There's little question that autonomous vehicle development will do more to spur electric vehicle sales than $6-a-gallon gas, but would a surge of EVs on our roadways bring an environmental benefit?
That depends on where you live. In Michigan, and most of the industrial Midwest, the answer is no, according to a study conducted by Stephen Holland, professor of economics with the University of North Carolina at Greensboro.
In Los Angeles, San Francisco, Portland, Seattle and the larger cities of Texas, the answer would be a resounding yes.
In New York, it's basically a wash.
"In the West, utilities don't use much coal, but (they) do use a lot of natural gas and hydroelectric power," Holland said.
As vehicles powered by electricity make up a larger percentage of the nation's fleet over the next generation, demand for electricity could surge. That extra power has to come from somewhere _ and right now, nearly two-thirds of electricity generated in Michigan comes from burning fossil fuels.
There is a movement already under way to retire aging coal-fired plants and replace them with capacity fueled by natural gas, hydroelectric, solar and wind. But some worry about future capacity as demand likely rises and the pressure increases to add a higher percentage of potentially less-reliable renewable sources to the mix. The sun does not always shine and the wind does not always blow. There is also an extra cost to ratepayers of bringing cleaner energy online.
According to the most recent state-by-state energy profiles published by the U.S. Energy Information Administration, between 37 percent and 38 percent of electricity generated in Michigan came from coal-fired plants, 27.5 percent comes from natural gas, 29 percent comes from nuclear, 5 percent from renewables such as wind and solar, and 1 percent comes from hydroelectric.
In California none of the state's electricity comes from coal. Nearly half, 48 percent, comes from natural gas, 27 percent comes from renewables, 17 percent comes from hydroelectric power and 8 percent comes from nuclear generators.
Holland cautions that the cost-benefit analysis is more complicated than the energy sources of a state's or city's grid. "Electricity doesn't stop at utility borders," he said.
In addition, tailpipe emissions from gas-burning cars can do more harm in regions such as Los Angeles, which is set in a basin or natural bowl rimmed by mountains where pollutants can become trapped.
Holland and his research team focused on five pollutants _ carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxide (NOx), particulate matter (PM 2.5), and volatile organic compounds (VOCs). They considered 11 different 2014 models of electric vehicles and the "closest substitute" gas car.
Whenever possible they used an exact equivalent, as with the Ford Focus, which comes in both electric and gas-powered versions.
To calculate the damage from gas-burning cars, they weighed the car's Environmental Protection Agency fuel economy ratings (city miles per gallon for urban counties, highway MPG for rural areas), average wind patterns, and number of environmental damages to health, infrastructure, and crops. Together, that data gave them the aggregate emissions of driving a certain gas car 1 mile in a given U.S. county.
To find the impact from electric vehicles, the researchers used the car's fuel-efficiency equivalent (kilowatt-hours per mile) to measure how much power it took from the grid. They also had information about the emission patterns from nearly 1,500 power plants throughout the country.
From that they could get an estimate of the draw from the grid when an EV owner plugs in, showing the environmental impact at the power source.
The Union of Concerned Scientists in 2015 published a two-year study that looked at emissions from production, operation and disposal of electric and gasoline vehicles. Among the findings: battery-electric cars generate half the emissions of an average comparable gasoline car, even after factoring in pollution from battery manufacturing.
The scientists group study looked at three life stages of any vehicle _ manufacturing, operation and end-of-life.
During the manufacturing phase, gas-burning cars are more efficient because of the materials and energy used in making lithium-ion batteries. The longer the batteries' range, the most emissions used in making them.
But during their operating lives, longer-range EVs (those that cover more than 250 miles per full charge) make up that difference within 18 months. Shorter-range EVs can make up that gap in about six months, and then become more efficient throughout their useful lives.
Yet the Union of Concerned Scientists acknowledges that the net benefit varies depending on the energy sources of a region's grid.
Their research tried to estimate how many miles per gallon a gas-burning car would have to achieve to match the carbon-based greenhouse gas emissions of an EV.
A gas-fueled car would have to get 87 mpg in California to match a comparable-size electric vehicle, but only 38 mpg in Michigan and 44 mpg in Ohio and Indiana, levels many mainstream passenger cars already achieve.
Still, in the end, the scientists' research puts a more pro-electric spin on the issue.
Among the conclusions the group emphasizes: "two-thirds of all Americans live in areas where driving an EV produces fewer climate emissions than almost all comparable gasoline and gasoline-hybrid cars" and "by the end of their lives, gas-powered cars spew out almost twice as much global warming pollution as the equivalent electric car."
