Pressure rises in ORC community

Professor Piero Colonna in his lab - Photo: Tomas van Dijk

Some 300 researchers from around the world visited the seminar on Organic Rankine Cycle power systems last week, organised by Professor Piero Colonna (3mE).

The interest in his field of research is directly related to the oil price, says Professor Piero Colonna. It was high in the 1970s and now pressure is building again, with major technology companies sniffing out start-ups as a means of entering the market.
The Rankine Cycle is what drives 90 percent of all electric power plants, as it describes the thermodynamic conversion of thermal energy into work, usually by boiling up steam, which drives a turbine coupled to a generator. For large systems (10 to 1,000 megawatts), there is nothing better. For smaller systems, however, water cannot be used, and the adoption of an organic fluid allows for very high efficiency rates. That’s what Organic Rankine Cycle or ORC stands for. Suitable organic fluids are less dense than water and the larger volume occupied by the organic vapour is key to the design of efficient turbines. By choosing the right fluid, ORC engineers can maximise the system efficiency.

You typically find ORC installations in smaller power plants that run on biomass, geothermal, solar or waste heat. The maximum efficiency of converting heat into power is about 30 percent, but currently most ORC systems achieve about 20 percent. Prof. Colonna notes that since most ORC units are run in cogeneration mode, the rest of the energy is used as heat in a greenhouse or for district heating.
The Delft renewable energy systems group (at the faculty of Mechanical, Maritime and Materials Engineering) operates at the forefront of the ORC development, says the professor, who received an NWO Vidi grant in 2005. With funding from STW and industry, his group is active in both fundamental and applied research.
What does bother Prof. Colonna, and his guests, however, is that it is so much harder to get funding for renewable energy projects than their conventional energy counterparts. “We have so many ideas to improve the technology,” he says, “but in comparison with conventional energy technology, we’re dramatically underfunded.”

The conference was dedicated to Professor Gianfranco Angelino, one of the founders of the technology, who passed away last year.