Clean energy
24.07.2019/XNUMX/XNUMX - Do electric cars only drive better with batteries or fuel cells? At the moment, car manufacturers are mainly focusing on all-electric cars. But doesn't the fuel cell vehicle offer more advantages? An analysis.
Electric car or fuel cell vehicle?
If we want to get a grip on climate change, then we have to take care of climate-friendly mobility and alternatives to fossil propulsion energy. Currently, the debate on alternative powertrains is centered around the question of whether electric vehicles are best used with fuel cells or with lithium-ion batteries. The answer to this question is determined by factors such as suitability for everyday use, costs and sustainability.
Currently, the race between fuel cell and lithium-ion battery seems to be running: pure electric vehicles (BEV), excluding hybrid vehicles dominate the new registrations, and charging stations can be found many, while hydrogen refueling stations are few and far between. Fuel cell vehicles (FCEV) are more expensive and hydrogen as fuel costs more than electricity. So is everything clear? Not quite. If you take a closer look at the fuel cell, you get a differentiated picture. We have put together the advantages and disadvantages of the drive variants for the electric car for you.
The fuel cell drive regularly buoys. However, it is alarming that this has been happening regularly for over 25 years. Also, as the advances in battery electric mobility are considerable, this H 2 technology always falls behind.
How environmentally friendly are BEVs compared to FCEV?
For the comparison between electricity and hydrogen, the greener the energy source, the better the environmental balance. In the eco-comparison to electric cars, the fuel cell is currently having a hard time: First, electricity must be generated from hydrogen. This is fueled in the car, in the car, electricity is generated from hydrogen again. This double conversion significantly reduces the efficiency. Anyone who directly charges the battery of their electric car with the same power will travel more economically and thus also more environmentally friendly. However, that could be different in the future. Once the electricity is produced predominantly from the sun, wind and water, a fuel cell car becomes competitive as it consumes less resources in its manufacture than a battery-powered electric car.
A recent study by the Fraunhofer Institute for Solar Energy Systems (ISE) on behalf of the H2 Mobility seems to confirm this: According to this, cars with hydrogen and fuel cells are more climate-friendly than battery vehicles when 250 kilometers are reached. The deciding factor is the much larger CO2 backpack, the battery cars have to carry through the production of the battery, the researchers said. The greenhouse gas (GHG) footprint of the production and recycling of a fuel cell system including a tank is roughly equivalent to that of an electric drive with an 45 to 50 kWh storage capacity. For cars with larger batteries, more GHG emissions are emitted than for the fuel cell system in a comparable performance class.
The study examined the generated GHG emissions in the production, operation and disposal of battery and fuel cell vehicles with ranges from 300 kilometers, for the periods 2020 to 2030 and 2030 to 2040. The study also makes restrictions. Among other things, the potential for improvement in the production of important materials (platinum, aluminum, etc.) was not taken into account. In addition, the study recommends investigating other categories of impacts in addition to GHG emissions, such as land and water consumption. Also, the environmental impact was not considered for the construction of the mobility infrastructure (charging infrastructure, H2 distribution, etc.) and a second-life use of batteries and fuel cells was not included.
In summary, this means: electric vehicles with medium-sized to smaller batteries (<50 kWh storage capacity) and ranges of up to 250 kilometers reduce emissions in traffic. For longer ranges, fuel cell vehicles have increasing advantages from the point of view of climate protection. The GHG footprint of both alternatives depends heavily on the production of the batteries or the hydrogen.
Based on the current situation of the electricity market in Germany, according to ADAC calculations, no major problems are to be expected in the medium term. Because ten million electric cars would require an additional power consumption of about 5,6 percent. In addition, improvements in efficiency and energy savings for lighting, as well as in buildings and industrial facilities could compensate for part of the additional demand for electromobility.
According to ADAC, the risk of local network overload increases with the number of electric vehicles. In particular, the distribution grids that deliver electricity to the end customer on the “last mile” are not able to cope with the additional demand from households with electric cars, as the ZEW Energy Market Barometer 2018 found. In the study “The E-Mobility Blackout”, the analysts from the consulting firm Oliver Wyman, together with researchers from the Technical University of Munich, calculated that the German low-voltage networks would not be able to cope with a coming boom in electric cars. Electric cars with a share of 30 percent or more would overload the local distribution network and provoke local power outages as soon as many vehicles are charged at the same time. However, bidirectional charging and intelligent load management could help. Here, however, it is important to clarify the legal consequences of bidirectional charging and how frequent loading and unloading affects the aging of batteries.
To gain hydrogen, large amounts of energy must be expended. Today, hydrogen is mostly produced by steam reforming. Here, carbonaceous fuel reacts with water vapor, which is not a big gain from the climate point of view, because carbon dioxide is produced again. Therefore, the hopes of many experts rest on the electrolysis. Excess electricity from wind power and solar energy can be transformed into hydrogen by electrolysis, which can either be stored or used in a variety of ways. In the case of renewable energies via electrolysis, the entire production path is almost completely emission-free, in contrast to conventional natural gas reforming. Hydrogen, which is produced by means of electrolysis from green electricity and water, serves as the source material for all Power-to-X technologies. With Power-to-X, for example, hydrogen can be produced for fuel cell vehicles. Hydrogen can therefore be used in many ways. But also by integrating the vehicle batteries into the power grid, surplus electricity can be better utilized.
However, the electrolysis process and the subsequent hydrogen liquefaction are very energy-intensive, since nearly half of the energy used is lost. In fact, the fuel cell vehicle powered by hydrogen only achieves an energy efficiency of around 26 percent, and battery electric vehicles reach around 69 percent. This means that in order to meet the energy needs of the FCEV, green electricity production would have to be expanded many times more than for BEV - which in turn has consequences for land use, material usage and overall environmental impact.
The electrified powertrain changes mobility as radically as the production location Germany. Instead of milling and honing, the German automotive industry has to master electrical storage technology and power electronics. The consequences are serious. Producing a powertrain for battery-electric electromobility not only requires significantly fewer parts but also fewer employees.
Are there enough resources?
According to the Öko-Institut, the occurrence of lithium, cobalt, nickel, graphite (batteries) and platinum (fuel cells) clearly exceeds demand. However, there could be bottlenecks if the extraction sites are not opened up in good time. In addition, environmental and social problems must be solved. Cobalt in particular is considered a “dirty” raw material. Over half of the world's cobalt comes from the Congo. Children are often used as cheap labor in the mines, reports Amnesty International. In addition, the cobalt extraction pollutes the environment.
Lithium mining also has consequences, especially for the populations in Bolivia, Chile and Argentina, as "Bread for the World" researched. Around two million liters of water are needed to produce one ton of lithium. As a result, the water table in the so-called lithium triangle sinks, the vegetation dries up, the soil becomes too salty and endemic bird species such as flamingos are dying out. In addition, the habitat of indigenous communities is being destroyed. Most of the platinum, on the other hand, is stored in the so-called "platinum belt" of South Africa; its mining also contributes to environmental pollution and is linked to human rights violations.
What about the charging and refueling infrastructure?
Due to the higher energy density with which the hydrogen in the tank can be stored against the electrical energy in the battery, they offer the advantage of higher ranges. Fuel cell cars can be refueled in just three minutes for ranges from 500 to 800 kilometers. However, the prerequisite for fast fueling is that you can find a H2 station at all. According to Now GmbH, 71 currently has H2 filling stations in Germany. For comparison: According to Statista data, the number of charging stations in Germany is currently around 15.880.
How long an electric vehicle takes to load depends primarily on the battery capacity and the charging infrastructure, ie the column, the station or the power supply. For example, an average battery at the domestic power outlet takes more than ten hours to recharge. But it is also faster: In the framework of the project Fastcharge, the prototype of a charging station with a capacity of up to 450 kilowatts was inaugurated. Electric research vehicles demonstrated load times of less than three minutes for the first 100 kilometer range and 15 minutes for a full charge (10 - 80 percent State of Charge (SOC)) at this ultra-fast charging station. With greater charging power, however, the thermal management of batteries is becoming more and more the focus of development. Here it is crucial how the growing heat loss can be cooled away to ensure a long life of the battery and to preclude the passage of individual cells.
In summary, this means charging stations can be much simpler and more cost-effective, according to Springer author Jürgen Rechberger, he explains in the chapter Fundamentals of Fuel Cell Technology from the book Fundamentals of Combustion Engines. A large part of these are however normal charging stations. Fast charging stations would have extremely high connection capacities, which represented an enormous burden on the existing electricity networks, the author said. Hydrogen, on the other hand, can be easily transported in large volumes in pipelines, even in the existing natural gas grid. Due to the short refueling time, there is also a high level of customer acceptance and a pump could supply up to 250 vehicles a day. In comparison, in a conventional charging station only four to six vehicles and on a fast charging station 60 to 80 vehicles could be loaded. The hydrogen refueling station needed about 50 kilograms of hydrogen per hour and the fast charging station needed a permanent power of 300 kilowatts. According to Rechberger, especially in urban areas, it will probably be much cheaper to build a hydrogen infrastructure than completely new electricity grids for the required number of fast charging stations.
Where to go with the traction batteries and fuel cells?
Batteries of electric cars are hazardous waste. According to the battery law, battery manufacturers or dealers must take them back and recycle them. Technologically speaking, recycling processes for lithium-ion drive batteries are already available today. Thus, according to ADAC, from traction batteries up to 95 percent of the relevant functional materials cobalt, nickel, lithium and copper can be recovered. However, since the recycling processes are at an early stage of development, as are the legal framework conditions and logistics concepts, the recycling of batteries is still a major challenge, as the Springer authors in the chapter Recycling of Batteries from Electric Vehicles from the book Behavior of Stress Lithium-Ion Batteries in Electric Vehicles.
Drive batteries that are no longer powerful enough for their use in vehicles can also be used as stationary electricity storage for many years in "second life". However, there is disagreement as to whether old batteries should better be recycled directly or reused as second-life batteries.
From a fuel cell, the platinum can be almost completely recovered at the end of its life, recycling rates in excess of 98 percent can be achieved. Another challenge is the characteristic of fuel cells and a low suitability for highly dynamic load changes, such as those in driving a motor vehicle. Therefore, lithium-ion batteries are still used today as buffer tanks in fuel cell vehicles, which must be taken into account in recycling as well as in the overall eco-balance of the fuel cell vehicle.
What do BEV and FCEV mean for the German automotive industry?
While the research and production of lithium-ion cells is firmly in the Asian hands and battery pack production requires high investment, the fuel cell drive of the German automotive industry can bring back a substantial part of the added value that comes with the battery. Electromobility is lost. The mass production of a fuel cell stack is no longer a major issue, lowering the cost of the hydrogen tank is the greater challenge, explains Andreas Burkert.
Conclusion
BEVs are the most efficient way to convert renewable electricity into driving performance. That's why this concept is ideal for smaller and lighter vehicles. However, the disadvantage is the longer loading times. These could become shorter in the future. The charging times are limited less by the battery technology, but rather by the power and energy supply of the charging infrastructure. FCEV are always an advantage where the direct use of electricity is difficult or impossible and where long distances have to be covered. The refueling time is fast, hydrogen can be made more easily available especially in the urban environment and already a few gas stations provide a very large vehicle fleet. Another big advantage of hydrogen is that it is a universal source of energy and storage. Water electrolysis for the production of hydrogen is the link between renewable electricity, other energy sources and basic materials. Resource use and dependence is comparatively low in the fuel cell drive. By contrast, the lithium degradation for the battery in the BEV, but also for the small buffer battery in FCEV, is enormously damaging to the environment. The fuel cell offers the opportunity to maintain the vertical range of manufacture of German automakers. In the case of BEV, this is lower because the battery cells have so far come from Asia.
What does that mean for the comparison BEV versus FCEV? Battery and fuel cell vehicles complement each other. Both drive variants have their authorization. However, the great advantage of hydrogen is that it can hardly be beaten as a transportable and stationary storage facility for large amounts of energy in the context of the energy transition. In general, however, the change in traffic must not be limited to replacing the fossil propulsion energy with renewable energy. The number of vehicles must also be reduced.
Source: Author: Christiane Köllner Springer proffesional
