Tag Archives: batteries

Denmark’s most fireproof battery

Lüders - Credit By & Havn / Peter Sørensen

Batteries in buildings ­– the so-called powerpacks – have arrived in Denmark. In 2017, a 460 kWh battery will be installed in the ground floor of Lüders multi-storey car park at Nordhavn in Copenhagen. Here, it will be encased in its own fire cell and secured by means of inert gas and sprinkler system and an automatic fire alarm system.

Battery technology is part of the solution to the energy issues of the future. These issues, which include how we are going to get more sustainable energy from the sun and wind into our electrical grids, and, at the same time, have energy when the sun isn’t shining or the wind isn’t blowing. Better and more cost-effective battery technology means that, in the USA and some places in Europe are already well underway with installing batteries in buildings that charge when the price of electricity is low and contribute to the building’s electricity consumption when the price is high.

And, the same technology is now coming to Denmark. Initially, it won’t provide electricity to buildings but provide it to the local electrical grid instead. Specifically, Lüders multi-storey car park in Copenhagen’s Nordhavn area, electricity network operator Radius is installing a 460 kWh battery – the equivalent of the daily electricity consumption of 32 average families.

– When the energy requirement is greatest, the battery will slice the top off the strain on the electrical grid. The grid is dimensioned to handle the peak loads that only arise a few times a year. If the battery can help ensure a power supply when the load is at its highest, we can reduce our plant and operating costs in the electrical grid, explains Ole Pedersen, Technical Asset Analyst with Radius.

The battery is one of several trials in an overall project entitled EnergyLab Nordhavn, which is testing the interplay between a number of energy solutions in the new neighbourhood in the capital.

– We anticipate that the battery, which is a lithium-ion battery supplied by ABB, will be operational in February 2017. The EnergyLab Nordhavn project will finish in 2019, but the battery’s service life is 10-12 years, Ole Pedersen explains.

Prepared for the worst
Battery technology of this type and size in a building is new and is associated with various other fire technical challenges. For example, lithium-ion batteries can overheat and burst into flames or emit explosive gases and oxygen, even though the battery’s BMS (Battery Management System) minimizes the risk.

Also, knowledge of how the batteries react to fire, extinguishing and whether or not they constitute a risk in the event of a fire, is limited. The fire safety properties of the battery have to be taken into account.

– The building’s electrical installations and the battery are kept separate from each other. The five racks of battery cells, which together make up the actual battery, are located in their own battery cell constructed with a minimum of 150 mm of reinforced concrete. In each rack there are sensors which constantly monitor each cell and register heat and fire, Ole Pedersen tells us.

If there are problems with the generation of heat, the system automatically sends an alarm to the fire brigade. In addition, an inert gas device, connected to each individual rack, has been installed. That way, the system can reduce the oxygen content in the specific rack in which the heat is being generated, thus preventing it from bursting into flames.

– There is also a sprinkler system with no water installed in the room with a sprinkler head located above each rack. When the fire brigade arrive, they will make an assessment as to whether they will go into the room containing the battery to take a closer look at it. If they don’t want to do that, they can attach a fire hose to the sprinkler system from the outside and inundate the room, explains Ole Pedersen, adding:

– We hope that it never comes to that, because the water would destroy everything in the room. But we need to have a plan for the worst case scenario.

A good place to start
The fire technical solution has come to fruition through a collaboration with ABB (who have previously installed similar batteries abroad) and DBI. The Copenhagen Fire Brigade was also involved. But, how do you actually assess fire safety when the technology is brand new and there are no rules governing it.

– There is nothing in Denmark we could compare it with. Instead, we looked to the USA, where the National Fire Protection Association (NFPA) has also been considering the same issue. Previously, we were used to dealing with acid and lead batteries whereby, according to NFPA’s rules, you could have up to 600 kWh in the same room. We have only just started looking at lithium batteries and whether they behave differently to the other batteries, says René Ruusunen, who is Senior Fire Engineer with Copenhagen Fire Brigade. He continues:

– On the basis of the NFPA’s 600 kWh rule, we came to the conclusion that the battery was adequately protected and that we would not have to lay down any specific requirements with regard to their installation in order to ensure safe extinguishing and rescue conditions. However, it doesn’t mean that you will be able to freely install all batteries under 600 kWh in future. The things that require approval will change as we learn more about the fire properties of the batteries. If you want to install a battery, you must contact the local fire authorities in all cases.

– At the same time, the battery has been installed in a multi-storey car park where the footfall is low and there is direct access from the open air so that we can get to it easily in the event of a fire. In that sense, it is a good place to install the first battery of its type, says Morten Valkvist, fire engineer with Copenhagen Fire Brigade.

More electricity for your money
If the technology lives up to expectations, the battery in Nordhavn could quickly become the first of many.

– We expect that it will make good economic sense. They can help us reduce construction costs and get the optimal return from the money we invest. In future, with less expensive batteries they could become an alternative to the traditional ways of supplying the electrical grid in peripheral areas. At the same time, the batteries can be used for spectrum regulation of the electrical grid, which will become more pertinent as energy production becomes less centralized due to solar cells and wind turbines, says Ole Pedersen.

Even though the level of fire safety is high, it won’t be the related costs that stand in the way of the technology. The fact is that fire safety only accounts for 3-5% of the total cost of the battery.

DBI investigates the fire safety of batteries in ferry project

e-ferry-web

Batteries are not only making their way into our buildings. They are also making inroads into the transport sector.

They can be found in, for example, hybrid cars and also in ferries, which use battery packs as a supplement to their diesel engines. And now, the first all-electric ferry is on its way to Denmark. It is being planned for the so-called E-Ferry Project, which is an EU project. The project is still in embryo and, more specifically, work is being carried out on the routes between the Danish islands of Ærø and Funen and between Ærø and Als.

It is hoped that the electric ferries will be put into operation in 2017. DBI is involved in the project and is focusing on fire safety with regard to batteries as well as the lightweight plastic components the owners would like to use in the construction of the ferry to reduce its weight.

– There are EU standards for batteries in which fire safety in relation to operational situations has been incorporated, but they do not deal with fire safety in the event of an accident occurring. For example, there is a big difference between handling a single battery in a safe way and handling a large bank of batteries that are involved in a fire. Battery systems have slipped under the radar slightly in relation to fire safety since batteries come under the standardisation organisation CENELEC, which normally doesn’t work with determining the impact on fire parameters such as heat and smoke generation. However, these parameters should be determined in order to assess the fire risk in the case of an accident, says Martin Pauner, who is a civil engineer with DBI, and involved in the E-Ferry Project.

Just as on land, batteries entail a lot of unknown factors in relation to fire safety at sea: How do different types of battery react to saltwater, when they get damaged during a sailing or if a fire breaks out elsewhere on the ferry. And, how good are the different batteries’ cells at preventing the spread of the fire in the event of ‘thermal runaway’ in an individual cell?

These are just some of the questions that DBI will attempt to find an answer to in relation to the project.

Batteries and fire hazards making their way into our buildings

solceller

Batteries are making their way into our buildings. Here, they collect energy from solar cells and provide us with smart energy consumption. However, they also constitute a fire hazard that is difficult to manage and, in actual fact, there are no regulations governing this area.

It makes good sense to store power. If you have solar cells on your roof, you can store energy during the day and use it in the evening and during the night. In particular, house-owners with solar cells installed under the new scheme which dictates that power from solar cells is used in the same hour as it is produced, can only sigh at such an opportunity. Not to mention the even greater potential in being able to store power from wind turbines which we currently export abroad for a pittance whenever the wind blows. This greater potential lies some way off in the future but solutions with large batteries for buildings, so-called power packs, are advancing at great speed – particularly in the USA.

The batteries will be installed in buildings where they will be used to store power from the solar panels on the building or to purchase power when prices are low – typically during the night when demand is low – to be used later when prices increase again. This phenomenon is called ‘peak shaving’, because you are shaving the top off the price of electricity, and there is the potential for saving large amounts of money.

However, installing such a large energy-storing component in a building is not necessarily without its problems. Especially not when the fire properties of the different types of batteries are largely unknown.

Explosions and flammable gas
There are many types of batteries that use different chemical components, all of which react differently to fire. One of the most commonly found types of battery is the lithium-ion battery that you see in various American power packs and also in the Tesla Powerwall. It has become popular because it is lightweight and is able to store a lot of energy in relation to its size. It also functions well when it is recharged and the power can be stored for longer periods without losing any voltage. And then, it reacts to heat.

– If a lithium-ion battery gets too hot, it will, at some point, experience ‘thermal runaway’, meaning, for example, that the electrolyte in the battery vaporises with the result that eventually the cell will no longer be able to contain the pressure. Many batteries have a safety mechanism in the form of ventilation if the pressure gets too high which prevents the battery exploding, explains Petra Andersson, who is a senior researcher in the Fire Research department at the SP Technical Research Institute of Sweden and who has carried out research into lithium-ion batteries and fire.

Regardless of whether the cell releases the vaporised electrolyte or explodes, the result is the immediate emission of highly flammable gas. This is because the vaporised electrolyte in lithium-ion batteries is combustible. It has more or less the same fire properties as propane, which you will be familiar with from the liquid gas in lighters.

Toxic gas and difficulty extinguishing
A battery can heat up if it is overcharged or used incorrectly. A Battery Management System (BMS) is intended to prevent this. However, it can also happen if a fire breaks out in a building in which a power pack has been installed. Different lithium-ion batteries have different electrolytes which react at different temperatures, but a battery temperature of around 100 degrees results in a risk of gas being emitted.

– If the gases from the battery escape when there is already a fire in the room, the gas is ignited immediately. If there is no source of ignition and the gas escapes from the batteries, it will accumulate as the individual cells, which make up large lithium-ion batteries release it, thus causing a bigger and more serious explosion, explains Petra Andersson.

A lithium-ion battery doesn’t just emit flammable gas when it gets hot or burns. Depending on the materials in the battery, it also releases large number of toxic gases, for example, hydrogen fluoride which, even in small doses, can be life-threatening.

And, as if flammable gas, the risk of explosion and toxic gas wasn’t enough, there is also the small detail in lithium-ion batteries that they are difficult to extinguish if they happen to catch fire. Tests from the USA show that even though a fire in a battery has apparently been put out, some cells in it can experience ‘thermal runaway’ and flare up again hours, days or even weeks after it has been extinguished. At the same time, thermal imaging of the battery will not show whether it will flare up again or not.

More research needed
As mentioned previously, different batteries have different fire properties. But, irrespective of which type of battery it is, there are no rules governing the set-up of batteries in the Danish Building Code or standards for how they are to be installed with fire safety in mind. This is because batteries in buildings are a new technology.

– As far as I am aware, no research has been conducted into how you fireproof buildings with batteries or how you approach batteries in a building with a view to extinguishing them if they catch fire. If the power pack technology starts to become more prevalent, there will be a real need for more research, explains Petra Andersson.

Research is necessary because, for example, different batteries react differently to, say, water. A lithium-ion battery can be extinguished using water in reasonable amounts. However, if you spray water on a lithium battery, there is a risk that the lithium mixed with the water can develop into the flammable gas, hydrogen. In the context of fire technology, it means that different batteries require different fire technology initiatives.

– There are a vast number of considerations in this area which require investigation and research. This is because it is simply unacceptable for us, as a society, are unable to do anything if, for example, a fire breaks out in a power pack installed in a block of flats, says Director for Customers & Relations in DBI, Ib Bertelsen, before continuing:

– At the moment, we know very little about how we should tackle this. It depends a lot on which type of battery you are talking about, whether it is a large system in an industrial set-up or a smaller system in a domestic set-up, and often customised solutions will be required. Some of the options you could consider for large power packs are, for example, aspiration smoke detection systems, which are extremely sensitive and take samples of the air at regular intervals in order to detect a fire, inert gas and, potentially, sprinkling. With regard to smaller power packs, the same could apply to BS-60 cabinets. However, there is a need for more knowledge and research in the area, he emphasises.