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E-Mobility - The challenges for charging infrastructure

  Knowledge

Progress in e-mobility and the development of the charging infrastructure are dependent on a variety of factors. To achieve a sustainable concept, it is important to understand the systems and the relationships between them. These include charging concepts, ranges, financing, resource acquisition and battery recycling.

Whether for a wholly battery-powered vehicle or a hybrid solution - the charging concept of an electric car follows a certain pattern. The on-board charger (OBC) of the vehicle handles the charging management. Charging per se is a simple "plug & play" affair, inserting the cable into the socket and observing the charging times, battery capacity and OBC charging power specified by the manufacturer. To ensure optimum charging and avoid errors, the battery and charger communicate with one another. This is how the car defines how much it needs to charge, while the charging station (Mode 2 or 3) confirms its capacity. This communication provides great flexibility in selecting a vehicle type - all that is needed is for the plug type to be compatible.

Example of Charging Time

A BMW i3 has a net capacity of 37.9kWh and an OBC of max. 11kW, which means that a battery should be recharged within 3.5 hours. This is consistent with the manufacturer's specifications that 80% capacity will be achieved with a maximum wallbox charge (Mode 3) after 3.12 hours. If charging is only performed using a normal "Schuko" wall socket (Mode 2), the manufacturer's specifications claim a charging time around 15 hours (37.9kWh / 15 hours = 2.5kW), which in turn is consistent with the maximum throughput expected of such a socket. In this case, a pure DC charge takes around 42 minutes (50kW).

Charging Connectors and Modes

Despite the desire for charging connector standardization, there are various systems that have become established, depending on the country of origin of the car. Because most electric cars around world had been produced in Japan until 2015, the common CHAdeMO standard has proven robust there. Europeans on the other hand insisted on their own standard (Type 2), but have not managed to establish it - the USA and China have faced the same problem. This means that car brands around the world currently share four different plug formats.

A charging station (wallbox) can offer different charging modes. Compliance with regional electricity standards (VDE) helps to ensure general safety. Ultimately, there are four different charging modes:

Mode 1: Uncontrolled charging without communication, no circuit breaker mechanism (danger), on-board charger (OBC); max. charging current: 16A/11kW, 1-phase/3-phase

Mode 2: Uncontrolled charging without communication, IC-CPD protection/pilot function built into cable (In Cable Control and Protection Device), on-board charger (OBC); max. charging current: 32A/22kW, 1-phase/3-phase

Mode 3: Controlled charging, AC charging at type-verified charging stations, protection/pilot function built into charging station, on-board charger (OBC); max. charging current: 63A/44kW, 1-phase/3-phase

Mode 4: Controlled charging, DC charging only at type-verified charging stations (Electric Vehicle Supply Equipment, EVSE), monitoring and safety mechanism/pilot function integrated into EVSE, on-board charger (OBC) is circumvented.

Range

Range is a very controversial subject. It currently varies between 100 and just under 1000km of driving distance and also depends on whether the vehicle is purely battery-powered or if it is a hybrid solution. There's also the greatly varying needs of the customer to consider - the average route to work in Germany is around 16.9km (in certain regions as much as 30km). Any car type can manage this with a daily recharge. But it becomes more complicated when covering longer distances such as vacation trips, which is where fast-charging stations come into play. It can be used to charge a BMW i3 at a 50kW charging station in around 42 minutes, for example.

There are now charging stations of up to 200kW that reduce the charging time to just under ten minutes (at 80% charge). If the charging connector is also cooled (500-850A), charging becomes almost as fast as filling up at a normal gas station.

Government Subsidies

Financing will substantially dictate how electromobility develops. The economic stimulus package introduced by the German Federal Government in relation to the coronavirus pandemic makes a purchase of an electric car a more compelling proposition. It has increased the net upper limit of the price of subsidized vehicles to €40,000, while the government subsidy when buying a fully electric vehicle is doubled to €6,000. Added to this are the VAT savings of 3% on invoices issued before the end of 2020 and the manufacturers' environment bonus (approx. €3,000). Funds are also earmarked by the Federal Government and Germany's federal states in the stimulus package for investment in infrastructure.

Fear of mains overload has kept many from having their own charging station or wallbox installed so far - but this worry is unwarranted. A standard family home is supplied with a line that is fused for at least 63A. By comparison, the largest power consumer in the home is an electric stove, which has a 16A fuse. Even with larger household consumers such as electric boilers (approx. 16A or 25A), there is still enough capacity for a wallbox.

Energy providers are also working on developing infrastructure. They aim to make the network of transformer substations denser and more efficient, and to incorporate charging lots into planning at an early stage. Such concepts also incorporate large-scale garages; future street lighting concepts feature public charging stations integrated into street lamps.

Lithium - A Key Resource

Lithium mining, which is currently essential for battery cell production for electric cars, leaves a damaging environmental footprint. The largest reserves in the world are located in Bolivia, Argentina and Chile, with resources of around nine million tons each. In Europe, the largest reserves are located in Portugal (100,000 tons) and Austria (50,000 tons). According to Statista, around 37.4% of demand for lithium today is attributable to batteries.

Mining causes the brine in which the lithium is found - a highly salty ground water - to be pumped to the surface, where it is dried in various evaporation steps. The water is not fed back, which results in a drop in groundwater levels, adversely affecting human and natural life in the regions concerned.

Even if data reports vary, these figures provide a glimpse into the scope of the issue - in Salar de Atacama, Chile, 21 million liters of water are reported to be required each day for the extraction of lithium. The amount of material mined also varies, with the latest data suggesting 23 tons of pure lithium per day, which translates to consumption of 900,000 liters of water per ton of lithium. If the production of lithium batteries entails such massive consumption, we should handle this raw material with care.

Battery Recycling

This also makes recycling batteries as secondary raw material an important subject. Car batteries use not only lithium but also lots of other raw materials, including manganese, cobalt, nickel and graphite, as well as liquid electrolyte, as well as 10 to 20kg of lithium (mid-class vehicle battery).

There are currently two recycling methods available to choose from. The first uses the different melting temperatures of the materials and involve smelting. The second involves crushing the individual components and then separating them chemically. Before either occurs, the connecting elements, safety electronics, insulation materials and packaging plastics must be removed by physical means. The advantage of crushing is that it can be done locally and the battery, which is considered to be a hazardous material, does not need to be transported (or at least not far). But recycling is only worth the expense when you're processing larger volumes.

The life of a battery also plays a role in how raw materials are consumed. For electric cars, a battery is already considered "dead" when it reaches as much as 80% of its maximum capacity. But it isn't fair to write off such a battery so early - it can have a second or third life. Once the battery pack has been checked and the individual cells have been rearranged, its second life as a buffer battery can begin for it to be used for temporarily storing solar, wind and hydroelectric energy, output peaks from energy providers or other surplus energy. There are also opportunities for mobile energy storage facilities for parking garages and much more. This is how the old 80% capacity rule can be redefined as 100% capacity with the same quality properties. Size and weight are secondary here.

Conclusion

The markets and plants for recycling and second-life batteries are not yet fully developed, but it is important to already be thinking about topics such as the mining and use of resources and the renaturalization of the earth, and to understand the underlying issues. Everyone can decide for themselves what form their mobility will take in the future.

 

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