Carbon footprint for electric vehicles far smaller with renewable power
Are electric cars really cleaner than their gasoline-powered cousins?
There are no tailpipe emissions from vehicles that run entirely on batteries, but skeptics question whether generating electricity to charge those batteries is just as dirty as burning petroleum within the confines of an internal combustion engine.
Historically, electric and gasoline cars came about concurrently in the late 1800s, but the dominance of Ford’s Model T in the early 1900s made gas the fuel of choice for the next century.
EVs remain the exception, accounting for more than 1 percent of United States vehicle sales for the first time in 2017.
But in an age of increasingly dire consequences from climate change, cars that don’t spew greenhouse gases are coming on strong around the world.
In California, Gov. Jerry Brown wants 5 million zero-emission vehicles on the road by 2030.
Electric vehicles are “always cleaner” than gas-guzzlers, said Nelson Lomeli, a program specialist at Sonoma Clean Power, which is once again offering cash incentives to EV buyers.
A gasoline engine is “extremely inefficient,” he said, citing U.S. Department of Energy reports that only 12 percent to 30 percent of the fuel put into a conventional vehicle is used to move it down the road. The rest is lost to “engine and driveline inefficiencies,” largely heat emitted from the radiator and exhaust system.
In an electric car, 72 to 94 percent of the energy goes to moving down the road without a radiator, transmission, exhaust, oil or gas involved, and with braking systems that generate energy to recharge the battery.
The energy department also calculates “well-to-wheel” emissions, which include all emissions involved in extracting petroleum from the ground, as well as refining, distribution to stations and combustion it in vehicles.
In the case of electricity, the tally includes emissions from power plants and from the extraction, processing and distribution of primary energy sources used for electricity production, such as natural gas, coal, nuclear power and renewables like solar, hydroelectric and wind power. In California, which generates more than half its electricity from natural gas (43 percent) and nuclear power (9 percent), nearly half from hydro power and renewables and hardly any from coal, a gas-powered vehicle produces 11,435 pounds of greenhouse gases a year, according to the U.S. Department of Energy. An all-electric vehicle puts out 1,965 pounds.
In West Virginia, which produces nearly all of its electricity from coal, an EV emits 9,451 pounds of pollutants a year, 80 percent as much as a gasoline-powered vehicle, according to federal figures.
In Connecticut, which gets nearly all its electricity from roughly equal amounts of natural gas and nuclear power, EVs produce 2,156 pounds of greenhouse gases, only a bit more than California.
For the U.S. as a whole, EVs emit 4,455 pounds of gases a year running on electricity that comes about 30 percent from both natural gas and coal, 20 percent from nuclear power and most of the rest from hydro power and renewables.
Gasoline engines produce roughly the same volume of emissions: 11,435 pounds a year.
Sonoma Clean Power says cars burning gasoline locally emit 11,247 pounds of greenhouse gases a year. An electric vehicle charged up by power from PG&E emits 1,586 pounds a year.
On the local power agency’s default service, which gets 45 percent of its power from renewables, an EV releases 793 pounds a year.
On the Evergreen service, which gets half its power from The Geysers geothermal field and half from a Petaluma solar facility, an EV emits just 208 pounds of greenhouse gases a year.