Optimal Design of a Hybrid Energy System for the Supply of Clean and Stable Energy to Offshore Installations

Abstract

This paper presents an innovative hybrid energy system for stable power and heat supply in offshore oil and gas installations. The proposed concept integrates offshore wind power, onsite gas turbines and an energy storage system based on fuel cell and electrolyzer stacks. It is expected to be an effective option to decarbonize the offshore petroleum sector as it allows a more extensive exploitation of the offshore wind resource by means of energy storage. To ascertain its potential, an integrated model was developed. The integrated model allows to simulate the process and electric grid performances. The inclusion of both domains provides a comprehensive picture of a given design operational performance. The feasibility of the proposed concept was first investigated through a parametric analysis where an understanding of its potential and limitations was gained. A rigorous optimization was then implemented to identify the designs resulting in the best performances and ultimately to obtain a comprehensive picture of the suitability of the concept. It is shown that a well-designed system can reduce carbon emissions compared, not only to a standard concept based on gas turbines (almost 1,300 kt less CO2 emissions, making up for a relative 36% reduction), but also to the integration of a wind farm alone (more than 70 kt less CO2 emissions, making up for a relative 3% reduction, but complying with grid dynamics requirements). Moreover, the energy storage system brings benefits to the electric grid stability and allows the integration of large wind power capacity without overpassing the 2% maximum frequency variation (as it is the case without energy storage). Not least, the optimization showed that the definition of an optimal design is a complex task, with little margin to further gains in terms of carbon emissions, likely due to technological limitations.

The Impact of Process Heat on the Decarbonisation Potential of Offshore Installations by Hybrid Energy Systems

“…This concept maximises the exploitation of carbon-free renewable power while minimising the contribution of conventional power generation systems such as gas turbines (GTs). However, in a previous study, the maximum CO 2 emission reductions obtained were only slightly higher than those obtained by a conventional integration of renewable wind power [17]. Apart from technological and design limitations, a reason for this was the need for process heat.…”

“…Different HES configurations have been proposed and thoroughly assessed for several stand-alone systems [22], including offshore installations [16]. In particular, the authors of this paper designed and optimised a socalled Hybrid Energy System for stable power and heat supply in OFFshore oil and gas installations (HES-OFF) in a previous publication [17]. The HES-OFF concept integrates and combines wind power, a hydrogen storage system (including a fuel cell and electrolyser stacks) and a gas turbine (GT), the flue gas of which is used to provide heat to the offshore processes requiring it.…”

Sizing of Hybrid Energy Storage Systems for Inertial and Primary Frequency Control

“…It should be emphasized that it is not the goal of this model to validate the design of the grid converter, its controllers, or its LC filter nor to evaluate harmonics or possible power quality problems. Moreover, the validation of the fuel cell and electrolyzer stack size and their required H 2 storage is presented by Riboldi et al (2021). For the sake of brevity, the validation model is not described further in this section.…”

“…For the first limitation, it must be noted that defining the rated active power and energy capacity of an ESS is a multi-stage process involving a techno-economical evaluation as emphasized by Sandelic et al (2018) and Riboldi et al (2021). Hence, the analysis of the ESS dynamic response is only one step of the problem, which requires integration into a broad optimization involving several time scales.…”

Hierarchical Power Allocation Control for Star-Connected Hybrid Energy Storage System Using Cascaded Multilevel Converters

“…They are characterized based on energy density, power density, ramp rate, and life cycle, etc. However, none of the existing ESDs can fulfill all expected features simultaneously, e.g., batteries have high energy density for long-term operation but limited ramp rate, and supercapacitors (SCs) have high power density and ramp rate for short-term fluctuations but low energy density (Riboldi et al, 2020;Xiao et al, 2015). Hence, ESSs integrated by single type of ESD require higher cost and size to meet all the demands for power density, energy density, and ramp rate.…”