Energy

Cogeneration

Among the innovative implementations of natural gas mention has to be made to cogeneration, i.e. the combined production of electric energy and heat. Cogeneration is the combined use of a primary energy, like natural gas, to produce heat and electricity. The concept is based on the recovery and the use of heat residues produced during electricity generation that in other plants would be lost, being therefore less efficient than cogeneration. For example, a methane engine produces electricity and exhaust emissions are then used as a thermal source, i.e. to heat water. In this way electric energy and thermal energy are produced in a combined way. If they were produced through separate processes, larger quantities of primary energy would be needed. This process optimises the use of energy resources with significant economic and environmental benefits. Natural gas is the most economically advantageous fuel with reference to industrial and commercial cogeneration applications, above all due to the lower fixed and management costs and because it is the cleanest fossil fuel. At the moment a wide series of cogeneration technologies is being used, including small pre-packaged units that comprise all the components that are needed for a cogeneration system. These systems are available from 2.2 kW to several hundred MW format. These are cases of micro-generation, which means simultaneous and localised production of thermal energy and electric energy. Thanks to the technological development of new and more efficient natural gas turbines and machines, cogeneration, which was only used by the large industrial sector, is now spreading to small and medium-sized industries and the third sector. In particular, cogeneration systems represent an efficient solution to reduce the costs of electric energy and heating for paper mills and the pharmaceutical, textile, oil refining industry, and in particular petrochemical industries, as well as hospitals, universities, hotels, calculation centres and shopping centres.