Novel supercritical CO₂/organic Rankine cycle systems for solid-waste incineration energy harvesting: Thermo-environmental analysis

ABSTRACT

Waste-to-energy is considered as an effective way to simultaneously digest the municipal waste and generate useful power. Steam Rankine cycle is conventionally adopted for solid-waste incineration energy harvesting. To further improve the energy conversion efficiency, cascade systems consisting of a supercritical CO₂ cycle and an organic Rankine cycle were proposed, where both the subcritical and transcritical organic Rankine cycle systems using R1233zd(E) as the working fluid were considered. Thermodynamic and the environmental analysis were evaluated comprehensively, with a follow-up comparison with the state-of-the-art technologies. The results show that compared with the original waste-to-energy plant, the turbine output (2.55 × 10⁷ W) and waste-to-energy efficiency (42.61%) of the supercritical CO₂ cycle/subcritical organic Rankine cycle power plant are increased by 9.50 × 10⁶ W and 59.41%, respectively. If changing to the supercritical CO₂ cycle/transcritical organic Rankine cycle system, the improvement will be greater, i.e., 10.19 × 10⁶ W and 63.71% respectively. The comparison with the state-of-the-art power plants also shows the new waste-to-energy plant has higher efficiency and better environmental performance. The ecological efficiency and sustainability index of supercritical CO₂ cycle/subcritical organic Rankine cycle system power plant are 88.82% and 1.54, while 89.14% and 1.57 with the supercritical CO₂ cycle/transcritical organic Rankine cycle system. The proposed cascade system demonstrated its potential in performance improvement in the field of waste-to-energy incineration. The study provides insights into the next-generation power plants for solid-waste disposal.

KEYWORDS:

• Supercritical CO₂ cycle
• organic Rankine cycle
• waste-to-energy
• thermodynamic analysis
• environmental analysis

Highlights

• A new system for waste-to-energy plant is proposed for the first time.

• It integrates a supercritical CO₂ cycle with an organic Rankine cycle.

• Evaluated the system with detailed thermodynamic and environmental analysis.

• Compared with the state-of-the-art systems to evaluate the proposed system.

• The power output and eco-efficiency increased by 63.69% and 5.64%, respectively.

Acknowledgments

The work is supported by Dean Project of Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology (No. 2020K009).

Declaration of competing interest

The author(s) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

CRediT authorship contribution statement

Xiaoting Chen: Conceptualization, Investigation, Methodology, Software, Formal analysis, Visualization, Writing - Original Draft. Mingzhang Pan: Investigation, Writing - Review & Editing, Funding acquisition, Supervision. Xiaoya Li: Conceptualization, Methodology, Visualization, Formal analysis, Writing - Review & Editing, Supervision.

Additional information

Funding

This work was supported by the Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology, Guangxi University [2020K009].