Understanding the Organic Rankine Cycle for Waste Heat Recovery
Funded through Round 1: Open Call in 2010, the project aimed to apply an Organic Rankine Cycle (ORC) system to convert waste heat from a gas plant’s steam and amine processes into 1.3 megawatts of electricity. However, due to an unexpected decline in waste heat availability from the partnering gas plant, the project became economically unfeasible and was ultimately discontinued before construction.
ORC is a thermodynamic process similar to the traditional Rankine cycle. Traditional Rankine cycles use water for steam generation and are widely used by power plants such as coal-fired power plants or nuclear reactors, whereas ORC uses organic fluids like refrigerants and hydrocarbons. These organic fluids have a low boiling point, allowing them to vaporize at relatively low temperatures compared to water in a traditional steam cycle. The ORC utilizes waste heat from the exhaust of the gas plant, converting organic fluids into steam, which then expands through a turbine, producing electricity. Because of the low boiling point, ORC systems are particularly efficient and can improve the overall efficiency of industrial processes. Specifically, the technology’s ability to work with various low-temperature heat sources makes it particularly well-suited for Alberta’s energy-intensive industries. ORC systems also have no net carbon emissions, support greenhouse gas reduction initiatives and align with renewable energy goals.
Providing Lessons Learned about Organic Rankine Cycle Technology
Despite the project’s cancellation, the design and learnings from the ORC system contributed to a valuable knowledge base for future waste heat recovery projects. Considering the reason behind its cancellation, the project highlighted the critical need for a guaranteed, stable energy source. Fluctuations in the availability of waste heat significantly impacted the project’s feasibility. ORC systems require consistent heat input to operate efficiently, and any decline or variability in the energy source can render the project uneconomic. To combat these variables, the project revealed that using multiple smaller ORC units could provide greater flexibility and efficiency compared to a single large unit, especially when dealing with variable energy inputs. The project also faced challenges due to the lack of local engineering expertise in ORC systems, leading to delays and increased costs. With strict availability and certification requirements as well as investment required for long-term customized training of operators, the project suggests that a strategy for attaining and maintaining operators should be accounted for when developing the operational philosophy and site infrastructure.
What’s next?
Overall, ORC technology remains a valuable tool for energy recovery and emissions reduction, but its success depends on overcoming the economic and technical challenges highlighted by the project. Since the project’s completion in 2013, ERA has funded other ORC waste heat recovery projects, including the relatively successful Whitecourt Energy Efficiency Project. ORC technology continues to evolve with a focus on improving operational efficiency, reducing costs and enhancing environmental performance. As a result, the technology has experienced increased adoption in Alberta but is still not widely utilized.