The exercise of the powers granted by this chapter shall be in all respects for the benefit of the inhabitants of the Commonwealth, for the increase of their commerce, and for the promotion of their safety, health, welfare, convenience and prosperity, and as the operation and maintenance of any project which the authority may undertake will constitute the performance of an essential governmental function, no authority shall be required to pay any taxes or assessments upon any project acquired and constructed by it under the provisions of this chapter. The bonds, notes, certificates or other evidences of debt issued under the provisions of this chapter, their transfer and the income therefrom including any profit made on the sale thereof, shall at all times be free and exempt from taxation by the Commonwealth and by any political subdivision thereof.