Reflecting on Some of My Carbon Emissions Numbers
I've been thinking about the environment cost of academic conferences lately, and looking into how we might use XR technologies to support remote attendance at conferences. I'm motivated by both CO2 emissions, as well as access issues for people with less money, ability, or desire to travel. I'm not alone; in recent years, academic and non-academic communities are taking the climate impact of flying more seriously, from the anti-flying flygskam movement to the “flying less” movement in academia.
When I started looking into the CO2 impacts of my personal actions, I really had no sense of what the big ones are, how they compare, and how much it would take to affect each one. So I thought I'd share some initial numbers for the obvious ones people know about: cars, home electricity, and travel. The cars and electricity numbers are grounded in our switch to an EV a few years ago, and our decision to install solar last year (it will finally come online this week, I think!).
Of course, there are lots of things we do that emit shocking amounts of CO2 (and do other sorts of damage to the environment) that many of us, including me, aren't conscious of (i.e., check out Hasan Minhaj's Patriot Act episode on The Ugly Truth Of Fast Fashion, it's horrifying), but I feel like I need to start somewhere, since every little bit adds up. I've finally started composing, for example, and have a small vegetable garden, even though these are small in the grand scheme of things. As Hasan points out at the end of the episode, keeping things longer, and buying just one or two pieces of used clothing per year would have a shocking impact on agregate.
(Aside: if you see any mistakes in the conversions below, please tell me and I'll update!)
How does your EV compare to Dinosaur-powered cars?
Lets start with cars. I've been asked by a lot of people how you can even compare them, since while EVs have zero tailpipe emissions (proudly proclaimed by the smug tagline plastered on the side every Nisson's Leaf), in most places in the world electricity generation isn't that clean. So I decided to do that simple comparison, based on what I could find about the CO2 created producing the electricity on the grid.
In Georgia, our electricity emits 933 lbs/MWh of CO2, or 0.423 metric tons (tonnes), putting us 26th-worst in the USA (the national average is 988, the worst is Wyoming at 2100, "hippie" California is 491, and the best are Idaho at 214, Washington at 201, and Vermont at a shocking 10 ... all the best states are primarily Hydroelectic, the worst are primarily coal). So, I'll use .933 lbs/kWh, or 0.000423 tonnes/kWh for me.
Our electric car (2015 Volkswagon eGolf) has a 24.2 kWh battery, and gets about 90 miles on a charge. So, 0.269 kWh per mile, or 0.251 lbs CO2/mile.
The tailpipe emissions of burning a gallon of gas is about 20 pounds of CO2 (see EPA.gov vehicle emissions FAQ) (That may feel high, since a gallon of gas doesn't weight 20 pounds, but this is apparently easy to calculate). An average new passenger car is supposed to get almost 40 mpg, so about 0.5 lbs CO2 / mile (the average light vehicle in the US currently gets ~22 mpg, so emits closer to 1 lbs CO2 / mile, but we'll stick with new vehicle target emissions since most EVs are relatively new). Your 2020 Prius claims to be only slightly better at 52-58 mpg (58 mpg would be 0.345 lbs CO2 / mile). Minivans and light pickups run about 20-24 mpg. At the low end, a Toyota Tundra pickup, Jeep Grand Cherokee or BMW X3 SUV are closer to 15 (or 1.33 lbs CO2 / mile).
So, your shiny SUV emits 5.3 times the CO2/mile that my cute little EV does. And that's on relatively dirty GA power. It'd be emitting more that 10 times my EV in CA, and an eye-popping > 500 times as if we lived in Vermont.
This is the root of my argument in favor of EVs, even in places with dirty power: sure, a "normal" Golf is "only" twice as bad as my eGolf where I live, but GA power gets cleaner each year, and every bit of improvement to the power grid impacts every EV. If Georgia Power cut it's emissions in half, your gas-powered SUV and sedan, and your hybrid Prius, will still chug along spewing CO2 at the same rate.
Looking at my personal impact on the environment, switching to an EV was mostly symbolic: we live 3.5 miles from work and only put about 4k miles on our car each year, so that's about 1076 kWh or 1000 lbs of CO2, or .45 tonnes. And our car millage is falling because we are biking to work more. But if you have a long commute, the impact of an EV could be significant (depending on where you live, where your power comes from, and what you are driving now).
On the other hand, half a tonne still sounds like a lot. What does that mean relative to other things?
Home Electricity Use
How about all the electricity I'm using at home. For context, we have a family of 4, in an small (1000 sq foot footprint), heavily-renovated-many-times-over-the-years, 1940's home (e.g., we have 3 separate AC systems, one system per floor, and a renovated attic that eliminates the insulation benefits of an attic – most of these structural renovations were done before we bought it, alas.)
So, we use a lot of electricity compared to the average Atlanta home of our size (a small amount of which went to charging our car). And I'll admit our CO2 impact is worse that just the electricity: we have gas furnaces, a gas hot water heater, and a gas stove ... I haven't figured out the CO2 impact of our gas use yet, but I'm sure it's not great, and we'll probably switch all of these to electric as they need replacing).
It's hard to tell all that electricity going, though. AC in the summer is a big, obvious one. Even though we keep the house "warm" in the summer and "cool" in the winter, the difference between summer and winter bills is all AC, and it's big. But the baseline is non-trivial, so I've been putting power meters around, and recently installed a whole-home monitor, to help sort this out. Most of our lights are LEDs, and the meter confirms they consume almost nothing, shockingly less than the four halogen lights that remain in one bathroom (which burn almost 400W when they are fully on, exceeding the sum total of all the rest of our household lights!).
Thanks to the whole house power monitor, I just discovered pretty quickly that our "always on" power draw is about ~700-800W, lets say ~7000 kWh/year. That's 3.1 tonnes of CO2/year. I'm sure the fridges and vampire devices are a lot of this, but it still seems shockingly high; figuring out what's consuming this is a big goal for the year.
We have a lot of computers and other electronics, and a quick back-of-the-envelop tally suggests they are only about half of this. Most are laptops and tablets and have surprisingly low consumption. The worst are the multiple gaming-grade PCs with powerful 3D graphics cards, that consume massive amounts when they are on (> 400 W each). It's an augment to upgrade and only the power you need; my 2018 27" iMac uses <1/4 the power of one of those PCs and is plenty fast. (Looking at the power used by old computers is a really strong argument to not "use that old PC to run some always-on service" in your house. If you must run a computer 24x7, get low-powered devices, like an Intel NUC.)
Our "networking and NASs and infrastructure gear" (including all the WiFi gear) consumes about 210 watts, pretty much continuously. At 8,760 hours per year, that's 1839 kWh/year, almost double the amount our car uses! That's 0.82 tonnes of CO2/year ... just for broadband, our wired networks, and some NASs.
As I said above, I started looking into this when we started considering solar and wanted to get my head around our high numbers. Once our solar and battery system is running (it's installed and should be online within the next week), it should generate an estimated 8,759 kWh / year. We'll easily use all that (including storing overflow in batteries), reducing our CO2 output by 3.7 tonnes. For many people, a system like this could get them off the grid entirely, with plenty to spare!
What about #FlyLess?
Lets return to the impact of flying. One of my big questions was how the seemingly huge numbers you see bandied about by the #flyless movement compare to the rest of my life. Armed with the numbers above, let's compare.
I'm flying to Berlin next week for work. Looking at various online carbon calculators, I see numbers anywhere from 1 to 2.2 tonnes of CO2 emitted per passenger for that flight (the low is likely a raw per/passenger calculation one site did, the higher ones are on carbon offset sites and probably try to include more of the carbon impact of flying, I'm not sure.) (The sites say that you should double this for business class, and double again for first, presumably because of the added room taken up by people in those classes – I'm don't get to fly first or business, so I suppose I can take consolation in that while I set back in coach).
ACM CHI decided to host their annual conference in not-very-accessible Hawaii, a location guaranteed to be a long trip for pretty much everyone. From Atlanta, it gives a similar calculation to my flight to Berlin. (I'm not planning on going to CHI, mostly because of this).
I was in Osaka last year for a conference (estimated cost is a bit more, but not much), and I fly occasionally to San Francisco and Seattle for work (each trip clocking in at about half a tonne). Short haul flights turn out to have more impact per mile, presumably because of the higher emissions during takeoff and landing.
Put in the context of my family's electricity usage per year (which is on the high side), these numbers are huge.
Focus on the big picture
Reducing the CO2 produced in your daily life is possible, but some of the choices aren't intuitive and many are hidden (see Hasan's video above for a single example).
Switching to an EV (given my short, in-town commute, and our growing use of bikes) has almost no impact. But, I prefer driving the EV much more than a gas car, so I'm fine with it being insignificant. It's peppy and fun to drive, especially compared to the Prius I traded in for the eGolf ... that was a car designed to take all the fun out of driving. And EVs last longer lives and have lower maintenance costs. So, it's a win-win-win for me, even if only a small win in terms of CO2.
Installing solar and batteries is a one-time thing many of us can consider doing (with ongoing benefit, obviously), and the reduction in CO2 is pretty significant, depending on where you live and how your local power is generated. Much more than I thought, actually. But is it expensive, and in the end it's still only equivalent to "a few less flights" per year. Ironically, if the grid power gets cleaner, the CO2 of personal solar go down. But, it also saves money, and we're also seeing more and worse storms in Georgia due to climate change, so have whole-house power backup is also a bonus.
Figuring out how to reduce the overall power consume at home can also have a big impact. I'm going to figure out how to reduce the always on power in my house (it's doable, I hope, although I suspect will be challenging in terms of time and money). But practically speaking, it will probably only reduce my family's CO2 emissions by about the equivalent to one international flight for one person.
For me, one message is clear: #flyless.
But what does this really mean for the rest of the efforts, if a family vacation to Europe exceeds the impact of our car, solar and reduced home energy use combined? Does this mean you shouldn't travel at all? For some people, that's exactly what it means. And for me, I certainly going to eliminate any travel I can (and continue to shift the focus of my research work toward support remote collaboration and meetings). But, I'm not going to stop flying, and I'm not going to #flightshame people who do ... although I hope more people will consider these numbers and adjust their lives and impact where they can.
But perhaps the message is really: #emitless.
Taken together (EV + solar + overall electric use reduction + less flights), that's a lot less CO2. Everything helps, and even if you can't do some of this, we should all do what we can.
Note: I am aware that CO2 isn't everything. Difference choices have additional impacts. Some power generation emits other harmful chemicals. Creating batteries has a whole set of impacts that we should also work to reduce, especially on laborers in 3rd world countries where a lot of the lithim and other materials are extracted. We can't ignore these, but we also cannot be paralized and let the perfect be the enemy of the good (as the saying goes). Our current climate crisis demands action on CO2 emissions, which is why it's in the news and peoples minds. And why it's the focus on this post.