DC Backbone with power-to-gas coupling
The rising share of renewable energy, which is often drawn from smaller, distributed sources, is having a growing impact on today’s distribution systems. This rising number of decentralized sources is putting new strains on today’s highly centralized distribution systems, a problem that manifests itself in local oversupplies and undersupplies of energy, in addition to heavy fluctuations.
The combination of new intelligent grid structures and electrochemical energy storage creates an opportunity to absorb this effect in the local microgrid and thus take the load off the mains. Smart meters and intelligent communications technologies make it possible to react to bottlenecks early enough and produce better load forecasts even as the share of decentralized sources/loads increases.
A large number of sources and systems for distributing, converting and storing energy are already available to serve industrial facilities, commercial buildings and residential dwellings. The downside is, this diversity makes integration into the overall mains an extremely complex task since it requires weighing the impact of a wide range of variances.
In order to merge the various sources into a common grid, power electronics systems play a major role. Key tasks for these systems include voltage regulation, safety functions (current and power restrictions, emergency shutdown), control and network stability, the measuring and monitoring of the current and voltage levels and communication with other components and users.
Selection of the right storage technology is highly dependent on the type of building, the installation site, the source and consumer profile, the capacity of the storage system, time of year and a host of other factors. For example, with an efficiency rate of 98 percent, the use of lithium ion battery storage can help compensate for fluctuations in an electrical grid. On the other hand, the low specific energy density and stringent safety requirements make this technology too expensive for large-scale storage solutions. For large storage systems, technologies that utilize chemical energy carriers (e.g. hydrogen, LOHC) are much more suitable. The size of the tank defines the storage capacity and therefor it can be easily expanded. This technology could also be used for refueling, transporting, buying and selling 100 percent renewable energy carriers.