Cruise ships docked at PortMiami can now plug in for power — a way to cut pollution, save fuel and pave a sustainable path.

The world capital of cruising on Monday unveiled what’s called shore power, with executives on hand from five major cruise companies: Carnival Cruise Line, Royal Caribbean International Group, Virgin Voyages, Norwegian Cruise Line and MSC Cruises.

Starting this week, as many as three ships from the five cruise companies can plug into the port’s shore power.

Ships docked at ports usually keep their engines running to stay operational for passengers and crew. Shore power allows ships to shut off their engines and plug into a giant electric outlet while docked.

The port is providing up to 16 megawatts, and each ship is expected to need between 8 and 13 megawatts during its stay, said PortMiami Director and CEO Hydi Webb in an interview with the Miami Herald

The power comes from individual substations built by Florida Power and Light at each terminal. The port also has its own larger FPL substation.

“People outside the port won’t be impacted,” Webb said. “We’re not taking away from anyone else.”

The new innovation is a way to make cruise ships more environmentally friendly. It could also make cruising more appealing to younger crowds, who place an importance on sustainability in their consumption patterns.

It’s also a move to get Miami-Dade County closer to its goals of reaching a 50% carbon reduction by 2030 and 100% by 2050, said Miami-Dade County Mayor Daniella Levine Cava in an interview with the Herald.

PortMiami will bring ships onto shore power gradually, starting with Carnival’s Conquest this week. Every three to four weeks, a new ship will give it a go.

The next in line are Royal Caribbean International’s Icon of the Seas, Virgin Voyages’ Valiant Lady, Norwegian Cruise Line’s Joy, and MSC Cruises’ Magnifica.

The port’s goal is to connect 21 cruise ships to shore power by year’s end.

The investment was prompted by reporting by the Miami Herald, which showed the county had promised to make shore power an option for more than a decade without delivering.

The costs are significant but Levine Cava, who has been advocating for shore power since she was a county commissioner, thinks they will more than pay off given the importance of cruising to South Florida’s economy.

The costs to Miami-Dade County to build the shore power program was about $125 million, or about $25 million per terminal, according to PortMiami. Of that, PortMiami obtained $21.7 million in grants, including $19.7 million from the Florida Department of Transportation and $2 million from the U.S. Environmental Protection Agency.

The investments in building terminals were much greater. Five terminals cost the County about $434 million.

Levine Cava said ultimately that having cleaner ships “creates more excitement and interest in our port,” meaning more business.