The beeping is like the sound a metal detector makes before it hits the mother lode. But this steady little chirp has a loftier purpose than ferreting out lost coins: It’s measuring wind speed.
City officials and environmentalists are hoping the sonic detection and ranging, or SODAR, machine will show that there is enough wind out at the South Essex Sewage District to push the blades of an alternative power-producing turbine. If there is, Salem could be in line to qualify for a $400,000 grant through the Massachusetts Energy Consumers Alliance to pay for it.
For now, a 6-foot-by-6-foot SODAR machine, which weighs from 150 to 200 pounds, is scheduled to go up on a building at the South Essex Sewage District next week. It will remain there for two months, then return sometime in the spring for another two-month stint.
“We’re primarily interested in looking at the wind speed at the location and then, secondarily, the wind turbulence and intensity, or the gustiness, of the wind and wind direction,” said Chris Clark, a senior project manager at the Massachusetts Technology Collaborative, which is funding the study. “Annual average wind speeds in excess of 6.5 meters per second, or 14.5 miles per hour . . . [and] at a height of 70 meters above ground are required for a wind project like this to be economic.”
That means there needs to be enough of a breeze to move dust, loose paper, and small branches. The SODAR device will measure the wind by sending an acoustic signal aloft and then listening for a return sound, Clark said.
The sewage district was chosen by city officials from nine potential sites in the city. The others were Winter Island, Salem Willows, Forest River, Salem High, Bertram Field, Salem Greens, and the Bentley and Saltonstall schools.
“They are such a large power user: They have big pumps at that facility. They spend a lot in electricity now to power those up,” Mayor Kimberly Driscoll said of why officials decided to test the South Essex Sewage District as the leading site for a turbine. The sewage district, she added, treats domestic waste from five communities, so any energy savings garnered from the wind turbine could lead to savings for energy consumers in Beverly, Danvers, Marblehead, and Peabody as well as Salem.
If the wind-measuring study at the sewage district is successful, officials then would look at how to buy, transport, install, and operate a turbine, which Clark said could be up to 240 feet tall. Such a turbine could produce about 500 kilowatts of power, depending on the amount of wind.
Driscoll has said she hopes to fund the turbine with a $400,000 grant from the Massachusetts Energy Consumers Alliance. The alliance procured the funds from Excelerate Energy, the company building the Northeast Gateway LNG offshore terminal about 13 miles southeast of Gloucester. The money is meant to mitigate the onshore and offshore impacts of the terminal.
If the city is not awarded the grant, Driscoll has pledged to apply for other funding through the Massachusetts Technology Collaborative and search for an entity willing to become a partner with the city on the project.
“Why do we want one so badly?” she asked in a phone interview. “We just see this as a natural outgrowth of some of the steps we’ve already taken.”
Those steps include forming a renewable energy task force and purchasing hybrid cars and BigBelly trash compactors that run on solar energy. “We’re leading the effort,” she said, “but clearly there is a community here that wants to see a greater emphasis on renewable energy.”
By Erin Ailworth
17 January 2008