How can combustion vehicles become greener?

At this point, there is no question that the car of the future must be emission-free. In the future, the vast majority of new cars, especially in the passenger car segment, will probably have an electric drive. However, it remains extremely important to find further solutions - independent of transport electrification, for example. It is true that newly registered passenger cars will no longer be allowed to emit climate-damaging CO2 from 2035. But the so-called ban on combustion engines will not mean that all cars with combustion engines will suddenly disappear. Even 10 years after the EU-wide ban on new registrations, experts estimate that a significant number of internal combustion cars could still be on the roads. This poses the question to car companies and politicians alike: Can even climate-damaging internal combustion vehicles become more environmentally friendly, either by using alternative fuels or engine conversions? 

The simplest way - at least on paper - to make an internal combustion car climate-neutral would be to make the internal combustion engine itself climate-neutral. A number of alternatives are available for this purpose, some of which have been around for decades. We are talking, for example, about biofuels, namely petrol solutions consisting of conventional petrol with a small proportion of mixed bioethanol - as well as the increasingly popular e-fuels. Both bring advantages from the point of view of sustainability. Bio-fuel, or the analogous biodiesel, releases only as much CO2 during combustion as was previously stored in the plants. In balance, they are thus climate-neutral. E-fuels, synthetically reproduced mineral oil fuel, are supposed to be similarly carbon-free. Here, e-fuels production is not based on food crops, but on chemical processes that supply the car engine with energy from atmospheric substances, hydrogen and green electricity. 

At the same time, both biofuels and e-fuels have their limitations. These are, for example, the consequences of growing oil crops for the agricultural system - as well as difficulties in obtaining resources such as hydrogen and green electricity in sufficient quantities and at affordable prices. A simple change of fuel type is therefore not always enough to make any petrol or diesel-powered car cleaner under the bonnet. Often it is precisely this that needs to be replaced to make the vehicle climate-neutral. Replacing the engine for retrofit electrification is not a cheap undertaking, however. Although more and more companies are offering vehicle retrofits, such an intervention still costs around 5,000 euros. An amount that could already cover the purchase of an e-car, at least in part. 

Whether it is one's own e-car, or bio-fuels and e-fuels - one will probably have to use a mixture of various approaches in order to let the passenger car population develop in the direction of climate neutrality in the foreseeable future. In the end, the important thing is to find a way to a clean, climate-friendly future for transport. However, all measures cost a relatively large amount of money. Therefore, it is most likely to pay off for most motorists to switch to electric sooner rather than later. Or, even better for the environment, to do without a car altogether - for example in favour of bicycles and public transport.