth seen in the wild. The key as it turned out was the surge of the waves. That rhythmic force mixes the water and helps to expose the plants fully to pulses of sunlight.

Adey went on to develop a method for growing algal turf on mesh screens and using them to help control water quality in coral reef aquaria. He created a 130-gallon experimental coral reef microcosm at the Marine Systems Laboratory, using an Algal Turf Scrubber as the only way to control its water chemistry. After eight years as a closed experimental ecosystem, the reef demonstrated coral calcification rates equal to the best four percent of wild reefs. Boasting an estimated 800 species, it ranked per unit area as the most diverse reef ever measured.

The secret behind the success of the Algal Turf Scrubber is biomimicry, explains Adey, replicating conditions like wave surge that optimize growth rates and productivity for algae in the natural environment. The mesh on the scrubbers attracts the settlement of diverse species of algae present in the surrounding water.

Like all plants, algae use nutrients like nitrogen and phosphorus to grow. They also remove or sequester carbon from the atmosphere and release oxygen as a byproduct of photosynthesis. Algae grow fast and are 5 to 10 times more efficient at photosynthesis than their more complex plant cousins. To keep photosynthetic rates high, the algae must be harvested every 6 to 12 days, which maintains their peak growth rate. These frequent harvests also mean that plenty of algae become available as raw material for producing a biofuel.

algal turf scrubber by Dail Laughinghouse algal turf scrubber diagram by Walter Adey
close-up of algal turf scrubber by Dail Laughinghouse
Spirogyra rhizoclonium by Dail Laughinghouse Cladophora by Dail Laughinghouse
Mimicking flow dynamics over coral reefs, nutrient-rich water from the Susquehanna River pulses down the aluminum raceway of an Algal Turf Scrubber (top and middle left). The raceway is lined with a highly textured plastic mesh that encourages algae to grow (diagram, top right - click here or on the image to view a larger image). Spirogyra (bottom left), an unbranched, weedy species of algae, currently dominates the mesh. Researchers hope to encourage the growth of Cladophora (bottom right), another common local species, whose highly branched geometry is better suited for producing biofuels. Credits: Diagram courtesy of Walter Adey; algae by Dail Laughinghouse; algal turf scrubber by Erica Goldman. Watch a video about using algae at Muddy Run from the Lancaster New Era.
Scaling up on the Susquehanna

With oxygen and pH measurements completed, Kangas makes his way back down to the bottom of the scrubber raceway. There the water collects in a big plastic bucket before being flushed down a black rubber hose back into the Susquehanna River. He glances at his notebook.

At the top of the apparatus, where untreated river water enters the system directly, the oxygen concentration measured 5.8 milligrams per liter. This is low, the equivalent of 64 percent saturated.

At the bottom of the raceway, after traveling across hundreds of thousands of algal filaments, the oxygen concentration of the water has roughly doubled, measuring 11 milligrams per liter or 134 percent saturated. The water is so saturated that oxygen is actually being lost to the atmosphere, Kangas explains. At night, with no solar energy available to enter the system, rates of photosynthesis drop. But by eight in the morning, the algae get to work again.

Kangas cannot measure nitrogen and phosphorus uptake in real time, as he can with oxygen and pH. But the results he's recently received — from water samples sent for analysis at the U.S. Department of Agriculture's laboratory in Beltsville, Maryland — show dramatic reductions. Nitrogen concentrations drop by a third from where water enters at the top of the algae raceway to where it exits at the bottom, dumping back into the Susquehanna. "It's amazing," Kangas says.

Kangas showed the nutrient reduction numbers he was getting from the Algal Turf Scrubber pilot study to his department chair, Frank Coale, an expert in agricultural nutrient management. Coale said that these scrubbers appear to be 50 times more powerful than cover crops, planted in winter months to take up excess nutrients from the soil.

What if this pilot project could be scaled up?

Adey has big dreams of doing just that. He envisions 3000 acres of scrubbers - an area more than four times the area of New York City's Central Park. That's only a tiny fraction of the Susquehanna watershed, but he estimates that a system that size could remove the entire Susquehanna portion of excess phosphorus delivered to the Chesapeake Bay (three million pounds per year). With this, he calculates, would come an oxygen injection to the river of approximately 200 million pounds per year. Adey speculates that this might be sufficient to remove algal blooms from the upper Bay and to make a sizeable dent in the extent of hypoxia in the main stem.

Exelon Power, which owns and operates the Muddy Run Storage Plant and the Conowingo Dam, has offered their support for the first step in the scale-up — an expansion that would take the size of the scrubber system up to 12 acres. Mary Helen Marsh, the general manager of Exelon Power's two hydro stations, helped Kangas and Adey to secure the site at Muddy Run for their trials and supports the expansion of the pilot onto land adjacent to the Muddy Run Reservoir.

Marsh says that she was excited by the opportunity to help with research that will protect the environment down the road. From a company perspective, she explains, it also complements Exelon's initiative to mitigate its carbon footprint by the year 2020. Since algae sequester carbon dioxide from the atmosphere, this project fits right in.

Walter Adey by Erica Goldman
Practical dreamer Walter Adey invented the Algal Turf Scrubber technology more than 30 years ago and he's working to implement it on a large scale in the Chesapeake Bay. Credit: Erica Goldman.

The technology for scaling up looks promising. HydroMentia, a company based in Florida that specializes in water pollution control, now holds the industrial license for the scrubber technology. They've designed a modular system of 12-acre units that can be put together to achieve the kind of acreage that the Susquehanna would ultimately need. Algal Turf Scrubber systems as large as three acres are currently used to treat the agriculturally contaminated waters of Taylor Creek, a tributary of the highly eutrophic Lake Okeechobee in Florida, the second largest freshwater lake in the United States. At that scale, the plant removes nutrients from 15 million gallons of water per day.

But the pilot project at the Susquehanna River has a long way to go before it could fulfill Adey's dream of reducing nutrient pollution. Two important hurdles block the path to such a scale-up in this region: Money and land.

Scaling up would not come cheap. According to Adey, to move up in size to the first 12-acre scrubber module would cost roughly $5.5 million. To make it all the way to a 3000-acre system would require on the order of $1 billion. This is real money.

Space poses another problem. "The problem with this technology is that you need land," says Kangas. "It takes a lot of land. That throws everything off because land is so expensive."

But the Algal Turf Scrubber systems could be installed in small strips on different pieces of farmland — the 3000 acres would not have to come in a giant, uninterrupted swatch — which means that little bits of land here and there could go a long way. And over the whole watershed, 3000 acres accounts for only a small fraction of the five million acres of farmland. Kangas and Adey have been working with the agricultural community to add the scrubber technology to the suite of incentives that already exist to encourage farmers to clean up polluted waters in the Chesapeake watershed.

"We already pay farmers to plant cover crops and riparian buffers," says Kangas. "Can we pay farmers to have an Algal Turf Scrubber system — as a tax incentive?"

In addition to cover crops, what if there were Algal Turf Scrubbers on every farm? On every creek? This is a vision for the Chesapeake that Adey and Kangas share.

Building an Economy

Harvest is still a few days away, but already algae grow thick on the mesh screen of the turf scrubber. The algae are mainly a weedy species called Spirogyra, explains Kangas. He and Adey had hoped to see more of another species called Cladophora, which is more highly branched and better suited for biofuel production. But in this real-world application, the mesh of the scrubber seeds with whatever species is most abundant and competes most effectively for space.

At the peak of summer, the team harvests the scrubber every five days. The weather is cooler now so the growth rate of the algae has slowed, spacing out harvests by several more days. Harvesting the algae is simple, explains Kangas. Turn off the water flowing into the system. Vacuum up the algae with a Shop-Vac, making sure to leave enough behind on the mesh to jumpstart further algal growth.

A Maryland-based company, Living Technologies, founded by Adey's former graduate student Tim Goertemiller, has built its business constructing and selling Algal Turf Scrubber systems. Now they're expanding the enterprise to become a "lawn service" for algae harvesting, beginning with the project on the Susquehanna River and another pilot project on the Eastern Shore. They don't have many algae customers yet, but they're hoping for business to grow.

"The notion of job creation is real. We're trying to build an economy, not just an academic experiment," says Kangas. Adey and Kangas hope that producing a biofuel will be the key driver that sets this new economy into motion.

The scrubber technology has begun to gain traction on its own merits in the water quality world, says Adey. But, he says it's been difficult to build financial support for large-scale projects. For example, HydroMentia designed a 1440-acre system for the Suwannee River of northern Florida, a plant that would be able to treat three billion gallons of water per day. But lack of sufficient funding has slowed the project.

In the Chesapeake Bay, it's going to be a "long, slow slog, because nobody really wants to pay," Adey says. "We have shown that we can reduce nutrients more cheaply and more completely than what is being done, but the money is locked up in the system."

One of Adey's former students completed a survey of restoration funding over a three-year period. The dollar amount added up to more than one billion dollars, but according to the survey, all of it had already been spoken for.

What could drive more financing for nutrient management in the Chesapeake Bay?

Adey thinks that the key lies in tapping into the nation's growing demand for bioenergy. At the sunset of his career, he is seizing on what he sees as a critical window of opportunity to put his 30-year-old invention to work at a large scale.

Adey is betting that the biofuel component of the project will draw considerable investment and interest, as well as demand for the final product. He plans to construct a pilot biofuel plant to accompany the proposed 12-acre scale-up of the scrubber system. With the algae harvested, the biofuel plant would produce an estimated 40,000 gallons per year as a combination of butanol and biodiesel. As a bonus would come 9000 pounds of hydrogen, which could be used to power operations at the plant. By Adey's calculations, an acre of algae produces more than 10 times the energy produced from an acre of corn.

Patrick Kangas and Tim Goertemiller by Erica Goldman
Researcher Patrick Kangas and Tim Goertemiller of Living Technologies, a Maryland-based company, discuss plans for a second pilot Algal Turf Scrubber at the Muddy Run Plant on the Susquehanna River. Credit: Erica Goldman.

The whole country is now poised at the tip of a bioenergy revolution, with a new federal administration that plans to make alternative energy a top priority. "But there is no market yet for ethanol- [or butanol-] based fuels in the state of Maryland," says Kangas. There are a few service stations that provide biodiesel, but that's it. Unlike in the Midwest, Maryland has no ethanol plants and only a handful of biodiesel plants that run on poultry carcasses and waste vegetable oil. "We are really at the beginning," Kangas says.

The choice of a plant for butanol, rather than ethanol, is unusual, since even beyond Maryland butanol doesn't yet have a market. But Adey's looking toward markets of the future. Butanol can be used as a direct, 100 percent replacement for gasoline, whereas ethanol is more volatile and needs to be mixed in with gasoline at 10 percent. Because it is less volatile, butanol can also be transported more easily.

Adey's collaborators at Western Michigan University and the University of Arkansas have identified a bacterial fermentation process to make butanol and hydrogen from algae, with the additional capability to remove oils to produce biodiesel. They are working now on fine-tuning a bacterial fermentation protocol called the Ramey Process. The algae vacuumed off the Algal Turf Scrubber system first will be processed to extract algae sugars and then fed directly to the biofuel reactor.

Cost and Benefit

According to Adey's master plan, biofuel production would ultimately help fund nutrient management in the Chesapeake. But setting the various pieces in motion will require a significant startup investment. The construction of a biofuel plant at the proposed 12-acre Algal Turf Scrubber site would cost roughly $1.3 million. The prospect for securing funding for the plant looks good. Adey has recently joined with a large group of scientists at the Virginia Institute of Marine Science and the College of William and Mary, as well as a consortium of engineering companies, to move the project forward. The William and Mary Research Institute has presented proposals to the Norwegian oil company Statoil, the U.S. Department of Energy, and Exelon to expand the pilot to a larger scale. But making a biofuel from algae is expensive. The cost of chemical conversion runs about $2.00 per gallon, and that doesn't include the cost of producing the algae. Though at this point the technology works well, and many companies are claiming that they can do it, the economics don't necessarily follow suit, says Adey. "We're not there yet. We can't make a biofuel from algae used to take nutrients out of the Bay and make a profit doing it," he says. "Not yet." Not unless we also get paid to remove the nutrients, he says.

But the country may be fast approaching a tipping point, says Adey, a tipping point that would make them willing to try bold new ideas. "People have to be afraid enough to try innovation. This is what has happened with energy," he says.

The key, says Adey, will be to link the cost of nutrient management directly to the production of biofuels. He offers the following scenario. Current estimates suggest that it costs $200 per kilogram to clean up phosphorus and $10 per kilogram for nitrogen. Suppose you invest half of this amount toward developing the 3000-acre Algal Turf Scrubber system and, at the same time, establish a nutrient trading program. Since the scrubber technology can remediate phosphorus for $25 per kilogram — roughly one-tenth the usual cost — and remove five times the amount nitrogen as phosphorus at the same time for no additional cost, this investment would completely cover the costs associated with biofuel production.

A nutrient trading system would also provide a strong financial incentive for farmers to maintain scrubber systems on their land. "In a trading system, one polluter buys credits from another," explains Dan Nees, the director of the Chesapeake Clean Water Fund, which focuses on establishing a market for improved water quality in the Bay. Nutrient trading functions much like the emerging carbon trading market, where emission credits can be bought and sold within a total allowable cap. Under such a system, if a farmer implements Best Management Practices on his land, such as cover crops or Algal Turf Scrubber systems, he can earn a profit by selling those credits to a farmer that chooses not to reduce his nutrient load, Nees explains.

Building Capacity for
Biofuels in the Bay
Next Generation of Biofuels Biofuels And The Bay
THE CHESAPEAKE REGION is aiming to position itself as a leader in the biofuel arena. [more]

A water quality market for nutrient trading in the Bay is still in the early stages, but if it's going to happen anywhere, it will be in the Chesapeake, according to Nees. "I think we are in the area with greatest opportunity to make it happen," he says. Groups such as Forest Trends, the World Resources Institute, and the Chesapeake Bay Foundation are actively exploring mechanisms to create such a market. "We have big opportunity in front of us," Nees says, "but we have a lot of work to do."

In Adey's vision, the biofuel piece of the equation could help jumpstart the revenue stream necessary to set a nutrient trading program into motion. Once the demand for biofuels really takes off in the marketplace — and Adey is confident that it will — producing a biofuel will become more profitable. Then incentives will grow for farmers to use the scrubber technology to supply algae for biofuel production, as well as to earn nutrient reduction credits for their efforts.

"We have a real shot," Kangas agrees. "We think this can clean up the Bay and produce biofuels at the same time."


Finished with his oxygen and pH measurements for the next several hours, Kangas heads off to speak with Tim Goertemiller and his crew, who are on site for the day working to construct a second pilot Algal Turf Scrubber raceway. He makes his way around pieces of wooden track laid out for assembly, navigating a narrow space between the existing raceway and a chain link fence. The air is pungent with the sharp smell of sealant, applied to the seams of the raceway to make it watertight.

The second raceway, which will soon be raised on aluminum stilts next to its neighbor, offers an opportunity to further refine the scrubber design for the Susquehanna River before advancing to the 12-acre pilot. Unlike the first design, the base of this new raceway has a series of heating coils, which help keep the test system from freezing during the cold winter months. Ultimately, the multiacre systems will lie flat on the ground where they will be less likely to freeze. Kangas is also working with Adey's graduate student, Dail Laughinghouse, to seed the mesh of the new raceway with Cladophora, the more branched species that he had hoped would dominate in the other scrubber.

The project is gaining steam. Adey just received word that the Norwegian petroleum giant Statoil plans to provide funding to the biofuel component of the project through the William and Mary Research Institute. With further help from the Department of Energy and Exelon, the team of scientists and engineers from the Virginia Institute of Marine Science and William and Mary will help hone the process for converting algae to butanol and biodiesel and help support an estuarine and offshore scrubber system that the team is developing in the lower Bay. The scientific team will also study the size and placement of the scrubbers to maximize their impact on the Bay's health. Thirty years after Adey completed the initial design for the Algal Turf Scrubber technology, he is starting to see the fruits of his efforts.

"Walter sees this as his legacy," says Kangas. "As he gets older, he wants to do something that will really make a difference." Even five years ago, no one was really thinking about biofuels. In 2004, project leaders anticipated that the algae harvested from Algal Turf Scrubber system at Taylor Creek would be considered waste and hauled away, increasing the cost of the project by more than 30 percent. But today the emerging biofuel market is what will help make the nutrient management merits of scrubber system financially feasible, Kangas says.

"[Adey] is a bold thinker. He came up with this idea that we could do away with the dead zone in the Bay by having all of these Algal Turf Scrubbers," says Kangas. Effects on that scale might still be a long ways off. But "you can see it," he says. "It is happening right here."

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March 2009
vol. 8, no. 1
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