Carbon Brainprint Case Study: novel offshore vertical axis wind turbines

As part of the transition to a ‘low carbon economy', renewable technologies are expected toplay an increasing role in reducing dependence on fossil fuels for energy and electricity. Windpower in particular is likely to become a much larger contributor to the UK's energy mix. Thecurrent dominant design for large, grid-connected wind turbines is a three blade rotor with ahorizontal rotating axis. The concept of a vertical axis wind turbine (VAWT) is relatively new, buthas several advantages over horizontal axis alternatives. It is able to capture the wind from anydirection, and the vertical axis is such that the rotor equipment is located at base level, makingit is simpler and less costly to install and maintain.

The Energy Technologies Institute (ETI) is a UK-based company formed from global industriesand the UK government. One of three projects looking at new turbine design and concepts foroffshore wind is the Novel Offshore Vertical Axis (NOVA) project, a UK-based consortiumlaunched in January 2009 to look at the feasibility of a NOVA turbine.

achieved through the installation of NOVA wind turbines, in comparison to conventionalhorizontal axis wind turbines (HAWTs) for offshore power generation. The increased powerrating of the NOVA turbines compared to current HAWTs is expected to provide considerablereductions in lifetime greenhouse gas emissions. It compared the emissions from 1 GWinstallations over 20 years, based on a life cycle analysis of construction, operation anddisposal. The comparison used the popular Vestas V90 3 MW model and the proposed NOVA10 MW units.

The estimated lifetime emissions were 521 kt CO2e for the conventional design and419 kt CO2e for NOVA. Using budget share to attribute the reductions to the project partners,Cranfield's brainprint was 34 kt CO2e.

As there are no current NOVA units in operation, there were high uncertainties associated withthe estimates. A Monte-Carlo simulation resulted in a mean difference in emissions betweenthe two installations of 102 kt CO2e, with a standard deviation of 108.