Large volumes of energy in the forms of gaseous fuels, such as, liquefied natural gas, compressed natural gas, compressed air, or liquid fuels, such as, propane, butane, are stored within an abandoned railroad, highway or aqueduct tunnel or similar such structure, in one or more pressure vessels or cylinders which have been permanently installed within the previously abandoned tunnel structure. The stored energy may be directly delivered at high rates to meet any nullpeaknull demand requirements, or may be delivered during times of normal demand based on market economics. The stored energy can also be utilized at the site to directly produce electricity for delivery to the end user.