How does it work?
Waste Heat to Power (WHP) works by capturing industrial waste heat with a recovery unit and converting it into emission-free electricity through a process called heat exchange.
There are two main forms of technology used in WHP: Steam Turbine Technology and Organic Rankine Cycle. In addition there are several exciting emerging technologies including thermoelectric and high pressure CO2 processes. Through the application of these technologies, industrial waste heat is no longer just a byproduct – it is a valuable resource for emission-free electricity.
Steam Turbine Technology
Steam Turbine Technology is more than 100 years old and has been utilized for WHP systems since the 1970’s. An effective and proven technology, steam turbines require waste heat to be generated at high temperature making this viable mostly in larger scale industrial facilities.
According to a 2008 DOE report, more than 90% of America’s waste heat is generated at lower temperatures than steam turbines can economically capture (p.54). Organic Rankine Cycle has been developed to utilize the same principles of successful steam turbine technology for smaller scale projects with lower temperature heat output.
Organic Rankine Cycle
A newer technology developed and proven in the geothermal industry, the Organic Rankine Cycle (ORC) is capable of capturing waste heat at lower temperatures from smaller scale projects. ORC technology is a heat exchanging process that utilizes a refrigerant for its working fluid rather than water, as used with steam turbines. The use of the refrigerant allows ORC units the ability to capture heat from lower temperature heat sources, currently as low as 200 degrees F. Since the majority of all industrial waste heat in the United States has temperatures below 600 degrees Fahrenheit, the ORC’s ability to capture low temperature resources opens up many new applications for waste heat to power (WHP) projects.
Thermoelectric technology uses solid state systems that require no moving parts and sit directly in the waste heat stream. They require no working fluid or operator and are designed for smaller applications. Compressed CO2 systems work similarly to the steam turbine and Organic Rankine Cycle technology but use CO2 as the working fluid.
Did you know? The technology that could be used to generate emission-free electricity from the world’s waste heat resources is the same technology currently being used to generate zero-emission electricity from geothermal and solar thermal resources?