Cargill bets big to fill electrical transformers on 'green chemical'

Over the past few years, the U.S. Department of the Interior has been testing the effectiveness of electrical transformers which use vegetable oil against electrical transformers which use mineral oil in an attempt to boost power production while lowering the threat toxic spills of and fires.

From using this green technology which has helped been perfected by Minnetonka-based Cargill Inc. the agency now plans a “very large project”. An engineer with the department’s Bureau of Reclamation, Bill Heckler said, “Our transformers sit on decks overlooking the flow of beautiful Western waterways. We fear ruptures or fires that will drop large quantities of oil into rivers.”

Easing that fear helped Cargill win a Presidential Green Chemistry Challenge Award on Wednesday in the nation’s capital.

Cargill was cited for its role in commercializing carbon-neutral vegetable oil transformer insulation fluids known as “natural esters,” by the Environmental Protection Agency. The oil in the transformers acts as a cooling and insulating agent. PCBs (Polychlorinated biphenyls), once filled this role, however studies found that they were toxic so was later replaced with a petroleum based mineral oil, which posed an environmental risk.

Cargill uses soybeans to makes its dielectric transformer fluid, while other companies use sunflower seeds and other vegetables. Regardless of what vegetable base it is, they will not catch fire or overheat the way mineral oil does. Petroleum based mineral oil if spilled cannot biodegrade naturally like vegetable oil fluids will.

David Roesser, who manages Cargill’s transformer fluids operations worldwide, said “Right now, vegetable oil-filled transformers make up only about 10 percent of the U.S. market.”

“Approximately 350,000 electrical transformers nationwide contained vegetable oil fluid in 2012. Now, just a year later that number has soared to more than half a million, ranging from small canister transformers to house sized transformers,” he added.

Studies show that vegetable oils catch fire at roughly 680 degrees Fahrenheit, while mineral oil catches fire at roughly 335 degrees. Once the Bureau of Reclamation had determined that its vegetable oil transformer worked as reliably as its mineral oil transformers, they began to improved the technology to improve health and safety.

Heckler said, “A higher flame point makes it a safer product to use around buildings and people, if standard mineral oil spills it can be damaging downstream. Natural ester oils revert to the food chain in two or three weeks.”