The Chesapeake Light Tower: A New Reference Facility for Offshore Renewable Energy

Offshore wind and marine & hydrokinetic (MHK) energy has the potential to supply a significant fraction of U.S. electricity needs. The raw potential of offshore wind alone is comparable to the entire current consumption of electricity in the U.S. While integrating such a large, variable source of energy into the national electrical grid presents challenges, the fundamental obstacle to tapping these offshore energy resources is cost, which is dropping but is not yet directly competitive with conventional energy production. One of the factors that increases cost for wind is uncertainty in the assessment of the resource. Meteorological tower-based resource assessment methods that are commonly used on land are prohibitively expensive at sea. Alternative technologies, such as buoy-mounted lidar, are being developed, but their measurement capabilities need to be validated in their environment of use for determining winds at hub height. A second factor that contributes to uncertainty, and therefore cost, is that the physical processes that affect winds and turbulence in resource assessment and weather forecast models are incomplete. To assess the errors in models from these knowledge gaps and to evaluate improvements, long-term measurements of winds, turbulence, and other variables at hub height are needed. These measurements do not currently exist in U.S. offshore waters.

To address these needs, the U.S. Department of Energy is developing a new Reference Facility for Offshore Renewable Energy (RFORE). The RFORE will take advantage of the existing structure of the Chesapeake Light Tower (CLT), which is in open water approximately 15 nautical miles east of Virginia Beach, Virginia. Ownership of the CLT is being transferred to the Department of Energy. The National Renewable Energy Laboratory (NREL) and Pacific Northwest National Laboratory (PNNL) will collaboratively carry out the design and refurbishment of the existing structure, manage facility operations, and lead the development of reference instrument specifications, data management, and the development of the research agenda. The major structural addition to the CLT will be a meteorological mast that provides a maximum measurement height of 100 m above mean sea level. The tower will be instrumented with meteorological mean and turbulence sensors at multiple levels. Near-surface measurements will also be made, as well as measurements of sea state and subsurface thermodynamic and current structure. The CLT has a helicopter landing pad, and a surface capable of supporting remote sensing systems such as Doppler lidar. It also has the capacity to support overnight visits of scientific and operational staff.

The RFORE will be a flagship facility for offshore renewable energy in the U.S., supporting both industry and research activities. In this presentation, we will discuss the scope of capabilities for this facility, the current state of planning and anticipated timelines, and mechanisms for access to both the data and the facility itself.