Clipper Windpower Plc has announced that it has entered into a design agreement with Northstar Wind Towers to provide a high-quality cost-effective tower design option that enables taller (from 80-120 meters)  wind turbine towers.

Under the terms of the design agreement, Northstar will produce a tower design certified by Germanischer Lloyd for utilization with Clipper's 2.5MW Liberty wind turbine. The taller tower will be an option that will become available for turbine sales in the 2009-2010 timeframe. The Northstar tower design is based on the modular application used in bridges and high-rise structures. Modular steel sections are held in place by slip-critical, or "friction" connections. Tower appearance is similar in form to standard tubular tower designs.