The traffic of the future: which drive is the best?



Status: 02/23/2021 10:32 a.m.

It is a charged debate: Are all-electric cars really the better solution than vehicles with fuel cells and hydrogen propulsion?  The  facts speak for themselves.

When it comes to the discussion about the future of the car, drive systems and fuels, there is a lot going on. Some accuse the government of unilaterally promoting electric cars; the others rail against paying too much attention to hydrogen. Business and interest groups are fueling the debate.

Werner Eckert

So far no climate contribution from traffic

One thing is certain: simply continuing to manufacture and drive gasoline and diesel engines is not an option. On the one hand, this is due to the international climate protection commitments that Germany has entered into. On the other hand, the German auto industry still wants to sell cars in a decade, while more and more states are considering bans on combustion vehicles for climate protection reasons.

In Germany, traffic has made no contribution to climate protection in the past 30 years. It causes 20 percent of CO2 emissions, and without climate-neutral solutions, total emissions will continue to increase in absolute terms.

What uses how much energy?

From a purely technical point of view, the most efficient system for private individual transport – i.e. for the car – is the electric car with a battery. It converts the energy from one kilowatt hour of electricity best. 70 to 80 percent of one kilowatt hour of electricity comes onto the road as drive power.

With the detour via hydrogen and the fuel cell, twice or three times as much electricity is needed to cover the same distance. Because hydrogen is not a naturally occurring raw material. It has to be produced with a high expenditure of energy, usually by hydrolysis from water.

Four to five times as much electricity is needed if you want to build artificial fuel from this hydrogen in order to drive a classic combustion engine. This is because it is much less efficient than an electric motor. Hydrogen and electric cars are not a contradiction in terms, because the hydrogen car is also an electric car. © The  difference lies in the energy storage: in one case it is the battery, in the other the hydrogen.

Environmental costs of battery production

© The  batteries are the ecological Achilles heel of the electric car – and not only because of the rare earths such as lithium, which are required for production. © The  Institute for Energy and Environmental Research IFEU in Heidelberg states that there are around five to nine tonnes of carbon dioxide equivalent in a battery through production alone before the first kilometer has been driven. However, the hydrogen vehicle also has a base load of around five tons – due to the fuel cell, the complex hydrogen tank and the, albeit smaller, battery that is also present there.

Contrary to older studies, the e-car is by far the most efficient solution with regard to the current energy mix in the German power grid, also from a climate point of view – and these figures will shift significantly in favor of electric drives due to the rapid development of batteries and the increasing share of renewable energies in the power mix .

Where does the energy come from?

Only “green” energy, i.e. electricity from CO2-neutral sources, can help against climate change. In case of doubt, this is wind or solar power, because the amount of hydropower and biogas can hardly be increased in the long term. If you want to drive ten million cars in Germany battery-electric, you need around five percent more electricity than today; with hydrogen and fuel cells it is around 15 to 20 percent.

One advantage of hydrogen, however, is that it can be traded internationally over longer distances, by ship or pipeline. This means that solar or wind power from South America, the Arabian Peninsula or North Africa can be used for hydrolysis. However, it must be ensured that there is enough energy to supply the population with clean energy and water. Here, too, the hydrogen has to be “green” in order to really improve the climate balance.

And what about biofuel?

In fact, around six percent of the fuel that is used on the road is currently “biofuel”: gasoline contains up to five percent ethanol and diesel fuel up to seven percent chemically treated vegetable oil. © The  question is how much of it can be produced sustainably; because the cultivation of energy crops always supersedes food crops. This is why this path is only possible to a limited extent. It leads to deforestation and other environmental problems.

© The  situation is different with residual materials such as waste wood and straw. However, even the representatives of the biofuel sector see only limited possibilities there: In theory, this would result in fuel for a maximum of 20 percent of cars in Germany. In addition, the use of bio-fuels from plant residues could quickly improve the carbon footprint of existing gasoline and diesel cars. But this may also mean that comprehensive solutions are delayed for a long time.

Will the market take care of it?

© The re is seldom a “free market” like in a textbook for energy topics. © The  reason: States create facts at an early stage and set the course in one direction or the other by deciding to invest in a certain infrastructure and subsidizing the relevant industries.

If, for example, a network of hydrogen filling stations is built for trucks instead of overhead contact line systems on the motorways with state funding, this could also influence the system decision for cars. However, with the help of several measures, politicians are currently setting the course for a drive shift towards e-mobility in private transport – for example with the subsidy for e-cars or the expansion of the fast charging network.

It is currently significantly more expensive to drive a hydrogen car than an electric car – both for the vehicle itself and in terms of energy consumption. How this will develop further depends heavily on political decisions.

© The  industry association Hydrogen Council anticipates that hydrogen filling stations could become cheaper than comparable electricity charging capacities within this decade. © The  association assumes that motorists are willing to pay significantly higher prices for hydrogen than industry.

© The  energy expert Claudia Kemfert from the German Institute for Economic Research (DIW), on the other hand, assumes additional costs of 450 to 500 billion euros by the year 2050 if the fuel cell were to become the predominant drive system – precisely because of the increased energy requirements for the production of hydrogen, but also because of the more expensive vehicles.

Many forms of energy are needed

In the debate about future mobility, it is sometimes overlooked that cars are only one aspect of the energy transition. Industry, the housing sector and air travel also compete for “clean” energy. © The  prevailing opinion in science is that residues such as straw and wood and green hydrogen are needed more urgently in industry than in private transport. Steel production, for example, can only become climate neutral in this way. Aircraft and ships will either rely on hydrogen or will continue to need liquid energy sources – i.e. synthetic kerosene made from hydrogen or from vegetable oils and sugar. In contrast, private cars can run directly on electricity more efficiently.

In the case of trucks, the situation is still confusing. According to a study by the Federal Ministry of Transport, overhead lines along the motorways would be the cheapest option; there are individual pilot routes. Alternatively, the fuel cell and a network of hydrogen filling stations could be an adequate solution. © The  decision in which system the state and the economy want to invest is still pending.

Problems caused by noise and particulate matter

© The  federal government is setting very different priorities in the transport transition. It supports the acquisition of e-cars and accelerates the expansion of the charging infrastructure, but with its hydrogen strategy also has an eye on the generation and utilization of H2. In order to be able to produce both forms of energy in a climate-neutral manner, the expansion of renewable energies is being promoted.

However, a real turnaround in traffic would not only consist of switching to climate-neutral forms of propulsion; it can only solve some of the ecological problems caused by traffic. A pure “drive turnaround” changes little in terms of fine dust, noise and congestion problems. To do this, the mix of modes of transport would have to change – towards buses and trains – and the overall volume of traffic would have to decrease.

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