Every such county shall have full power to acquire by dedication, gift, lease, contract or purchase all property, sites, facilities and rights within such county necessary to process coal in the manner authorized by this Act and to pay for the purchase or other acquisition and construction of such plant and system by the issuance of revenue bonds payable solely from the revenue derived from the operation thereof. Such bonds shall bear interest at the rate of not to exceed the maximum rate authorized by the Bond Authorization Act, as amended at the time of the making of the contract, payable semiannually, and shall mature within twenty years from the date thereof. Each such county is also authorized to issue, sell and transfer warehouse receipts for such coal and prepared fuel and the by products thereof.
     With respect to instruments for the payment of money issued under this Section either before, on, or after the effective date of this amendatory Act of 1989, it is and always has been the intention of the General Assembly (i) that the Omnibus Bond Acts are and always have been supplementary grants of power to issue instruments in accordance with the Omnibus Bond Acts, regardless of any provision of this Act that may appear to be or to have been more restrictive than those Acts, (ii) that the provisions of this Section are not a limitation on the supplementary authority granted by the Omnibus Bond Acts, and (iii) that instruments issued under this Section within the supplementary authority granted by the Omnibus Bond Acts are not invalid because of any provision of this Act that may appear to be or to have been more restrictive than those Acts.