Moneys appropriated to enable the commission to guarantee the payment of the interest or principal of its bonds shall be available to the commission as a continuing revolving fund, and moneys so appropriated, and any unexpended balances thereof, including interest on the moneys and unexpended balances, shall not revert to the state general fund at the end of any biennial fiscal period but shall be available for use by the commission to insure and guarantee the payment of, or pay, to the extent provided in this chapter, the interest and principal of its bonds until otherwise required by law.