Today, the blades on energy-generating wind turbines are all made in the same shape. Researchers have found that changing the shape of the blades throughout the field could improve their efficiency, but the cost of creating different tools for each blade have been too high.
“We’re trying to show that with large-scale additive manufacturing you can significantly reduce the cost of the tooling so that you can have as many different types of blade designs as you want,” says Lonnie Love, corporate fellow and group leader, ORNL’s manufacturing systems research group. Researchers at the Manufacturing Demonstration Facility are currently using ORNL’s Big Area Additive Manufacturing (BAAM) equipment to print tools for 12 different 50-foot turbine blades.
Tool manufacturers now start with a fiberglass, foam or wood plug, then coat it with fiberglass to produce a long, thin mold that requires a steel frame to support it. The process takes many months and costs can exceed a million dollars. When it’s time to actually produce the blade, the manufacturer must integrate long runs of heating wires on the tool’s backside to heat up the resins and cure the composite part.
With BAAM, ORNL produces the tool directly. The 3-D printed design includes air ducts where heaters and blowers can be inserted to cure the resins, so there is no need for the extra wiring for heating. The printed tool is structurally supportive, too, so it doesn’t require a metal support cage.
“We are removing many of the steps that they typically have to go through for manufacturing molds, cutting costs and enabling them to innovate a lot faster than they’ve been able to do in the past,” says Love. Manufacturers are most excited about the time saving potential; while conventionally produced blade tools takes months, even a year to produce, BAAM can produce a tool in about a week.
Love expects the final cost of the 3-D-printed molds to be very close to the costs of conventional production. ORNL researchers are looking at ways to reduce them even more by using glass fiber instead of carbon fiber to reinforce the polymers. That could cut the materials costs in half, making additive manufacturing even more attractive.
When the molds are complete, ORNL will ship them TPI in Fall River, Mass. After TPI makes the blades, it will ship them to a wind farm in Texas. Transporting blades is expensive – 20 to 30 percent of their production cost – but additive manufacturing might be able to help there as well, says Love. Manufacturers might someday be able to move the additive manufacturing tool-printing equipment and the blade production facilities from wind farm to wind farm as needed.