Songs in the Key of Green
Piano Manufacturer Installs World’s Largest Rooftop Solar Thermal Array
|The solar troughs are curved (U-shaped) mirrors made of aluminum and steel with a steel absorber tube mounted along the trough’s center. The tube is filled with a water/glycol mixture. (Photo courtesy of Steinway & Sons.)
Steinway & Sons, the company that perfected handcrafted pianos for the country’s top concert halls, is now putting the same passion and effort into an innovative renewable energy system.
The $875,000 project is constructing the world’s largest rooftop solar thermal array at Steinway’s 11-acre Long Island City, N.Y. facility. The operation employees 400 people making 1,500 pianos a year.
When completed in late spring, the system will pump superheated water from the solar arrays to an absorption chiller. Chilled air produced by the system will dehumidify the factory, lowering moisture levels that can damage wood components integral to making pianos.
When dehumidification is not required, the superheated water will generate steam for space and process heating.
The project started four years ago when Steinway enlisted Energy & Resources Solutions, Inc. (ERS), Haverhill, Mass., to perform an energy study of its facility. During a meeting discussing results of the study, ERS suggested the solar thermal project.
ERS had recently completed a study for the New York State Energy Research and Development Authority on the feasibility of solar thermal projects in New York, says Mark DiAntonia, ERS vice president of engineering operations. NYSERDA agreed to a follow-on project, sponsoring ERS to find a demonstration site for the technology.
Steinway’s operation was well-suited for the demonstration project. The facility’s flat rooftops can accommodate the solar arrays and the company’s year-round requirements for dehumidification and/or heat fit well with solar thermal technology.
“They need heat for process and space heating,” DiAntonia explains. “But they also have a process cooling requirement for space conditioning to control humidity in their action department.”
The action department crafts a piano’s action mechanism, which causes a felt hammer to strike the piano’s strings when a key is depressed. Manufacture of the hammers and intricate wooden components comprising the mechanism is highly sensitive to changes in moisture.
Steinway expressed interest in the solar thermal project but needed to understand the economics. With funding from NYSERDA, ERS conducted a conceptual design and economic assessment of the system, which proved favorable.
The economics sold Steinway on the project, says Bill Rigos, Steinway’s Facilities manager. “It really has to make business sense for any company to actually embark on a project like this.”
Funding for the system is provided by a $266,000 grant from NYSERDA and $209,000 in accelerated tax credits. Steinway is contributing the remaining $400,000.
Savings from replacing purchased power with solar energy is estimate at $45,000 to $55,000 per year, Rigos says. “We are hoping for a payback between four-and-a-half to five years.”
Steinway’s solar thermal system is composed of 38 parabolic troughs occupying 22,000-sq.-ft. of roof space. Each trough is 7.5-ft high by 20-ft long and weighs about 280 lbs. Abengoa, a Spanish company, manufactures the system.
|Lifting the solar troughs to the roof presented a few logistical challenges. Sunshine Plus Solar needed to develop new strapping methods to hoist the material to the roof. (Photo courtesy of Steinway & Sons.)
The troughs are curved, U-shaped mirrors made of aluminum and steel with a steel absorber tube mounted along the trough’s center. The tube is filled with a water/glycol mixture and surrounded by a glass envelope that insulates the tube. An anti-reflective coating on the glass increases transmittance of light to the absorber.
Sunlight is reflected off the trough to the absorber tube. Concentrating solar energy on the absorber tube causes the fluid in the tube to get quite hot and do so quite efficiently, explains Ken May, division director at Abengoa Solar, Lakewood, Colo. At peak conditions, the fluid can reach 350 degree Fahrenheit (F).
During the day, a tracking system connected to a mechanical drive rotates the troughs to follow the sun. Sensors on the troughs communicate with a computer that optimizes the troughs’ positioning relative to the sun.
The troughs sit on an eight-inch concrete roof slab. The roof, originally designed to support addition floors, was structurally sound and didn’t require reinforcement to support the troughs, says Kevin Creamer of Sunshine Plus Solar, Babylon, N.Y., the solar installer.
Fastening the troughs to the roof presented some engineering challenges. “Troughs are normally mounted on the ground,” DiAntonio explains. “There are considerable wind loads on these collectors when you mount them high up on a building.”
Designing the appropriate anchoring system to withstand wind gusts of 100-mph was complicated by the condition of the concrete slab, which contained an unknown level rebar, DiAntonio explains.
To secure the troughs the engineering team devised a system of anchors fixed to the concrete and a support system that goes through the concrete, Rigos says. To further cut down on the wind, the roof’s 3.5-ft parapet wall will be supplemented with a fence.
During the summer, superheated fluid from the troughs will be pumped to a 99-ton Broad double effect (2E) absorption chiller with dual energy input. “The system will work akin to a conventional absorption chiller, except that solar troughs replace the boiler,” explains Kevin Duffy, project engineer, Schuyler Engineering, Lindenhurst, N.Y.
|The solar thermal troughs were laid out on the roof prior to mounting on steel pylons. Each trough is 7.5-ft high by 20-ft long and weighs about 280 lbs. (Photo courtesy of Sunshine Plus Solar.)
The chiller runs on a thermal water source (from the solar arrays) or an integral natural gas burner or both in parallel. “The system is always going to look for the high temperature water from the arrays,” Duffy explains. “But on cloudy days or when the system can’t provide adequate hot water, it will automatically kick on the gas.”
Steinway selected the 2E chiller because it is more efficient. “A single stage chiller has a coefficient of performance (cop) of 0.7 and runs at temperatures from 200 to 220 degrees F,” May explains. “The cop of a two-stage (2E) chiller is 1.2 to 1.3, almost double what you get with a single stage chiller. To get the higher efficiency requires higher temperatures, so you need water at 320 to 330 degrees F.”
“During the summer the absorber will get first crack at the high temperature water,” Duffy explains. “Anything left over will go to the steam generator.” When humidity is not an issue, all of the superheated water will produce low pressure steam for space heating or for use by kilns that dry wood for the manufacturing process.
Integration and Monitoring
Duffy’s team is integrating the system components. “We are putting in the auxiliary equipment for the high temperature water system and the air handlers for dehumidification in the action room, laying out the piping and selecting the pumps and other components to make the system functional.”
The NYSERDA grant requires the project to track and to report on system performance. The solar troughs come with an integrated monitoring and control system. But there are no canned packages for the controls that marry the solar array to the chiller, the downstream chilled water supply, the cooling tower and other components, DiAntonia explains.
GCF, Inc. of Montvale, N.J., is custom developing the controls for the system and tying them into Steinway’s building information system. The controls for the solar arrays will also be integrated with the building system.
“Steinway has invested a lot of priceless time into the system,” Rigos says. “You really have to have a passion for this stuff. We are not the people who invented the piano but we are the people who perfect it. Now we are going down the same road trying to perfect solar thermal.”
Owner: Steinway & Sons, Long Island City, N.Y.
Energy Consultant: Energy & Resources Solutions, Inc., Haverhill, Mass.
Solar Installer: Sunshine Plus Solar, Babylon, N.Y.
Solar Array Manufacturer: Abengoa Solar, Lakewood, Colo.
MEP Engineer: Schuyler Engineering, Lindenhurst, N.Y.
Controls Contractor: GCF, Inc. of Montvale, N.J.