Dynamic Analysis of a Power Plant Producing Liquefied Biomethane for Heavy Road Transport

Abstract

In the recent years, European Countries are paying more and more attention to the issue of greenhouse gases emissions due to the road transport sector. In particular, the fuel consumption due to the heavy road transport is one of the most relevant issues both for the weight and the long distances that they cover. In addition, the cost of the natural gas dramatically increased in many European countries due to recent international crisis. Thus, finding alternative ways of producing natural gas from renewable sources would be of great economic and environmental impact for the current global asset. In this work, a dynamic thermoeconomic analysis of a plant producing bio liquefied natural gas (bio-LNG), driven by renewable sources, to meet the fuel demand of a fleet of heavy trucks is proposed. The plant consists of a plug flow reactor digesting the organic fraction of municipal solid wastes in mesophilic conditions. The biogas upgrading model and the biomethane liquefaction models are in detail developed in MATLAB. The whole system is integrated in TRNSYS for dynamic simulation purpose. Then, the bio-LNG is used to meet the fuel demand of heavy trucks which cover relevant distances all over the region of Campania, in the South of Italy. The environmental impact related to the avoided emissions due to the use of bio-LNG is analysed together with the economic feasibility of the proposed system. The results of the thermoeconomic simulation show that the system has high capital costs, close to 85 M€ despite the fundings granted for bioLNG trucks purchasing. However, the fundings for the biomethane production and selling are enough to guarantee a remarkable economic feasibility with a Simple Payback period of less than 2 years and a Net Present Value of 402 M€. Furthermore, the solution proposed is effective for the pathway of the green mobility, with a Primary Energy Saving of 91% and a reduction of CO2 emissions by 86%.