Peak Load Electricity Production with Cryogenic Fuels

Abstract

Natural Gas is often liquefied (LNG) for its transport by ships over long distances. In order to prepare it for further transport by pipelines it has to be reduced again to a gaseous state, normally by heating it with sea water. A similar technology is envisaged for long-distance transport of Hydrogen as an energy carrier. The scope of this article is the thermodynamic investigation of two power plants for peak load energy production. These two power plants use as fuel the fluids obtained by the re-gasification of the cryogenic fluids. The first proposal is a Hydrogen-fired steam power plant, while the second considers the use of LNG in an oxy-combustion arrangement with subsequent CO2 separation, which is obtained by a three-stage intercooled compression train. The power cycle performance was verified in both cases by exergy analysis. Since the size of these power plants is relatively small (10 MWe), they can be easily built inside the area of LNG gasifiers, or inside the area of the plant producing liquid Hydrogen; the cryogenic fuel and oxidizer are thus considered available, and the purpose of the power plant is peak load energy production rather than obtaining high values of conversion efficiency. This paper is an updated version of a paper published in the ECOS'08 proceedings.