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Integrated Organic Rankine Cycle system for simultaneous utilization of solar energy and LNG cold energy

Periodic Reporting for period 1 - SO-LNG-ORC (Integrated Organic Rankine Cycle system for simultaneous utilization of solar energy and LNG cold energy)

Reporting period: 2020-12-01 to 2022-11-30

Rising electricity demand, finite fossil fuel reserves and environmental concerns motivate the switch to renewable energy sources, increasing energy efficiency, and recovery of unused energy streams. Solar energy represents the most promising renewable energy source. However, the limitation of solar energy lies in intermittency and low energy density. Energy storage technology can resolve the intermittent character of solar energy. Among the technologies converting solar radiation into power, Organic Rankine cycle (ORC) presents significant advantages in terms of flexibility, modularity and downscaling potential, but the limited thermal efficiency is a barrier to its commercial deployment. This project will develop an integrated ORC system for the simultaneous utilization of LNG cold energy and solar energy.



However, previous studies only focus on ONE or TWO factors since more factors require a more difficult multidisciplinary approach. Thus, the previous designs are probably either inefficient, impractical, high risky or unsustainable. Currently, there exists no literature on energy system design methodology considering system configuration, working fluid selection and operating conditions simultaneously, not to mention process uncertainties, risk analysis and environmental impact assessment due to a lack of multidisciplinary approach which is exactly what this project seeks to address.

This project aims to develop a holistic systematic method for a future energy system design for an integrated Organic Rankine Cycle (ORC) for simultaneous utilization of solar energy and LNG cold energy. Through various training during my Ph.D. research, I am equipped with good knowledge regarding (ORC), process integration and optimization.
The fellow has mainly advanced the researh work in the first two work package tasked as stated in the research plan.

WP.1 Modelling of concentrated solar collector and energy storage system

This WP aims to develop the mathematical model of concentrated solar collectors and energy storage technologies. The fellow proposed an integrated system considering sensible thermal energy storage and a concentrated solar collector. The major scientific contribution to the state of the art was the discovery of the synergy between the energy storage system and the power generation system. The system efficiency is improved substantially and the power output is at a constant level, which alleviated the problem of the intermittency of solar energy.

The main difficulty encountered in carrying out this WP lied in the development of the model in both Aspen Hysys and Matlab. The data exchange between two platforms is tricky sometimes. With close collaboration with my previous colleagues, this issue has been solved in two weeks. Another technical problem was solved by combining advanced statistical techniques, in-house professional knowledge from Prof. Gurkan Sin’s group. By conducting this WP, the fellow received excellent training not only in dealing with complex real-world problems but also in collaborating with both colleagues.

WP2: Superstructure-based optimization of the system configuration
The fellow constructed a superstructure of the power system to recover LNG cold energy. ORC and CO2 power cycles are compared. The detailed performance of each system is analyzed. The power systems are optimized with a genetic algorithm within the Python platform. This work has been pioneering work in the field of CO2 power cycle for LNG cold energy utilization.


The research outcomes have been published in Energy Conversion and Management, which is a high-level international journal in the field of energy utilization. This work will be highly visible and it is open access thanks to DTU’s open access publication policy. The other work on the comparison of ORC and CO2 cycle for LNG cold energy recovery will be presented during the 6th international seminar on ORC power systems. This seminar is one of the most important events in the field of ORC technology for power generation. The fellow will present the research findings in October 2021.
A novel methodology to determine the solar energy power system with a sensible energy storage system was proposed. The efficiency of the solar power system has been improved substantially and the power output is stable.

Even though the project is terminated in advance, the last three work packages will be performed at the fellow's new affiliation. The expected objective is to develop a systematic methodology for future energy system design and deliver novel applicable energy systems featuring high efficiency and profitability, but low risk and low
environmental impacts.
Summary of the project