The production of fuels using green electricity makes a significant contribution to the energy transition and climate protection, in addition to its direct use in real estate and vehicles. They also partly solve the “storage problem” of (green) electricity and emit much less fine dust and nitrogen oxides during combustion.
It makes sense to use gaseous fuels for heating real estate and to leave the liquid fuels to mobility (e-bikes, e-scooter, electric cars etc.). Logistics such as transport and storage of gaseous fuels to use in real estate is simpler and cheaper than that of gases liquefied by compression (e.g. CNG) for mobility. For the latter, the containers for transport and storage as well as storage in the vehicle must be pressure-resistant, which is associated with high infrastructure costs. For real estate, on the contrary, natural gas pipelines usually exist that can also be used or are already being used for transport (and in some ways storage) of biogas, hydrogen or similar.
Biogas from agricultural installations and industrially produced biomethane from plant residues using special bacteria are able to replace a certain part of the natural gas used today for heating buildings. The hydrogen produced from surplus production of renewable electricity from wind power or photovoltaics (also known as wind gas or power-to-gas) can also take over part of the heating of buildings. The advantage of these gases is that combined heat and power (CHP), fuel cells and Stirling engines can not only generate heat for heating buildings but also electricity for building operation or electric mobility. When compressed liquid methane or hydrogen is used in motor vehicles, the heat always remains as waste and is emitted into the environment, with the exception of heating in winter.
Nevertheless, it does not make sense to rely entirely on pure electromobility for motor vehicles. The demand-based use of purely electric vehicles for short distances, as is often the case with urban vehicles, as well as the use of (plug-in) hybrid vehicles for longer distances or for users who do not have adequate access to electric charging stations, is much more practical and suitable for everyday use. The reason is that hybrid vehicles can also change the proportion of their fossil fuels, e.g. by a chemical process that industrially produces fuel from methane (gas-to-liquid) or from carbon dioxide, hydrogen and electricity from renewable sources (hydroelectric power, wind power, photovoltaic, etc.) from diesel fuel. This also emits less soot, particulate matter and nitrogen oxides during combustion than diesel from crude oil. Petrol or diesel produced from algae, sugar or carbon dioxide and water as well as alcohol produced from sugar or carbohydrates (bioethanol) are also good substitutes for fossil fuels.
The following graph shows the efficiency rates of green electricity (renewable electricity), which is used directly or indirectly by motor vehicles for driving:
The way in which green electricity is stored should also be adapted to individual needs: salt water electric storage systems could be used for electricity generated, for example, by heating buildings with CHP or fuel cells or by photovoltaic systems on building roofs and not directly consumed or charged into the batteries of electric vehicles. In the case of industrially produced electricity from wind and hydropower plants and solar parks, mechanical storage facilities (e.g. electrically lifted weights that re-generate electricity when lowered) are another option. Today, lithium-ion batteries are used instead of lead-acid batteries in motor vehicles because their high charge density and comparatively low weight are ideal for electromobility and will considerably improve in the future.
Last but not least: the green electricity produced in the context of real estate as described above and which will possibly account for up to 100% of our ‘electricity mix’ in the future, can also be used to heat buildings which, for example, use heat pumps or in certain cases even heat generated directly from electricity.
The following graph shows the efficiency rates of green electricity (renewable electricity) used directly or indirectly in real estate for heating and partly also for re-generating electricity (a cogeneration plant as a CHP plant is missing in this analysis):
One can conclude that despite the fact that the world is becoming increasingly “electric”, fuels and combustibles will still exist in the future. To drive the change in sustainable energy development, however, fossils fuels should be discouraged accordingly and renewables – along with with research on innovative solutions – have to be promoted. At the same time, all possible efforts should be made to increase the energy efficiency of all consumers, even if renewable energies may be abundant in the medium to long term.