Tesla's coal-powered cars and trucks

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EVs just move their carbon emissions upstream

Tesla’s mission is “to accelerate the advent of sustainable transport by bringing compelling mass market electric cars to market as soon as possible,” wrote Elon Musk in The Secret Tesla Motors Master Plan. The large-scale shift from internal combustion engine powered automobiles to electric vehicles (EVs) is a crucial part of this ‘sustainability’ mission. Governments around the world have bought into electric cars as a way to lower their countries’ carbon emissions and have coughed up the generous subsidies electric car makers need to make themselves competitive (but note: the current versions of the U.S. Senate and House tax bills end these subsidies). 

But in many countries, internal combustion engine-powered compact cars like the Mitsubishi Mirage have a smaller total carbon footprint than electric cars. How is this possible? There are two main sources of EVs’ hidden carbon footprint: first, carbon-intensive manufacturing processes including aluminum and copper extraction and refinement and second, the dirty electric grids charging the cars’ batteries.

Electric carmakers prefer lightweight aluminum over steel to maximize range: Tesla builds the body and chassis of its Model S almost entirely from about 410 lbs (190 kg) of aluminum.  Average total aluminum content per car is expected to grow from roughly 397 lbs per car in 2015 to 565 lbs by 2028. The highly energy-intensive processes involved in aluminum production mean that a car’s worth of aluminum costs about 30% more in emitted CO2 than a car’s worth of steel. In China, the world’s leading manufacturer of EVs, 14 tons of CO2 is emitted for every ton of aluminum produced, three times more than the CO2 emitted by Alcoa, the U.S.’s largest aluminum producer. China now worries that their dirty smelting operations mean that switching to electric cars will actually make their smog problem worse.

“If the USA had 10% more petrol cars by 2020, air pollution would claim 870 more lives. A similar increase in electric ones would cause 1,617 more deaths a year, mostly because of the coal burned,” said Danish researcher Bjorn Lomborg.

EVs’ intensive copper use—an electric car uses about 6 km of copper wire weighing 45 kg, compared to a conventional auto’s 20 kg of copper—also poses a carbon emissions problem. In the mid-1800s, copper ore contained about 10% usable copper, but over the course of the twentieth century, that purity has decreased to less than 1%, making the mining and production of copper extremely energy- and carbon-intensive. The energy used to smelt copper increases exponentially as the ore grade falls below 1%. The new copper mines being constructed to meet increased demand have to be factored into the carbon footprint of electric vehicles—and in general, new copper ore stocks being developed are deeper and require more energy to exploit than currently productive reserves. 

What about the power grids that charge EVs’ batteries? Energy sources vary wildly by country. Globally, in 2014, 66% of global energy came from coal (29%), oil (22%), and gas (5%). China, the country with the largest number of EVs on the road, got 72% of its energy from coal alone in 2014; the United States produced 68% of its energy from coal (38%) and gas (30%) in 2014. Coal use in the United States is trending downward as a proportion of overall energy use, partially due to the new shale gas deposits being exploited by fracking.

Shifting the energy burden of the American transportation industry from gasoline and diesel fuels to the power grid will result in enormous increases in electricity demand. In temperate places like San Francisco, plugging an electric car into a dedicated circuit like Tesla’s PowerWall is the equivalent of adding between 5 and 10 houses to the grid. The supercharging stations required to charge Tesla’s Semis will require surge capacities far beyond anything the American grid was designed to handle. Finally, to get EVs closer to being considered ‘carbon-neutral’—because of their raw materials they never truly will be—the American energy system will have to go green. 

But it’s an open question as to whether solar and wind plants can generate enough power to not only replace fossil fuel plants but also match the increased demand for electricity as hundreds of millions of vehicles start plugging in. The largest, most powerful solar plant in the United States is the Ivanpah Solar Power Facility in the Mojave Desert, which generates 392 MW; the largest wind plant in the United States is the Alta Wind Energy Center in California’s Tehachapi Pass, which generates 1,547 MW; by comparison, the largest coal plant in the United States, Plant Scherer in Georgia, generates 3,389 MW. 

Ironically, Tesla’s electric cars and trucks may end up prolonging America’s reliance on fossil fuels to generate electricity, because renewable sources cannot yet meet rising demand.

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