Hybrid Power-Generation Concept Incorporates Offshore Wind

Abstract

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 204901, “Hybrid Offshore Power Generation,” by Izleena Md. Iqbar, SPE, Fauzi O.B. Othman, and Hasmi Taib, Petronas, et al. The paper has not been peer reviewed. _ The operator has developed an offshore hybrid power-generation concept to leverage and optimize wind-turbine systems for power generation in weak-wind areas such as Malaysia. In this concept, one gas-turbine generator is replaced by an offshore wind turbine adapted to low wind speeds. This lowers maintenance costs and carbon exposure. Additionally, the fuel gas will be diverted to sales gas, thereby improving economics and making offshore renewable power generation feasible for oil and gas platforms. Background Malaysia is situated in a weak-wind area. Most of the operator’s oil and gas platforms are in water depths of more than 60 m, which are considered deep water for offshore wind-turbine systems. Offshore wind-turbine systems generally are expensive and not cost-effective for low-wind-speed areas where the annual average wind speed at hub height is less than 6.5 m/s. For economic reasons, offshore wind turbines are multimegawatt turbines designed for sites of International Electrotechnical Commission Class I or II only. However, a need exists to install CO2-effective, renewable electrical generators with high power density to support industrial plants that cannot follow the wind but are bound to local offshore oil and gas resources. In view of these challenges, specific criteria have been identified for this project, namely specific rated power, maintenance costs, risk of hazards, capability of a black start (the ability of generation to recover from a blackout), and offshore capability. Hybrid Offshore Power-Generation Project From preliminary studies, it was concluded that a reasonable value for specific power is less than 200 W/m² to achieve high-capacity factors in a weak-wind region. The need for low maintenance costs calls for a solution with little technical complexity and a minimum of components. Capability for a black start in an island situation requires storage and parameters for the generator or invertor system of the wind power plant. At the time of writing, no wind turbine can be bought off the shelf for the purposes mentioned. A wind turbine found closest to these criteria is provided by a European manufacturer based in Estonia. The offshore wind-turbine system consists of a customized wind turbine adapted to harness the energy from the weak-wind area and a microgrid system to integrate the wind turbine with the turbine generators, which are housed on a tension-leg-platform (TLP) floating structure. This floating platform is held by a gravity anchor.