The Opportunity: 25 quadrillion British Thermal Units per year are wasted as low-level heat, costing the US economy over $200 billion per year, and contributing to associated greenhouse gas emissions. Ten percent recovery of this waste heat would create over 700 terawatt hours of emission-free electricity annually. At 20 cents per kilowatt-hour (¢/kWh), this translates to $140 billion worth of clean electricity to support decarbonization efforts.
The Solution Technology: A Waste Heat to Osmotic Power Engine upgrades low-level heat into electricity without any incremental emissions. The Waste Heat to Osmotic Power technology converts chemical potential into hydraulic potential, to produce clean electricity using a water turbine. The conventional heat to power cycles, such as Organic Rankine Cycle or Kalina Cycle, use gas turbines and steam turbines that are expensive and suffer from lower efficiency. Water turbines, on the other hand, are much lower in capital cost, higher efficiency, and require significantly less maintenance. The working fluid in the Waste Heat to Osmotic Power engine is pressurized in specially designed water purification membranes. The waste heat is used to regenerate the working fluid to its original chemical potential, thus creating a continuous power cycle for currently stranded waste heat.
Technology Progress: The working fluid pressure was progressively increased from 5 pounds per square inch (psi) to 1000 psi. This is equivalent to more than a 2,300-foot-high hydroelectric dam, an unprecedented accomplishment. As a matter of comparison, most conventional hydroelectric dams are about 500 feet high. This first of a kind Waste Heat to Osmotic Power engine promises to be a game-changer technology by upgrading currently stranded waste heat.
Author(s)
Pinakin Patel, Ludwig Lipp, John Webley, Michael Greene
