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The Diesel Engine at 120

It seemed a no-brainer invention, but it took quite some time to become the world’s leading source of locomotive power

3 min read
opening illustration for Numbers Don't Lie column
Illustration: Stuart Bradford

On 17 February 1897, Moritz Schröter, a professor of theoretical engineering at Technische Universität, in Munich, conducted the official certification test of Rudolf Diesel’s new engine. The goal of the test was to verify the machine’s efficiency and hence to demonstrate its suitability for commercial development.

The 4.5-metric-ton engine performed impressively: At its full power of 13.4 kilowatts (18 horsepower) the engine’s thermal efficiency was 35 percent and its mechanical efficiency reached 75 percent, resulting in a net efficiency of 26 percent. With obvious pride Diesel wrote to his wife, “Nobody’s engine design has achieved what mine has done, and so I can have the proud awareness of being the first one in my specialty.” Later in that year the engine’s net efficiency reached 30 percent, making the machine twice as efficient as the gasoline-fueled Otto engines of the day.

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We Need More Than Just Electric Vehicles

To decarbonize road transport we need to complement EVs with bikes, rail, city planning, and alternative energy

11 min read
A worker works on the frame of a car on an assembly line.

China has more EVs than any other country—but it also gets most of its electricity from coal.

VCG/Getty Images
Green

EVs have finally come of age. The total cost of purchasing and driving one—the cost of ownership—has fallen nearly to parity with a typical gasoline-fueled car. Scientists and engineers have extended the range of EVs by cramming ever more energy into their batteries, and vehicle-charging networks have expanded in many countries. In the United States, for example, there are more than 49,000 public charging stations, and it is now possible to drive an EV from New York to California using public charging networks.

With all this, consumers and policymakers alike are hopeful that society will soon greatly reduce its carbon emissions by replacing today’s cars with electric vehicles. Indeed, adopting electric vehicles will go a long way in helping to improve environmental outcomes. But EVs come with important weaknesses, and so people shouldn’t count on them alone to do the job, even for the transportation sector.

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