3 exciting ways to cut shipping’s ridiculously big carbon footprint

Ships carry more than 80% of world trade, and they rely heavily on some of the least environmentally friendly transportation fuels available.

There are no cheap, widely available solutions that can lower the shipping industry’s planet-warming carbon emissions – in fact,shipping is considered one of the hardest industries on the planet to decarbonize – but some exciting innovations are being tested right now.

As a professor of naval architecture and marine engineering, I work on ship propulsion and control systems, including electrification, batteries and fuel cells. With attention focused on climate change this week as world leaders meet at the G-7 summit and negotiators discuss shipping emissions at a meeting of the U.N.‘s International Maritime Organization, let’s take a look at what’s possible and some of the fuels and technologies that are likely to define the industry’s future.

Shipping’s climate problem

Shipping is the cheapest way to move raw materials and bulk goods. That has given it both an enormous economic impact and a large carbon footprint.

The industry emits roughly 1 billion metric tons of carbon dioxide per year – nearly 3% of global emissions, according to the IMO, a specialized U.N. agency made up of 174 member nations that sets standards for the industry. If shipping were a country, it would rank between Japan and Germany as the sixth-largest contributor to global carbon dioxide emissions. Moreover, nearly 70% of ships’ emissions occur within 250 miles (400 kilometers) of land, meaning it also has an impact on air quality, especially for port cities.

Technological innovation, in addition to policies, will be crucial for achieving low-carbon or zero-emission shipping. Academic research institutes, government labs and companies are now experimenting with electrification; zero- or low-carbon fuels such as hydrogen, natural gas, ammonia and biofuels; and alternative power sources such as fuel cells and solar, wind and wave power. Each has its pros and cons.

Why electrifying ships matters

Just as on land, electrification is one key to cleaning up the industry’s emissions. It allows engines operating on fossil fuels to be either replaced by alternative power generation technologies, or downsized and modified for low-emissions operation. It also allows ships to connect to electric power while in port, reducing their emissions from idling.

Ship electrification and hybridization are significant trends for both commercial and military vessels. Electrifying a ship means replacing its traditional mechanical systems with electrical ones. Some fleets have already electrified propulsion and cargo handling. Hybrid power systems, on the other hand, integrate different power-generation mechanisms, such as engines and batteries, to leverage their complementary characteristics.

I see deeper electrification and broader hybridization as a core strategy for achieving green shipping.