The bonds may be issued as serial bonds or as term bonds or a combination of both types. All bonds issued by the State authority shall be payable solely out of the revenues and receipts derived from the leasing, financing or sale by the authority of the environmental facilities financed with the proceeds thereof as may be designated in the proceedings of the directing body under which the bonds shall be authorized to be issued. Such bonds may be executed and delivered by the authority at any time and from time to time, may be in such amounts, may be in such form and denominations and of such terms and maturities, may be in fully registered form or in bearer form registrable either as to principal or interest or both, may bear such conversion privileges and be payable in such installments and at such time or times not exceeding 40 years from the date thereof, may be payable at such place or places whether within or without the State of Illinois, may bear interest at such rate or rates per annum without regard to any interest rate limitation appearing in any other law, may be payable at such time or times and at such place or places and evidenced in such manner, may be executed by the manual or facsimile signatures of such officers of the authority, and may contain such provisions not inconsistent with this Act, all as shall be provided in the proceedings of the directing body of the authority. If deemed advisable by the directing body there may be retained in the proceedings under which any bonds of the authority are authorized to be issued an option to redeem all or any part thereof as may be specified in such proceedings, at such price or prices and after such notice or notices and on such terms and conditions as may be set forth in such proceedings, but nothing herein contained shall be construed to confer on the authority the right or option to redeem any bonds except as may be provided in the proceedings under which they shall be issued. Any bonds of the authority may be sold at public or private sale for such price and in such manner and from time to time as may be determined by the directing body of the authority, and the authority may pay all expenses, premiums and commissions which its directing body may deem necessary or advantageous in connection with the issuance thereof. Issuance by the State authority of one or more series of bonds for one or more purposes shall not preclude it from issuing other bonds in connection with the same environmental facility or any other environmental facility or for any other purpose under this Act, but the proceedings whereunder any subsequent bonds may be issued shall recognize and protect any prior pledge made for any prior issue of bonds. Any bonds of the State authority at any time outstanding may at any time and from time to time be refunded by the authority by the issuance of its refunding bonds in such amount as the directing body may deem necessary but not exceeding an amount sufficient to refund the principal of the bonds so to be refunded, together with any unpaid interest thereon and any premiums, commissions, service fees and other expenses necessary to be paid in connection therewith. Any such refunding may be effected whether the bonds to be refunded shall have then matured or shall thereafter mature, either by sale of the refunding bonds and the application of the proceeds thereof for the payment of the bonds to be refunded thereby, or by the exchange of the refunding bonds for the bonds to be refunded thereby with the consent of the holders of the bonds so to be refunded, and regardless of whether or not the bonds to be refunded were issued in connection with the same environmental facility or separate environmental facilities or for any other purpose under this Act, and regardless of whether or not the bonds proposed to be refunded shall be payable on the same date or different dates or shall be due serially or otherwise. All such bonds and the interest coupons applicable thereto, if any, are hereby made and shall be construed to be negotiable instruments.
     The aggregate principal amount of bonds which may be issued and outstanding under this Act by the State authority is $2,500,000,000. In order to carry out the purposes expressed in paragraph (c) of Section 2 hereof, $75,000,000 of such amount shall be allocated by the State authority for the issuance of bonds to finance environmental facilities for small businesses. The State authority shall keep a record of all bonds issued by it under this Act.