Following last week’s introductory article, the next instalment in our series exploring current topics in electromobility looks at the environmental impact of electric vehicles. We cover CO2 emissions throughout the full life cycle of electric vehicles, the sustainability of battery technologies, and an alternative technology: hydrogen fuel cell vehicles. We will again encounter Kate, our “heroine” introduced in the preceding article. Being an environmentally conscious user, she takes extra care not to generate air pollution while travelling, which is why she uses electric car sharing and electrified public transport. The question, though, is whether Kate is really behaving in an environmentally-conscious manner when she travels by electric vehicles? The answer may not be as trivial as it seems. Let’s take a closer look!
It is common knowledge that conventional (diesel- and petrol-powered) vehicles emit many harmful substances that affect our health and the environment, including carbon dioxide, carbon monoxide, hydrocarbons, nitrogen oxides, organic compounds, and particulate matter. Most people, including Kate, also tend to think that electric vehicles emit no harmful substances that pollute the air or soil. One of the main drivers behind the spread of electromobility is the belief that this technology is eco-friendly. We know, however, that zero emissions only apply locally, at the place of use of electric vehicles. If we look at electromobility in broader terms, and consider, for example, vehicle manufacturing, and compare electric vehicles to conventional-propulsion vehicles, the answer as to which type has a lower environmental impact is not so straightforward.
To examine the environmental impact of different vehicle technologies, researchers usually compare emission figures for CO2, the gas thought to be most responsible for global warming. It is no wonder that the European Union’s environmental principles place great emphasis on reducing CO2 emissions. To determine which vehicle technology is “greener”, we compare carbon dioxide emissions by all-electric and conventional vehicles. We do not cover hybrid propulsion systems in this article.
Carbon dioxide is emitted not only when a vehicle is used, but also when it is manufactured or its battery is recycled. We will rely on the life-cycle assessment method for a comprehensive analysis and comparison.
In a joint study, Vrije Universiteit Brussel and Transport & Environment, a Brussels-based NGO have examined how much CO2 is generated during the life cycle of electric vehicles and conventional diesel vehicles. They broke down CO2 emissions during the life cycle of an average conventional diesel vehicle into four stages, according to the source of emission. The vehicles compared were assumed to have a life time driven distance of 200,000 km, which corresponds to 1.5 battery replacement cycles over the life time of an electric vehicle.
1) Well-to-Wheels (WTW): CO2 emitted during production and use of fuel (for electricity, calculated by the European Union’s electricity mix), taking into account engine/powertrain efficiency.
2) CO2 emitted during manufacture, maintenance, and recycling of the vehicle chassis.
3) CO2 emitted during manufacture of the powertrain.
4) CO2 emitted during manufacture of the battery and electronics.
The figure below presents the results of full life cycle assessment, which shows that a conventional diesel passenger car emits more than 41 tons of carbon dioxide during its life cycle. That is almost twice as much CO2 as the 18 tons emitted by an all-electric vehicle, calculated by emission figures based on the EU28 electricity mix.
It is clear that the manufacture of battery packs required for all-electric vehicles adds significant extra CO2 emissions (15%). Over the full life cycle of an electric vehicle, however, the cleanness of electric propulsion easily compensates for such extra emissions.
In 2030, using electric transport will be natural for Kate, and most of Budapest’s public transport will be electrified. By then, there will be an increasing number of all-electric vehicles on the roads, including not only private cars but shared vehicles and taxis, not to mention electric buses.
At present we are no doubt quite far from that vision of the future. We have nevertheless examined a fully electrified public transport scenario for Budapest, on the basis of the average CO2 emissions of and the number of kilometres run by the current passenger car and bus fleet.
Currently, conventional buses and passenger cars emit 540,000 tons of CO2 annually, while CO2 emissions would only be one-fifth of that figure under a fully-electrified scenario. In practice this means that the equivalent of 60% of the annual CO2 emissions of Budapesti Erőmű Zrt. (BERT) could be eliminated through full electrification (Budapesti Erőmű Zrt. (2017): Annual financial statements). BERT’s power plants supply 60% of Budapest’s inhabitants with district heating, and cover 3% of Hungary’s total electricity needs.
The question is when this ideal state will be reached. It is hard to say precisely, but it could be indicative that sales of new vehicles equipped with an internal combustion engine will no longer be permitted in Norway from 2025, in Germany from 2030, and in the UK and France from 2040, while conventional passenger cars are expected to be banned from large cites even sooner.
Research results indicate that CO2 generated during the manufacture of batteries represents a relatively small part of emissions during the full life cycle of electric vehicles. We would, however, draw an incorrect conclusion regarding the environmental impact of electric vehicles if we disregarded the other effects that batteries can have on the environment in addition to CO2. What materials are used to manufacture batteries and what happens when they are recycled? Could, if also taking these into consideration, Kate’s choice for electric vehicles prove not to be so “green” after all?
Electric vehicles use lithium-ion, lead-acid, or nickel-metal hydride batteries, or ultracapacitors to store electricity. Of the above technologies, the latter three are no longer considered fully relevant (US Department of Energy (2017): Batteries for hybrid and plug-in Electric Vehicles), as most plug-in hybrid and all-electric vehicles now use lithium-ion batteries. (Electric buses typically use lithium iron phosphate batteries). Lithium-ion batteries have high energy per unit mass relative to other battery types, as well as a high power-to-weight ratio, high energy efficiency, good high-temperature performance, and low self-discharge. When operated within design parameters, lithium-ion batteries can be considered an environmentally friendly solution, as their use does not generate significant emissions of harmful substances (if damaged, however, these batteries could release toxic gases into the atmosphere). On the other hand, both the manufacture and recycling of these batteries have a real environmental impact: mining, purifying, and resource recovery of their rare metal components (lithium, copper, nickel, cobalt) all contribute to drinking water pollution and soil erosion through emissions of harmful substances.
In addition to environmental damage, the other dilemma of recycling is efficiency: due to its toxic and flammable nature and complex structure, processing lithium is a rather complicated and costly process, while the value of any recoverable material represents only a fraction of the cost of processing. This serves as a disincentive for companies to develop efficient recycling processes, despite a likely increase in demand for such processes in the future. According to an estimate by a Canadian battery recycling company, at the current pace of the spread of electric vehicles an estimated 11 million tonnes of spent lithium-ion batteries could accumulate on Earth by 2030, and their disposal will need to be managed by governments, battery producers, and ultimately, the auto industry itself.
When evaluating electric propulsion and battery technologies, another often mentioned potential problem in addition to environmental pollution is the limited availability of lithium. Lithium mining in Europe is not a substantial industry; the only significant deposit, representing 3% of the world’s identified lithium resources, is found in the Czech Republic, while the largest deposits are located in Chile, Bolivia, Argentina, and China. However, according to a study by Bloomberg, even if electric vehicles continue to spread at the current pace, less than 1% of the known lithium reserves on Earth would be extracted by 2030. So, despite the fact that lithium is used not only in car manufacturing, and new sites will need to be explored, the current technology is not at risk from a shortage of raw materials, and it would be an exaggeration to talk about energy policy exposures to lithium-rich countries. To support the above statement, we only need to consider the advances in energy storage technology in the past 50 years, which allow for an optimistic outlook.
When will the market respond to the arguments against conventional battery technology? Will there be more adequate and environmentally friendly battery technologies in the future? How will energy storage technologies develop?
According to a study by scientists at Stanford University, sodium-ion batteries could be the energy storage solution of the future. Their research is supported by a Swiss group of researchers, who have developed two new types of batteries in which lithium is replaced by sodium and magnesium, respectively.
Both materials have an advantage over lithium in that they are relatively cheap and abundant. Sodium electrolyte is non-flammable, which addresses the safety concerns associated with lithium-ion batteries. Magnesium offers the advantage of storing almost twice as much energy in the same volume as lithium. It is also light and is not susceptible to exploding. Battery size, however, remains a challenge, and the underlying technologies need to be further tested before they are ready for practical application.
In addition to the above, solid-state batteries, with an energy density 2.5 times that of lithium-ion batteries, could prove to be the most efficient energy storage solution yet. Compared to lithium-ion batteries, which contain liquid electrolytes, solid-state batteries use solid electrolytes and electrodes, can be charged faster, and have a significantly longer life time.
At the same time, fuel cell (or hydrogen cell) technology is considered to be one of the main challengers of current battery technologies used in electric vehicles. Fuel cells used in vehicle propulsion systems generate electricity from hydrogen through a chemical reaction, without any local harmful substance emission. Widespread use of hydrogen cell vehicles is currently limited by the cost of producing hydrogen in an environmentally-friendly manner, as well as the fact that compression and safe storage of hydrogen presents a technological challenge, which, if solved, would offer a much larger effective radius than all-electric vehicles at a charge time of only 3–10 minutes. Fuel cell technology has significant potential, but it cannot currently be considered a major competitor to battery-powered vehicles, and it needs further development and substantial government and corporate commitment to become widespread.
Therefore, although battery manufacturing today still involves environmental pollution, in terms of CO2 emission electric vehicles do offer a cleaner solution for Kate over conventional vehicles. We can state that the current environmental impact of alternative battery technologies can be expected to be significantly reduced through development, and the spread of electromobility could eventually contribute to a more sustainable and cleaner future. In other words, Kate has made the right decision by supporting electromobility.
Having looked at environmental impact, which is often evoked by sceptics of electromobility, our next article we will focus on another pillar: the charging infrastructure.
 Electricity used in the territory of any given country originates from a variety of sources (e.g.: coal-fired or gas-fired power plants), the electricity mix is a composite of all of those sources. Use of the EU electricity mix corrects for discrepancies and extremes between regional and national emission values. The specific CO2 emission figure attributable to the electricity mix is 300 g CO2/kWh, 2015.
 An electric vehicle taken into account for our calculation purposes emits 25% less CO2 than a conventional passenger car when, for example, using the Polish electricity mix, and 85% less when using the Swedish electricity mix.
Manager, PwC Hungary