This cargo ship made of wood will cross the ocean without fossil fuels

You might have heard that shipping goods by ocean is the most environmentally friendly form of transportation. While that's broadly true, the shipping industry is massive and therefore accounts for 3 percent of global emissions. And the world is shipping more and more things every year, meaning that emissions from boats are only going up.

Several companies are trying to address this by making boats more efficient — and one called Sailcargo aims to make a boat capable of crossing oceans without using any fossil fuels at all.

Zero-emissions — Already under construction in Costa Rica, the Ceiba is Sailcargo's first ever shipping vessel. The boat is made almost entirely out of timber and uses sailing masts alongside solar panels. The idea is that when wind conditions are ideal, the masts can propel the boat forward. At all other times, energy from the solar panels powers an electric engine and underwater propellers. According to Danielle Doggett, managing director of Sailcargo, "the only restrictions on how long [Ceiba] can stay at sea is water and food on board for the crew."

The company notes that it plants more trees than it chops down for its boats, making it even carbon negative rather than simply neutral.

There are caveats here. The boat will only be capable of carrying nine standard shipping containers — far less than the 20,000 that a conventional container ship can hold. And the Ceiba is slow, only able to travel 16 knots (18 mph) at its fastest compared to 22 knots (25 mph) for a traditional ship.

The Ceiba is really a proof of concept, however. According to Sailcargo, the boat is intended to prove that clean technology can work. If all goes well, the company has plans to build a much larger, commercially viable vessel.

Technology and policy — Even still, shipping companies won't transition to clean energy in the name of altruism so long as fossil fuels remain cheap. For-profit companies have no incentive to transition to boats that are slow and consequently more costly to operate (more time on the water means higher labor costs). Unless, of course, they're forced to. Regulators will need to introduce strict emissions targets like they do in the automotive industry.

Sailcargo even suggests that since emissions can be reduced by dropping speeds, slower ships like the Ceiba would be more competitve under new rules as all boats would slow down.

If you look to automotives as an example, higher emissions standards in the U.S. imposed by the Clean Air Act of 1970 didn't destroy industry. The Ford's and Toyota's were able to produce cars that are more efficient, the companies continue to rake in profits, and the polluted air in cities like Los Angeles is no more. Increased costs may lead to lower profits for the shipping industry, but any profits lost are arguably inefficient as they are made possible thanks in part by damaging the environment. And increased spending on new vessels would go back into the economy where people might... use it to buy more stuff shipped to their door.

Sailcargo's Ceiba is a small step, but the industry has to start somewhere. The company initially plans on transporting cargo between Costa Rica and Canada. Already, companies selling electric bicycles, premium hops for beer, and bio-packaging have booked space on the Ceiba when it begins operating in 2022.

The BBC has a full story where you can learn more about Sailcargo and the Ceiba.