Heating oil (extra-light heating oil, heavy fuel oil, bio heating oil)

What is heating oil?

Heating oil is a mainly petroleum-based fuel for use in furnaces, central heating systems, and industrial furnaces. There are essentially two different types of heating oil available: extra-light heating oil, which is a middle distillate, and heavy fuel oil, which is classified as fuel oil. In the area of extra-light fuel, heating oil with a defined proportion of biogenic content is also offered: bio heating oil (“A Bio” extra-light heating oil).

Heavy fuel oil (HFO)

Heavy fuel oil is primarily used in the chemicals industry, but also, for example, to a smaller degree in the iron, steel and electricity industry. Heavy fuel oil, defined in Germany in DIN 51603-3, needs to be preheated for transportation and combustion. For more information about viscous heating oil products please refer to the glossary item “fuel oil.”

Light heating oil

Light heating oil is mainly consumed by households and commerce, but also by industry. A small proportion is used for electricity, district heating and gas generation.

Extra-light heating oil

The standard heating oil is extra-light heating oil, which in Germany is defined in DIN 51603-1. In contrast to heavy fuel oil, extra-light heating oil can be used in burners without preheating.

Extra-light heating oil according to DIN 51603-1 consists of various hydrocarbons that are obtained from the distillation of crude oil. The fraction with a boiling range between 200°C and 400°C is referred to as gasoil. Extra-light heating oil is a refined gasoil. Blending brings gasoil to within the necessary parameters in the respective fuel standard.

1 liter of heating oil contains about 11 kilowatt hours of energy. Standard extra-light heating oil has a sulfur content of between 50 and 1,000 milligrams per kilogram. Since 2011, low-sulfur heating oil has prevailed as the most common heating oil, with a market share of over 99%. The maximum sulfur content for low-sulfur extra-light heating oil is 50 milligrams per kilogram.

No pan-European standard exists for the liquid fossil fuels used in the heating market. Quality specifications are set at national level. In Austria, for example, this is ÖNORM C 1109. The maximum sulfur content is limited to 0.10% (m/m) across Europe level by Directive 1999/32/EC.

Bio heating oil (“A Bio” extra-light heating oil)

For several years now, bio heating oil in accordance with DIN SPEC 51603-6 has been available on the market. This is a low-sulfur, extra-light heating oil to which biogenic content has been added, e.g. in the form of canola methyl ester/rape methyl ester (CME/RME) obtained from rapeseed. The minimum biogenic content is 3% (v/v). The number in the product name gives information about the amount of their biogenic content. The formal name for an admixture of, for example, 3% (v/v) to 5.9% (v/v) biogenic content is “A Bio 5” extra-light heating oil, but names like Bio 5 or B5 are also used. The use of bio heating oil according to DIN SPEC 51603-6 is only permitted in oil systems that have been approved for biofuel use by the equipment manufacturers. Most oil-fired boilers are approved for heating oils with a biogenic content of up to 10% (v/v). However, with proportions of more than 5% (v/v) conversions to the heating system may be required.

Taxation of heating oils, and fuel dyes for heating oils

In Germany, for example, low-sulfur heating oil has tax advantages compared to the extra-light standard heating oil; the energy tax rate in Germany is 1.5 cents per liter lower than for conventional heating oil, i.e. 6.135 cents per liter instead of 7.635 cents. There are oil heating systems that can be operated with low-sulfur heating oil only, for example oil-fired condensing boilers without a neutralization system. Their filling pipe should have a green safety cover.

In addition, fuel used for heating is taxed at a different rate than fuel used in vehicles. Heating oil and diesel fuel are very similar in many ways. So because heating oil is taxed at a lower rate in Germany than diesel fuel, its use as a vehicle fuel to evade taxes is illegal. To avoid confusion, heating oil (and low-sulfur heating oil) is labeled with heating oil dye (HKZ, also known as Euromarker) consisting of a red dye and a marking substance known as Solvent Yellow 124. The red color serves to create a visual distinction between heating oil and diesel fuel. The addition of the Solvent Yellow 124 dye allows for chemically detecting a mixture of heating oil and diesel fuel, as the yellow dye in heating oil will turn red in acidic water phase. This characteristic is helpful for quick tests by customs officers, e.g. at highway service areas.Section 4 of the German EnergieStV obligates the owner of the labeling operation to carry out a proper identification of the heating oil and to regularly monitor it. Incidentally, all EU Member States are required to add a chemical marker to heating oil.

Additives for heating oils

Special additive packages can also be used to deactivate specific traits of heating oil. These packages include flow improvers (e.g., in “winter oil” goods) that ensure better flow characteristics at sub-zero temperatures by inhibiting the formation of paraffin crystals. Antioxidants, for example, also slow the aging of heating oil caused by atmospheric oxygen, and odor maskers ensure a more pleasant odor during fuelling – all of these are characteristics of “premium” heating oils, too. Among the other products available on the market are organic combustion improvers to eliminate the formation of ash.

Status: December 2015
All information subject to change. Errors and omissions excepted.