## 2 Background
### Main Drivers and Barriers  
Previous studies focused on barriers and incentives to PtG are intimately connected with the deployment of RES, and the intermittent nature of power generated by exploiting renewables. Currently, the stability of the grid can be affected by mismatches between demand and electrical supply, and the security of the grid limits the technical and economic exploitation of RES. To some extent, it also limits PtG expansion [26]. Other limits to PtG could be related to the availability of CO\({}_{2}\), the scarcity of water, the low efficiency of these systems, other processing steps, or the economic and financial issues related to this technology [11]. Some authors observe that the use of surplus renewables [22] and the volume of H\({}_{2}\) production are influencing the PtG capacity that is linked to electricity generated from RES [27]. In addition, the supply of CO\({}_{2}\) also determines PtG development [28]. Thus, the integration of PtG systems with biogas and other power plants, energy intensive industries, or waste treatments, is highly recommended because these plants could provide the CO\({}_{2}\) that is needed for PtG [29]. However, other transport or storage options may be necessary depending upon the CO\({}_{2}\) source, and the relative costs and technical feasibilities have to be taken into account [30]. At present, there is agreement that PtG will increase the flexibility of the energy supply and connections between gas and electricity networks [31]. The distribution and use of synthetic natural gas is a mature technology compared to other options such as electrolytic hydrogen [32]. In addition,PG technology paves the way for the production of sustainable fuels that can be easily adapted to the existing markets in which natural gas has a considerable participation. These processes have been tested and the necessary technologies for both hydrogen and synthetic methane production have been found to technically and technologically ready. The tested levels are from 7 to 9 for alkaline electrolyzers; from 4 to 8 for polymer electrolyte membrane (PEM) electrolyzers, which are more suitable for distributed production; and from 5 to 7 for catalytic methanation [33]. Therefore, in the short term, technical barriers to the deployment of PtG mainly involve unanswered questions regarding process efficiencies, system integration, and accessibility of the reactants. From the analysis of the literature, we can affirm that economic barriers are currently limiting the extensive diffusion of PtG technologies [19]. Prospective costs of PtG are sufficiently high that its investment costs will fall with scale and the amount of developed facilities. Therefore, financial barriers are relevant for the deployment of these technologies (e.g., initial investment or low returns from investments). Recent works have highlighted the relevance of financial actors for PtG development because financial concerns influence the investors in innovative technologies [34]. Other common barriers that are noted by researchers are the difficulties of access to capital, the lack of investments in energy efficiency, lack of information, financial limits, or the pay-back of investment [35]. Another relevant actor in PtG deployment is the public sector, which is financing R&D in low-carbon technologies due to their positive environmental impact [36; 37; 34]. Public incentives are often channeled through oriented projects according to the guidelines of the financing organizations [38]. Other studies in the energy sector show that RES investments could be stimulated by removing barriers and leveraging the drivers of the investment decision process [39]. [PERSON] et al. (2020) explore barriers to resource efficiency investments from the theoretical perspective of market imperfections that may prevent rational decision-making. Certain investors are more prone to provide capital, or to finance high-risk innovations, with clear differences between public and private sectors [34].