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Back Driving a global zero carbon future

Sustainable fuels are on the rise, but what exactly are they? Is there a difference between SAF and biofuel? How can you reduce the carbon footprint of your shipments with sustainable fuel today? We asked our sustainability experts to answer these and other key questions to help you begin or continue your journey to a zero carbon future.

Regardless of the mode of transport we look at – land, sea, air – engines are needed to move our ships, aircraft and trucks. To run these engines we normally use fossil fuels. These fuels are all based on oil that has been extracted from far below the earth’s surface. It contains carbon and other chemical compounds that would normally not surface the earth and therefore would not come into our atmosphere.

The majority of CO2e emissions from transportation comes from the burning of fossil fuels. The logistics industry is making great efforts to achieve a reduction in these emissions through engines; ideally so that there are no carbon emissions at all.

What is sustainable fuel?

Known as biofuel in sea and road logistics and Sustainable Aviation Fuel (SAF) in the aviation industry, sustainable fuels have almost identical chemical and physical characteristics to those of conventional fuels, and are the most effective measure for the industry to significantly reduce its carbon footprint. Sustainable fuels are defined as renewable or waste-derived fuels that meet certain sustainability criteria. Furthermore, in case seeds or vegetables are used as a feedstock for producing these sustainable fuels, it is ensured that it meets comprehensive sustainability criteria (such as ISCC and RSB) and is certified for criteria such as food safety.

What is sustainable fuel made of?

Sustainable fuels can be categorised in different ways, e.g. according to the production technology or the type of feedstock. A common classification for SAF distinguishes between two types of sustainable fuels: Biomass fuels and synthetic or eFuels. For sustainable marine biofuel, it is possible to distinguish between biofuel from green electricity, biomass or biowaste and natural gas. At the moment, only biologically produced sustainable fuels are commercially available. 

As the type of biomass used is not available in unlimited volumes, there is a natural limit to the availability of biofuels. For the aviation sector, this means that bio-based SAF will not be able to cover the entire global fuel demand. Sustainable synthetic fuels can fill the gap. Using renewable energy, they are made from carbon dioxide from the atmosphere and water, both of which are abundantly available "feedstocks". 

Synthetic SAF and biofuel in sea freight (sustainable marine fuels) are considered to be crucial to achieve the industry’s long‐term target of net-zero emissions in 2050 as it can be produced without availability limits, avoiding biomass supply limitations, and can reduce emissions up to 100 %. Their deployment to reduce emissions has the potential to become important also because, for example, new propulsion technologies such as electric and hydrogen aircrafts will not be available for long-haul flights in the foreseeable future.

However, the production of synthetic SAF and biofuel is very energy-intensive and more expensive compared to fossil fuel; probably also in the long term. Therefore, the introduction of SAF in aviation and biofuel in sea freight must be accompanied by measures to increase fuel efficiency. Synthetic fuels have not yet been produced industrially and are available only in pilot quantities.

In sea freight, further low carbon fuels are in an advanced development stage such as ammonia and methanol with some first methanol propelled vessels on order. However, the availability of larger, fully CO2 neutral container ships that can cover global routes on a larger scale is still 5-10 years away.

Is sustainable fuel entirely carbon neutral?

Technically, biofuels emit the same amount of CO2e as normal fuels when burned. However, the CO2 of the biofuel is biogenic and has no additional effect on global warming (i.e., it is neutral). If you take plants as the sources of the waste-based feedstock, they will absorb CO2 as they grow. The same carbon atoms are released again in the form of CO2 (so-called biogenic emissions) when the biofuel is burned and are therefore considered neutral, as they are part of the natural carbon cycle.

Today, biofuel is not entirely carbon neutral as it involves growing, harvesting and transporting the raw material, and producing the fuel. Currently, available biofuels reduce CO2e emissions by up to 94% compared to fossil fuels during extraction, production, distribution and combustion.

How much sustainable fuel can be put into an aircraft, ship or truck?


In theory, it would be possible to fly an aircraft 100% with SAF. There have been some test flights and the newer engine models work with SAF only. However, current regulations by the aviation authorities allow a maximum blend of 50% SAF. In practice, due to limited availability of SAF and related costs, we never see such a high blend and typically have less than 1% of SAF inside an aircraft tank. It doesn’t mean that shippers can`t choose to use 100% SAF on their shipments. At Kuehne+Nagel, we operate under the book & claim sourcing model, which is a common practice to increase sustainable fuels adoption and optimise its sustainability avoiding transport emissions. With the book & claim principle, SAF is not physically transported to a specific airport and fueled into a specific aircraft. Instead, it goes into the fuel system at an airport close to the SAF production facility. This way we can purchase any volume of SAF without technical limitations such as blending limits. Then the volume of SAF that was used is linked to the corresponding amount of carbon emissions reduction.


In sea freight, biofuels are usually blended with conventional fuels by up to 30%. Theoretically, it is possible to run marine engines on 100% biofuel. There are trials by Canada Steamship Line that have completed almost 30,000 hours of operation with B100 / second generation biofuels (waste based) without engine modifications. Following the same principle as in air freight, Kuehne+Nagel offers the Mass-Balance-Concept allowing to allocate fully traceable biofuel contingents to cargo shipped on a regular fuel vessel.


For trucks, we see Hydro-treated Vegetable Oil (HVO) as a strategic bridging technology that will increase in demand over the next three years. It is a long haul focus, offers up to 90% reduction in CO2 emissions and is already being used in our own fleet of trucks and carriers on select routes in Europe.

In addition, trucks can run 100% on HVO and it can be added directly to the truck without having to make any modifications and without any reduction in vehicle performance. HVO also has the added flexibility that it can be handled as a ‘drop-in’ alternative to fossil diesel without the requirement to clean out the existing oil stock. For example, a round-trip averaging 3,700 km requires just one fuel up at the onset.

Kuehne+Nagel sustainable fuel offering

As one of the world’s largest logistics providers, operating globally, we are driving our own transition to a zero carbon business model and support our customers with their transition as well.

This entails a close relationship where we can offer our customers specific services:

  1. Measuring the emissions in the transport and logistics of their supply chain;
  2. Avoiding emissions by providing them with alternative transport modes, routes and carrier options;
  3. Reducing their emissions by procuring and allocating sustainable fuels.

We provide innovative and easily customised shipping options for all transport modes:

Sea Logistics

Air Logistics

Road Logistics

What are the key benefits of using sustainable fuels?

  • They lead the way to a zero-carbon economy, boost innovation and fulfil your emissions reduction targets.
  • Our sustainable solutions are available on all routes for all modes and all customers worldwide.
  • Power your products with alternative fuels with one point of contact, directly via the logistics provider.

With our sustainable fuel solutions for all modes of transport, you can shift from intent to action by creating the low-carbon economy of the future today. Our experts are ready to support!