VPS publishes paper on importance of testing for accurate energy content of marine biofuels

VPS announced Jan. 15 that it has carried out significant research across numerous test parameters that enables potentially problematic characteristics of marine biofuels to be measured and controlled.

VPS research has shown that by using these test methods, biofuels can be used as drop-in fuels onboard vessels enabling the benefits of such fuels to be realized in the shipping sector.

VPS has published a white paper covering one specific test parameter: the energy content of biofuels.

Energy content is a key parameter, representing the amount of heat transferred within the combustion chamber during the burn process and indicates the available energy from the fuel. 

Higher energy content results in higher power generation and better combustion efficiency. 

The energy content has a direct impact on fuel economy and greenhouse-gas emissions, and is therefore an important parameter for ship operators to consider in preparation for the EU’s Emissions Trading System.

The paper covers a range of fuel types, from 100 percent fatty acid methyl esters (FAME), commonly referred to as biodiesel, through FAME blends with marine gasoil (MGO), heavy fuel oil (HFO) and very-low sulfur fuel oil (VLSFO).

For conventional residual and distillate fuels, the energy content can be calculated within an acceptable degree of accuracy using a formula specified in Appendix H of the International Marine Fuel Standard ISO 8217:2017.

The VPS research paper compares data from a variety of fuel samples to correlate the calculated energy content versus the measured energy content (using ASTM D240) of conventional fuels and FAME blends through to 100 percent FAME.

The data shows that this correlation falls away at FAME content above 10 percent.

This proves that the ISO 8217 calculation method cannot be relied upon to provide accurate energy content for fuel blends containing more than 10 percent FAME and that for these blends the accuracy of the calculation formula is not acceptable.

This inaccuracy is due to the greater oxygen content of FAME as compared to conventional fuels.

Furthermore, there is no calculation method available to calculate the energy content of biofuels accurately due to the variability of the oxygen content in the FAME.

Measuring the energy content in fuels is crucial for assessing fuel efficiency, managing operational costs, evaluating environmental impact, ensuring compliance, and maintaining engine performance and safety.

It provides valuable information for ship operators to make informed decisions regarding fuel selection, consumption and environmental responsibility.

The full VPS paper includes:

• Methods to determine energy content in marine fuels

• Methodology applied to compare different methods of determining energy content

• Comparison of energy content of HFO, VLSFO, MGO and biofuel samples

• Significant conclusions relating to the energy content of marine biofuels

To receive the full VPS white paper, “The Importance of Testing for Accurate Energy Content of Biofuels,” click here.