Modeling and control of a novel compressed air energy storage system for offshore wind turbine

2012 ◽  
Author(s):  
M. Saadat ◽  
P. Y. Li
Keyword(s):  
Energy Storage ◽  
Wind Turbine ◽  
Storage System ◽  
Energy Storage System ◽  
Compressed Air ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Compressed Air Energy Storage ◽  
Modeling And Control ◽  
And Control

Modelling the Dynamic Response and Loads of Floating Offshore Wind Turbine Structures With Integrated Compressed Air Energy Storage

2017 ◽  
Author(s):  
Tonio Sant ◽  
Daniel Buhagiar ◽  
Robert N. Farrugia
Keyword(s):  
Energy Storage ◽  
Dynamic Response ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Compressed Air ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Compressed Air Energy Storage ◽  
Floating Offshore Wind Turbine ◽  
The Impact

Nowadays there is increased interest to incorporate energy storage technologies with wind turbines to mitigate grid-related challenges resulting from the intermittent supply from large-scale offshore wind farms. This paper presents a new concept to integrate compressed air energy storage (CAES) in floating offshore wind turbine (FOWT) structures. The FOWT support structures will serve a dual purpose: to provide the necessary buoyancy to maintain the entire wind turbine afloat and stable under different met-ocean conditions and to act as a pressure vessel for compressed air energy storage on site. The proposed concept involves a hydro-pneumatic accumulator installed on the seabed to store pressurized deep sea water that is pneumatically connected to the floating support structure by means of an umbilical conduit. The present study investigates the technical feasibility of this concept when integrated in tension leg platforms (TLPs). The focus is on the impact of the additional floating platform weight resulting from the CAES on the dynamic response characteristics and loads when exposed to irregular waves. A simplified model for sizing the TLP hull for different energy storage capacities is initially presented. This is then used to evaluate the dynamic response of nine different TLP geometries when supporting the NREL1 5MW baseline wind turbine model. Numerical simulations are carried out using the marine engineering software tool ANSYS Aqwa©. The work provides an insight on how TLP structures supporting wind turbines may be optimised to facilitate the integration of the proposed CAES concept. It is shown that it is technically feasible to integrate CAES capacities on the order of Megawatt-Hours within TLP structures without compromising the stability of the floating system; although this would involve a substantial increase in the total structure weight.

Integrating Compressed Air Energy Storage (CAES) in Floating Offshore Wind Turbines

2019 ◽  
Author(s):  
Peter P. Vella ◽  
Tonio Sant ◽  
Robert N. Farrugia
Keyword(s):  
Energy Storage ◽  
Wind Turbine ◽  
Heat Exchangers ◽  
Storage System ◽  
Energy Storage System ◽  
Hot Water ◽  
Compressed Air ◽  
Offshore Wind ◽  
Round Trip ◽  
Storage Vessel

Abstract The design of an offshore energy storage system carries unknowns which need to be studied at an early stage of the project to avoid unnecessary costs of failures. These risks have led to an increasing dependence on more sophisticated mathematical models. This paper refers specifically to energy storage in the offshore wind farming industry and has the objective of proposing an adiabatic compressed air energy (A-CAES) system which would be integrated on a semi-submersible offshore wind turbine (OWT) platform. Calculations in respect to the sizing of the main sub-components of the system are included and estimates for the overall round trip efficiency are presented. Preliminary calculations to size the various parts of the energy storage system (ESS) have been carried out based on the energy availability of an offshore 8 MW wind turbine with real wind data from the North Sea. The load data to determine the lowest 12-hour demand period was taken from the Nordpool database. The calculations of the proposed conceptual design are based on an operational scenario in which the 24-hour period of a particular day is split in a 12-hour charging and 12-hour discharging cycle. For charging, a 5-bank, 2-stage compressor train is used to pressurize a number of steel cylindrical vessels with compressed air. This is followed by a process in which the compressed air is discharged across 12 hours using a 2-bank, 2-stage expander turbine. The multiple compression banks enable a modular power delivery to the air storage vessels, with the number of compressors utilized varying subject to wind availability. The two stages allowed for the air to be cooled in between the stages using heat exchangers, transferring the heat of compression to a pressurized sea water circuit. The hot water would be stored in thermally insulated vessels at 350°C to heat the inlet expanding air in the discharge period. A 70 and 100 Bar charging scenarios, both with a cushion pressure (CP) in the air storage vessel (ASV) of 10 Bar at the end of the discharge cycle have been considered. Standard performance criteria are calculated such as compression and expansion ratios, inlet and outlet temperatures for the respective expansion and compression air streams and flow rates within the heat exchangers to come up with an indicative sizing proposal for the respective turbo machinery and storage vessels making up the system. Round trip efficiencies are also calculated. The study determined that a CAES system consisting of 9 compressed air storage vessels operating with a peak pressure of 100 Bar should meet the storage requirements. It is also estimated that the entire CAES system would require around 1082 m2 of deck area on the platform to accommodate the pressure vessels, the compressor and expander trains, the heat exchanger and the hot water storage vessel.

Analysis of the wind and wave-induced dynamic response of a floating offshore wind turbine integrating a compressed air energy storage system

2019 ◽  
Vol 44 (5) ◽  
pp. 469-482
Author(s):  
Daniel Farrugia ◽  
Tonio Sant ◽  
Daniel Buhagiar ◽  
Robert N Farrugia
Keyword(s):  
Energy Storage ◽  
Renewable Energy Sources ◽  
Storage System ◽  
Compressed Air ◽  
Offshore Wind ◽  
Hydrodynamic Characteristics ◽  
Offshore Wind Turbine ◽  
Compressed Air Energy Storage ◽  
Tension Leg Platform ◽  
Hydrodynamic Behaviour

In order to address the intermittency of offshore renewable energy sources, a novel form of compressed air energy storage integrated within a tension leg platform is proposed. The energy storage concept involves a hydro-pneumatic accumulator. The objective of this study was to investigate the variation in the physical and hydrodynamic characteristics of a hypothetical full-scale prototype of the proposed system. The design was developed so as to analyse the effect on said characteristics of the tension leg platform diameter and the inner diameter of the umbilical connecting the floating and seabed-mounted compressed air chambers. Results indicate that better hydrodynamic behaviour was observed for smaller diameter tension leg platforms, whereby the resulting motion became more restrained. Moreover, the dynamic characteristics were observed to indicate marginal improvement for increasing inner diameters of the pneumatic umbilical.

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