10-Minute Insight: How Accurate Are the Default (Method 1) NGER Factors?

With the recent increased attention around Safeguard and the push to achieve net zero by 2050, it has become apparent that large greenhouse gas emitters have become more intune with their emissions and are looking for ways to increase the accuracy of estimates used.

The NGER Determination sets out 4 methods for the estimation of fuel emissions released during combustion. The methods range in level of complexity.

At Greenbase, we have recently embarked on an investigation into the accuracy of the default Method 1 factors under the National Greenhouse and Energy Reporting (NGER) scheme. We wanted to understand how these defaults compare to more precise methods like Method 2. To this end, we carried out fuel sampling of retail-grade diesel obtained from a local service station.

Our procedure involved collecting a diesel sample, which we then sent to a laboratory in Sydney for analysis. The lab tested for energy content, carbon content, and fuel density. Finding a lab that can conduct tests compliant with methods prescribed by the NGER Determination is quite a challenge!

Upon analysing the results through the NGER Determination equation, we found that our fuel sample showed 2.5% lower emissions compared to the default emissions calculated using Method 1. Although a single sample does not constitute a comprehensive study, this result suggests that the default factors might be intentionally conservative to motivate reporters to adopt more accurate methods.

While we would not advise reporters to shift away from using the default factors without careful consideration — owing to the compliance costs associated with higher-order methods — this finding provides intriguing food for thought.