Benefits and downsides. The main advantage of a fuel cell is obviously its emission-free operation, provided that the fuel was also produced in an emission-neutral way. This is nowadays still a great challenge. At full load and at some partial load states a fuel cell provides high efficiency. Because of the modular design, the stack size is customizable for the individual vessel. Manufacturers also state that the mainte- xxxxx effort is extremely low. Also, the increased comfort due to low noise and no vibrations is favour- able. The EMSA study from 2017 [30] clearly shows that since the early 2000s there have been and continue to be new initiatives aimed at finally establishing the fuel cell as a propulsion system for ships of all sizes. There have also been some setbacks during this time, such as the loss of the fuel supply for the Alsterwasser. In the recent past, many new exemptions have been granted for retrofit inland vessels that are to be equipped with a PEMFC system. They are addressed in the WP 2.1 database. In addition, the first projects for the maritime use of ammonia SOFCs have been launched. In 2020 it was announced that the offshore supply vessel VIKING ENERGY will be equipped with a 2 MW SOFC in 2024 [31]. The conversion is being carried out as part of the ShipFC project [32]. However, the disadvantages of fuel cells cannot be disregarded. Fuel cell systems are still the technol- ogies with not only the highest investment cost, but also with the highest fuel costs, if pure hydrogen is needed, the shortest lifetime and are very sensitive to the purity of the fuel. Therefore, it is still hard if not impossible to find a business case, comparable to a standard Diesel engine, but also to other technologies involving combustion engines with alternative fuels or pure battery electric solutions. More- over, due to still comparably low experience in field testing, it is not yet fully clear what the maintenance effort and costs will be. Replacing the membranes, for example, is again associated with high invest- ments. In conclusion, it can be said that fuel cells have potential, but their application is still overshadowed by the problems and high costs associated with the widespread use of a technology in a new field. Author | Xxxxxxxxxx Xxxxxx-Xxxxxx Xxxxx agreement no. | 101096809 Funded by the Horizon Europe Programme of the European Union under grant agreement No 101096809 Funded by the Horizon Europe guarantee of the United Kingdom, under project No 10068310 Funded b...
Benefits and downsides. With our design and implementation, we showed that we successfully implemented the planned system architecture on top of Besu’s already existing system without changing the codebase. The clients are simple modules that send requests and receive replies to/from the execution nodes via sockets. The ordering layer is implemented by writing a log smart contract as the log structure on top of the ordering Blockchain. The execution layer is the most complex layer with the largest functionality: each execution node is itself a one-node Besu Blockchain that has to interact with the log contract to execute the client commands. In particular, by implementing the planned architecture, we also materialized its design character- istics. We were able to develop each layer as an individual component of the system, which can be changed without altering the other, or affecting the client – for instance, Xxxx’x consensus can be changed by changing a few lines on the Blockchain genesis file. Additionally, the clients can have their commands executed through four main simple methods, without needing to know how the system works. Moreover, the execution layer can be expanded by simply adding more execution clusters (i.e., scaling out) to accommodate more clients, and to further reduce the load among the existing clusters and effec- tively parallelize the execution of smart contracts belonging to different execution clusters. Furthermore, because the execution clusters can constantly contact the log structure through their Back-end 1 mod- ules, smart contract execution in each cluster becomes even more efficient for each Back-end 2 module to execute smart contracts. Finally, since the order of the commands is already agreed upon and all the commands on the log structure must be executed, the execution clusters are not slowing down the consensus protocol, nor are they wasting any command executions. However, as predicted, some of these characteristics handicap our system. Since we defined inde- pendent layers, the communication between them is a source of overhead. Specifically, the execution nodes are constantly reading from the log in an infinite loop, which can be very inefficient. Likewise, each client establishes a socket connection every time they want to send a command or get a status, which can be resource-intensive. Added to this, there is the extra challenge of having all the clients securely learn about the result they have obtained. To this end, an extra, simplifie...
