For the past few years, the U.S. Department of the Interior has tested the effectiveness of electrical transformers that use vegetable oil instead of mineral oil to boost power production while lowering the threat of fires and toxic spills.
The Department is planning a project which will include the usage of green technology that Minnetonka-based Cargill Inc. helped perfect.
“Our transformers sit on decks overlooking the flow of beautiful Western waterways,” said Bill Heckler, an engineer with the department’s Bureau of Reclamation, which operates hydroelectric dams. “We fear ruptures or fires that will drop large quantities of oil into rivers.”
The Environmental Protection Agency awarded the Presidential Green Chemistry Challenge Award to Cargill citing its role in commercialising carbon-neutral vegetable oil as transformer insulation fluid known as “natural esters.” Polychlorinated biphenyls — PCBs were once used as oil in transformers but they turned out to be toxic. They were replaced by petroleum-based mineral which posed an environmental risk.
Cargill makes its dielectric transformer fluid out of soybeans. The fluid can also be made out of sunflower seeds and other vegetables and regardless of the base material, vegetable oil fluids do not catch fire or overheat the way mineral oil does, and they biodegrade naturally within weeks if spilled, something that petroleum-based mineral oil does not do. With vegetable oil insulation, lightning strikes to transformers may no longer lead to fires and spills will be less toxic. Cargill makes the fluid at plants in Chicago and Wichita, Kan. and at a plant in Brazil.
Last year about 350,000 US electrical transformers contained vegetable oil fluid . This year there are more than half a million.
Pacific Gas & Electric from California has decided to only use vegetable-oil-filled transformers and this decision is important for Cargill because convincing major utilities to use the product will be the key to commercialisation of natural esters.
Vegetable-oil-filled transformers are smaller, cheaper carbon-neutral and will be able to produce the same amounts of energy because they can run at higher temperatures than mineral oil transformers.
“You start to look at total cost for an end user,” Roesser said. “You have areas where a soybean oil transformer is less expensive than a mineral oil transformer.”