Tesla says the battery for its Semi electric truck would charge in just 30 minutes with enough electricity to last 640 kilometers.

Transport & Environment, a consortium of European environmental organizations, conducted a study comparing the energy consumption of classic diesel trucks with those of electric trucks on long-haul journeys.

Though electric trucks might seem to come out favorably in the study, several experts took a much more critical view of Tesla's announcements.

Daimler, Renault, Volvo, and Tesla are all working on large electric trucks.

While traditional manufacturers' models have a maximum travel distance of 300 kilometers, Tesla is trying to get ahead of competitors. The Tesla Semi was originally due to launch this year, and CEO Elon Musk recently tweeted that he was looking forward to getting the truck into production.

Tesla said the Semi would have a maximum distance of 800 kilometers and be able to accelerate from 0 to 100 kilometers per hour in 20 seconds with 40 tons. According to Tesla, the battery will charge in 30 minutes with enough electricity to last 640 kilometers, and the truck will cost about $180,000.

Transport & Environment, a consortium of European environmental organizations, is taking Tesla's plans for the Semi seriously. It conducted a study in which six scientists compared the energy consumption against the environmental costs of classic diesel trucks with those of electric trucks on long-haul journeys.

The authors looked at two diesel-truck models: an ordinary truck with an average consumption of 33 liters per 100 kilometers, and a more aerodynamic truck with a consumption of 22 liters per 100 kilometers.

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Diesel trucks consume 2.2 to 3.3 kilowatt-hours per kilometer, while the average electric truck would require 1.44 kWh per kilometer, and particularly advanced models such as the Tesla Semi would require 1.15 kWh. According to the authors, the calculations showed that a battery electric drive reduced energy consumption by a factor of 1.5 to 2.9.

Several experts, however, took a much more critical view of Tesla's announcements.

"The battery for a Tesla Semi must have a capacity of about 1,000 kWh per 100 kilometers, about 130 kWh," Markus Lienkamp, the chair of automotive engineering at the Technical University of Munich, told Business Insider. "This is technically not easily feasible, and it's also pointless both economically and ecologically."

Martin Daum, the head of Daimler's truck division, went one step further.

"If Tesla really delivers on this promise, we'll obviously buy two trucks: one to take apart and one to test, because if that happens, something has passed us by," he told Bloomberg at the start of last year. "But for now, the same laws of physics apply in Germany and in California."

There are also issues with the efficiency of electric vehicles

Lienkamp said he also saw problems with the efficiency of the electric drives.

The study found that a diesel-truck engine had an efficiency of 40% to 45% on long-haul journeys and only 10% in city traffic with traffic jams. With an electric drive, the efficiency was 90% on long distances and 75% in urban traffic.

"However, the efficiency of the electricity mix used for the truck battery is important," Lienkamp said. "If the energy comes from a gas-fired power plant, for example, the overall efficiency quickly drops back to 40%. If, on the other hand, 80% to 90% of the electricity comes from renewable sources, as planned in the EU for 2040, long-distance trucks would be attractive from an ecological point of view."

However, this isn't the case at the moment.

To the authors of the study, the greatest challenge for electric trucks is the demands placed on the power grids

The Tesla Semi requires 1 megawatt-hour of electricity for a single charge, a third of the annual electricity consumption of an average European Union household.

Assuming the Semi charges at a 1-megawatt fast-charging station, the study found that it would consume as much energy per year as 2,500 EU households.

The study's authors said the greatest challenge for electric trucks would be the demands placed on power grids. Flickr/Kool Cats Photography

Using the current number of trucks in the EU and an average distance of 50,000 kilometers per year, the authors estimated an energy requirement of 324 terawatt-hours for a purely electric truck fleet in the EU, which works out at roughly 10% of the energy generated in the EU in 2015.

The authors proposed several solutions to prevent the networks from collapsing under this enormous power consumption.

On the one hand, trucks could be charged mostly at night when electricity demands are lower. However, if a freight forwarder were to use electricity at night, the building would need a connection to a medium-voltage grid. For long distances, where a driver might spend the night in the truck or at a hotel, the network of charging stations would also have to be massively expanded.

According to the study, priority charging at rapid-charging stations, as Tesla has in mind, is also possible. For this, the power grid would have to be not only extended but rebuilt, as rapidly charging a fleet of five to 50 trucks would require between 1.5 and 20 megawatts with today's technology.

To make this possible, the authors proposed stationary power-storage facilities, smart power grids, and high-voltage infrastructure near fast-charging stations.

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Lienkamp favors a different approach.

"I see the most promising concept for the charging problem of electric trucks in replaceable batteries," he said. "A truck would simply replace an empty battery with a full one at a designated station. Such a change would only take two to three minutes."

When the batteries aren't in use, they could also be used as storage for the power grid, the vehicle technician said. "In the future, this electricity could be supplied by idle truck batteries without significantly losing any of the energy."

To compare the total costs of a long-distance electric truck with those of a diesel truck, Transport & Environment looked at a variety of cost types.

According to the authors of the study, repair and maintenance are half as expensive for electric trucks as diesel trucks, because the driving system is much simpler and there's no gearbox. There's also less wear when braking because a portion of the braking power can be redirected back to the motor.

For now, electric trucks make sense only for short distances

The study is based on the current EU average of 0.14 euro per kWh, the current cost of a Tesla fast charge of 0.27 euro/KWh, and Tesla's promise to reduce this price in the US to 0.07 euro/kWh in the long term.

Further costs can be seen below.

Transport & Environment didn't include the costs of the construction of the electricity grids, as it's not yet clear to what extent government agencies will cover that. The authors estimated it at 60% of the vehicle's price. Earl et al. 2018

Martin Wittmer from the Laboratory for Commercial Vehicle Technology at the Dresden University of Applied Sciences had a much more skeptical stance on electric trucks and long-haul journeys.

"Battery-powered trucks are realistic for distribution, the post office, or refuse collection," Wittmer said, "but today's lithium-ion batteries are too heavy and too expensive for transporting goods over long distances, and after just two to three years, their storage capacity will already be in significant decline.

"I see engines powered using natural gas as a bridge for long-distance trucks," Wittmer added. "They don't pose any problems with nitrogen oxide, they emit significantly less carbon dioxide and soot than diesel engines, and they emit half the noise. In the longer term, I see the fuel cell as being a particularly promising option."

Lienkamp said: "For distances of 500 kilometers and beyond, battery-powered trucks simply won't make any economic sense until 2030. With electric vehicles, the cost of trying to reduce CO2 levels is simply too high."

The situation is different for short and medium distances, such as 100 to 200 kilometers per day — the shorter the distance a truck covers per day, the more sense a completely electric vehicle makes.

"At weights of between 3.5 and 7.5 kilograms within in the city or for inter-city trips, electric trucks will soon become commonplace," the expert said.