Graphene oxide (GO) is well known as an excellent amphiphilic material due to its oxygen-containing functional groups and its chemical tunability. By intercalation chemistry, organo-modified GO containing sulfonilic terminal groups were prepared and used as nanoadditive in Nafion polymer for the creation of hybrid exfoliated composites. The incorporation of hydrophilic 2D platelike layers in the Nafion membranes is expected to induce advantages in terms of thermal stability and mechanical and barrier properties (limitation of the methanol crossover by increased tortuosity and obstruction effect), although it may negatively affect the proton conductivity. In this work, we show how different preparation methods of the nanocomposites influence morphology, transport properties, and barrier effect to methanol. The hybrid membranes are characterized by powder X-ray diffraction and microscopies (SEM, TEM, and AFM). Water and methanol transport properties inside the nanocomposites are investigated by NMR spectroscopy (diffusivity and relaxation times), unveiling a reduction of the methanol diffusion and, nevertheless, an increase in the proton mobility and water retention at high temperatures. Finally, the electrochemical properties are investigated by direct methanol fuel cell (DMFC) tests, showing a significant reduction of the ohmic losses at high temperatures, extending in this way the operating range of a DMFC.

The present work introduces an empirically ground agent-based modeling (ABM) framework to assess the spatial and temporal diffusion of rooftop photovoltaic (PV) systems on existing buildings of a city district. The overall ABM framework takes into account social, technical, environmental, and economic aspects to evaluate the diffusion of PV technology in the urban context. A city district that includes 18 720 households distributed over 1 290 building blocks and a surface area of 2.47 km2 is used to test the proposed ABM framework. Results show how the underlying regulatory framework (i.e., the rules of the internal electricity market) influences the pattern and intensity of adoption, thus realizing different shares of the available potential. Policies that support the establishment of 'prosumers' within Condominiums (i.e., energy community buildings), and not in single-family houses only, is key to yield high diffusion rates. The installed capacity increases by 80% by switching from the one-to-one configuration to the one-to-many paradigm, i.e., from 5.90 MW of rooftop PV installed on single-family households and/or single PV owners to 10.64 MW in energy community buildings. Moreover, the possibility to spread the auto-generated solar electricity over the load profile of the entire population of Condominium results in self-consumption rates greater than 50% and self-sufficiency ratios above 20% for the majority of the simulated buildings. INDEX TERMS Agent-based modeling, complex adaptive systems, consumer behavior, distributed power generation, energy technology diffusion, geospatial analysis, photovoltaic systems, public policy, sustainable development, technology adoption, urban areas.

Innovative renewable routes are potentially able to sustain the transition to a decarbonized energy economy. Green synthetic fuels, including hydrogen and natural gas, are considered viable alternatives to fossil fuels. Indeed, they play a fundamental role in those sectors that are difficult to electrify (e.g., road mobility or high-heat industrial processes), are capable of mitigating problems related to flexibility and instantaneous balance of the electric grid, are suitable for large-size and long-term storage and can be transported through the gas network. This article is an overview of the overall supply chain, including production, transport, storage and end uses. Available fuel conversion technologies use renewable energy for the catalytic conversion of non-fossil feedstocks into hydrogen and syngas. We will show how relevant technologies involve thermochemical, electrochemical and photochemical processes. The syngas quality can be improved by catalytic CO and CO2 methanation reactions for the generation of synthetic natural gas. Finally, the produced gaseous fuels could follow several pathways for transport and lead to different final uses. Therefore, storage alternatives and gas interchangeability requirements for the safe injection of green fuels in the natural gas network and fuel cells are outlined. Nevertheless, the effects of gas quality on combustion emissions and safety are considered.

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