The University of Virginia School of Engineering and
Applied Science is currently researching the viability for a
large Segmented Ultralight Morphing Rotor (SUMR), which
is funded by the Department of Energy’s (DOE) Advanced
Research Projects Agency-Energy (ARPA-E) program.
Recently, the agency awarded a three-year $3.56 million
federal grant to a team led by Professor Eric Loth, Chair of
the Department of Mechanical and Aerospace Engineering.
His team will use the grant to build a small-scale prototype of
the SUMR wind turbine.
The project also includes researchers from the University
of Illinois, the University of Colorado, the Colorado School
of Mines, Sandia National Laboratories, and the National
Renewable Energy Laboratory.
“There are multiple aims of the project, the biggest one is
driving down the cost of energy for offshore wind,” explains
Todd Griffith, lead blade designer on the project and
technical lead for Sandia’s Offshore Wind Energy Program.
“The blade length we’re proposing is 200-meters. By going
larger, we anticipate the cost of energy will come down.”
In theory, the ultralight segmented rotors could produce
enough energy to power a small town. “One megawatt will
power roughly 300 average U.S. homes; so a 50-MW wind
turbine will power 15,000 average U.S. homes. A farm of
these could power a sizable city,” muses Griffith.
A Palm Tree Design
Currently, a 50-MW wind turbine doesn’t exist. The
latest advancements only produce 8-MW and 10-MW
with a standard three-blade design. If Loth and his team
are successful, the DOE could attain its goal of providing
20 percent of the nation’s energy from wind by 2030, as
outlined in the recently updated Wind Vision Report.
According to Loth, the U.S. will need to start taking
advantage of its offshore wind resources to accomplish
the DOE’s objective. However, offshore installations are
expensive, meaning turbines must become larger to capture
energy at an affordable price.
“These turbines will be much bigger and more powerful
than anything in production,” says Loth. “Not ten percent
more powerful, but ten times more powerful than the largest
turbines in the U.S.”
Unfortunately, at about 10-MW, weight and gravity
becomes problematic, which forced the researchers to
propose an outside-the-box design. Their solution, inspired
by palm fronds, utilizes blades that face downwind and fold
together in dangerous weather.
“Under storm loads – for example, hurricanes – the blades
will fold up, similar to the way a palm tree will fold up under
a hurricane,” says Griffith. “I refer to this as a natural defense
The concept incorporates a vertical plane geometry at
below-rated speeds and then converts to a load-aligned
downwind deflection between rated speeds and cutout
speeds. The design relies on curvature and coning to
balance gravity, aerodynamic, and centrifugal forces.
Anovel design for enormous 200-meter-long blades could help bring offshore 50-megawatt
(MW) wind turbines to the United States.
If constructed, the blades would be longer
than two football fields and span two and
a half times longer than any wind blades
By Kaylie Duffy, Associate Editor
Eric Loth poses with a model of the SUMR wind
turbine. Image courtesy of the University of Virginia
School of Engineering and Applied Science.