Offshore wind energy remains an untapped power resource in the United States of America considering the strong offshore wind power potential (of approx.. 4,150 GW according to NREL) along the US coasts, where major population centres are located. Due to slow wind speeds in regions with shallow waters located along the Gulf Coast and mid-Atlantic Coast, proven technology which is currently widely deployed in European shallow waters cannot be directly applied in the US. In contrary, US has significant potential in deep-water locations where floating offshore wind turbine structures are required.
Dr Todd Griffith from Sandia National Laboratories gave a prestige lecture on the 21st of April in Cranfield University providing an overview of the research projects currently taking place at Sandia National Laboratories addressing the unique conditions of the US offshore environment. Sandia is a US Federally Funded Research and Development Centre with the mission to deliver essential science and technology to address National Security challenges.
Figure 1 Snapshots from the Prestige Lecture given by Dr Todd Griffith from Sandia National Laboratories
Dr Griffith presented projects conducted by the Wind Energy Technologies Department of Sandia National Laboratories, covering:
- Large-scale hurricane resilient wind turbine blade designs
- Novel floating vertical axis wind turbines for deep-water siting
- Offshore wind farm code development, and
- Structural health monitoring & prognostics management systems.
Sandia has developed a series of detailed 100-meter blade reference models that are available to designers and researchers for design studies and cost analysis; while turbine models reaching 50 MW rated capacity using segmented ultralight morphing rotors based on bio-inspired load alignment (e.g. palm tree) have also been designed. The rotor’s load alignment reduces the required mass for blade stiffening, and makes the turbines more resistant to storms, while their segmented design allows the massive blades to be manufactured in segments which reduces the transportation and manufacturing costs.
Figure 2 Load alignment configuration. Source: Dr Todd Griffith’s presentation
Further research studies conducted at Sandia National Laboratories involve: Hi-resolution modeling of floating wind turbines, wherein a state of the art eddy simulation code has been formulated in order to simulate atmospheric turbulence with wind farms in both land-based and offshore environments; structural health and prognostics management with a focus on damage detection and analysis of effects of damage (state of health and remaining life), and floating offshore vertical-axis wind turbines, among others.
Figure 3 Results for Floating 13.2 MW Turbine. Source: Dr Todd Griffith’s presentation
Sandia has developed 6 public domain designs, covering a range of different areas: power performance models, structural models, economic models, anchor and mooring design, PTO design, O&M / Installation, permitting & environment.
Conclusively, this is an exciting time for marine renewables with significant growth prospects within the next decade. However, while there is the necessary technical know-how and proven technology is already deployed in European waters, as we move further from shore and as extreme scale wind turbines start to be deployed, conventional designs will no longer be applicable. Hence, innovative solutions focusing on reducing technology risks and cost of energy (COE) adjusted to location specific conditions need to be invented for different marine hydro-kinetic technologies.
More information on Sandia’s activities may be found here: http://energy.sandia.gov/energy/renewable-energy/wind-power/offshore-wind/
Anastasia Ioannou