SAEV 02: The EV Emissions Story
I spent over 1000 words motivating a discussion of electric vehicles by harping on the importance of reducing carbon emissions. So the most important question to address first is: do electric vehicles reduce emissions, and if so, by how much?
Electric vehicles (EVs) are powered by, you guessed it, electricity. They look and taste like conventional cars, but instead of being propelled by an internal combustion engine, they rely on chemical energy stored in batteries, the same kind that power our laptops and cell phones. There’s no motor oil, no gears, no spark plug, and no engine grease. Danny Zuko would be appalled.
In conventional cars, greenhouse gases are produced as byproducts when gasoline is burned in the engine, and then expelled out of the tailpipe. The more efficient the engine, the higher the miles per gallon (MPG) rating, and hence fewer emissions per mile driven. In contrast, EVs do not have tailpipes. The emissions due to EV driving are those associated with the electricity generated to charge it. The cleaner the electricity (where “clean” is any generating source that doesn’t result in a net increase of carbon dioxide, including wind, solar, hydro, biomass, and nuclear), the lower the associated emissions.
To help compare these emission scenarios apples to apples, the Union of Concerned Scientists created a very useful map that shows the equivalent MPG from charging an EV in all 50 states, based on the greenhouse gases produced by that state’s electricity “grid.” The grid is the network of power plants, poles, and wires that deliver electricity to our homes, offices, factories, stadiums, and yes, even decrepit shopping malls where the only stores left standing are Cinnabon, Lids, and Champs Sports.
To complement the map, there is also a tool where you can type in a zip code and vehicle type and get an even more accurate MPG estimate based on the equivalent emissions: https://www.ucsusa.org/clean-vehicles/electric-vehicles/ev-emissions-tool
According to the article where the map was published, “Seventy-five percent of people live in places where driving on electricity is cleaner than a 50 MPG gasoline car.” This means that an EV achieves significant carbon savings even in areas where the grid is primarily fossil-fuel driven. How is this possible? Because even those types of power plants burn more efficiently than a gasoline combustion engine. In other areas like New York, where grid electricity comes mainly from hydroelectric dams, the savings are enormous. To get into more concrete numbers, an analysis by the Acadia Center (page 6 of this report) showed that right now, in the Northeast and Mid-Atlantic states, purchasing an electric vehicle instead of a mid-size sedan will reduce transportation-related greenhouse gas emissions by an average of 60%.
This tool only tells part of the story, though, because it’s based on historical emissions. The grid is becoming cleaner due to the increase of wind and solar to complement other zero-carbon resources like nuclear and hydropower. So these MPG numbers are only going to keep getting better. That same Acadia Center analysis showed that if we achieve 75% clean energy on the grid, EVs will represent a 90% emission reduction from current gasoline cars.
But wait, there’s more: the map assumes the average annual electricity mix at the regional level. If instead the EV in question is charged by rooftop solar panels, or plugged in overnight in a region where the base electricity load comes from nuclear power (which despite all its issues, does not emit carbon), then EV driving can be virtually emission-free!
Let’s think about the enormous potential of linking transportation and electricity generation on a large scale. Up until now, the way we have tried to tackle transportation emissions has been to focus only on fuel economy standards for conventional automobiles. This hasn’t exactly worked…
Fuel economy standards are set at the federal level and are subject to political winds of change. The average fuel efficiency of passenger cars on the road was 22.0 MPG in 2016 according to the US Department of Transportation. For goodness sake, the Ford Model T got 21 miles per gallon! Newsflash: car companies have almost zero incentive to build more efficient engines. As if trying to prove this point, in 2017 they spent $47 million lobbying congress for weaker standards. Regulators can barely get these companies to abstain from poisoning our air and cheating emissions tests (see here for a summary of the Volkswagen emissions scandal and for the Netflix users out there, there’s also a great documentary on the subject). You see, car makers don’t pay for the gas and besides, consumers are generally bad at considering total cost of ownership when making car purchasing decisions (more on this in a later post).
Most recently, the Trump administration rolled back Obama-era targets, which would void any fuel economy progress past the year 2020. Our friends at the Union of Concerned Scientist calculated that this retreat on efficiency standards would cause the nation to burn an additional 250 million barrels of oil and force consumers to spend an additional $36 billion on fuel to fill their tanks…in 2030 alone!
On the other hand, clean electricity standards are set at the state and local levels. Over 100 US cities & states have committed to 100% clean energy, and countless more have targets in excess of 50%. If we electrify transportation, then as the grid becomes cleaner, it will be a double whammy (in a good way) for reducing emissions, hitting the two largest offending sectors.
Plus, more EVs on the road today means better charging infrastructure, more research into denser batteries, and more models available as car companies strive to meet the growing demand.
Beyond that, because EVs only emit indirectly, they work wonders for reducing air pollution and urban smog. Even the Department of Energy, which is run by a man who once proposed that fossil fuels can help prevent sexual assault (yes, really), attests to this benefit on its website.
Lastly, beyond the emissions from operating vehicles, there are also emissions associated with their production, including resource extraction, assembly, and delivery. It is a fact that electric vehicles require more energy to build than conventional cars, but let me stress that this is far outweighed by the operating savings.
An MIT lab built a nifty tool that shows the total lifecycle emissions for different type of cars plotted against cost, and it doesn’t take an MIT scientist to see the glaring gap. Emissions reductions of 50% are standard. But again here, this tool is based on an average emissions profile in the US. In places with very clean energy supplies (or where charging coincides with high solar generation) the lifecycle emissions of EVs can be as low as 1/6th those of conventional cars! Beyond that, some EV manufacturers (most notably Tesla) are striving for 100% renewable energy at their factories, driving the lifecycle emissions even lower.
The “too long, didn’t read” summary here is this: EVs cut emissions significantly. If they didn’t, I wouldn’t be writing this blog. Now that we’ve got that out of the way, it’s time to tell you about the joy of owning one, from both a cost and driving experience perspective. That’ll be next time…(I always wanted to write a cliffhanger!)
Carbon-saving tip of the week: choose locally-grown produce at the grocery store. Not only does this help support local farmers, but there are also much lower transportation emissions associated with getting it to the shelf!
