Upstream Impacts of Electric Vehicles Depend on Kicking Coal

In a previous post on my blog, comparing the nitrogen oxide (NOx) emissions of electric and fossil-powered vehicles generated a number of comments (via social media and the blog) to the effect of:

“Power plants may be dirty, but you’re leaving out the upstream impact of refining the fossil fuels to power an internal combustion engine (ICE) vehicle!”

That I did. It was only an analysis of (mostly) local NOx emissions, either from the car’s tailpipe, or the power plant used to generate the electricity (in MInnesota). NOx emissions can have significant local health impacts (inhalation, formation of ozone and smog, etc), but they can also travel long distances. Lifecycle or upstream impacts are also important to consider since we shouldn’t only be concerned about the local air quality impact of our transportation choices.

In an attempt to respond to these comments, I went digging for information on the upstream NOx impacts of the different vehicle fuels discussed in the post (electricity, gasoline and diesel).

The best, most usable, resource I found was the National Energy Technology Laboratory’s Upstream Dashboard Tool (NETL is part of the US Department of Energy). The UDT is “a fast and easy to use tool to determine the environmental profile of various energy feedstocks” according to the documentation. It includes emissions impact information on various “upstream” portions of energy fuels acquisition like raw material acquisition (mining or drilling), raw material transport (the truck, train or pipeline trip fuels must make before they are used) and the “energy conversion facility” (in the case of gas and diesel, this means the refinery process). Basically, you tell it to look at a fuel, and it will give you outputs like air and water emissions, solid waste generation, and water and land use requirements. And it’s all in an easy-to-use excel spreadsheet, just like they advertised!

This tool allowed me to look at the “upstream” impact of the coal and natural gas used in Minnesota’s power plants (to “fuel” an EV), and gasoline and diesel which would be used in ICE vehicles. So now I can answer the question: how do the fuels of ICE and electric vehicles used in Minnesota compare to each other in terms of NOx emissions, accounting for both the “tailpipe” emissions and the upstream emissions?

The upstream emissions

Here are the results from the Dashboard, translated into grams of NOx pollution per mile of vehicle travel:


The Tesla is in fact cleaner in terms of upstream emissions (before the creation of any kWh sent to the electric grid) – responsible for one third as much upstream NOx as either an average gas vehicle or one select diesel vehicle (without a defeat device). This is assuming Minnesota’s electricity mix, which includes 50 percent coal and about 14 percent natural gas. The tesla has no “energy conversion facility” emissions equivalent to a refinery for the liquid fuels, since I’m counting the burning of the coal as part of the downstream emissions.

So, extracting and refining liquid fossil fuels is in fact dirtier (in terms of NOx pollutants) than the extracting and transporting the fuel for an electric vehicle (powered from roughly 75 percent fossil fuels).

The complete picture

Now let’s take a look at the whole picture: from extraction to turning wheels. Here are the results with the downstream emissions included:

LifecycleNOxElectricity production in Minnesota is responsible for 1.4 pounds of NOx pollution per MWh, meaning an electric vehicle like the Tesla produces 0.21 grams of NOx per mile driven. With Minnesota’s current electricity generation mix, an EV is responsible for emitting about 30 percent more NOx “well to wheels” than typical gasoline vehicle, and 50 percent more than a diesel vehicle.

Electric vehicles can be better for NOx, if we kick coal

NOx rates change significantly based on the amount of coal in the electricity mix. In Oregon, which only gets 6 percent of its electricity from coal (and 32 percent from natural gas), the lifecycle NOx emissions of an EV like the Tesla would be 20 percent lower than an average gasoline vehicle. In Washington, where 75 percent of electricity comes from hyrdopower or other renewables, emissions would be less than half of a gas vehicle. In Wyoming, where 89 percent of electricity generation comes from coal, an EV would emit 80 percent more NOx per mile than a gasoline vehicle on a lifecycle basis. The United States as a whole emits 1.2 lbs of NOx per MWh, translating into a lifecycle per mile emissions rate for an EV that is about 10 percent higher than a gasoline vehicle.

Some Minnesota utilities are on a trajectory to reduce their coal use. However, there is an active political discussion going on right now about the future of coal-fired electricity in Minnesota, and the outcome is uncertain. As I said in the previous post, I think we need to electrify the transport sector to reduce climate risks. However, the choice cannot be between deploying electric vehicles or cleaning up the grid, both must be done simultaneously.


  1. If you’d like to check my math, here is the spreadsheet.
  2. This is still not a full supply-chain analysis, which would account for things like the mining of materials used to build EV batteries and car parts. This is just an analysis of fuels.
  3. Liquid fossil fuels, like gasoline, are getting dirtier over time, measured by carbon impacts, with the addition of new sources like tar sands. The UDT is based on national average compositions for gasoline, so the impact on pollutants like NOx is unclear using this approach. Regardless, electricity still needs to get a lot cleaner. is a non-profit and is volunteer run. We rely on your support to keep the servers running. If you value what you read, please consider becoming a member.

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22 Responses to Upstream Impacts of Electric Vehicles Depend on Kicking Coal

  1. Nick October 2, 2015 at 11:56 am #

    I’d suggest adding another note about your charging assumptions because when you charge makes a big difference. Average emissions and marginal emissions are not the same. If people charge over night when wind tends to be strongest (and on the margin for utilities that have a lot of it connected to their system), the impact is much lower. Of course coal could also be on the night time margin at other times of the year. Still, a utility could have the same amount of coal, build lots more wind, and effectively achieve a lower emissions rate for EVs.

  2. Mike Hicks October 2, 2015 at 12:24 pm #

    I wonder how long-lived this problem is, though — Are there upcoming regulations to force coal plants to reduce their NOx output? The big trigger for VW circumventing emissions testing was the 20x reduction in allowable emissions from 1 gram per mile under old Tier 1 rules to 0.05 g/mi under today’s Tier 2. If power plants are going to be subject to a similar swing, then there’s still the option of letting that play out (though that remains a huge problem area for CO2 emissions).

    It appears that power plants can also use selective catalytic reduction (SCR) systems much like what have been used in diesel trucks and other vehicles that are trying to properly meet emissions targets. Those smaller systems inject a fluid containing urea into the tailpipe, which converts to ammonia and then reacts with the NOx compounds to primarily form nitrogen and water. Something on the scale of a power plant would probably just feed straight ammonia into the exhaust stream to get the same effect.

    But for anyone who wants to get an electric car in Minnesota, I strongly recommend signing up for Xcel’s WindSource program (or hopefully something similar if you have another electrical provider), which requires the company to purchase wind power or other renewable energy to offset the amount of usage you want (you can buy a couple “blocks” of energy each month, or choose to get all of your energy offset by renewables).

  3. Monte Castleman October 2, 2015 at 1:32 pm #

    A few questions:

    Is there a realistic solution to the coal problem that won’t cost everyone that buys electricity in Minnesota a fortune and/or impact their lifestyles? I know wind power is finally getting competitive with coal, but do we have room for enough windmills? What if the wind doesn’t happen to be blowing.

    If there’s a revolution in battery technology over the next few years (and a lot of smart people are trying to make it happen) so that an electric car is practical as an only car for the average person, is there enough electrical capacity for everyone to charge their car overnight?

    • Mike Hicks October 2, 2015 at 2:37 pm #

      Renewable energy is becoming much cheaper, and we’re reaching an inflection point where renewable energy projects are beginning to win bids when directly competing against coal and natural gas power plants. Wind in particular competes well against coal. It has problems with variability, but we’ll probably see energy storage become much more common going forward.

      A lot of the variability gets evened out by getting more systems connected into the grid over a larger geographic area. If the wind dies down in one area, it is still probably blowing 100 miles to the north or south.

      Charging cars shouldn’t be a problem. There’s enough leftover capacity in the grid today to power about 150 million cars, according to calculations done by the Pacific Northwest National Lab, which is around 60% of the total number of passenger vehicles in the country. The cars are potentially able to act as energy storage devices themselves to even out the fluctuations from renewable energy installations.

      • Monte Castleman October 2, 2015 at 3:35 pm #

        I guess if we ever need to charge 100% of the cars, we’ll deal with the problem at that time. I can never get a straight answer as to whether there’s a revolution in battery technology just around the corner and it’s just the matter of devoting the right resources to development, or there’s some law of physics that says there isn’t. The Tesla is good enough, or pretty close to it, to be an “only car for everyone” if it didn’t cost a bazillion dollars for the amount of space you get. So is there some fundamental reason that Tesla batteries can never be sold for what Leaf batteries cost today?

        Of course it might not matter. If the rental model of self-driving cars comes to pass, you can summon a Leaf to take you to work every day, and a Tesla (or a gasoline or whatever liquid fuel we’re using car) to take you to Chicago for the weekend.

        • Joey Senkyr
          Joey Senkyr October 2, 2015 at 5:55 pm #

          Well, there isn’t really a straight answer. As far as I’m aware, there’s no law of physics limiting potential battery storage capacity, but there’s no obvious path forward for future development either. It’s gotta be a breakthrough, and there’s no real way to predict when it’ll happen.

          As far as Tesla batteries vs. Nissan Leaf batteries, they’re pretty much the same. It’s just that the battery pack in a Model S is nearly 3x the size of a Leaf battery pack.

          • Monte Castleman October 2, 2015 at 6:43 pm #

            So is it realistic that within 5-10 years or whenever, batteries will be a third of the price they are now. So you can get the range of the Tesla for the price of the Leaf? Which is what, absence other developments, I feel it will take to have widespread acceptance of electric vehicles?

            I’m about to drywall my garage, so I was thinking about roughing in electrical service for a future EV. However other people basically told me not to bother. I generally buy used vehicles at 100,000 miles and drive the until they literally fall apart, so by the time a practical EV comes out and ages to that kind of mileage it could be quite some time indeed.

            Is there any chance batteries are simply a dead-end, and we’ll need to go to switchgrass ethanol or hydrogen fuel cells instead once gasoline runs out or gets too expensive? I’m aware ethanol production involves a net loss of energy, but if we have windmills to provide it, the point is converting it into a portable, quickly refuelable form.

            • Mike Hicks October 2, 2015 at 8:27 pm #

              Whether we’re talking about fossil fuels or biofuels, we’re really talking about forms of stored solar energy. Each year, the petroleum we burn is the equivalent of hundreds of thousands of years of collected algae/plant material — maybe more than a million years worth! It’s estimated that it will take tens to hundreds of millions of years to replenish fossil fuel reserves at this point.

              Of course, only a small portion of the total biological material on the planet goes through the process of turning into petroleum. We can direct plant matter through human-engineered processes to create biofuel (and I do think that we have processes that extract more energy than they require to run, with that excess coming from the sun, but many methods aren’t very effective — I don’t think corn is a good feedstock, for instance).

              At any rate, one of our best options is to cut out the middleman and just use solar energy in as direct of a manner as possible. I think most cars would need the equivalent of 700 to 1000 square feet of solar panels to offset their energy needs. In comparison, cars fueled by biodiesel or ethanol would need tens or hundreds of thousands of square feet of farmland to provide enough feedstock to produce the fuel necessary to both run the car and run the whole process that creates the fuel (and the land needs to be replanted every year, while the solar panels would probably last 20 years with fairly little maintenance).

              So the question really becomes, what is the best way to store energy that comes from the sun? Batteries are improving, though it’s hard to say how fast they will get better and if they will improve enough to allow cars to be as cheap as they have been until now.

              One option that hasn’t been explored much as of yet is the possibility of using renewable power to generate liquid fuel by pulling CO2 out of the air. It is possible to essentially reverse the process of combustion and spit out a liquid hydrocarbon, which could be fed straight into the fuel tanks of existing vehicles. That’s probably going to continue to be very expensive for a long time, though.

              The potential expense of vehicles and fuel is a reason why we really need to work hard on restoring and expanding a good public transit network plus creating bikeable and walkable communities. If electric cars never get cheaper than an average new car today (about $32,000), or if fuel reclaimed from the atmosphere never gets cheap enough to be usable, then a lot of people will be stuck without the mobility that they have today. (And really, we’d need to make the fuel cheap enough that a large portion of it could be fed back into the ground to sequester the excess of carbon we already have in our atmosphere.)

              • Walker Angell
                Walker Angell October 3, 2015 at 1:21 pm #

                Good points. I think any way you look at it we need to significantly reduce our energy use. This in transportation, housing, manufacturing, and other areas.

                Do you know what the realistic outlook is for how much more petrol and natural gas is available? EG, when do we run out?

            • Joey Senkyr
              Joey Senkyr October 3, 2015 at 2:49 pm #

              I think it is realistic to think that. Not certain, but very probably. Tesla and GM are both planning to release a 200+ mile range EV priced in the high $30s in 2016-17 (the Model 3 and the Bolt, respectively), and both are projecting that economies of scale will continue to drive battery costs down. I really do think that in 10 years or so, EVs will be the default choice.

              • Monte Castleman October 3, 2015 at 3:29 pm #

                Maybe not the most unbiased or knowledgeable source, but The Tesla owner at the state fair (who drove his car to Florida and back) I talked to seemed to think that there’d be no reason for gasoline cars within a decade. Right now a Tesla is still troublesome for extended trips off the interstate, but back in the day sourcing gasoline was an issue too.

                The Volt could conceivably have replaced probably 90% of our driving with electric power, but that seems to be a dead end. The Tesla owner I talked to and I are agreement that it failed because it was just too complicated compared to a pure electric car, and it wasn’t distinctive looking enough- buyers couldn’t use it to make a statement like a lot of Prius drivers do. If it was a weird shape with “Range Extended Electric” lightning bolts plastered all over it we think it would have sold better.

                • Walker Angell
                  Walker Angell October 4, 2015 at 9:14 am #

                  It is getting better quickly though. The Arrowhead region of MN is becoming quite doable with high amperage charging available at a number of places (see

                  As well, low amperage charging is available at thousands of places. A 15a outlet will provide about 5 miles of range per hour of charge so 10 hrs overnight will provide 50 miles of range. A 20a which is not uncommon for engine heater outlets provides about 7 miles per hour of charge. Most campgrounds also have 240v 50a outlets available for charging which provides about 50 miles per hr of charge.

                  A friend and his wife drove up around there last week to paddle, hike, and photograph leaves changing. They charged in Duluth during dinner. Charged overnight at Grand Superior and Bearskin Lodge each night they were up there and then charged over lunch in Duluth on their way back. He said it took a few minutes of planning but worked well.

    • Joey Senkyr
      Joey Senkyr October 2, 2015 at 3:05 pm #

      In the short term, like within five years, the answer to both questions is no. The grid is just too big to make sweeping changes like that without spending tens of billions of dollars, even just within Minnesota.

      Longer term, Mike is right on both counts. I don’t expect to ever see another coal unit built in Minnesota, or in the US, except for maybe a few states where the coal lobby is strong.
      This means that, when the existing coal units reach the ends of their lives in the coming decades, they’ll absolutely be replaced by something cleaner. Some of that will be wind and solar, some will be natural gas, or, if the stars align, nuclear. It’s not really a question of if, but when.

      As far as charging capacity goes, there’s enough overall grid capacity, no question. It becomes a local distribution problem, and, barring an overnight paradigm shift, the utilities should be able to handle the required upgrades without trouble. The areas least able to handle increased load are the oldest ones that happen to be next in line for investment anyway, so it should mostly be a non-issue.

      Disclaimer: I work for Xcel Energy, but not in the energy supply or distribution groups. These are my own views.

      • Brendon Slotterback
        Brendon October 2, 2015 at 3:14 pm #

        Everybody should read Xcel’s updated comments on their 15 year resource plan, released today:

        If this plan is adopted by the PUC, and implemented as laid out, the Minnesota grid (and thus electric vehicle charging) will get significantly cleaner over the next 15 years in terms of both CO2 and NOx. This plan includes significant additions of wind, solar and natural gas generating resources. This is the kind of thing we need to happen if we want EVs to be a good alternative to ICE vehicles.

        • Bill Lindeke
          Bill Lindeke October 2, 2015 at 3:49 pm #

          Congratulations to Xcel and the environmental/energy community for this significant change in direction.

        • Monte Castleman October 2, 2015 at 5:21 pm #

          No Sherbune coal and no nuclear after 2030? Plus electric cars. Will renewables be ready to provide that kind of capacity?

          • Joey Senkyr
            Joey Senkyr October 2, 2015 at 6:25 pm #

            Less Sherco coal. Unit 3, the biggest, (and, relatively, cleanest) one, is a decade younger than 1 and 2, and was just rebuilt a couple years ago. It’ll still be retired eventually, but probably not until a while after 2030.

            The proposal also specifies that Sherco 1 and 2 will be replaced by natural gas combined cycle units, like what was done at the Riverside and High Bridge plants a few years ago. So, there’ll still be a whole bunch of power coming out of Becker, it’ll just be cleaner and less susceptible to rail snafus.

            As far as nuclear, the current licenses for the plants expire in 2030-2035 timespan, but at that point, they’ll still be producing infinity percent less carbon than natural gas. If renewables aren’t ready to pick up that load, license extensions could potentially be applied for. So says the plan, anyway. That’s getting a ways out of my area of expertise.

  4. Walker Angell
    Walker Angell October 3, 2015 at 1:16 pm #

    This is all a long way out of any area of knowledge for me…

    Wouldn’t Sherco and other power plants as well as petrol production all fall under energy conversion? I assume energy conversion above includes petrol production like Flint Hills?

    Do you know what the NOx is for our local petrol plants like Flint Hills? Would it be appropriate to compare an EV + local electrical production (Sherco, etc.) to an ICEV + local petroleum production (Flint Hills, St Paul Park)?

    • Joey Senkyr
      Joey Senkyr October 3, 2015 at 3:13 pm #

      As I’m reading the graphs, since actual tailpipe emissions for EVs are zero, the purple tailpipe emissions section of the EV bar are the power plant emissions. It would be equally accurate to color that whole purple bar green instead. For the gas vehicles, the green section represents the petrol refinery’s pollution.

      It winds up being misleading to focus too much on how clean the local powerplants/refinerys are, though. Is the gas we buy here in the cities refined at Flint Hills, or is it brought in from refineries in other states? I have no idea, but I suspect it’s some of both. Likewise, if you’re an Xcel customer, your power is coming from Sherco and Prairie Island, etc, but if you’re with one of the co-ops that buy from/own GRE (Wright-Hennepin, Connexus, MVEC, etc.), then the majority of your power is coming from coal plants in western North Dakota.

      • Walker Angell
        Walker Angell October 4, 2015 at 9:02 am #

        Considering ultra-local (like within 1 to 30 feet), an EV is much cleaner than an ICE. Walking down Shelby Ave I think I’d much rather have a bunch of Tesla’s or LEAF’s than a bunch of ICEV’s driving by.

        Moving out a bit (from the city and one level up stream) we bring Sherco electrical production and Flint Hills petrol production in to the mix. How much NOx do they produce and how does that affect us? How much NOx involved in xporting petrol to gas stations? Overall how would our air change if we went 100% EV? Would the air become considerably cleaner or would extra effluent from Sherco drift in and make it worse?

        For that matter, if we add a bunch of EV’s to the system that require more electricity, how do the power companies acquire that? Does the marginal increase come from increasing production at coal plants or from other sources?

        Next would be from a national perspective though I think my questions would be the same as from a metro perspective and likewise for worldwide. These though also bring raw material extraction and xport in to the picture. Here too we may need to include these for batteries though given their long life might be roughly equivalent to lubricating oil in an ICE.

  5. Alex Cecchini
    Alex Cecchini October 6, 2015 at 2:53 pm #

    I mentioned this on Twitter, but it would be cool to see a full analysis of the social impacts of fuel use in Minnesota including all emissions and pollutants (CO2, PM2.5, O3, SO2, NOx, CO). A 30 year picture would be interesting as a comparison of business as usual to Xcel’s updated plan to a more robust rollout of wind and solar. This is an older report from MPCA detailing some of the outputs for conventional vs PHEVs with different generation scenarios, which is a good starting point.

    Maybe I’ll take a stab at it 🙂

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