Engine that Uses Cryogenic Energy Storage to Improve Vehicle Fuel Efficiency and Greatly Reduce Fossil Fuel Dependence

Technology #14863

Utilizes Heat from Existing Exhaust to Recover Cryogenically Stored Renewable Energy, More Than Doubling Fossil Fuel Efficiency

Cryogenic power extraction increases fuel efficiency by applying exhaust heat from a vehicle engine to expand a cryogenic liquid (e.g. liquid nitrogen, liquid natural gas) into gas that runs a turbine. Available engine designs waste excess heat and energy. Researchers at the University of Florida have developed a cryogenic power extraction system that uses the exhaust heat to convert cheap, environmentally friendly liquid nitrogen into an extremely high-pressure gas. A car with this engine uses this high-pressure fluid to produce more engine power, more than doubling fuel efficiency. Cheap and abundant, liquid nitrogen provides a cost-efficient and reliable resource. The market for fuel efficient vehicles is one of the fastest growing markets, with a growth rate near 30 percent annually. More than 1.3 million hybrid electric vehicles were sold in 2013. This liquid nitrogen heat extraction is a significant fuel efficiency improvement, positioning it well in this large, dynamic market.


Fuel-efficient engine design dramatically decreases mileage cost with no environmental degradation


  • Doubles vehicle fossil fuel efficiency, decreasing environmental impact
  • Recovers renewable work energy using previously wasted exhaust heat, simultaneously providing engine cooling and reducing waste
  • Reduces fuel costs to consumers, providing a significant competitive advantage
  • Reduces air conditioning and engine coolant weight, further improving vehicle efficiency
  • Utilizes excess heat to charge battery after engine shuts off, providing an alternative energy source for hybrid and electric vehicles


In available technologies, the waste heat from vehicle engines produces no work. University of Florida researchers have designed an engine that utilizes a cryogenic working fluid, such as nitrogen (LN2), to extract heat from car exhaust. This design uses the waste heat from an existing engine to convert the cryogen into a high pressure gas, which runs a turbine to recover the stored energy. A vehicle with this system could operate without any cryogen on board or with only cryogen and no fuel. It is also possible to create a system that uses liquid natural gas (LNG) or liquid hydrogen (LH2) in place of, or in combination with an inert cryogen such as LN2. In this case, the engine would use the expanded natural gas or hydrogen as a fuel in the combustion engine.