(1) Any public power district which is a member of the joint authority may contract to buy from the joint authority power and energy required for its present or future requirements, including the capacity and output of one or more specified projects. As the creation of a joint authority is an alternative method whereby a public power district may obtain the benefits and assume the responsibilities of ownership in a project, any such contract may provide that the public power district so contracting shall be obligated to make the payments required by the contract whether or not a project is completed, operable, or operating notwithstanding the suspension, interruption, interference, reduction, or curtailment of the output of a project or the power and energy contracted for, and that such payments under the contract shall not be subject to any reduction, whether by offset or otherwise, and shall not be conditioned upon the performance or nonperformance of the joint authority or any other member of the joint authority under the contract or any other instrument. Any contract with respect to the sale or purchase of capacity or output of a project entered into between a joint authority and its member public power districts may also provide that if one or more of such public power districts shall default in the payment of its or their obligations with respect to the purchase of such capacity or output, then the remainder of the member public power districts, which are purchasing capacity and output under the contract, shall be required to accept and pay for and shall be entitled proportionately to use or otherwise dispose of the capacity or output which was to be purchased by the defaulting public power district. Any such contracts with respect to the sale or purchase of capacity, output, power, or energy from a project may extend for a period not exceeding fifty years from the date a project is estimated to be placed in normal continuous operation; and the execution and effectiveness of such contract shall not be subject to any authorizations or approvals by the state or any agency, commission, or instrumentality, or political subdivision thereof.