As the current debate concerning diesel fueled-vehicles makes clear, the internal combustion engine must be retired as soon as possible. And if transportation is to become increasingly sustainable, traffic planners around the world will need to focus on electric propulsion. So could transportation be decarbonized simply by replacing combustion engines with electric motors? Unfortunately, it won’t be that easy.
The Future of Mobility
Plugging Transportation into the Grid
In order to make transportation systems emission-neutral, we will need far more electric vehicles than we have today — and they will have to run exclusively on electricity that has been generated from renewable sources. The challenge here is that the need for these sources is expected to grow enormously — far more than has been planned to date. To ensure that road traffic won’t grind to a halt in the future, we need solutions that help to link the transportation and energy sectors more closely together.
Electricity Generation 30 Years from Now
A major obstacle is the rapidly increasing demand for electricity. Electric vehicles are still relatively rare — even in Germany, which is undergoing an energy transition. According to Agora Verkehrswende, an initiative of the Mercator Foundation and the European Climate Foundation, Germany’s entire transport sector consumes only 12 terawatt-hours (TWh) per year, i.e. only two percent of all the electricity produced in the country (2015: 651 TWh). However, experts calculate that Germany’s transportation sector would need about 900 TWh annually by the middle of the century if the scenario of a completely decarbonized transportation sector becomes a reality, with most private cars, freight transporters, rail vehicles, airplanes, and ships powered by electricity or synthetic fuels. And 900 TWh per year is far more than the total amount of electricity produced in Germany today. So that’s the challenge: The need for power would increase so strongly that much more electricity would have to be produced. What’s more, this power would have to be climate-friendly and thus generated almost exclusively from renewables.
Germany’s government originally even pursued the ambitious goal of reducing gross electricity consumption by 25 percent between 2008 and 2050. This translates into around 460 TWh per year. Another official goal is to increase renewables’ share of total energy production to 80 percent by 2050, while also reducing total energy consumption. This means that only around 370 TWh of electricity would be produced from renewable sources in 2050. Any additional electricity that might be required would have to be generated by means of additional renewable energy sources and conventional power plants.
The Dilemma of Wind and Solar Power
Moreover, energy suppliers will have to offer enough electricity at all times and ensure stable voltages. However, they can only do so as long as the sun shines brightly and strong winds blow. And that doesn’t happen very often. What should be done? For one thing, sophisticated energy storage devices could ensure that enough energy is available even when solar and wind power systems are not generating any electricity. Siemens is developing a variety of energy storage methods. Grid loads could also be reduced if the considerable capacity of the growing number of electric car batteries were used for temporary electricity storage. The batteries would store surplus electricity and release it again when needed.
A precondition for all of these projects is the availability of smart computing techniques that dynamically adjust the charging of batteries to fluctuations in the grid. This would ensure that not all batteries are charged simultaneously, and that charging preferably takes place whenever large amounts of electricity are generated. By feeding electricity back into the grid, batteries could have a stabilizing effect during times of peak demand (such as around noon) and whenever there’s a risk of electricity becoming scarce.
However, such solutions are only a first step. That’s because the transportation and electricity sectors will have to be linked together much more closely than they are today. This is the only way the biggest challenge — the capacity problem — can be solved. And that means the transportation sector’s demand for electricity will have to be coordinated with the expansion of power generation capacities from renewable sources. Not until this happens will the good old combustion engine perhaps be able to retire.