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German Town Uses 100% Renewable Energy as it Disconnects from the Power Grid

December 16, 2019 by Luke James

Bordesholm, a small German town in Schleswig-Holstein, has attracted international attention after disconnecting entirely from the power grid and relying on 100% renewable energy sources for a whole hour.

Just last week, the 7,500-strong population of Bordesholm became the first residents in Germany to have their electricity provided via 100% renewable sources for an entire hour when they were disconnected from the electricity grid. After the hour was up, when the town was reconnected to the grid, not a single person noticed the seamless switch back to it. 

Bordesholm, a town that is already 75% powered by renewable energy sources, hopes to reach the 100% renewable mark at some time during 2020. 


Bordesholm’s 10 MW Storage System

The switch from the grid to renewable energy and back again went ahead with zero issues. This was enabled by the use of a 10 MW storage system in addition to Sunny Central Storage battery inverters and a Hybrid Controller XL made by SMA Solar Technology AG (SMA). 

In January 2018, RES Group won a competitive tender from Versorgungsbetriebe Bordesholm (VBB), a local energy supplier, to build the 10 MW storage system in the town. The project, which officially broke ground in June 2018, was supported by the local state and funded through the EU and VBB. 

According to RES Group, the storage system has 10 MW peak power output, a 15 MWh storage capacity, and utilizes lithium nickel manganese cobalt (Li-NMC) batteries. 

Normally, the storage system is used to provide frequency containment reserves to the local network that is operated by TenneT, a grid company. However, as demonstrated by disconnecting Bordesholm from the power grid, it can also act as a standalone system as an independent local grid, be used to fire the local grid back up into operation and step in during emergencies and power outages. It also helps reduce carbon emissions. 

During the one-hour window, local energy networks were powered reliably and stably using 100% renewable energy. 


An aerial view of  Bordesholm town.

An aerial view of  Bordesholm town. Image Credit: Kieler Nachrichten.


A Seamless Switch

When Bordesholm was disconnected from the grid at the end of November, the town’s energy was provided in whole by renewable resources. Frank Gunther, VBB Managing Director, said that the trial was an “impressive demonstration of how it is already possible and economically profitable to systematically expand renewables along with the required storage capacities without endangering supply reliability whatsoever”.

The test, however, was not a demonstration of how renewable energy sources can be used in place of traditional ones. Rather, it was a test designed to demonstrate how the fallback system would work in case of power grid failure. However, it is hard to ignore the obvious here—it also demonstrated how an economically profitable system can be used to expand the capacity of renewable energy without making sacrifices on reliability. 

In the UK, the National Grid has gone on record to say that it wants to see a similar energy storage system play a similar role and carry out the same function. Now that we have seen that these systems can reliably power an entire town on renewable sources, it may only be a matter of time before this happens. 

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