Electric cars vs gasoline cars. Who wins on climate change? We’re two engineers and we’ve been asking the same question (and finding some pretty cool answers). Ask us anything!

Hi! I found your State of Charge report back in 2012 to be very informative in showing the regional variation in electric car emissions (and I've put your work to good use here in informing users when relevant), and I hope to find the time to read your latest lifecycle analysis soon. In the meantime, I've got some questions for you.

There are critics of electric cars who claim that the environmental costs of mineral extraction and manufacturing of an electric car's batteries ultimately make them worse for the environment than gasoline cars, outweighing any and all benefits from reduced emissions and improved efficiency. While I do not personally hold such a position, how do you respond to these claims?

The second one's a bit tougher: As you are no doubt aware, the National Bureau of Economic Research recently produced a paper which produced maps showing that electric cars exhibit greater marginal damages on the east coast than the west coast, which seems to be somewhat at odds with your maps, which show EVs are also a net benefit on the east cost. The principal difference that I can discern is that your work incorporates upstream emissions while theirs does not, but do you have anything else to add in terms of a rebuttal to their work?

Unfortunately, the data available for other emissions related to mining and extraction are more uncertain than data on global warming emissions. However, many of these pollutants are subject to local environmental regulations to manage local emissions and environmental impacts. We do expect, because of the residual value of the batteries when they are no longer needed in the vehicle, they will most likely be reused or recycled. In the case of reuse or recycling that could mean reduced mining impacts use the batteries or their parts for other applications instead of using new materials. We encourage increased research in battery development and pilot projects with a focus on reuse and recycling so we are getting the most out of the batteries with the least environmental impact. -RN

There are a couple of key shortcomings with the NBER working paper. I’ve discussed some of them on my blog, but as you note, the lack of upstream emissions is an important omission. In addition, Eric Jaffe at The Atlanic’s CityLab site has a great round up of expert opinion on the NBER report. -DR

hey...talking about how much better for the environment electro cars are..ive read, most electricity for them will be produced by burning coal, which will result in the us in a 80% cost increase for health costs, so do you really think its usefull to buy a electro car?

No region in the US today produces electricity solely from coal, and we’re seeing the amount of electricity produced by coal decreasing across the US. In 2004 it was about 50% and in 2013 coal generation in the U.S. fell to under 40%. With policies like the Clean Power Plan finalized by the EPA this year, we expect the emissions from coal to decrease even more in the coming years.

With less coal electricity generation and more renewable electricity generation, like wind and solar, we expect health impacts across the board, not just global warming emissions, to decrease. In short, yes, we think EVs are clean and getting cleaner as we shift away from coal and add more renewables to the grid. One great thing about EVs is that as the grid gets cleaner, ALL electric cars get cleaner, not just the new ones.

Almost 98 percent of all energy here in Kentucky comes from coal.

Most of Kentucky is in the region covered by the Southeast Electric Reliability Council -Tennessee Valley grid. The most recent data on that electric grid shows about half of the power comes from coal (54%), (down 5% from the last report).

What is the greatest challenge in battery development? It seems like we have made little progress since lithium ion batteries. Or have we?

There has been significant progress with lithium ion batteries, as costs have come down and that’s letting longer range batteries enter the market (200+ mile range). Researching the best chemistries for vehicle applications is still happening and support for that research is necessary to bring costs down to make EVs available for more people at a range of vehicle prices. In terms of emissions we want to make sure that we are producing batteries with the greatest efficiency and as we bring more chemistries from the labs to the roads, we anticipate the global warming emissions per battery will decrease.

Even with the established Li-ion technology, costs have fallen much quicker than anticipated.

Was there anything in your results that really surprised you as you were going through the analysis?

The most surprising result was how quickly the additional manufacturing emissions from EVs, mostly from producing the lithium ion battery, are offset by the lower emissions from driving the EV compared to a similar gasoline vehicle. We found, on average, it takes the 84-mile range battery electric vehicle only 6 months to offset the manufacturing emissions, and the 265-mile range battery electric vehicle about 16 months to offset the manufacturing emissions due to the larger battery required to get the longer range.

How do you think groups like the Union of Concerned Scientists can help the public better understand issues like climate change and their impact on humanity?

At UCS we provide scientists with a platform to convey their technical messages to a wide range of audiences (from concerned consumers to policy-makers). This report and the online tool to calculate EV emissions are examples of how we explain important environmental issues to the public. Another important role for UCS is to make sure that science and scientists have a voice in the public sphere and policy conversations.

Do electric cars have any future potential to be more than city vehicles due to limited range and long recharge times? Wouldn't we be better off investing in public transit for cities than encouraging people to drive in single passenger cars?

We are now seeing more and more longer range battery electric vehicles (BEVs) coming to market. Currently the Tesla Model S range is 265 miles for the larger battery, and there are more BEVs like the Chevy Bolt and a longer range Nissan LEAF that will be available in the coming years. These advancements in BEV range will make the vehicles suitable for a wider range of people. Investing in public transportation is also important, but not necessarily a tradeoff to increasing BEV range. We like the investment in public transport (especially zero-emission buses and trains) and EVs!

Hi, I'm curious to know: How does the average lifespan of current electrical cars compares to their gas cars equivalent? And what were the lifespans used in the report?

Because EVs are still relatively new and have only been on the road for about 5 years now, we are uncertain whether there will be a difference between EV retirement and gasoline car retirements. Most experts assume cars stay on the road about 15 years, but early data on shorter-range battery electric vehicles suggest they travel less mileage annually than a gasoline car due to the limited range. Therefore, in the report we assume the midsize 84-mile BEV travels about 75% of the annual mileage of the average gasoline vehicle as reported in an Idaho National Lab study. We also assume the similar midsize gasoline is driven similarly with both the midsize gasoline and battery electric cars having a 15-year lifetime of 135,000 miles. We assume the full-size vehicles both gasoline and electric cars drive about 179,000 miles over 15 years, because the range is much higher (265-miles). Though the bottom line is, whether you drive these cars 135,000 or 179,000 miles, the BEV produces fewer global warming emissions compared to its gasoline counterpart.

What are your thoughts on hybrid animals?

My favorite is the liger! -RN

Pro Zonkey, but the electric cheetah scares me. -DR

Since replacing the U.S. fleet with alternatively fueled vehicles also requires a massive infrastructure overhaul (i.e. fueling stations), what are some of the advantages that come with the fuel flexibility of EVs versus say pushing for more natural gas powered vehicles?

We see plug-in EVs, (plug-in hybrids and battery-electric vehicles) as well as other alternative fuel vehicles (fuel cell and biofuel-powered vehicles) all playing a part in the transportation future. Each type of vehicle has capabilities that may suit various types of drivers. However, swapping one fossil fuel (gasoline) for another (natural gas) doesn’t look like a long-term solution and we see electrification of passenger transportation (using renewable sources) as the best path forward. For more information on the tradeoffs of natural gas in general you can see our report The Natural Gas Gamble.

What technologies and/or infrastructure do you envision as necessary before electric cars are more able to take hold on the roads? Is it battery charging speed, charging locations, range improvements, variety of vehicles, cleaner power plant sources, carbon taxing, or autonomous driving? Or something else entirely?

I haven't had a chance (at work) to read the report yet, so apologies if you covered this in depth there.

I don’t think there are significant technical barriers to electrification of the vehicle fleet. We did a survey and found that over 40% of households could use one of the first generation EVs in their daily driving. The major barrier to increasing that figure is to increase the availability of charging, especially in shared housing like apartments and condos. Updating building codes and engaging the utilities can help with this. Vehicle availability is another important factor. We’re starting to see more types of EVs and at competitive prices. We need to see those trends continue.

As a quick follow up: I notice in your list you've included "updating building codes." Are there other specific subsidy, tax, or policy changes you think are necessary? Are there specific ones you see as critical?

Having just read this: http://blog.ucsusa.org/dave-cooke/automakers-safe-vehicles-fuel-economy-952 I was contemplating how one levels the playing field in an industry this well entrenched....

Protecting the federal tax credit for EVs and supporting and protecting state level subsidies is critical. Also changing the building code to provide unified guidance for EV charging station installation is important to get more EVs on the road. Overall, the most critical part to reducing global warming emissions from EVs is to reduce emissions from electricity generation. Policies like the Clean Power Plan have the potential to do so, if we use these policies to introduce more renewable sources of electricity and reduce our use of coal. Chapter 3 of our report goes into more details about the ways policy-makers can support EVs getting cleaner over time. -RN

We also support policies like the Zero Emission Vehicle program in California, New York, and 8 other states that make sure that car buyers have clean vehicle choices at car dealerships. -DR

Has anyone calculated the average emissions produced by refining a gallon of oil to compare it with emissions produced at electrical plants per KWh?

Yep, that’s exactly what we did in this report. The MPG (miles per gallon) value listed for each region is the combined city/highway fuel economy rating of a gasoline vehicle that would have global warming emissions equivalent to driving an EV. So when we say an EV gets 87 MPG in California, we’re saying that producing and delivering the electricity to the car produces the same emissions as extracting, refining, and burning gasoline in a 87 MPG car.

Which companies do you think have the most promising electric vehicle, battery and infrastructure developments? Tesla seems like the 800 lb gorilla here, but are there other companies that were making parallel advances in the field, or in similar important fields for EV application?

Of course Tesla’s commitment to advancing EVs is very promising, but BMW, Nissan, and GM are also working on advancing EVs through things like producing lightweight BEVs to increase the efficiency of the vehicle (BMW i3 that uses a carbon fiber body for example), and improving the range of BEVs (Nissan LEAF and Chevy Bolt as examples). -RN

BMW is also doing some interesting work in testing smart charging of the i3 so that electric vehicle charging can help utilities reduce emissions and enable more renewable energy on the grid. -DR

How promising are lithium-air batteries (have heard some stuff about them recently but know virtually nothing about them)?

Also, is there any sort of truth to the claim that battery technology is a huge limiting factor in technological advancement in recent times? For example, lead acids are still around (although they're pretty much phased out by lithium-ions at this point, from what I understand) and they were invented in the goddamn 19th century.

Lithium ion battery technology is still relatively new and developing the right batteries for the vehicle application is still being researched. There are many new types of batteries being tested at the lab level and we need to support those technological developments and bridge the gap between the research labs and getting the technologies scaled up for vehicles on the roads. -RN

Lithium air batteries do have the promise of being much more energy dense than the current technology and so could enable longer range EVs, especially in the bigger size vehicles. However, my understanding is that the technology is pretty far from being ready for commercial use, where cost, safety and reliability all have to be proven. -DR

To the question's second part:

[RN] Developing batteries to vehicles means producing them at much larger sizes than in the past. Battery technology has come a long way in recent years and we see with over 20 models of battery electric and plug in hybrid electric vehicles being sold today that battery technology is no longer a limiting factor. -RN

And I think that while better and cheaper batteries will help EVs, today’s technology is certainly working. There are now over 300,000 EVs on the road in the U.S.—better battery tech will help accelerate the market, but isn’t the limiting factor. -DR

What stops us from going completely electrical? Is it the battery technology or something else?

Where to charge, availability of the vehicles, and the costs of batteries are the biggest hurdles at this time. There are many efforts to increase the amount of chargers available outside the home to reduce range anxiety, and there is significant battery research happening to find the best batteries for vehicle applications.