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CTI-Maritec: Why accurate testing of energy content is essential for bio bunker fuels

Owing to the composition of bio-marine fuels, accurate measurement of NSE / Net Heat of Combustion to correctly gauge energy content of bio-marine fuels is key for efficient fuel management onboard ships.

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Marine environmental services and fuel testing solutions company CTI-Maritec on Wednesday (8 January) shared on why one of the most important testing parameters or properties of bio-marine fuel is energy content.

Owing to the composition of bio-marine fuels, the accurate measurement of Net Specific Energy (NSE) / Net Heat of Combustion to correctly gauge energy content of bio-marine fuels is key for efficient fuel management onboard ships: 

Introduction

Bio-marine fuel is widely adopted as a drop-in fuel to achieve the current emission requirements in the shipping industry. ISO 8217:2024 specification allows bio-marine fuels to contain up to 100% fatty acid methyl ester (FAME). The major production route of FAME is transesterification of vegetable oils, animal fats or used cooking oils with methanol using alkaline catalysts. The ISO 8217:2024 version has included additional test parameters to measure FAME content, energy content and oxidation stability for bio-marine fuels.

Accurate Net Specific Energy (NSE) assists with efficient fuel consumption management

In this newsletter article, we review why one of the most important testing parameter or property of bio-marine fuel is Energy Content. Accurate measurement of NSE for energy content of bio-marine fuels is essential for efficient fuel management onboard ships with respect to:

  • Fuel consumption
  • Voyage planning
  • Operating cost
  • Machineries or equipment performance
  • Emission & environmental implications

Why accurate testing of Energy Content is an essential test parameter for Bio-marine fuel

Marine fuel containing FAME typically has lower energy content compared to conventional marine fuels.

The heating value of a fuel is the total energy released as heat when a fuel undergoes complete combustion with oxygen under standard conditions. The chemical reaction is typically a hydrocarbon reacting with oxygen to form carbon dioxide, water and heat as shown in the equation below:

Hydrocarbon + Oxygen à Carbon Dioxide + Water + Heat Released

Conventionally, NSE of marine fuels (which consist of predominantly hydrocarbons from petroleum sources) is calculated using a formula specified in Annex of ISO 8217 (Annex J of ISO 8217:2024) with acceptable accuracy. For marine fuels containing FAME, the NSE cannot be calculated using the formula specified in Annex J of ISO 8217:2024 and shall be measured using ASTM D240 method. FAME molecules contain the Carbonyl group and Ester bonds as shown in Figure 1 below and do not consist purely of carbon and hydrogen atoms.

Figure 1: An Ester of a Carboxylic Acid

Figure 1: An Ester of a Carboxylic Acid

The density of potential energy of a hydrocarbon is determined by the number of carbon to hydrogen bonds that can be replaced by oxygen to carbon (CO2) and oxygen to hydrogen bonds (H2O), in other words, the amount of energy released is dependent on the oxidation state of the carbons in the hydrocarbon. For marine fuel containing FAME, the FAME molecule itself contains oxygen atoms in the Carbonyl group and Ester bond. The Ester group of FAME has a carbon forming 3 bonds with oxygen atoms, this means esters are more oxidised than hydrocarbons and esters release less energy content when compared to hydrocarbon since higher oxidation reactions are needed for hydrocarbons.

The paragraphs above explain the reasons marine fuel containing FAME typically have lower energy content compared to conventional marine fuels, which consist of predominantly hydrocarbons and the calculated formula for NSE is not applicable to marine fuel containing FAME.

According to ASTM D240 test method, heat of combustion is determined by burning a weighed sample in an oxygen bomb calorimeter under controlled conditions. The heat of combustion is computed from temperature observations before, during, and after combustion, with proper allowance for thermochemical and heat transfer corrections. The average of gross specific energy (GSE) or gross heat of combustion, and NSE or net heat of combustion of MGO, VLSFO, HSFO and Bio-marine Fuels are tabulated in Table 1 below:

Why accurate testing of Energy Content (Net Heat of Combustion) is essential for Bio-Marine Fuels

Note: The average GSE and NSE for each of the fuel types was obtained from at least 50 samples.

Based on Table 1, bio-marine fuel B30 has 8% lower energy content when compared to MGO. The energy content of bio-marine fuel will become lower when the FAME content is higher.

Energy content of marine fuel containing FAME shall be determined by ASTM D240 method and cannot be calculated using the current NSE formula, which is commonly used for the conventional marine fuels.

Note: The full article by CTI-Maritec can be found here

 

Photo credit: Louis Reed from Unsplash
Published: 9 January, 2025

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Alternative Fuels

DNV: Alternative-fuelled vessel orders hit highest monthly level since October 2024

LNG-fuelled vessels accounted for the vast majority of August activity while the strong summer performance marked a significant acceleration in ordering activity after a relatively slow start to the year.

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DNV: Alternative-fuelled vessel orders hit highest monthly level since October 2024

Latest data from classification society DNV’s Alternative Fuels Insight (AFI) platform alternative-fuelled vessel ordering was strong in August, with 52 new vessels added to the platform.

This is the highest monthly total since October 2024 and follows another active month in July, when 47 vessels were added to the database.

LNG-fuelled vessels accounted for the vast majority of August activity, with 46 orders recorded. The container segment led the way with 30 orders, while the car carrier segment contributed a further 12 LNG-fuelled vessels. In addition, four ethanol-fuelled bulk carriers and two hydrogen-powered bulk carriers were added during the month, as well as one LNG bunker vessel.

The strong summer performance marked a significant acceleration in ordering activity after a relatively slow start to the year. In total, 242 alternative-fuelled vessel orders have been placed in the first eight months of 2026, representing a 27% increase compared with the same period in 2025.

LNG remains the dominant fuel choice, accounting for 63% of all alternative-fuelled vessel orders registered so far this year. Container vessels represent the largest share of these LNG orders (59%), followed by car carriers (30%).

Jason Stefanatos, Global Decarbonization Director at DNV Maritime, said: “The past two months have been particularly strong for alternative-fuelled vessel ordering, with August recording the highest monthly total we’ve seen since October 2024. This has helped lift year-to-date orders to a level well above the same period last year.

“LNG remains the leading fuel choice, driven largely by activity in the container and car carrier segments. These sectors have been among the earliest adopters of alternative fuels, supported by predictable liner operations and increasing demand from cargo owners to reduce emissions across supply chains. 

“For many owners, LNG offers a combination of emissions reductions, fuel availability and future flexibility while the longer-term fuel landscape continues to evolve. 

“At the same time, the latest figures include orders for ethanol- and hydrogen-fuelled vessels, highlighting that owners continue to explore a range of decarbonization pathways. Different segments are making different fuel choices, but the overall level of activity demonstrates continued investment in lower-emission shipping.”

Screenshot 2026 09 04 at 12.29.26 PM Screenshot 2026 09 04 at 12.29.36 PM

 

Photo credit: DNV
Published: 4 September, 2026

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Alternative Fuels

Hercules Tanker Management’s ‘Ultra-Spec Series’ tanker “Vanessa” begins maiden voyage

Designed for worldwide deployment, the series can transport and supply conventional marine fuels as well as alternative fuels up to B100 and methanol.

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Hercules Tanker Management’s ‘Ultra-Spec Series’ tanker “Vanessa” begins maiden voyage

Hercules Tanker Management (HTM) on Wednesday (2 September) said its latest Ultra-Spec Series of next-generation tankers, Hercules Vanessa, has commenced her maiden voyage.

HTM is the shipping venture launched by John A. Bassadone, founder and CEO of independent marine fuel supplier Peninsula.

The 10-vessel programme forms part of the company’s long-term fleet renewal strategy, replacing ageing tonnage with more efficient vessels while delivering the future-ready capability needed to support the maritime industry’s evolving energy landscape. 

Designed for worldwide deployment, the series can transport and supply conventional marine fuels as well as alternative fuels up to B100 and methanol. 

Hercules Vanessa is also the first in the series to feature MarineLINE, a high-performance cargo tank coating system. 

The vessel is currently en route to Port Louis to take bunkers and provisions before continuing southbound towards Cape Town. It is scheduled to discharge a cargo of biofuel, loaded at Nansha Terminal in China, in Ghent later this year.

“HTM’s Ultra-Spec Series continues to gather momentum as we build a modern fleet capable of supporting cleaner marine fuel supply chains,” the company said. 

Related: Hercules Tanker Management launches ‘Ultra-Spec Series’ bunker tanker “Harriet”

 

Photo credit: Hercules Tanker Management
Published: 3 September, 2026

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Alternative Fuels

NYK and Stolt-Nielsen target LNG, bio-LNG bunkering growth through Avenir LNG JV

NYK says joint venture will pursue opportunities in LNG and bio-LNG bunkering, supporting the maritime industry’s transition to lower-emission fuels.

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NYK and Stolt-Nielsen target LNG, bio-LNG bunkering growth through Avenir LNG JV

Avenir LNG on Tuesday (1 September) announced the completion of the transaction first announced in March, establishing Avenir LNG as a 50/50 joint venture between NYK Line and Stolt-Nielsen.

The partnership brings together the global reach, expertise and capabilities of two leading maritime groups, providing an even stronger platform from which Avenir can continue to grow.

“For Avenir, our focus remains clear: expanding our global LNG bunkering and small-scale LNG activities, accelerating the adoption of Bio-LNG, and helping our customers navigate the transition towards lower-carbon shipping,” the company said. 

“We are incredibly proud of what the Avenir team has built to date and excited about what this new partnership makes possible.”

With the completion of the transaction, NYK said it has established a joint ownership and operating structure with Stolt-Nielsen for Avenir LNG, an operator in the LNG bunkering sector with one of the world’s largest fleets of LNG bunker vessels.

“The joint venture will pursue opportunities in LNG and bio-LNG bunkering, supporting the maritime industry’s transition to lower-emission fuels,” NYK said in a separate statement. 

 

Photo credit: Avenir LNG
Published: 2 September, 2026

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