BOSTON--The Museum of Science in Boston shared data Tuesday for an experiment it's conducting on small wind turbines. Five turbines have been operating on the museum's roof for the past several months, three of which you can see here.
The bottom line on the return on investment is that this location does not have enough wind to make the turbines economical, according to the museum. However, the wind turbines are gathering data for a wind lab and an educational exhibit in the museum. And wind professionals from the area, and even around the country, are interested in the museum's experience with the different technologies and permitting processes.
The small wind lab at the Museum of Science quickly discovered that the wind resource on the roofs of the museum buildings was moderate, and not sufficient to deliver a compelling return on investment. As an educational endeavor, though, the project is still providing information, including data on the performance of the five different turbine types.
This Skystream small-wind turbine from Southwest Windpower, one of the more popular products, has been shown to perform as advertised, according to the staff of the small-wind lab. This turbine was the closest to being plug and play, the staff said.
Here's a closer look at the Windspire vertical axis turbine from Windspire Energy, with the Leonard Zakim Bunker Hill Bridge in the background. The product first came out last year, and the manufacturer was willing to donate one of its first turbines to the museum's experiment.
The turbine, made of aluminum air foils, is actually designed in three sections, which reduces stress on the structure when there's a significant difference in wind speeds between the top and the bottom of the turbine. Though it spins even in slow winds, it doesn't start generating electricity until wind reaches 8.5 miles per hour.
The size of this turbine from Proven Energy in Scotland made it a challenging installation job, which required structural engineers and the metal footing you see here. A solid foundation is required for safety reasons, but also because the turbine is placed above a domed Imax theater. The Museum of Science wanted to ensure the turbine didn't cause vibrations or noise, which it hasn't. The building on the left is the Boston Garden.
This view of the back of the Museum of Science shows a bank of fanlike small wind turbines from Aerovironment on the roof. These turbines, which are also installed at Boston's Logan airport, didn't perform as well as they should have, according to the museum, and had technical problems, including a broken fin.
This view shows the complex nature of the Museum of Science project, where there are eight different buildings on top of a dam at the mouth of the Charles River. Permitting was challenging, as the site is half in Cambridge and half in Boston and the landlord is the state's parks agency.
This a closer view of the Aerovironment turbines and their placement on the building. The idea is to have banks of these turbines on the roof edge of buildings, where they can capture the energy of gusty wind that comes up the sides of buildings. The wind installers did a study of the "pressure waves" from gusty wind but said they have been disappointed with the results of these turbines.
This Swift turbine, which has a ring around the fans to cut noise and vibration, has not come anywhere near to operating according to the manufacturer's power curve, or expected power at different speeds, according to the Museum of Science's wind lab. But the wind lab realized late into the project that the location of this turbine is very bad for capturing wind, so it might work perfectly well in other locations.
Also visible here, on the left, is an anemometer for measuring wind speed, which is logged, and the bank of Aerovironment turbines, on the right.
This picture shows how software designed for computational fluid dynamics can be used to visualize wind. This model, created by software company Ansys, showed--too late, as it turned out--that the location for the Swift turbine was the worst possible spot on the museum's roof because of wind turbulence. Based on this visualization, the turbine was put on a higher tower and moved a few feet. Though these visualizations are very helpful to understand wind flow, they are meant as a complement to gathering actual wind data.
To give an idea of size, here's one blade from a Skystream small-wind turbine from Southwest Windpower. It's made of fiberglass and is very light but can withstand winds of more than 100 miles per hour.
The Museum of Science has also invested in this rooftop solar array on the back of the building, which has proved to be much better economically compared with the small wind turbines, the museum said. But the array is less visible. The five turbines, on the other hand, make a "terrific landmark," said David Rabkin, the director for current science and technology at the Museum of Science.