Green Shipping: How the Maritime Industry Is Moving Toward Cleaner Seas
Eco-Awareness and the Future of the Shipping Industry
Global shipping moves most of the world’s traded goods. It connects manufacturers, retailers and consumers across continents. However, moving such large volumes of cargo over long distances requires significant amounts of energy and produces greenhouse gas emissions.
For decades, the shipping industry focused primarily on efficiency, capacity and reliability. Environmental performance has now become an equally important issue.
The concept of green shipping covers a wide range of measures designed to reduce fuel consumption, air pollution and greenhouse gas emissions from ships. These measures include more efficient vessel designs, cleaner fuels, renewable energy technologies, improved voyage planning and stronger environmental regulations.
The industry is now moving from voluntary environmental initiatives toward a combination of mandatory efficiency requirements and longer-term decarbonization measures.
Why Green Shipping Matters
Ships can transport large quantities of cargo efficiently compared with many other forms of freight transportation. Nevertheless, international shipping remains a significant source of global greenhouse gas emissions.
Reducing these emissions is challenging because commercial vessels operate over long distances and need dependable energy supplies. Ships also have long operating lives, meaning that today’s vessels may remain in service for decades.
As a result, the transition to cleaner shipping requires action on several fronts:
- Improving vessel energy efficiency
- Reducing fuel consumption
- Using lower-emission and zero-emission fuels
- Developing renewable propulsion technologies
- Improving port infrastructure
- Optimizing routes and voyage speeds
- Reducing emissions while ships are at berth
- Introducing stronger international environmental standards
Green shipping is therefore not about one single technology. It is a long-term transition involving ships, ports, fuel producers, regulators and cargo owners.
International Rules Are Driving Change
The International Maritime Organization (IMO) has become a central force in the industry’s environmental transition.
The IMO adopted its revised 2023 Strategy on Reduction of Greenhouse Gas Emissions from Ships, setting a long-term ambition for international shipping to reach net-zero greenhouse gas emissions by or around 2050.
The strategy also establishes indicative checkpoints. It calls for total annual greenhouse gas emissions from international shipping to fall by at least 20% by 2030, striving for 30%, and by at least 70% by 2040, striving for 80%, compared with 2008 levels.
The strategy also aims for zero- or near-zero-emission fuels and energy sources to represent at least 5% of the energy used by international shipping by 2030, while striving for 10%.
These targets have significantly changed the environmental agenda for shipowners and operators.
EEXI and CII: Measuring Ship Efficiency
Green shipping is increasingly based on measurable performance rather than general environmental claims.
Under amendments to MARPOL Annex VI, ships are subject to new energy-efficiency and carbon-intensity requirements.
The Energy Efficiency Existing Ship Index (EEXI) measures the technical energy efficiency of existing vessels. Meanwhile, the Carbon Intensity Indicator (CII) measures operational carbon efficiency.
The requirements became effective from January 2023. Ships of 5,000 gross tonnage and above are subject to CII requirements, while EEXI requirements generally apply to ships of 400 gross tonnage and above.
CII ratings are based on the relationship between greenhouse gas emissions and transport work. This means that how efficiently a vessel operates can affect its environmental rating.
Ship operators can therefore have strong incentives to improve voyage planning, reduce unnecessary fuel consumption and introduce technical modifications.
Cleaner Fuels for Ships
One of the biggest challenges facing green shipping is finding fuels that can provide enough energy for long-distance voyages while significantly reducing greenhouse gas emissions.
Several alternatives are being developed or deployed.
Methanol
Methanol can be used in specially designed marine engines and is already being adopted for some new vessels. Its overall environmental performance depends on how the methanol is produced.
Renewable or low-carbon methanol can offer greater emissions reductions than conventional fossil-based production.
Ammonia
Ammonia is being investigated as a potential zero-carbon fuel at the point of combustion because it contains no carbon. However, its full environmental impact depends on how it is produced.
Green ammonia made using renewable electricity could become an important option for future ocean-going ships.
Hydrogen
Hydrogen is another potential low- or zero-carbon marine fuel. It can be used directly in fuel cells or adapted for other propulsion systems.
However, storage, energy density, production costs and infrastructure remain important challenges, particularly for long-distance shipping.
Biofuels
Sustainably produced biofuels can potentially reduce the lifecycle greenhouse gas emissions associated with shipping. Their environmental benefits depend heavily on their feedstock, production method and supply chain.
LNG
Liquefied natural gas, or LNG, has been used as an alternative marine fuel because it can reduce some conventional air pollutants compared with traditional marine fuels.
However, LNG should not automatically be considered a zero-emission or fully green fuel. Methane leakage and the fuel’s lifecycle greenhouse gas emissions remain important considerations.
For this reason, the industry’s long-term transition is increasingly focused on fuels and energy systems that can provide deeper lifecycle emissions reductions.
Renewable Energy Comes to the Sea
Fuel is not the only area where innovation is taking place.
Several technologies can reduce the amount of conventional fuel a vessel needs.
Wind-assisted propulsion systems, for example, can use modern sails, rotors or other aerodynamic devices to provide additional thrust. Solar panels can supply electricity for onboard systems, although their contribution to the propulsion needs of large ocean-going vessels is generally limited.
Battery-electric propulsion is particularly relevant to smaller vessels and shorter routes. Ferries, harbour vessels and other short-distance ships can benefit from battery systems because they can recharge more frequently.
Hybrid propulsion can also combine conventional engines with batteries or other energy sources to reduce fuel consumption during selected operating conditions.
Making Ships More Efficient
Green shipping does not always require completely new propulsion systems.
A significant amount of fuel can potentially be saved through better ship design and more efficient operations.
Modern efficiency measures include:
- More efficient engines
- Improved hull designs
- Advanced propeller technology
- Air lubrication systems
- Waste-heat recovery
- Energy-efficient onboard equipment
- Route optimization
- Weather routing
- Slow steaming
- Digital fuel-management systems
- Predictive maintenance
- Improved cargo planning
Even relatively small efficiency improvements can become significant when applied across large commercial fleets.
Greener Ports Are Part of the Solution
Ships are only one part of the maritime supply chain.
Ports also have an important role in reducing emissions. When ships remain alongside a port, their engines may continue operating to provide electricity for onboard systems.
Shore-side electricity, also known as shore power or cold ironing, allows suitable vessels to connect to the local electricity grid while at berth. This can reduce the need to operate auxiliary engines, particularly where the electricity supply is increasingly renewable.
Ports are also investing in infrastructure for alternative fuels, renewable electricity, energy storage and more efficient cargo-handling equipment.
A successful green shipping transition therefore requires coordination between vessels and the ports they serve.
The IMO Net-Zero Framework
The next major step in international shipping regulation is the proposed IMO Net-Zero Framework.
In April 2025, the IMO Marine Environment Protection Committee approved draft amendments to MARPOL Annex VI containing a proposed global fuel standard and an economic mechanism for greenhouse gas emissions.
However, the framework has not yet become legally binding.
In October 2025, the IMO extraordinary session considering adoption was adjourned for one year to allow Member States more time to work toward consensus.
The work continued during 2026. At MEPC 84 in April 2026, the IMO agreed to establish an intersessional working group to address concerns and develop greater convergence around the proposed framework.
The IMO’s September 2026 working-group meeting also reported progress on proposals concerning the draft framework. Further discussions are scheduled ahead of MEPC 85, which is due to meet in November and December 2026.
Therefore, the proposed Net-Zero Framework should currently be described as a developing regulatory framework rather than an already adopted global shipping regulation.
Measuring the Full Environmental Impact
An important development in green shipping is the growing emphasis on lifecycle emissions.
A fuel that produces fewer emissions while a ship is operating is not necessarily low-carbon across its entire lifecycle. Production, transportation, storage and use can all contribute to its environmental footprint.
The IMO is developing lifecycle assessment methods for marine fuels to account for these factors.
This approach is particularly important when comparing emerging fuels such as hydrogen, ammonia, methanol and biofuels.
The future of green shipping will therefore depend not only on what fuel a vessel uses, but also on how that fuel is produced.
The Road Ahead for Green Shipping
The maritime industry has moved considerably beyond the environmental discussions that dominated the sector in the early 2010s.
Today, green shipping involves measurable carbon-intensity requirements, alternative fuels, digital optimization, renewable energy, efficient vessel design and increasingly sophisticated international regulation.
There is no single solution that can decarbonize every type of vessel.
Large container ships and bulk carriers may require different technologies from ferries and harbour vessels. Long-distance shipping also faces different technical challenges from short-sea transportation.
The transition will therefore likely involve a combination of technologies and fuels.
What is clear is that environmental performance is becoming an increasingly important part of the shipping industry’s future. As regulations develop and cleaner fuels become more available, shipowners, ports and cargo operators will need to adapt.
The goal is not simply to build ships that consume less fuel. It is to create a maritime transport system that can move goods efficiently while progressively reducing its impact on the climate and marine environment.
Frequently Asked Questions About Green Shipping
What is green shipping?
Green shipping refers to efforts to reduce the environmental impact of maritime transportation. It includes cleaner fuels, energy-efficient ships, renewable propulsion, optimized operations and emissions-reduction technologies.
What is the IMO’s target for shipping emissions?
The IMO’s 2023 GHG Strategy establishes an ambition for international shipping to reach net-zero greenhouse gas emissions by or around 2050. It also includes indicative emissions-reduction checkpoints for 2030 and 2040.
What are EEXI and CII?
EEXI measures the technical energy efficiency of existing ships, while CII measures the operational carbon intensity of applicable vessels.
Are electric ships possible?
Yes. Battery-electric and hybrid vessels are already relevant to certain short-distance routes, particularly ferries and harbour operations. Their suitability depends on vessel size, range, energy requirements and charging infrastructure.
Is LNG a green shipping fuel?
LNG can reduce certain conventional air pollutants compared with some traditional marine fuels, but it is not a zero-emission fuel. Methane emissions and lifecycle greenhouse gas impacts must also be considered.
Which alternative fuels could power future ships?
Potential options include renewable methanol, ammonia, hydrogen and sustainably produced biofuels. The appropriate solution will depend on vessel type, route, infrastructure, cost and lifecycle emissions.
Conclusion
The shipping industry is entering a major environmental transition. Energy efficiency remains important, but the long-term challenge is to reduce greenhouse gas emissions across the entire maritime fuel and transport system.
From efficient ship design and digital voyage optimization to alternative fuels, renewable propulsion and cleaner ports, green shipping is becoming a broad industry transformation.
As international regulations continue to develop, the maritime sector will need to balance environmental objectives with safety, reliability, affordability and the enormous role shipping plays in global trade.
