Selection of fluids for a polygeneration plant with LNG cold recovery.

Natural gas is forecasted to be one of the most important primary energy sources for the next decades. Particularly, Liquefied Natural Gas (LNG) demand is growing, mainly because of its flexibility in transport. Moreover, its cryogenic temperature makes LNG an important exergy source. However, the conventional LNG regasification process implies that LNG cold is not recovered, but it is wasted. In this sense, polygeneration is a promising way to exploit LNG exergy. The objective of this paper is the selection of the most suitable natural working fluids and heat transfer fluids for a polygeneration plant with cold recovery from LNG regasification. The polygeneration plants exploits the LNG cold for the simultaneous production of electrical power and cold at three temperature levels in a District Cooling network. The plant is not only analyzed from the thermodynamic point of view, but also its environmental impact is evaluated.