Sustainability: Keeping an eye on everything

Oct 10, 2018

Despite requiring more energy during production, the Mercedes-Benz plug-in hybrids and electric vehicles already fare far better than their conventionally powered counterparts in the life cycle assessment (LCA) when it comes to CO2 emissions. Only an analysis of the vehicles' entire lifecycle provides a realistic picture here. Thanks to emission-free driving, electric vehicles can compensate for a large part of the additional CO2 emissions they initially cause. There is still great potential in this field. The use of resources in production will continue to fall in future. Daimler AG has set itself the target of reducing the use of primary raw materials for electric drives by 40 percent by 2030. Apart from the economical use of resources, the reconditioning of components and the recycling of the raw materials used play an important role, too. This holistic approach also includes the use of vehicle batteries in stationary energy-storage devices.

In order to gauge a vehicle's environmental compatibility, Daimler considers the emissions and the use of resources over the entire lifecycle. This is achieved by means of a lifecycle assessment (LCA), which records the key environmental impacts – from extraction of raw materials to production and use to recycling. This reveals the following: the environmental balance (LCA) of electric vehicles and plug-in hybrids with regard to CO2 emissions is already extremely positive despite the higher expenditure during production. Despite requiring more energy during the production phase, the Mercedes-Benz plug-in hybrids and electric vehicles offer substantially lower CO2 emissions in the lifecycle assessment (LCA) and, in the best-case scenario, account for around 45 percent of the total emissions. This more than compensates for the extra 'investment' of CO2 emissions during production.

On average, the production of a conventional car with petrol engine today accounts for around 20 percent of the CO2 emissions that this vehicle will cause during its service life of 200,000 km. In other words, the energy consumed while driving – including the extraction, production and distribution of the fuel – accounts for 80 percent of a petrol car's CO2 emissions.

The figures for diesel-engined vehicles are more favourable: their production causes similar emissions, but fuel consumption is much lower. This ultimately results in a CO2 reduction of around 13 percent during the course of the lifecycle.

Great potential if used correctly: the plug-in hybrid

A new-generation Mercedes-Benz plug-in hybrid causes 20 percent more CO2 emissions in production than a comparable car with conventional powertrain due to the technology components, especially the high-voltage battery. Consistent use of the plug-in function by regularly charging the battery from the mains and more efficient operation mean 40 percent lower CO2 emissions on the road, even with the current electricity mix. If the vehicle battery is charged solely using power from renewable energy sources, the reduction in CO2 emissions during normal operation is as high as 70 percent.

Despite the much higher energy use during production, the plug-in hybrid can therefore avoid a large share of the CO2 emissions over its entire lifecycle and, in the best-case scenario, accounts for around 45 percent of the total emissions of a combustion engine. It is therefore more than justified to 'invest' more CO2 emissions during production.

This tendency is even more true in the case of all-electric vehicles. In production, these vehicles still cause 80 percent higher CO2 emissions than vehicles with combustion engines; however, during operation with a conventional electricity mix, they cause around 65 percent less CO2 . This means that their total CO2 emissions during the course of their entire lifecycle are at least 40 percent lower over the same distance.

If it is possible to operate the battery vehicle using only renewable energy, the CO2 emissions over the entire lifecycle fall by 70 percent compared with combustion-engine vehicles. The figures for fuel-cell drive are similar: compared with a battery vehicle, it causes lower emissions during production and slightly higher emissions during operation, with the provision of the hydrogen having a great impact on the overall effect.

Battery technology making electric drive increasingly appealing

In future the EQ models will have even more of an edge when it comes to their carbon footprint as the optimisation of the battery technology and production harbours great potential for further reductions. Even today's batteries cause around 25 percent lower CO2 emissions than first-generation high-voltage batteries during production. Experts hold out the prospect of similar reductions for the next generation: the future batteries will cause only half the CO2 emissions of the first generation and a third less than the current generation during production.

The use of primary resources, i.e. raw materials, will likewise decrease. Some materials in particular – such as cobalt, whose extraction is associated with a heavy environmental burden – will be replaced almost entirely. The batteries will have a higher energy density and offer the same range despite being smaller and lighter, or they will allow far greater ranges despite being the same size and weight. The environmental balance and appeal of electric mobility for motorists will increase over the long term – especially if the energy is obtained from renewable sources. Daimler has set itself the target of reducing the use of primary raw materials in the electric powertrain by 40 percent by 2030.

In view of the expected increase in the number of electric vehicles, this will not be enough for truly sustainable production, however. The recycling of the raw materials used such as lithium, nickel, platinum, cobalt and rare earths is an integral part of the considerations right from the moment the components are conceived. These considerations include everything right up to the monitoring of the entire supply chain from mine to recycling, with great importance attached to the observance of human rights in the employees' working conditions.

For this Mercedes-Benz Cars performs on-the-spot checks with interdisciplinary teams. To reinforce the effect of the in-house measures, Daimler AG is committed to numerous initiatives, including the Responsible Cobalt Initiative. By joining such initiatives, the company pools its efforts with those of other commercial enterprises. With the Human Rights Respect System, Daimler has adopted a systematic approach to prevent infringements of human rights in supply chains. The aspiration: raw materials from safe origins, certifiable standards, and a transparent supply chain from the mine to vehicle recycling.

CO2-neutral energy supply for the assembly plants

The aspect of energy supply in production likewise plays an important role in Daimler's holistic strategy. All Mercedes-Benz plants in Germany will therefore switch to CO2-neutral energy supply, e.g. wind power and hydropower, by 2022. This will reduce the CO2 expenditure in the lifecycle of the vehicles by the amount accounted for by assembly of the components. (See production section)

Recycling concept: from recycling to further processing

To implement the recycling process chain and safeguard future raw material demand for electric mobility, Daimler AG is actively involved in the research and development of new recycling technologies. It has already been possible to gain insights into the recycling of lithium-ion batteries in a number of different research projects, and in collaboration with suppliers and waste-disposal partners. This has involved the development of innovative recycling concepts that allow high-quality recycling of the valuable components or constituents. The company has therefore defined four stages and developed corresponding procedures for the recycling process:

  • ReUse: Battery reuse. Here the reprocessing is limited to cleaning work and exchanging parts that have a limited useful life, e.g. fuses. 
  • RePair: This more in-depth repair stage also includes repair work on the battery. In this way individual modules of the battery system can be replaced.
  • ReManufacturing: This process includes completely dismantling the battery into its component parts. After sorting and checking these parts and exchanging components where necessary, the battery system can be rebuilt.
  • ReMat: This process comprises recycling and recovery of valuable content materials. Daimler AG has already established a central reconditioning centre for the product recycling of high-voltage batteries at its Mannheim location.

With respect to "ReUse" in particular, Daimler has focussed on stationary energy storage devices with the establishment of its wholly owned subsidiary Mercedes-Benz Energy GmbH: because the lifecycle of a plug-in or electric-vehicle battery does not have to end after it has done its duty in the vehicle, as it can be reused for stationary energy storage units. Stationary applications are not susceptible to minor power losses, which means that economical stationary operation is possible for at least ten more years, it is estimated. Reusing the lithium-ion modules in this way almost doubles their economical usage.

The first second-life battery storage system was launched in October 2016 at the main REMONDIS site in the Westphalian town of Lünen. This 13-megawatt-hour project is a joint venture between partners Daimler AG, The Mobility House AG and GETEC. All in all, 1000 used battery systems from second-generation smart battery-electric vehicles have been combined to create a stationary storage facility that is made available on the German, primary regulation energy market.

Even battery systems that have not yet been used in electric cars and are instead stored as spare parts can double up as energy storage units.

  • Around 3000 of the battery modules available for the current fleet of smart electric vehicles are pooled to create a stationary storage device in the form of a "living spare parts depot" near Hanover. The spare parts depot can compensate for fluctuations in the German power grid and thus supports the energy revolution. The entire system with a total storage capacity of 17.4 MWh is scheduled for completion during 2018.
  • Another large storage device comprising battery modules for electric mobility went into operation in Elverlingsen/southern Westphalia in June 2018. Here some 1920 battery modules for the third-generation electric smart are stored as a "living spare parts depot". These modules with an installed output of 8.96 MW and an energy capacity of 9.8 MWh are available to the energy market as battery storage devices, for providing primary control power among other things