Bonneville Pacific Corp., the Salt Lake-based independent power producer, has been awarded a contract by San Diego Gas & Electric to sell 50 megawatts of electric power produced at a natural-gas cogeneration facility Bonneville will build in Arizona.

The contract is one of four awarded to independent power producers by the San Diego utility. Bonneville will build the power plant in Yuma because of the low cost of natural gas.Bonneville officials also announced negotiations are under way to complete an operating agreement with a thermal host. A thermal host purchases the heat produced in the generation process and uses it for industrial purposes.

Completion of the power plant is scheduled for early 1992 and projected annual revenues are $13 million.