Each electric utility which enters into an agreement with a term of more than one year for the purchase of generating capacity, transmission capacity or energy shall furnish a copy of the agreement to the commission no later than the time at which the agreement is filed with the Federal Energy Regulatory Commission pursuant to the Federal Power Act or, if no such filing is required, at the time such agreement is executed. The commission may disallow, in whole or part, any amounts paid by such utility under any such agreement if it finds that the utility’s decision to enter into the transaction was unreasonable and not in the public interest.