Power to Gas technology implementation in the Aragonese Pyrenees

摘要

One of the future challenges for energy systems is the reduction of pollutant emissions from fossil fuels. The use of renewable energy is an essential option to achieve this objective. Nevertheless, renewable energy has to overcome some difficulties and to demonstrate its economic feasibility and operational flexibility. Lately, the efforts in the scientific research are devoted to produce a more relevant utilization of renewable energy. For this reason it is essential to have several options for energy storage in order to fit the supply of renewable energy with the demand. One of the options for energy storage is called Power-to-Gas. It is a technology for storage the excess of electricity (produced by renewable systems) and produce Synthetic Natural Gas (SNG) that could be distributed and storage in an easy way. The excess power is used to produce hydrogen through an electrolyser and then it is combined with CO2 in a methanation reaction to produce synthetic methane (CH4). One of the main advantages of the system is that the SNG is CO2 neutral or even CO_2 negative. The CO2 released in the SNG combustion has been previously separated from flue gases from a typical combustion system and hydrogen could be produced by renewable energy excess in an electrolyser. Moreover, naturardistribution network facilitates the management and use of the storage energy. The aim of this work is to present a novel Power-tb-Gas concept combining CO2 capture by means of oxyfuel combustion, hydrogen production by electrolyser and the methanation reaction in a single system able to-produce thermal energy and storage renewable energy,: excess as SNG [1]. The feasibility of this concept is analysed in one Aragonese region in the Pyrenees. A detailed analysis of the availability of renewable energy resources (wind energy, solar and hydropower) has been carried out to select the most appropriate renewable,source. It has been concluded that hydropower is the bes,t option and more flexible for this kind of pro'ject. Wind/energy is located far from thefPyrenees regional and solar energy is influenced by orientation and not suitable for the reduction of available working hours. It has been studied the options to qbtain CO2 with capture systems in the region. There are several important sources of CO_2 in the industrialized area but most of them are far from the renewable sources. One specific case has.been selected in the Pyrenees region because the industry has also possibilities of excess hydrogen. Finally it has been verified that the area selected is not affected by environmental regulations. The deployment of Power-to-Gas in the region could have several possibilities. Two of them have been selected in this work: the implementation in tourist sector as hotels and the industrial sector. For the first case a small size installation has been designed to obtain environmental-benefits and being able to supply the thermal demand by renewable energy and Power-to-Gas. In the second case a commercial installation has been sized to work-in parallel with an industrial process and take advantages of the hybridization. Two options for the size have been) selected in the application in the touristic sector. Both are based in a medium size hotel of 80 rooms. Option A is dimensioned with a 30 kW electrolyser and able to produce the 25 % of the natural gas demand. Option B is bigger with a 72 kW electrolyser and able Jo produce 60 % of the [natural gas demand. A business model has been developed to obtain the,economic results. The conclusions show, that with actual costs both installations are not feasible without subsidies.Nevprtheless, social and environmental benefits (employment and CO2 reduction) have been calculated and they seem relevant for the touristic region if these systems are installed in the hotels. For the industrial installation, results of the economics-feasibility are better than in touristic sector moreover; the social and environmental benefits for the Pyrenees region are relevant enough to consider the technology for a near future.