Concrete foundations "greener" than rivals, study claims

Gravity bases have smaller carbon footprint than steel jackets

The production of concrete gravity base foundations for offshore wind turbines is a far greener process than that for steel jacket turbine foundations, a study published today claims.

According to the study by The Concrete Centre, which examined the resources used in the production of turbine foundations from cradle to grave, the average carbon footprint for six different concrete gravity base solutions was an estimated 1,186 tonnes CO2 per unit. This compared with an estimated steel jacket carbon footprint of 2,771 tonnes CO2.

The study was set against requirements for a deep-water installation of a 5MW turbine at 42m depth, 50km offshore, with a manufacturing facility to build a batch of 200 foundations and five units per visit for ballasting, scour and seabed preparation — where required.

"This is a comprehensive study that set out to determine the CO2 impact of a concrete gravity base foundation against a comparable steel jacket foundation," said Andrew Minson, executive director of The Concrete Centre, part of the Minerals Products Association. "Offshore wind farms represent low-carbon solutions so it is important that their major foundation element can support and underline this representation."

The majority of installed offshore wind capacity sits on steel monopile foundations. However, as Eize de Vries points out in Windpower Offshore’s recent special report on Foundations, projects across Europe have experienced problems with slippages of the transition pieces that connect the turbine tower to the monopile.

As a result, offshore developers are searching for alternatives to the monopile, with concrete gravity bases and steel jacket foundations leading the field.