SALT LAKE CITY — A school district here has added a new heat recycling system to its school buses in an effort to curb idling and emissions.

The Utah Clean Air Partnership recently awarded a $30,000 grant to Idle Free Heat to install its technology on 40 of Granite School District’s buses.

Idle Free Heat uses residual heat from the engine to keep the interior of the bus warm, circulating the heat through the vents when the bus is turned off. According to inventor and owner Joel Ewell, the system produces no emissions and consumes no fuel.

“A typical school bus spends one to three hours a day idling just to keep the inside of the bus heated,” Ewell said. “With Idle Free Heat installed, the bus no longer needs the engine idling in order to keep the heat flowing. Now, the driver and passengers can stay warm without polluting our air with vehicle emissions.”

Ewell secured a patent for his Idle Free Heat system and opened for business in January 2017. The system consists of an electronic control unit, a small pump, and an activation button for the driver.

The Idle Free Heat technology was installed on two of Granite School District’s school buses last year. The move was part of a pilot program aimed at reducing pollutants that create particulate matter and ozone.

The 40 additional systems funded by the Utah Clean Air Partnership grant were installed on Granite buses earlier this year.

“By eliminating bus idling, Granite School District will eliminate hundreds of pounds of pollution emissions, save money on fuel, and extend the life of vehicle engines,” the district said in a press release.