Geothermal energy generation is – in the context of the energy transition – becoming an increasingly relevant topic alongside electricity generation from solar, wind and hydropower. Generating sustainable electricity remains a key priority. Organic Rankine Cycle (ORC) plants play an important role in this context, as they open up possibilities for power and heat generation that were previously not feasible. Discover the advantages and future potential of this technology here.
Why is the ORC process considered a key technology for geothermal energy?
Geothermal energy has been used for a long time - thermal water has always been an important source for supplying heat in buildings. However, for the generation of electricity through steam power processes, very high temperatures from the earth's interior are required. However, this is not possible from many geothermal sources.
The Organic Rankine Cycle (ORC) is a thermodynamic process that generates electricity and heat even at lower temperatures:
- Instead of water, another organic process medium with a low evaporation temperature is used for the steam power process.
- These organic evaporation media have a higher steam pressure compared to water, which is usually used in power plants.
- The organic steam drives the electricity generator via a turbine.
- This makes it possible to use temperatures as of 80 °C to generate electricity.
- A popular process medium is Pentane.
- Pentane is a hydrocarbon compound with a very low boiling point.
The Organic Rankine Cycle (ORC) process is mainly used when the available temperature gradient between heat source and heat sink is too low to operate a turbine driven by steam.
ORC process is ideally suited for power generation, producing electrical and thermal energy from various sources such as renewable energy (biomass, geothermal, solar), conventional combustibles and waste heat from industrial processes, waste incineration plants or gas turbines.
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An ORC plant is a turbine with two circuits (binary machine). Via a heat exchanger, this working fluid absorbs thermal energy, e.g. from the thermal water. The thermal water itself does not enter the turbine.
The ORC process makes low-temperature heat usable for electricity generation:
Source: Geothermal Energy Association: Organic Rankine Cycle (ORC)
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Good to know!
The Organic Rankine Cycle (ORC) is named after the Scottish physicist and engineer William John Macquorn Rankine (5 July 1820 - 24 December 1872). He is considered one of the founders of thermodynamics and introduced the concept of "energy" for the physical quantity previously referred to as "living force".
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What advantages does the ORC process offer in practice?
The advantages of the Organic Rankine Cycle (ORC) process are obvious and powerful arguments when it comes to sustainable energy production. This also applies in the context of achieving the climate targets of the European Green Deal:
- Sustainable, efficient and environmentally sound energy production.
- Geothermal plants are not problematic in terms of landscape architecture, as they require little space and are not enormous in height.
- Power generation is independent of weather and seasonal fluctuations, unlike solar, wind and hydro power.
- Possibility of using any waste heat, i.e. not only in connection with geothermal energy.
- The electricity production process can be adapted to the temperature of the heat source: the decisive factors here are the level of evaporation pressure and the choice of solvent.
Why is solvent Pentane frequently used in the ORC process?
Pentane ensures sustainable electricity generation. As an important solvent, Pentane is characterised by
- low boiling point,
- low density and
- high vapour pressure.
Pentane is one of the most commonly used organic process media in ORC systems. Find out why it plays a crucial role in ORC systems:
Discover the Pentane characteristics by visting our Pentane Product Page or contact us directly:
Conclusion: The ORC process as an efficient and sustainable solution for electricity and heat production
Using the Organic Rankine Cycle (ORC) process, geothermal plants and other waste heat sources can use even low temperature heat to generate electricity and heat. The important thing is to choose the right evaporation medium, such as Pentane. The ORC process enables more efficient use of heat for power generation and can thus make an important contribution to the climate goals of the European Green Deal.
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FAQ:
Organic Rankine Cycle (ORC)
What is the difference between ORC and the traditional Rankine cycle?
The ORC uses organic process media instead of water as the working fluid. This allows the process to operate at significantly lower temperatures, as organic media have lower boiling points. As a result, low-temperature heat sources can be utilised efficiently that would not be economically viable in the conventional Rankine cycle using water.
Which heat sources can be used in ORC systems?
In ORC systems, geothermal energy, industrial waste heat, biomass combustion and solar thermal energy sources can be utilised.
Why are organic process media such as pentane or isobutane used instead of water?
Organic process media such as pentane or isobutane have lower boiling points and better thermodynamic properties for low-temperature applications.
Is ORC technology suitable for industrial applications?
Yes, ORC systems are frequently used to recover industrial waste heat in industrial processes.
Which process media are commonly used in ORC plants?
Hydrocarbons such as pentane are frequently used due to their thermodynamic efficiency and stability.
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