Green shipping refers to the broad effort to reduce the environmental impact of moving goods by sea, primarily by cutting greenhouse gas emissions from the vessels that carry roughly 90% of global trade. The shipping industry currently runs on heavy fuel oil, one of the dirtiest fossil fuels available, and the push toward greener alternatives involves new fuels, stricter international regulations, redesigned ships, and changes to how ports operate. For businesses and consumers alike, it signals a fundamental shift in how the world’s supply chains will function over the next two decades.
Why Shipping Needs a Green Overhaul
International shipping accounts for roughly 3% of global greenhouse gas emissions, a share comparable to the entire output of major industrialized nations. The industry has historically relied on heavy fuel oil, a thick residual product left over after refining crude oil into gasoline and diesel. Burning it releases not only carbon dioxide but also sulfur oxides and particulate matter that affect air quality in port cities worldwide.
The International Maritime Organization, the United Nations body that governs global shipping, has set a target of net-zero greenhouse gas emissions from international shipping by or around 2050. Intermediate checkpoints call for at least a 20% reduction by 2030 (striving for 30%) and at least a 70% reduction by 2040 (striving for 80%), both measured against 2008 levels. The IMO also wants zero and near-zero emission fuels to represent at least 5% of the energy used by international shipping by 2030, with an ambition of reaching 10%.
Alternative Fuels Driving the Shift
The centerpiece of green shipping is replacing conventional fossil fuels with cleaner alternatives. Several options are in various stages of development and adoption.
Green methanol and e-methanol: Methanol engines are already entering service on new container ships. When methanol is produced using renewable energy and captured carbon (making it “e-methanol”), it offers a significant lifecycle emissions reduction. It has the advantage of being a liquid at room temperature, which simplifies storage and handling compared to gases.
Ammonia: Anhydrous ammonia contains no carbon, so burning it produces zero CO2 at the ship’s exhaust. When produced with renewable energy (“green ammonia”), it offers a near-zero carbon solution across its full lifecycle. Engine manufacturers are developing ammonia-ready designs, though the fuel’s toxicity requires careful safety protocols.
Green hydrogen: Hydrogen produced with renewable energy is considered a near-zero carbon fuel on a full lifecycle basis. Its main challenge is energy density: it needs to be stored as a compressed gas or cryogenic liquid, both of which take up significant onboard space.
Biofuels: These offer what the industry calls “drop-in” capability, meaning they can replace conventional fuel without major engine or tank modifications. That makes biofuels an immediate, cost-effective option for the existing global fleet, which numbers tens of thousands of vessels that can’t all be replaced overnight.
Nuclear power: Nuclear reactors produce zero emissions during operation and low carbon over their lifecycle. Research is underway to explore small modular reactors for commercial shipping, though regulatory hurdles and public perception remain significant barriers.
Beyond Fuel: Other Green Technologies
Switching fuels is not the only approach. Several complementary technologies are reducing emissions from ships already at sea.
Wind-assisted propulsion systems use rotor sails, rigid wing sails, suction wings, or towing kites to harness wind energy and reduce engine load. These systems don’t replace engines entirely but can cut fuel consumption by a meaningful percentage on favorable routes. Six distinct categories of wind propulsion technology are currently being developed or deployed commercially.
Shore-side electricity, sometimes called “cold ironing,” lets ships plug into the local power grid while docked instead of running their diesel engines to generate electricity. This eliminates exhaust emissions in port, which directly benefits air quality in coastal cities. The concept has decades of operational experience, and newer variations include battery charging, battery swapping, and onboard power banking systems.
Fuel cells convert chemical energy directly into electricity without combustion, offering higher efficiency and lower emissions. Battery-electric systems are viable for shorter routes like ferries and coastal vessels, though current energy storage technology limits their range for deep-sea voyages.
How Ships Are Measured and Rated
Since January 2023, international regulations require ships to meet specific energy efficiency and carbon intensity standards under amendments to the MARPOL convention (the main international treaty on marine pollution).
The Energy Efficiency Existing Ship Index (EEXI) sets a minimum efficiency standard for ships of 400 gross tonnage and above. Each vessel’s calculated efficiency must fall below a required threshold based on its type and size. Think of it as an efficiency floor: if a ship doesn’t meet it, modifications are needed.
The Carbon Intensity Indicator (CII) goes further by tracking operational performance year over year for ships of 5,000 gross tonnage and above. Each ship receives an annual rating from A (best) to E (worst) based on how much CO2 it emits per unit of cargo transported over a given distance. A ship rated D for three consecutive years, or E for even one year, must submit a corrective action plan showing how it will improve to at least a C rating. These ratings are publicly recorded, which creates market pressure since cargo owners increasingly prefer booking space on cleaner vessels.
The CII reduction factor tightens each year, meaning a ship that earns a C rating today will need to keep improving just to maintain that grade. This ratcheting mechanism is designed to drive continuous efficiency gains across the global fleet.
What Green Shipping Costs
The transition carries a real price tag. Alternative fuels being developed for container shipping could be up to five times more expensive than conventional fossil fuels. Fuel already represents a large share of a ship’s operating costs, and layering on new carbon levies makes the gap even wider.
The European Union’s Emissions Trading System (ETS), which now covers maritime shipping, imposed compliance costs exceeding $3.2 billion in 2024, with projections reaching $9.1 billion by 2026 according to calculations by Hecla Emissions Management. These costs don’t disappear. They flow through the supply chain to cargo owners, freight forwarders, and ultimately to the price of goods on store shelves.
For businesses that ship products internationally, this means green shipping surcharges are becoming a standard line item on freight invoices. Some carriers offer tiered pricing, letting shippers pay more for cargo transported on vessels using green fuels versus conventional ones. The premium varies by carrier and route, but the direction is clear: low-emission shipping costs more today than the conventional alternative.
What Major Carriers Are Doing
Maersk, one of the world’s largest container shipping companies, accelerated its net-zero target to 2040 across its entire business. Its 2030 milestones include a roughly 50% reduction in ocean greenhouse gas emissions intensity per transported container, a 70% absolute reduction in terminal emissions, and transporting 25% of all ocean cargo using green fuels. The company has ordered methanol-fueled container ships and is investing in green methanol production facilities to secure fuel supply.
Other major carriers are placing similar bets. Orders for vessels capable of running on LNG (liquefied natural gas), methanol, and ammonia have surged in recent years. LNG is often framed as a “transition fuel” because it produces lower emissions than heavy fuel oil but is not zero-carbon. The industry is broadly moving toward dual-fuel engines that can run on conventional fuel today and switch to cleaner alternatives as they become available at scale.
What It Means for Businesses and Consumers
If you run a business that imports or exports goods, green shipping will affect your logistics costs and your sustainability reporting. Many large retailers and manufacturers now track “Scope 3” emissions, which include the carbon footprint of transporting their products. Booking cargo on higher-rated (A or B on the CII scale) vessels lets companies report lower supply chain emissions, which matters for corporate sustainability commitments and, increasingly, for regulatory disclosure requirements.
For consumers, the effects are more indirect but still real. The cost of transitioning the global fleet will gradually show up in the price of imported goods, from electronics to clothing to food. The increases are spread across billions of tons of cargo, so the per-item impact is small, but it adds up across entire economies.
Green shipping also creates new jobs and industries. Producing green methanol, green ammonia, and green hydrogen at the scale the shipping industry needs requires massive investment in renewable energy, electrolyzer capacity, and fuel distribution infrastructure. Ports need upgrades to provide shore-side electricity and handle new fuel types safely. Shipyards are retooling to build vessels with new propulsion systems. The transition is expensive, but it’s also generating economic activity across multiple sectors.