As the world transitions from fossil fuels to renewable energy to mitigate climate change, Canada has set a target for achieving carbon neutrality by 2050. As part of Canada's plan to achieve net-zero carbon emissions, a study was undertaken to examine the feasibility of using floating offshore wind turbines to reduce emissions from oil and gas facilities offshore Newfoundland. This paper examines the risks to the turbines due to atmospheric icing from freezing sea spray and precipitation, and offers possible mitigation measures. Results show that icing offshore Newfoundland tends to be light, but still poses a risk to turbine operability.
Energy Research and Innovation Newfoundland and Labrador (NL) is managing and administering the offshore research, development, and demonstration (RD&D) component of Natural Resources Canada's Emissions Reduction Fund (ERF). ERF applied research and innovation projects are looking at ways to reduce greenhouse gas (GHG) emissions in Newfoundland and Labrador's offshore oil and gas industry. The Intecsea study is looking at the use of offshore floating wind turbines to provide power to offshore oil and gas production facilities. The Governments of Canada and Newfoundland and Labrador are also supporting projects through the NL Offshore Oil and Gas Industry Recovery Assistance Fund (OOGIRA), where projects provide direct and indirect employment within the province and offshore sector, generate positive environmental benefits or co-benefits, and support the existing oil and gas installations and infrastructure linked to existing installations. OOGIRA funds, which the Government of NL is managing, is augmenting the offshore floating wind turbines study.
In this paper, we examine the risk of atmospheric icing during the fall, winter, and spring, to the wind turbine blades. Icing on offshore wind turbines can occur due to three mechanisms: one, wind and wave-generated sea spray icing, two, ice build-up due to the accretion of freezing rain or wet snow (e.g., precipitation icing), and three, frost icing due to vapor freezing directly into the blade surface. Wind turbine icing can impede power generation, damage turbine blades in extreme ice build-up scenarios, and can present hazards to personnel in their vicinity due to ice falling off the turbine blades. For floating offshore wind turbines, ice build-up can additionally create balance issues. The rate of ice build-up due to super-cooled sea spray freezing on contact with the turbines is a function of the air and sea surface temperatures, the wind speed, and the saltwater freezing point. When precipitation icing occurs, the rate of ice accretion on turbine blades is a function of the wind speed, the liquid water content of the precipitation, the mean droplet size, the fraction of the precipitation that freezes, and the efficiency with which the turbine blades collect the freezing precipitation. The rate of precipitation icing on wind turbines is not an explicit function of air temperature, as it occurs only due to freezing rain or wet snow when air temperatures are typically 0-3°C (e.g., see Laforte and Allaire, 1992). The region of interest (ROI) for this study is defined by 45° to 51°N, 51° to 45°W, which is further divided into 144 (12 × 12) 0.5° × 0.5° "cells" (Fig. 1).
