RAMSI management model and evaluation criteria for Nordic offshore wind assets

The offshore wind energy sector is in the early stages of development, but it is growing fast. Due to the European Union's renewable-energy and climate goals along with national legislation, the offshore wind sector will develop strongly over the coming years in Europe. In the offshore wind energy sector, there are many different wind-turbine designs ranging from traditional monopile structures to floating platforms, depending on the water dept7h. Today, most offshore turbines are based on onshore turbine designs, and turbine technology continues to develop incrementally. At the same time, there is strong demand in the market for new, innovative designs for offshore wind turbines whose main focus is reliability and cost efficiency. For floating offshore wind turbine designs, there may be new types of uncertainty and system risks compared with onshore wind turbines. Wind turbines in cold climates, such as those experienced in the Nordic countries, may be exposed to extreme conditions, such as formation of ice or very low temperatures that are outside the design limits of standard wind turbines. In the offshore wind energy sector, specification, implementation and verification of the so-called RAMS+I (Reliability, Availability, Maintainability, Safety and Inspectability) requirements during development work are important for companies delivering wind turbines, from the perspective of system integrity. Decisions made before the formal design phase strongly determine the costs and benefits gained during the whole lifecycle of a wind turbine. The benefits of implementing the RAMS+I program include support with investment decisions, cost management, improved management of resource requirements, systematic support with development & implementation of products, and integration of dependability and safety requirements. This publication outlines a model for managing RAMS+I factors during the conceptual design phase of an offshore wind turbine. The model is based on the product development process, concurrent design principles and the Stage-Gater model. The model concentrates mostly on technical decisions made in the early development phases. This publication also presents guidelines for comparing different offshore wind energy assets and their critical components from a system availability and safety viewpoint. The classification and evaluation criteria for RAMS+I factors are outlined and discussed, and a multi-factor risk-profiling (MFRP) method introduced.