The river runs through it

“The focus on renewable energy started about 15 years ago. At that time the lab made some strategic investment in renewable energy and environmental fluid mechanics, and over the years that has grown rapidly and now it has become one of the major research thrusts of the lab.”

Of the hundreds of thousands of people each year who traverse the historic Stone Arch Bridge—the iconic transitway in Minneapolis offering Instagram-worthy views of the downtown skyline, joggers, pets, and of course St. Anthony Falls—very few would ever exclaim, “Oh look, there’s St. Anthony Falls Laboratory!”

And if they did, precious fewer could tell you what goes on there.

But since 1938, this aesthetically challenged building nearly adjacent to the falls has taken advantage of the natural 50-foot drop in the river to research and teach all things fluid mechanics, with a special emphasis on the environment, energy, and renewable energy.

“The scope of the research in the lab is very wide and includes atmosphere, oceans, lakes, rivers, and groundwater,” says Lian Shen, director of SAFL and professor in mechanical engineering. “We are looking at environmental issues including pollution, plus renewable energy—wind energy and hydrokinetic energy—and more. There are a lot of processes in the Earth’s surface related to fluid flows, and that is what we try to address.”

Over its 82-year existence, SAFL (a part of the College of Science and Engineering) has hosted and conducted more than 500 major research projects. It currently houses 15 affiliated faculty members from 4 departments, 39 research and administrative staff, and 46 students.

For students, the lab is a huge draw; it can be one of the main reasons they come to the University of Minnesota. The projects at SAFL are interdisciplinary to the Nth degree, engaging students and researchers from CSE departments including civil and environmental engineering, mechanical engineering, earth and environmental sciences, and aerospace engineering and mechanics—all working alongside one another. And their hands-on research often leads to jobs in the industry.

“Nationally, it’s very well known,” says Mirko Musa, who earned his PhD from the University in 2019 and now works in hydropower at a U.S. Department of Energy lab in Tennessee. “Every time we talk about hydropower and we go back to the old manuals to look, there’s always a reference to somebody that did some work at SAFL. So we always refer to the groundbreaking work that’s been done there.”

“The lab is incredible in many different ways,” adds Musa, who came to the United States and to SAFL after obtaining bachelor’s and master’s degrees in Italy. “For research, it’s one of the most renowned hydraulic labs in the world. If you’re talking about St. Anthony Falls [Lab] to a hydraulic professor anywhere in the world, they know what it is.”

Originally called the St. Anthony Falls Hydraulic Laboratory, the vision for the building was brought to life by Lorenz Straub, a scientist who was well known internationally and who gained the nickname of “the river doctor,” according to Barbara Heitkamp, communications specialist for SAFL.

It was built using funding from the WPA (Works Progress Administration) on the site of the former Minneapolis Pumping Station (some remnants of which are still visible) and completed in 1938. Straub was SAFL’s director till his death in 1963.

Before the pandemic, SAFL offered monthly in-person tours to visitors, and you really need a tour to take in all the features.

There are seven flumes and channels, five model basins, two water tunnels, one wind tunnel (the site of fascinating atmospheric research), three calibration facilities, and the Outdoor StreamLab (see sidebar below).

(There’s also a vintage 1938 auditorium complete with stiff wooden chairs for old-time’s sake, and plenty of reminders of the building’s origins during the Great Depression.)

Every second there are 2,200 gallons of water running through the lab to drive the water flumes.

Water from the reservoir just upstream flows through the building, “and the amount of water is huge,” Shen notes. “Every second there are 2,200 gallons of water running through the lab.”

The main channel is 250 feet long, was designed by Straub, and is one of the largest research channels in the United States. “We have people coming from all over the U.S. and the world to use this facility,” says Heitkamp.

Not only is it built to take on a steady flow of river water, it also was designed to accommodate flooding. The lower level of SAFL is frequently underwater—waterproof equipment and all—come spring flooding. There are plaques on the wall showing water levels during the major floods of 1952 and 1965—the latter about six feet off the ground—and a video celebrates the recreation options occasionally available for staff.

But what’s most noteworthy about SAFL is its focus on addressing problems of the day while pursuing solutions for the future. “One of the missions for the lab is to address major societal challenges associated with fluid flow problems in the natural environment and in renewable energy applications,” Shen says.

“The research that we do here really plugs into what people are thinking about at the moment,” adds Heitkamp. “The media talks about all these scary, big, complex problems, but there are really amazing and smart people working on [them here], and that’s a really inspiring thing to be able to come to work to every day.”

Even though the building she works in is, as she describes it, rather “nondescript.”

“The cool thing about SAFL is, you never know what’s going to come in the door next,” she says.

Except the river that it’s built on. That’s a given.

The Outdoor StreamLab (OSL) is literally SAFL’s most visible research feature; the meandering stream and the sun-worn signage can be seen from the Stone Arch Bridge. The OSL is essentially a hybrid of field and laboratory, allowing researchers “to study flow and sediment movement, nutrient dynamics, and stream biota, and their interactions in streams,” says Jess Kozarek, research associate at the OSL for the last 10 years.

“It’s unique in that our location next to St. Anthony Falls allows us to collect laboratory-resolution measurements in this field-scale stream. That really doesn’t exist anywhere else.” --Jess Kozarek, research associate at the OSL

Over the years Kozarek has trained some 40 undergraduate students—with a wide range of academic backgrounds—in stream restoration methods, nutrient dynamics, and remote-sensing techniques. “[OSL] allows us to bring many undergraduates into the research process,” she says.

One big project studied native freshwater mussels and their reactions to flow and sediment transport—research that’s important because “freshwater mussels are a good indicator of the overall health of our rivers and streams, but they’re often hidden in the riverbed and we can’t see what’s happening with them,” Kozarek says.

She adds that working with undergraduates is by far the favorite part of her job. “To watch students grow through learning about the scientific process and how to collect, analyze, and interpret data and move on to the next steps is really a fun process.”

Back in 2009, the University of Minnesota was part of a consortium that received a large U.S. Department of Energy (DOE) wind energy research grant. As part of that, the U of M dedicated a $5.5 million, 2.5-megawatt wind turbine, named the Clipper Liberty, at the EOLOS wind energy research field station in Rosemount.

At 426 feet from the base to the tip of an extended blade, the wind turbine dwarfs everything in the vicinity but its companion meteorological tower, which aids in measuring atmospheric conditions at the site. “We have been able to measure the data in the atmosphere around the wind turbine continuously since 2012,” notes Shen.

While the turbine generates power for a local grid, what makes it really stand out is its role in the next generation of wind energy research. DOE’s vision was for universities to work with industry and other partners to test ideas for wind energy improvements in the field, as opposed to on computers or in a lab.

And over the years EOLOS has collaborated with industry partners including 3M, Lockheed Martin, Barr, and Xcel Energy, plus other universities and governmental agency partners. You can learn more about EOLOS wind energy research.

Turbines in the river

While traditional hydropower from dams is recognized as a clean, renewable energy source, it can significantly affect overall river flow, sediment transport, and the general ecology of waterways. So SAFL is exploring new technologies that keep environmental impacts to a minimum. One emerging technology is in-stream turbines, which harness the flowing water of tidal channels and rivers to produce electrical energy.

Picture a wind farm on the floor of a river, and imagine the potential energy gains with a relatively invisible footprint. Mirko Musa, who obtained his PhD at the U of M and worked on in-stream turbines at SAFL, is excited about the potential.

“Rivers are ubiquitous, and cities grow around big rivers,” Musa says. “Also, rivers flow 24-7; it’s not like wind, where sometimes it ‘flows’ and sometimes it does not. You always have a source of energy.”

Musa studied that potential for hydrokinetic energy in rivers while at SAFL. “Specifically, I was looking at the interaction between these in-stream turbines and the physical environment. We were looking at the local effect that a pack of these turbines could induce on a river system.”

Through experiments in different flumes and in SAFL’s main channel, he said they discovered that it’s very likely the turbines would be installed on just one side of a river, but that packing on one side may lead to “non-local disturbances,” i.e., changes in the river shape.

“We realized that the installation of these turbines in rivers is feasible, and we can reduce the potential harmful environmental effect by reducing the width of the array of turbines—the lateral obstruction within the river.”

And it’s not just Musa and SAFL excited about the new technology. A year ago Musa landed a job working in hydropower at the DOE’s Oak Ridge National Lab in Tennessee, and he knows firsthand that the U.S. is looking at in-stream turbines “to complete their portfolio of renewable energy.”

“The cool thing about SAFL is, you never know what’s going to come in the door next.”

Heitkamp’s handy tagline for the laboratory certainly rings true.

Case in point: the new watersport of wakesurfing—in which wakes generated by speedboats are large enough to surf on—has surged in popularity on lakes in Minnesota and beyond.

But while big wakes are a boon for wakesurfers, they’re not as warmly received by small watercraft like canoes and kayaks, and there’s a concern as to their effect on lake ecology.

So this late summer and fall, SAFL will be researching the impacts of boat wakes and propeller wash on shorelines and lake bottoms in a research project funded entirely by interested community members and organizations. Through the URaiseMN crowdfunding site, the project has raised more than $103,000, exceeding the fundraising goal.

“What’s unique about SAFL is that we have a robust research team, and we work on problems like this that affect Minnesotans and affect Midwesterners,” says Jeff Marr, associate director of engineering and facilities at SAFL and a University of Minnesota alumnus. “It was nice to confirm that we’re accessible … and we do our best to respond to those needs.”

Researchers will place calibrated sensors in lakeshore environments typical of Minnesota to measure wave heights, wave energy, turbulence, and other variables. They’ll also test to see how propeller wash (the backwash of a propeller) affects the lake bottom and its vegetation, and how it stirs up sediment.

As funding allows, SAFL will also work toward designing a simple and affordable open-access system that organizations can use to monitor waves on their own lake of interest. That will lead to citizen science—much like the U of M has helped develop with aquatic invasive species detectors in Minnesota—and the development of a statewide wave and boat-wake monitoring program.

“The topic is of interest,” Marr says, and “there’s a real need for data as soon as possible.”

Learn more about St. Anthony Falls Laboratory.