Mazda is bringing back the rotary engine, but not as we know it.

The automaker on Wednesday confirmed production plans for a rotary range extender for battery-electric versions of the MX-30. The compact crossover SUV, which went on sale in Japan this year, is also offered with a hybrid powertrain.

Mazda MX-30

Mazda MX-30

Mazda said MX-30 prototypes with the range extender will hit the road in 2021. Sales are scheduled to start the following year, though availability of any versions of the MX-30 in the United States is yet to be announced.

No details on the rotary range extender have been announced, though Mazda in the past has hinted that the system should take up no more space than a pair of shoeboxes.

Mazda MX-30

Mazda MX-30

The pure battery-electric version of the MX-30 has a 35.5-kilowatt-hour lithium-ion battery, which Mazda said will deliver approximately 130 miles of range. It isn't clear how much range the vehicle would have with the rotary range extender.

Mazda has already shown an electric car with a rotary range extender: the Mazda 2 RE Range Extender concept (shown below) unveiled in 2013. Its rotary was a single-rotor, 0.33-liter unit that with a full tank of gasoline could provide an additional 111 miles of range.

Mazda 2 RE Range Extender concept

Mazda 2 RE Range Extender concept

Mazda's struggles to reduce emissions of its rotary engine means a rotary-powered sports car is unlikely to return to market, unless Mazda can somehow develop an electrified version that meets ever-tightening emissions regulations.

Every vehicle in Mazda's lineup will have some form of electrification by 2030. It's part of the automaker's overarching goal to achieve a 90% reduction in emissions versus its 2010 levels, by the year 2050.