Concept clash: Which is better - a battery, a fuel cell or e-fuels?

How do we compare the alternative drive systems?

2024/03/15 - Various criteria are relevant when it comes to evaluating alternative drive types. In view of finite resources, primary energy consumption is particularly important – this is the total amount of energy that is directly obtained and consumed from natural sources before it is converted into other forms of energy. Primary energy consumption therefore measures the energy input in its original form. This metric helps with getting a better sense of the scope and structure of the energy requirements of a particular technical solution. It is also important for planning the energy supply and evaluating the sustainability of energy consumption in terms of environmental impact and resource conservation.

Energy efficiency is closely related to primary energy consumption – and yet it means something else. Energy efficiency is the ratio of performance, benefit or output to the amount of energy used. It is therefore a measure of how well energy is converted into the desired output. Energy efficiency aims to reduce energy consumption, cut costs, minimize environmental impact and improve energy security. Efficiency improvements can be achieved in all areas of energy consumption, from generation and transmission to end consumption.

Another criterion is the charging infrastructure. This includes all facilities and technologies required for charging or refueling, including private and public charging stations, fast charging stations and hydrogen refueling stations. The availability, accessibility and efficiency of the infrastructure are crucial for user acceptance and the widespread adoption of alternative drive systems.

Operational costs are also a significant factor to be considered when answering the question of which form of drive is best for the future. These costs involve the cost of fuel or charging/electricity, but also the costs of purchase and maintenance.

Finally, the environmental impact must also be considered when comparing different drive types. This refers both to global impacts in the form of CO₂ emissions and the contribution to the greenhouse effect and to the local effects of pollutant emissions.

The comparison

Primary energy consumption

The primary energy consumption of battery-powered electric vehicles (BEVs) is heavily dependent on the type of electricity generation. If the electricity comes from renewable sources such as wind or solar, then the primary energy consumption of BEVs is particularly low and CO₂ emissions are minimal.

For vehicles with fuel cells (FCEVs), primary energy consumption largely depends on the method of hydrogen production. Green hydrogen, which is produced by electrolysis using electricity from renewable sources, is a more sustainable solution. However, most hydrogen is currently produced by the steam reforming of natural gas, which is an energy-intensive process that creates CO₂ emissions.

In direct comparison, BEVs generally have a lower primary energy consumption, especially if the electricity used comes from renewable sources. FCEVs can offer advantages in certain applications where long ranges or fast refueling are required, but the challenges of hydrogen production and distribution need to be considered. The promotion of green hydrogen can at least improve the sustainability of FCEVs in the long term.

E-fuels are produced through synthetic processes, typically by combining hydrogen (produced by electrolysis using electricity from renewable sources) with carbon dioxide extracted from the atmosphere or captured as a by-product of industrial processes. Their primary energy consumption must be considered critical due to the complexity of these processes, especially in comparison to BEVs.

Assuming the availability of sufficient green electricity, which FCEVs and e-fuels also require, the primary energy consumption of BEVs is therefore comparatively the lowest.

1 : 0 : 0

Energy efficiency: Electric cars are generally more efficient at converting energy into propulsion power. The degree of efficiency of electric cars is around 60-70% when the entire path from electricity generation to the movement of the vehicle is considered. This is because BEVs convert electricity directly into motion.

Fuel cell vehicles convert chemical energy from hydrogen into electrical energy that drives an electric motor. However, each step in the energy conversion chain results in some losses, making FCEVs less efficient in terms of overall energy utilization. The process involves the production, compression or liquefaction, transport and storage of hydrogen, followed by its conversion to electricity by the fuel cell. This multi-stage conversion process leads to higher energy losses, and the overall efficiency from source to vehicle motion is around 20-40% for FCEVs.

Even with advanced e-fuels, internal combustion engines are still significantly less efficient. This is mainly due to their complex manufacturing process with several energy-intensive steps. However, it is also due to the lower efficiency of the internal combustion engine itself, which produces heat as well as movement. E-fuels have a significantly lower overall efficiency than battery electric drives – often even below 20%.

Thus, BEVs are clearly also ahead of FCEVs and e-fuels in terms of energy efficiency.

2 : 0 : 0

Charging infrastructure: The charging infrastructure for electric cars is already widespread and growing rapidly. The availability of fast charging stations along major transport routes enables longer journeys and reduces charging time, which increases the acceptance of BEVs for everyday use and long journeys. A dense network of charging stations reduces concerns about low range and makes electric vehicles attractive to a wider range of users. In addition, BEVs can be charged at home, at work or at public charging stations, making them practical for everyday use.

The number of hydrogen refueling stations is still small compared to conventional gas stations and electric vehicle charging stations, but is growing steadily. As of the beginning of February 2024, there were only 921 hydrogen refueling stations worldwide. Countries such as Germany, Japan and South Korea are investing heavily in the expansion of this infrastructure. However, the technological and financial challenges are significant: due to its physical and chemical properties (high pressure, low temperature storage), the storage and transport of hydrogen require special and complex solutions to ensure safety when handling the highly explosive gas.

Vehicles that run on e-fuels can also refuel with conventional fuels – but are then no longer climate-friendly when driving. Based on current availability, an analysis by Transport & Environment (T&E) concludes that CO₂ emissions could only be reduced by around 5 percent over the entire life cycle of a combustion engine vehicle by adding e-fuels. The infrastructure for e-fuels is still in early stages. There are only a few pilot plants and demonstration projects worldwide that are testing various aspects of e-fuel production, from carbon capture and hydrogen production to e-fuel synthesis. There is a considerable need for research, development and investment in order to scale up the technology and reduce costs. According to fuel industry forecasts, the availability of e-fuels in 2035 would be able to cover just 3 percent of the total global fuel demand. Despite the challenges, e-fuels offer promising potential for the decarbonization of transport, especially in areas that are difficult to electrify.

BEVs are also a clear winner when it comes to charging and refueling infrastructure. Refueling and charging is unproblematic and simpler for this alternative drive form than for any of the others.

3 : 0 : 0

Operational costs:

The acquisition costs of electric cars are lower than those of fuel cell vehicles. This is mainly due to the lower complexity of the technology, the greater availability of BEVs on the market and economies of scale. The lower maintenance requirements of electric motors alone are a cost advantage – especially compared to e-fuels. The low energy costs help to ensure that the higher purchase price of an electric vehicle is amortized over the course of its entire life cycle. A study commissioned by BEUC and the Federation of German Consumer Organizations (vzbv) shows that first-time buyers can save 11,000 euros on the cost of a mid-range electric car within four years. The LeasePlan Car Cost Index 2021 calculated monthly operating costs of 760 euros for an electric vehicle, which was significantly cheaper than the 960 euros for a comparable mid-range combustion engine vehicle.

There are currently only two hydrogen vehicles being offered in Germany, both of which cost more than 65,000 euros to purchase. The production of the fuel is complex and expensive due to the high energy loss during hydrogen production, storage and subsequent conversion to electricity. Due to the high production costs of hydrogen and the low efficiency – hydrogen cars are about as efficient as combustion engines – 100 kilometres of driving in a fuel cell car costs around 13 euros, compared to 8 euros for a BEV.

Vehicles that run on e-fuels are cheap to buy. However, the worse and less efficient carbon footprint and the diversions and losses in energy conversion (electrolysis, synthesis to e-fuels, combustion) suggest that operational costs would be higher compared to directly electrically powered vehicles – the more so, the higher the proportion of e-fuels used.

To summarize, battery electric vehicles (BEVs) are the cheapest and most efficient option in terms of operating costs, followed by fuel cell vehicles (FCEVs), which are more expensive to operate due to the inefficient energy conversion chain. Vehicles with e-fuels could cause even higher operating costs due to the high energy expenditure in the production of the fuels and the lower efficiency in the conversion into drive energy, although they cannot yet be directly compared in a specific analysis.

4 : 0 : 0

Environmental benefits: If electric cars are charged with electricity from renewable energy sources, they can be operated nearly emission-free and climate-neutrally. Although fuel cell vehicles also don’t produce emissions when driving, the environmental impact of hydrogen production strongly depends on the method used. In this respect, there is a tie between the two technologies: it all depends on the method of primary energy production.

However, this aspect distinguishes BEVs and FCEVs from vehicles with combustion engines because even if combustion engine vehicles are powered by e-fuels, they still locally emit nitrogen oxides (NOx) and particles, which can be harmful to health.

5 : 1 : 0

Conclusion

It’s a clear victory for the battery drive! BEVs are significantly more efficient in terms of primary energy consumption when using electrical power directly from renewable sources. The ever-improving charging infrastructure, the continuously expanding range of vehicles on offer and the low operating costs are also opening up BEVs to user profiles that were previously reliant on conventional drives. This makes them the preferred option for minimizing energy consumption and environmental impact while maximizing the environmental benefits of road transport.

FCEVs and vehicles that can run on e-fuels offer the potential to make existing internal combustion engine vehicles more climate-friendly and can be used in sectors where BEVs are not practical due to technical limitations (such as aviation and shipping). In these cases, they can be a valuable option for decarbonization. As a solution for the sustainable and climate-friendly individual mobility of the future, however, they are clearly inferior to battery electric vehicles.