Benefits of Bio-based Fluid

The biodegradable bio-based transformer fluid developed in recent years is a superior “green technology” alternative to petroleum-based mineral oil. It is proven to help utilities achieve higher levels of environmental stewardship. Not just an environmental sustainability initiative alone, however; it also demonstrates a utility’s commitment to higher levels of public and workforce safety, performance, and system reliability, while keeping costs and liability down.

Consider this comparison.

Attributes of petroleum-based mineral oil:

  • Potentially harmful to the environment
  • Flammable at 145˚C, significantly lower than the minimum industry requirements of 300 ˚C for “less flammable” fluid
  • Costlier to clean up in the event of a spill
  • May contain of traces of known carcinogens

Attributes of biodegradable bio-based fluid, which has been on the market since 1997:

  • Environmentally preferred, non-toxic per standard tests, renewable
  • Highly biodegradable according to U.S. EPA Environmental Technological Verification (ETV)
  • Natural remediation option available for spills
  • Less flammable; rated with the highest flash (330˚C) and fire (360˚C) points of any less-flammable transformer fluid on the market

Side-by-side comparison

Here is a side-by-side comparison that demonstrates in detail the advantages of bio-based fluid over petroleum-based fluid.

Bio-based Dielectric Fluid (Vegetable Oil)

Petroleum-based Mineral-oil Fluid

Key Properties

Produced from domestically grown, renewable sources, such as soybeans and corn

Produced from increasingly scarce and non-renewable special petroleum crude

Environmental Properties

Highly biodegradable; non-toxic; does not contain petroleum, silicone, or halogens

Contains compounds that do not readily biodegrade. May contain traces of a confirmed carcinogen*

Leaks and Spills

Relatively rapid biodegradation may eliminate the need for environmentally related clean-up operations

Spill clean-ups are required by regulation and typically necessitate special equipment and material to help capture contaminated runoff

Fire Point

360°C (680°F)

155°C (311°F)

Flash Point

330°C (626°F) Extremely resistant to ignition

145°C (293°F) Can catch fire at a relatively low temperature

Fire Risk

Higher fire point reduces the frequency and impact of transformer fires; virtually eliminates sustained fires

Catches fire more easily, leading to higher probability of transformer fires

Transformer Performance

Proven to slow down the aging rate of the insulation system, resulting in an increase in the expected life of a transformer by decades; also promotes automatic dry-out of paper insulation

Does not slow down the standard insulation aging rate; requires special and expensive processing to dry out the paper insulation

Utility Cost

Upfront investment promotes transformer life and leads to longer-term economic benefits

Smaller investment leads to shortened life of transformer and diminished economic returns; increases liability

*While today’s mineral transformer oils are highly refined, there are hundreds of millions of gallons in existing older transformers that contain significant quantities of polynuclear aromatics. According to U.S. Environmental Protection Agency (EPA) Environmental Technology Verification (ETV) Report EPA 600/R-02/042, the primary component of this mineral oil-based transformer fluid was a hydrotreated light naphthenic petroleum distillate, ranging from 30 to 100%. Due to this content, such oil “was identified in Chemical Abstract Service (CAS) No. 6472-53-6 as an International Agency for Research on Cancer (IARC) confirmed carcinogen based on experimental data for animals.”