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Trucking Goes Green

Why are short-range electric trucks so much more energy efficient than long-range?

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Tesla made a big splash with the announcement of its Semi electric truck with a planned top 800 km (500 mile) range. But the future is closer than it sounds. Multiple companies have been developing e-mobility trucks that could make a strong impact on global climate change.

 

By Erik Sherman

In the not too distant future, belches of black smoke and deep growling from trucks may become no more than a memory.

Trucks create more than a third of all transportation-related CO2 emissions, according to the Organisation for Economic Co-operation and Development. One way to cut the greenhouse gases that contribute to climate change is to make trucks electric.

Elon Musk recently announced Tesla’s first electric truck, the Semi, but the move had already started. Traditional manufacturers, including Daimler, Volkswagen, Mitsubishi, and Cummins, and startups have been pushing to introduce their own electric trucks.

E-mobility in commercial transport may sound futuristic, but it’s already mainstream. Logistics and transport companies DHL and Ryder in the U.S., Titanium Transportation Group in Canada, and Italy’s Fercam have all placed small initial orders of the Tesla Semi, when it eventually ships. The more trucks can be converted from fossil fuels to electric, the better the environment (assuming the constant growth of renewable sources) — and, potentially, the cheaper the cost of transportation because of enormous energy savings.

First attempts to hybridize trucks’ powertrains already demonstrated their potential. Long-distance hauling could reduce overall energy use by 2 percent to 4 percent. Short-distance transport, with a higher amount of braking that can be used to recharge batteries, can achieve between 15 percent and 25 percent savings. As for passenger cars, the ambition is to achieve a full powertrain electrification.

However, big challenges remain to the further development of electric trucks. One model of the Tesla Semi will have an 800 km (500 mile) range. “Referring to the official Tesla figures, this would mean a consumption of about 125 kilowatt-hours per 100 kilometers,” says David Gagliardi, Director, Business Development Automotive and Global Hybrids and E-Drives of Oerlikon Graziano.

The problem is storing the electricity in the truck. For the Tesla Semi, the required battery would be massive. “If you get one battery with 1,000 kWh, it is like having ten times the batteries of a Tesla S100,” Gagliardi says. That would be a 7.5 tonnes (16,500 lbs.) battery: nearly 20 percent of the weight capacity of the largest EU trucks.

Charging batteries, particularly long-distance trucking, is also tricky. Transport companies would need a web of charging stations — the electrical equivalent of diesel truck stops.

Musk has said that he wanted the trucks to charge 80 percent of their battery capacity in half an hour. “It means a power of 1.6 megawatts in the charging station,” Gagliardi says. That would be like having a small power station instead of a diesel pump. “There is no infrastructure in the world currently able to sustain this type of power demand.”

Such problems can and will be addressed over time, and possibly faster than anyone thinks. A decade ago, experts predicted that a kilowatt-hour of power storage in a battery would drop to $250 by 2020. But innovation made the estimate obsolete. “There are companies already buying batteries for $150 per kilowatt-hour,” Gagliardi says.

One design task facing manufacturers is the gearing and drive train necessary to power an electric truck. The working principles are the same as those of an electric passenger car, but trucks need far more mechanical power to move their loads.

“You can either increase the electric motor torque or increase its speed for more power,” Gagliardi says. Increasing speed is cheaper than increasing the torque, which requires longer vehicles. Higher speeds, though, bring other considerations, like high-pitched motor noise and stringent design considerations for gear boxes. However, gear and drive train design companies like Oerlikon Graziano are finding new ways to meet those challenges.

Oerlikon Graziano has 20 years of experience in developing e-mobility vehicles, from the first golf/utility transaxle to contemporary transfer cases that enable light commercial vehicles, including zero-emission city cars.

2 comments

  1. Hugo Alberga

    Very interesting to see things brought in perspective. Particularly the bit about the power requirements for the charging stations.

  2. andrewpass

    Thanks for the support!

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