Evaluating microbial contaminations of alternative heating oils

Abstract

Since 2008, legislative initiatives for climate protection and reduced dependency on fossil resource imports led to the introduction of biofuels as CO2-reduced alternatives in the heating oil sector. In the case of biodiesel, the oil industry or its customers were confronted with accelerated and escalating microbial contaminations during heating oil storage. Since then, other fuel alternatives, like hydrogenated vegetable oils, gas-to-liquid products (GtL), or Oxymethylenether (OME) have been or will be developed and potentially introduced to the market. In this study, we use online monitoring of microbial CO2 production and the simulation of onset of microbial contamination to investigate the contamination potential of fuel alternatives during storage. As reference and blends, fossil heating oils of various refineries, in the course of this from various crude oils, and refinery processes reveal considerable variation in potential microbial activity. Oxymethylene ethers have an antimicrobial effect, while various forms of biodiesel confirm the promotion of microbial activity and diversity. The paraffinic Fischer-Tropsch products and biogenic hydrogenation products demonstrate high resistance to microbial contamination despite allowing microbial diversity. Through an array of analytics, including advanced chromatography coupled mass spectrometry, elemental analysis, and microbial sequencing, we can discuss critical fuel properties that promote or inhibit microbial contaminations. In summary, novel, non-fossil heating oils show different strengths and weaknesses for long-term storage. Designing blends for microbial activity reduced long-term storage might be an option. While being niche products, these fuels will contribute to the rapid reduction of fossil resource use.