Powering buses and trucks

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E-Mobility for trucks and buses: Batteries, hydrogen or both?

Hydrogen fuel cells and electric batteries are the two main contenders to take the place of petrol and diesel in powering trucks and buses in the future, so how does each stack up?

 

The race is on to find the most efficient and also the most sustainable method of powering networks of passenger buses and the road haulage industry.

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Powering sustainable vehicles

There are four ways that trucks could be powered sustainably in the future, explained Professor Dr. Dirk Uwe Sauer, Director of the Institute for Power Generation and Storage Systems at the E.ON Energy Research Center/RWTH Aachen.

These methods are also being considered or are already in use for passenger buses too.

  • Electric batteries – An average-sized truck could run for about 4.5 hours before needing a 45-minute recharge of between 700 and 800kw of power. This requires an investment in high-power charging stations across the country.
  • Overhead cables – Vehicles could be directly powered by overhead lines on major roads and move to battery propulsion for just the last few delivery miles. This is probably the most energy efficient solution but it requires a major infrastructure investment (with aligned standards across multiple countries) and will be particularly expensive for sparsely populated areas where truck and bus traffic is low.
  • Hydrogen fuel cell systems – Currently, hydrogen requires more electricity in its production than battery or overhead wire systems, so this method is the least efficient.
  • Synthetic fuel – Vehicles could stick to the standard combustion engine and use a synthetic e-fuel in place of petrol or diesel. This solution requires the least investment in terms of infrastructure, but synthetic fuels are not particularly efficient compared to other solutions.

Batteries make economic sense

In the European logistics sector, margins are already tight, said Dr. Götz von Esebeck, e-mobility coordinator for the commercial vehicle manufacturing firm Traton Group. Consequently, he believes battery power is the most attractive model for haulage operators.

"We expect that battery electric vehicles will show the best total cost of ownership," he says.

Dr. Lioudmila Simon, E.ON's Head of Innovation for Networked Mobility, agrees that for journeys up to 125 miles - and city driving - battery power has the edge for buses and trucks.

"I am convinced that e-mobility will play an important role in fulfilling environmental targets, especially in cities and towns," she says. "For ranges over 300 miles, there are still many questions to be answered. But I look at the whole topic from the infrastructure perspective. Take hydrogen, there are 84 hydrogen filling stations in Germany, which is not a lot, and there are still no hydrogen trucks for covering long distances.

"If you look at overhead lines, there are three pilot projects in Germany and it's proving a complicated and costly process to install and operate over a broad geographical area. E-mobility using high-power charging will emerge the winner because there are already 4,000 such charging points in Germany."

Simon conceded that, in the main, these charging points currently only have the capacity for between 150 and 300kw and that they will need to be upgraded for mega-watt charging, but the infrastructure is half way there.

However, hydrogen may still be the best option for very large trucks covering long distances.

"With liquid hydrogen on board one could make 1000km easily and it's more convenient than electricity," points out Professor Detlef Stolten, Director of the Institute of Energy and Climate Research, Electrochemical Process Engineering.

"I am convinced that e-mobility will play an important role in fulfilling environmental targets, especially in cities and towns."

Dr Lioudmila Simon, E.ON's Head of Innovation for Networked Mobility

For ranges over 300 miles, there are still many questions to be answered. But I look at the whole topic from the infrastructure perspective. Take hydrogen, there are 84 hydrogen filling stations in Germany, which is not a lot, and there are still no hydrogen trucks for covering long distances.

"If you look at overhead lines, there are three pilot projects in Germany and it's proving a complicated and costly process to install and operate over a broad geographical area. E-mobility using high-power charging will emerge the winner because there are already 4,000 such charging points in Germany."

Simon conceded that, in the main, these charging points currently only have the capacity for between 150 and 300kw and that they will need to be upgraded for mega-watt charging, but the infrastructure is half way there.

However, hydrogen may still be the best option for very large trucks covering long distances.

"With liquid hydrogen on board one could make 1000km easily and it's more convenient than electricity," points out Professor Detlef Stolten, Director of the Institute of Energy and Climate Research, Electrochemical Process Engineering.

E-transport is a more economic option

The cost of electricity will be a big driver for e-mobility too.

"The big question is how much can you bring down the cost of the energy? says von Esebeck. “40% to 50% of the cost of driving for our long haulage vehicle customers is energy or fuel costs. So far electricity has the advantage here and I think we are close to reaching breakeven."

E-trucks and buses are also more sustainable than most e-cars.

"A car battery is typically used for an hour a day. Truck batteries are in use for nine or ten hours a day, so from a co2 and ecological perspective this is a much better use case," Uwe Sauer says.

E-buses already powering ahead

The case for e-buses is best made by looking at their successful take up. They are already driving around cities worldwide, with China leading the way.

"There are more than 400,000 e-buses on the road in China and this figure should more than double in the next five years," says Simon.

Europe, where just 4% of newly-registered buses are electric, lags behind, but Simon is optimistic that "nearly 60% of newly- registered buses in Europe will be electric by 2030".

It seems that battery power will soon be the dominant power source for passenger buses, particularly in urban areas. And, it makes economic sense for it to become the fuel of choice for the haulage industry too. For long-distance vehicles covering areas with limited charging points, however, hydrogen might remain the best green alternative.