It was a nightmare scenario for Samsung: batteries in Galaxy Note 7 phones were found to spontaneously ignite due to overheating. The cause? A faulty design. But what about the risks and safety requirements of large energy storage systems? Jos van der Burgt, who works at DNV GL, will be presenting the results during the Energy Storage event this topic to deepen.
By: Dimitri Reijerman
As a technical consultancy, DNV GL provides insight into technological issues to many parties. Van der Burgt specializes in storage systems. He says: “We regularly receive questions from investors or inventors who have made an improvement to a battery. They want to know whether this invention is economically and technically feasible. At DNV GL, we also work on factory acceptance tests at a manufacturer, followed by a site acceptance test upon delivery and installation.”
According to the senior consultant, the rise of electric cars has led to a lot more attention for storage systems, but large-scale storage of electricity for electricity grids and home batteries are also on the rise. “There are multiple battery technologies, but this growth is mainly due to lithium-ion. This type of battery is becoming technically better and cheaper. That opens the way to new applications,” says Van der Burgt.
As a practical example, Van der Burgt mentions a project with grid operator TenneT: “They asked for expertise in pilot projects for frequency control of the grid. We performed the qualification tests of those systems. TenneT had various requirements, such as the response time and power control.”
Fire hazard
Despite the many advantages of increasingly cheap electricity storage, there is a downside to using chemical processes: the risk of fire. Van der Burgt explains: “The battery has a very high energy density. It contains more chemical energy than you can extract electrically. Overcharging, damage or overheating can cause fire. That is why you need to take measures. Such as the question of which elements you put in a cell (the cell chemistry, ed.).”
In the eyes of the DNV GL consultant, Samsung made a crucial mistake with the Galaxy Note 7 debacle: “Samsung proved how not to do it,” says Van der Burgt. “When assembling the cells, they took the tolerances too closely. As a result, the temperature became too high.” The Korean manufacturer was therefore forced to quickly remove this device from the market, with all the damage to its image that entailed.
Need for control system
In addition to safe cell chemistry, a second requirement is a properly functioning control system. This management layer must ensure, for example, that a battery is not overcharged. In addition, manufacturers of such batteries must also pay attention to the packaging of the whole: sufficient distance must be kept between different cells in order to prevent a chain reaction if a single cell fails.
According to Van der Burgt, the chance of a fire is relatively low, but more standardisation is still needed: “Until a few years ago, manufacturers only used a probability calculation. But 'never' does not exist, a fire always breaks out somewhere. In the last two years, that way of thinking has changed. Manufacturers must also have actual solutions to prevent the risk of fire.”
In order to keep a possible fire under control, certain extinguishing agents are available to remove the oxygen in a closed space. This concept is used for containers that serve as energy storage. But according to Van der Burgt, there is still a lot of room to tighten the standards in this area: "You still get a lot of different advice at the moment. The IEC (international standardization) is currently busy recording these kinds of things in standards. The current international requirements state that you must perform a risk analysis and take sufficient measures. But these specifications do not say which measures that need to be taken.”
Recommended practice
DNV GL has also taken the initiative to harmonize the standards for safer energy storage by drawing up the GRIDSTOR recommended practice. This guideline, which describes various energy storage systems, provides a start on improving existing standards. According to Van der Burgt, the IEC uses the GRIDSTOR guidelines as a guideline when drawing up the new standards.
Finally, Van der Burgt pleads for extra attention for home batteries. These are useful for storing excess solar power for consumers, for example. “These home storage systems will soon be in people's basements, for example. There should be good rules for that too.”
Would you like to attend this lecture? Register for free in for the Energy Storage event on Tuesday 12 February in NH Conference Centre Koningshof.
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