Why Electric Cars Can Also Run on Hydrogen
Jülich, 17 December 2019 – As part of the transformation of the German energy and transport sectors, the use of electric motors with batteries and fuel cells, as well as electricity- and biomass-based fuels in internal combustion engines, is currently the subject of much debate. Scientists from Jülich’s subinstitute for Techno-Economic Systems Analysis are investigating the different options from an economic perspective. The director at the subinstitute, Prof. Detlef Stolten, recently gave an interview about the facts surrounding the debate.
Prof. Stolten, both the media and politicians are currently showing a lot of interest in transport solutions using fuel cells. What are the main advantages of fuel cell cars in your view?
The current interest can certainly be attributed to the limits of application for battery-powered cars, as well as the fact that fuel cell vehicles from Asian manufacturers have now gained visibility on the market and, most notably, in many different areas of application.
Compared to batteries, one of the advantages of fuel cell drives is the energy density of the electricity generation system, which is five times higher. What’s more, they can be refuelled in three minutes, making them at least ten times faster than battery-powered vehicles. These properties allow for high performance in continuous operation, for example for passenger cars that frequently travel long distances, along with trucks, buses, and trains.
But fuel cell cars are supposed to be inefficient. Is that true?
No, it’s not true. Fuel cell drives are energy-efficient, even if not to the same degree as battery-powered cars. However, that is compensated for by hydrogen’s ability to be stored, an essential aspect for energy systems with a high proportion of renewable energy.
If we look at the well-to-wheel balance of the two types of drive, which is to say the entire efficiency chain from generating the primary energy to delivering it at the vehicle’s wheels, fuel cell passenger cars come in at around 40 %. The equivalent figure for battery-powered passenger cars is almost 70 %. Modern-day passenger cars with internal combustion engines are at about 18 %.
By comparison, liquid synthetic fuels that are produced using electricity from renewable energy sources (power-to-liquid) have a well-to-wheel balance of about 10 %. There are several reasons for this low figure. The starting point here is always the generation of hydrogen by electrolysis, which today has a maximum efficiency of 70 %. Then there are the efficiency of the fuel synthesis process and the energy required to supply the necessary carbon dioxide. Finally, the drive efficiency of internal combustion engines, at 25 %, is much lower than that of battery-powered or fuel cell vehicles.
The well-to-wheel efficiency for the use of fuels from biomass-to-liquid processes, which are produced by gasification of biomass, is around 13 %.
Today we are faced with the task of completely rethinking the way that we use energy. In your view, what role would hydrogen play in a future energy system that meets the new requirements?
Here I would like to touch upon the key element in the transformation of the energy sector, and that is electricity from renewable energy sources. Because of their unsteady nature, renewables demand a greatly increased storage component in the energy system. To this end, hydrogen produced from green energy can be used as a seasonal energy storage system. This means that any electricity that is not immediately needed in the grid is used to generate hydrogen. This hydrogen can be stored for long periods and is available at times when the weather conditions do not allow for solar or wind energy to be generated and fed into the grid. Conditions like these, which statistics show can last up to one or even two weeks every ten years in Germany, for example, demand industrial-scale storage systems, which with today’s technology can only be achieved using chemical energy carriers – such as hydrogen.
What’s more, hydrogen is excellently suited for use as a transport medium for the increasing volumes of renewable energy imported from sun- and wind-rich regions, such as Patagonia or North Africa. The result would be a flexible hydrogen “pool” fed from local and transregional hydrogen sources that could supply energy for applications in the transport sector and industry.
A common point of criticism of fuel cells is their cost. Are fuel cell cars marketable?
The prices of today’s systems are indeed higher than those of battery-powered cars, for instance. However, we believe that competitive prices for fuel cell passenger cars are definitely viable in the medium term. Fuel cell systems are only manufactured in relatively small numbers currently. Mass production will bring down the costs considerably – international studies show as much.
Another cost factor in fuel cell technology is catalytic converters, which require noble metals such as platinum. Developments in recent years have shown that the required volumes of such metals can be reduced drastically, and over the past 15 years have indeed been reduced by a factor of about ten. I think a further reduction by a factor of four is viable, which would then match the level of today’s catalytic converters in internal combustion engine vehicles. The costs of the pressure tank can also be greatly reduced thanks to improved production methods.
What’s more, the costs of the electric drive itself will be reduced by the intensive development of battery-powered and hybrid-electric drives, which will then bring overall benefits for zero-emissions concepts based on batteries and fuel cells overall. One trend to take into account in this regard is that the costs for passenger cars with internal combustion engines will increase considerably in the medium to long term as a result of factors like stricter emissions standards and the required increases in efficiency. Cars with fuel cells or batteries are likely to be the more affordable alternative in the long term.
The discussions about batteries vs. fuel cells are no less animated when it comes to the issue of refuelling, i.e. charging with electricity or filling up with hydrogen. Doesn’t that also have to be taken into account in the cost analysis?
Absolutely. Both supply systems demand new investment, with the costs of the infrastructure involved in each depending heavily on how many vehicles need to be supplied. For fuel cell cars, the bulk of the infrastructure still needs to be built – and we also need to get through the transition period, which will involve expanding the generation and storage of green hydrogen using excess electricity and building the necessary filling stations across the country. In contrast, the electrical grid already exists – but there is still no nationwide public charging infrastructure and, in the event that battery-powered cars gain larger market shares, the grid still needs to be reinforced.
This will make battery-powered vehicles cheaper to charge, particularly at the start of their market launch, while a hydrogen supply will only become more affordable once market penetration has increased. We found out in a study that if there were 20 million cars on the roads, the cost of the hydrogen supply would be about € 40 billion – by comparison, a charging infrastructure for battery-powered cars would cost about € 40–60 billion. If we take the averages, that makes the hydrogen infrastructure 20 % cheaper than the battery-charging infrastructure.
What do you understand to be behind the huge uncertainty surrounding the charging infrastructure?
The main thing that still remains unclear is how motorists’ charging behaviour will evolve in the future. So far, it is impossible to predict, for example, whether motorists, when given a sufficiently expansive supply infrastructure, will prefer to charge their vehicles overnight or at fast-charging stations during the day. Refuelling with hydrogen, by contrast, would be much the same as today’s situation, with the result that the costs involved here can be stated with much greater certainty.
It should also be noted that some of the cost analyses are based on conservative assumptions. For example, it was previously assumed that new pipelines would need to be built to supply hydrogen. If existing natural gas pipelines were repurposed for hydrogen transport instead, the pipeline costs involved in the long-distance transport of hydrogen could be reduced by 50 to 80 %. At the same time, and this is something we think is particularly important for the market launch, the lead times for planning, approval, and construction would fall by about half, which would drive the implementation of the energy transition forward significantly.
So your analysis shows that both types of infrastructure demand significant expansion. How much has the expansion of hydrogen filling stations progressed so far?
The hydrogen filling station infrastructure in Germany is currently designed along corridors, making it suitable for long-distance transport. These filling stations are sufficiently sized to also be able to serve growing demand. The 78 filling stations that currently exist will initially increase to 100 by the beginning of 2020, and in the years that follow – as the number of hydrogen vehicles increases – another 300 filling stations will be added. This is still a small number compared to the 10,000 filling stations that are expected for 2050, but it is a real start on the road to a comprehensive supply.
Let’s finish with a question that might be of great interest to economic policymakers: what impact do you think hydrogen and fuel cell technology will have on value creation in Germany, as a country so famed for its automotive industry?
A great deal of attention is paid by those in economic and research policy and in industry to the issue of value creation in Germany overall. At the moment we believe that hydrogen technologies especially have significant potential to create value at a regional level. While the market for battery technology is largely dominated by China and the USA, the race to come out on top in fuel cell technology is definitely still wide open. Germany and Europe are well positioned to be at the forefront of this. If we’re looking at application in passenger cars and trucks though, we need to act fast, since the most promising vehicles at the moment are coming out of South Korea and Japan in particular. If Germany succeeds in gaining a foothold here with its own models, new regional supply chains can be established and jobs in the automotive industry can also be secured.
Prof. Dr. Detlef Stolten
Direktor des Instituts für Energie- und Klimaforschung, Techno-ökonomische Systemanalyse (IEK-3)
Tel.: +49 2461 61-3076
Dr. Regine Panknin
Tel.: +49 2461 61-9054