Natural Gas Decarbonisation Technologies for Advanced Power Plants

In this paper two options for H₂ production, by means of natural gas, are presented and their performances are evaluated when they are integrated with advanced H₂/air cycles. In this investigation two different schemes have been analysed: an advanced combined cycle power plant (CC) and a new advanced mixed cycle power plant (AMC). The two methods for producing H₂ are as follows: • steam methane reforming: it is the simplest and potentially the most economic method for producing hydrogen in the foreseeable future; • partial oxidation of methane: it could offer an energy advantage because this method reduces energy requirement of the reforming process. These hydrogen production plants require material and energetic integrations with power section and the best interconnections must be investigated in order to obtain good overall performance. With reference to thermodynamic and economic performance, significant comparisons have been made between the above introduced reference plants. An efficiency decrease and an increase in the cost of electricity has been obtained when power plants are equipped with a natural gas decarbonisation section. The main results of the performed investigation are quite variable among the different H₂ production technologies here considered: the efficiency decreases in a range of 5.5 percentage points to nearly 10 for the partial oxidation of the natural gas and in a range of 8.8 percentage points to over 12 for the steam methane reforming. The electricity production cost increases in a range of about 41–42% for the first option and in a range of about 34–38% for the second one. The AMC, coupled with partial oxidation, stands out among the other power plant solutions here analysed because it exhibits the highest net efficiency and the lowest final specific CO₂ emission. In addition to this, economic impact is favourable when AMC is equipped with systems for H₂ production based on partial oxidation of natural gas.