HOUSTON, July 15 (Reuters) - MidAmerican Energy Holdings Co., the utility arm of billionaire Warren Buffett's Berkshire Hathaway Inc. (BRKa.N: Quote, Profile, Research), said on Friday it would spend at least $5 billion on new projects if its purchase of Pacificorp receives regulatory approval.

The statement was made in testimony that was submitted to regulators in six states, whose approval is needed to finalize MidAmerican's planned purchase of the Portland, Oregon-based utility.

MidAmerican announced in May it would buy the utility for $5.1 billion from Britain's Scottish Power Plc (SPW.L: Quote, Profile, Research), making it Buffett's largest acquisition since the 1998 purchase of General Re Corp.

MidAmerican will spend $1 billion per year for at least five years to install pollution equipment at power plants, develop new transmission lines and add 100 megawatts of new wind power generation, President Greg Abel said in a statement.

The company said it also plans to lower corporate and financing costs by $6 million over five years and pass the savings on to consumers.

"MidAmerican's business strategy should provide Pacificorp customers, employees and regulators with valuable stability. Indeed, we intend that MidAmerican will be the last owner of Pacificorp," Abel said.

In addition to the approval from the states of Oregon, Washington, Wyoming, California, Utah and Idaho, MidAmerican needs the approval of the U.S. Securities and Exchange Commission, the Federal Energy Regulatory Commission, the Nuclear Regulatory Commission and the Federal Communications Commission.