The "very long blade project" is being developed with the Energy Technologies Institute (ETI), a research and development body set up by the UK government in conjunction with private companies.
The project was proposed by the ETI in 2011 and launched in partnership with UK blade company Blade Dynamics in January, with the aim of developing long high-performance blades for the next generation of large offshore turbines.
The modular blade incorporates carbon fibre rather than the usual fibre glass in order for the blade to deal with the greater stresses it will undergo due to its exceptional length. The material will also help reduce the weight of the blade by as much as 40%, claimed the ETI.
A scaled-down 80-metre prototype of the blade has now been designed, and work on constructing the blade has begun at Blade Dynamics' plant on the Isle of Wight in the south of England.
The prototype is expected to be completed by the end of 2014 for static and fatigue testing to take place.
The blade has been designed specifically for the SWT-6MW machine, with the prototype blade ultimately destined to be tested on one of the turbines.
If a full-size blade is produced, it is expected to be the largest in the world.
Andrew Scott, programme manager for offshore wind at the ETI said: "The ETI's vision is to support the development of next-generation blade technology because improved rotor performance is fundamental to achieving the goal of reducing the cost of offshore wind energy."
David Clarke, ETI chief executive, added: "Creating very long blades with the right stiffness and aerodynamic performance while maintaining an acceptable cost is a huge challenge for the industry and is going to need the best design and manufacturing team."
ETI announced in January that it has invested £15.5 million (EUR 18.4 million) in the project.