# Special Issue on Cutting-Edge Technologies for Renewable Energy Production and Storage
###### Abstract  
The proposed approach to the development of energy production in renewable energy production is based on the concept of energy production in renewable energy production. The proposed approach is based on the concept of energy production in renewable energy production.  
-aviation sector, considering that limited alternative fuels for a CO\({}_{2}\)-neutral aviation sector have already been accepted by ASTM-certificarion process [7]. Among others, synthetic paraffinic kerosene from hydrotreated esters and fatty acids (HEFA-SPK) is a sustainable aviation fuel. This fuel can be produced via power-to-gas pathways, and alternative scenarios on feedstocks, electricity supply, necessary hydrogen supply, and different main products are analyzed. As a result, the attainment of at least 50% GHG mitigation might be possible: this highly depends on the renewability grade of the hydrogen provision as well as on the used feedstock. The scenario in which hydrogen is produced by steam reforming of internally produced naphtha proves to be the best combination of highly reduced GHG emissions and low HEFA-SPK production costs.  
Energy storage can also be based on chemical molecules. Ethanol production from cellulosic material is considered one of the most promising options for future biofuel production contributing to both energy diversification and decarbonization of the transport sector [8], especially where electricity is not a viable option (e.g., aviation). In the paper \"What is Still Limiting the Deployment of Cellulosic Ethanol? Analysis of the Current Status of the Sector\" by [PERSON], [PERSON], and [PERSON], a comprehensive overview of the status of cellulosic ethanol production in the EU and outside the EU is presented. This was made by reviewing the available literature and highlighting technical and non-technical barriers that still limit cellulosic ethanol production at a commercial scale. The review shows that the cellulosic ethanol sector appears to be still stagnating, characterized by technical difficulties as well as high production costs. Competitiveness issues against standard starch-based ethanol are evident, considering many commercial-scale cellulosic ethanol plants appear to be currently in idle or on-hold states.  
Beside road and aviation, maritime transport is a mode of transport that is seeking low-GHG alternatives [9]. In the paper \"Analysis of Internal Gas Leaks in an MCFC System Package for an LNG-Fueled Ship\" by [PERSON], [PERSON], [PERSON], and [PERSON], a 300 kW molten carbonate fuel cell (MCFC) for maritime application system was studied. The paper presented the challenge to ensure safety in case of a gas leak by applying computational fluid dynamics (CFD) techniques.  
On the same subject, the paper \"Analysis of a Supercapacitor/Battery Hybrid Power System for a Bulk Carrier\" by [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON], presented a hybrid power system combining conventional diesel generators with two different energy storage systems (ESSs) (lithium-ion batteries (LIB) and supercapacitors (SC)) focused on port operations of ships. The results show that the proposed system can reduce emissions (CO\({}_{2}\), SOx, and NOx) substantially and has a short payback period, particularly for ships that have a long cargo handling time or visit many ports with a short-term sailing time.