Air pollution from cars and factories has been regulated in much of the world since the 1970s. When it comes to the smoke-belching ships that carry global trade, the rules have been a lot looser.

Big changes start next January, though, when long-debated standards from the International Maritime Organization mandate steep cuts of sulfur emissions associated with respiratory disease and acid rain. Much tougher rules are supposed to take effect in 2050, when the IMO will require ships also reduce carbon dioxide emissions by at least half.

By itself, next year’s cap could prevent 150,000 premature deaths and millions of childhood asthma cases each year, according to research published in the journal Nature. It will also cost tens of billions of dollars for an industry that’s dragged its feet on the environment.

Necessity being the mother of invention, some of the world’s most conservative companies are starting to experiment with cleaner fuels and cutting-edge technologies. Here some of the brave, new ideas in green shipping:

Sails

A.P. Moller-Maersk A/S is considering using a modern version of the old-fashioned sail to help power its ships. The devices, which are being tested on one of Maersk’s giant tankers, look more like huge marble columns than anything you’d expect to see on a traditional yacht. Together, the two 10-story-tall cylinders can harness enough wind to replace 20 percent of the ship’s fossil fuels, according to Norsepower Oy Ltd., which makes them.

Eco Marine Power, a startup based in Japan, has designed another sail — this one with solar panels in its body. Chief Technology Officer Greg Atkinson says the firm is in talks with one of the world’s biggest shippers to test the device this year.

Underbelly Bubbles

Just as carmakers fine-tune the aerodynamics of their vehicles to get better gas mileage, shipbuilders also try to reduce the friction between a vessel’s body and the water. Optimizing hull shape is one strategy. Another, being tried by firms including Samsung Heavy Industries Co. and Mitsubishi Heavy Industries Ltd., is streaming bubbles out of tiny holes in a ship’s underbelly, as a lubricant, to help it slice more cleanly through the water. It’s a little like floating on a carpet of air.

Samsung says it’s already installing the system on one vessel being built for Mediterranean Shipping Co. and has received two other orders. The tech can cut fuel consumption by 4 or 5 percent, according to the company.

Robot Cleaners

Since the earliest days of sea voyages, sailors have been troubled by grasses, barnacles and other organisms that grow on hulls. All the biggest cargo lines are now using submarine robots to strip away such debris and improve fuel efficiency.

One device, developed by a Japanese startup called Hullbot, looks like a propeller-powered go-cart with nylon brushes and a vacuum on its belly. Thrusters on its back keep it pinned to the vessel’s hull. No divers are needed, but the machine still requires a human operator to guide it by remote control.

Hydrogen Fuel

The world’s biggest shipbuilder, Hyundai Heavy Industries Co., last year announced it’s developing hydrogen-fueled engines for its massive vessels. The tech is in its infancy, but some proof of concept may come later this year when a small ship being billed as the first fuel-cell passenger ferry, the Water-Go-Round, begins operating on San Francisco Bay. Hydrogen-based ferry systems are also planned in Norway and Scotland’s remote Orkney islands.

Battery Boats

The challenges faced by electric cars, with their limited driving ranges, are even more daunting when it comes to ocean-going ships, which can weigh 600,000 tons and must often travel thousands of miles. Shipbuilders are experimenting with smaller river vessels and other craft that stay near shore.

In Norway, where the government wants two-thirds of all ferries carrying passengers and cars along its Atlantic coast to be electrified by 2030, Kongsberg Gruppen ASA is offering battery-powered ship engines and developing a short-haul electric container vessel.

A Chinese-built ship launched in 2017 on the Pearl River, near Hong Kong, was the first fully-electric cargo carrier of any size, according to the China State Shipbuilding Corp. The vessel is emissions-free, but even with batteries sufficient to power three dozen Tesla sedans, the 2,000-ton ship can only travel about 50 miles without recharging, says the China News Service.

Exhaust Scrubbers

Within the next few years, some 10 to 15 percent of ships are projected to install scrubber systems, like the ones used on factory chimneys, to capture sulfur and fine particulate emissions before they escape exhaust funnels.

Makers of the devices, such as Finland’s Wartsila OYJ and Sweden’s Alfa Laval AB, say there’s already a big backlog of orders, so many ships won’t be outfitted in time for the 2020 rule change. Bloomberg NEF estimates some 4,800 vessels will be scrubber-equipped by 2025.

Fossil Fuel Switch

The most immediate — and consequential — change is the most mundane: switching to lighter marine gas oil, which is something closer to the diesel used for highway trucks. It’s still a fossil fuel, but less polluting because it’s been more thoroughly refined.

Marine gas oil is already used in Emission Control Areas, like the ones around Europe’s coasts, but using it full time in order to meet the new emissions rules will cost shipping companies an extra $40bn to $60bn annually, according to Goldman Sachs Group Inc. and researcher Wood Mackenzie.

Liquefied natural gas is another option, but the cleaner fuel requires whole new engines and port facilities to store it. In 2016, Nippon Yusen KK launched the world’s first LNG-powered car carrier and last October a Russian super tanker the length of several football fields crossed the Baltic Sea, running on the condensed gas.