A staggering 90% of traded commodities depend on shipping, making maritime international trade a
significant component of the global economy. Ships, which were once powered by wind during the
age of sail, are now powered by fossil fuels. Propulsion of ships using fossil fuels causes air pollution,
which has negative health effects for residents around ports, and contributes to climate change with
carbon emissions approximating 940 MtCO 2 e annually. The use of fossil fuels in port infrastructure
and docking machinery further exacerbates the environmental impact of the shipping industry.
A number of regulations and goals have been implemented in recent years to cut the amount of
greenhouse gases (GHG) produced by the shipping industry. By 2030, international shipping should
aim to cut its carbon footprint by at least 40% compared 2008 levels, according to targets set by the
International Maritime Organization (IMO). Port cities are required by the 2021 EU Green Deal to cut
their greenhouse gas emissions by 90% by the year 2050. Additionally, the EU has publicly stated
that shipping should be covered by its Emissions Trading System (ETS), which establishes annual
emission caps for businesses and levies fines for those that go over the limits.
Heavy fuel oil (HFO), which accounts for 72% of all fuel use, is currently the fuel of choice for the
maritime industry. The combustion of HFO releases pollutants such CO x , NO x , and SO x as well as
particulate matter (PM), which is of particular concern in port cities. According to estimates, the
shipping industry is responsible for 13% of global SO x emissions. Emissions of SO x and NO x have been
shown to impact human health and contribute to numerous medical conditions. A key issue with SO x
emissions is that they can exist as PM 2.5 , which are particles small enough to directly enter a person’s
bloodstream through the lungs.
The shipping sector is resolutely shifting towards alternative fuels to lessen its environmental
impact, with a wide range of potential fuel types being considered.
Liquid natural gas (LNG) and hydrogen are currently the font-runners for future fuels. These choices, however, present issues with sustainability and dependency on fossil fuels.
Currently, roughly 2% of fuel used for shipping is LNG. When comparing LNG to fuel oils such as HFO,
it produces noticeably lower pollutants, offering reductions in PM by over 95%, NO x by over 80% and
SO x by over 90%. However, LNG is liquified methane, a potent GHG with a global warming potential
28 times greater than that of CO 2 . A crucial issue with LNG as a fuel is its pertinacity to escape as
unburnt fuel in ship engines, “methane slip”. According to research by the European Transport and
Environment (T&E) department, even under positive assumptions about methane slip, LNG may not
significantly cut GHG emissions compared to HFO. Additionally, the capital cost of manufacturing
LNG ships is substantially higher than that of HFO-powered ships.
The promising fuel, hydrogen, burns exceedingly cleanly when combusted, releasing water as its only
by-product. However, current hydrogen production is dependent on the reforming of fossil fuels
with 96% of all hydrogen produced in this manner. Although it is possible to create hydrogen from
water using renewable electricity utilising technologies such as electrolysis, reforming fossil fuels is currently more economically viable. Another significant problem is the NO x emissions that result
from burning hydrogen, which are larger than when using fossil fuels; however, this can be reduced
by using existing technologies such as catalytic converters.
Low- and zero-emission technologies and fuels are currently being tested in numerous ports
throughout the world.
In order to actively contribute to the realisation of the Paris Climate Agreement, the World Ports Action Climate Program (WPCAP) was established in 2018. Efficiency, cooperation, encouragement, and policy are all covered by initiatives implemented by WPCAP. Smart digital solutions optimise the approach and handling of ships in ports, and reduced turnaround times result in fuel savings and emission reductions. The introduction of shore-based electricity is accelerated through cooperation among member ports, which reduces pollutants and improves local air quality. There is encouragement to use low-carbon and carbon-free fuels to reduce emissions e.g., in terminal equipment. Cooperation initiatives between port authorities and terminal operators are put in place to introduce innovative, emission-free terminal and storage equipment, such as container cranes and policy – cooperation and exchange in fields such as
incentive schemes to encourage the shipping industry’s emission reductions.
A shift away from conventional fossil fuels is necessary for the shipping sector’s journey towards
decarbonization. Through the provision of ship to shore electricity and the electrification of port-
based operations (such as cranes and forklifts), ports can minimise their emissions. Utilising cleaner
fuels or renewable energy sources can cut down on ship-based emissions, whilst financial objections
to these might be addressed by the introduction of carbon taxes. Ports and government agencies
can accelerate and incentivise improved fuel efficiency by utilising technologies, which can be
immediately implemented.
By lowering greenhouse gas emissions in-port and assisting in the reduction of emissions at sea,
ports can play a dual role in the decarbonization of shipping. Ports can provide incentives for
environmentally friendly ships to help minimise emissions whilst at sea. Both carbon emissions and
local air pollution will be reduced by on-shore carbon reduction strategies for port operations and
incentives with access and provisions to allow ships to use shore-based electrical power once
docked.
by
Nathan D. Wood, Dr Robert Moorcroft, Dr Torill Bigg
Tunley Engineering
