# Organic Rankine, Kalina and sCO2 cycles

Cycles using special fluids to make power from lower-temperature heat.

Source page: https://www.materialinsights.org/energy/e_orc/

Recovery and reuse · Heat to power and cogeneration · No. 126

- Recovery and reuse
- Heat grade: Low to medium
 Recovery and reuse · Heat to power and cogeneration · Foundation · Energy

Swap water for a fluid that boils far lower, and heat too cool for steam can still spin a turbine.

Chart: Illustration: Organic Rankine, Kalina and sCO2 cycles

##### Where it comes from

Chart: Map of where it comes from

An organic Rankine cycle works like a steam plant but uses a fluid that boils at lower temperature, taking heat from about 95-260 C. Most units sit behind a thermal-oil loop that keeps out dust and acid.

##### Three things to know

1. Low-temperature ORCs convert only 8-9% of heat to power, yet that is about 35-40% of what thermodynamics allows at 120 C.
2. ORC turbines run efficiently down to about 10% of rated power, so they cope with fluctuating kiln gas better than steam.
3. A supercritical CO2 pilot turbine spins at 27,000 rpm and cost USD 169 million for a 10 MW test facility.

##### The journey

1. 1 **Warm source**Kiln air, engine water, geothermal brine
2. 2 **Oil loop**Thermal oil carries heat, protecting the turbine
3. 3 **Evaporator**Organic fluid boils at low temperature
4. 4 **Turbine**Vapour spins a generator, often air-cooled
5. 5 **Electricity**Fuel-free, water-free power for the site

##### Go deeper pick a tab to open it in full

## Other sections

- [Overview](https://www.materialinsights.org/energy/e_orc/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_orc/correlation/index.md)
- [Science and thermodynamics](https://www.materialinsights.org/energy/e_orc/rc-sci/index.md)
- [Engineering and integration](https://www.materialinsights.org/energy/e_orc/rc-eng/index.md)
- [Economics and contracts](https://www.materialinsights.org/energy/e_orc/rc-econ/index.md)
- [Impact and additionality](https://www.materialinsights.org/energy/e_orc/rc-impact/index.md)
- [What to track](https://www.materialinsights.org/energy/e_orc/tracking/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_orc/links/index.md)