You often hear questions about the “true” carbon footprint of one renewable industry versus another. Life cycle analysis provides the answer. This short post from Yale Climate Connections answers the question “What’s the carbon footprint of a wind turbine“?
Italian-Swiss shipping company MSC is now the 6th largest emitter in Europe. Look at all those aging eastern-bloc power plants… and then a transport company right in the center.
Wondered about the carbon impact of software development? The Green Software Foundation was established by Microsoft, Accenture, Github, and Thoughtworks to build an ecosystem of people, standards, tooling, and best practices for sustainable software development.
Electric vehicle critics will often tell you that the environmental cost of the batteries is the “dirty little secret” that nobody is telling you about. The claim is that the manufacturing impact of the batteries is so high that we might as well just keep burning gasoline. The origin of this statement is an early and flawed study from 2017.
Let’s examine their claim in more detail.
Battery technology is advancing rapidly. You can see this in the price curve. In December of last year, Bloomberg NEF reported the first instances of vehicle batteries priced at below $100/kWh. At $100, most analyses show EVs priced equivalently to internal combustion engines. For comparison, a decade early that price was $1100/kWh. That means that 10 years ago, the price of the 53 kWh battery in Tesla’s original roadster was over $50,000. It’s no wonder those early Roadsters were so expensive!
The assertion made by the EV industry is that the increased environmental impact of manufacturing the vehicle is offset by the decreased impact of using the vehicle. Is that true?
To figure out the answer to that question, we need to know the CO2e impact of running a conventional vehicle vs an EV. Then, let’s add in the CO2e impact of the battery pack, divided over the expected lifetime of the battery, and we should have our answer.
For the sake of simplicity, let’s assume that the manufacturing impact of a conventional vehicle and an EV is roughly the same, excepting that the EV has the added impact of the battery pack. It’s not entirely true, because the conventional vehicle has a higher carbon cost to build than the EV (without the battery), but for the sake of simplification, let’s assume that they are the same.
My previous vehicle, a 2015 Ford Fusion, averaged about 23 mpg in actual usage. Ford rated it for 28 mpg, but I tracked my gasoline purchases over the lifetime of the vehicle, and it was roughly 23 mpg. I may have a bit of a lead foot. Gasoline combustion produces an estimated 18.95 lbs of CO2e per gallon used. Annually, I drive around 10,000 miles, which means that car was producing 8,226 lbs of CO2e annually.
My new vehicle, the Tesla Model Y AWD, is rated by the EPA for 28 kWh / 100 miles of driving. The Tesla should use about 2,800 kWh of electricity to drive the 10,000 miles I drive in a year. Now all we need to know is the CO2e costs to generate the electricity. According to the EPA, in the United States, the electricity industry as a whole produced an average of 0.92 lbs of CO2e per kWh of electricity generated. So, assuming that my power utility emits the same CO2e as the EPA average electrical utility, my CO2e costs will be 2,576 lbs. More on that in a minute…
18.95 lbs / gal
0.92 lbs / kWh
Annual operating emissions comparison
So for me, my old Ford emitted 5,650 lbs more CO2e annually than my new Tesla does.
Now let’s get back to that battery pack. Recall that the manufacturing CO2e impact of a battery is about 75 kg CO2e / kWh of capacity. So manufacturing the Tesla’s 75 kWh battery will emit about 5,625 kg of CO2e, which converted to lbs is 12,375 lbs. And then we have a simple calculation.
Years to "break even" = Battery Manufacturing CO2e / Annual CO2e savings.
So, for me, it will take about 2.2 years before the manufacturing impact of the battery is recovered completely.
My Utility is PSE
I buy my energy from Puget Sound Energy here in the King County, WA area. PSE’s generation mix is roughly 1/3 renewable, 1/3 coal, and 1/3 gas.
2.2 lbs / kWh
1.0 lbs / kWh
0 lbs / kWh
1.06 lbs / kWh
Compared to the national average, PSE is actually a pretty dirty utility. My Tesla driving will generate 2,968 lbs of CO2e annually. And my emissions “payback” will extend to 2.35 years. What a calamity!
Fortunately, PSE has a green energy option, which we have chosen for our household. For an extra $.01/kWh (about $15/mo) we buy an energy mix which is generated 95% from solar and wind, and 5% from biogas. Biogas has about the same emissions profile as NG, which means that the PSE clean energy option produces about 0.05 lbs CO2e / kWh. Some folks consider biogas neutral environmentally, but let’s leave that for another day. In any case, my new Tesla’s CO2e footprint using PSE green energy is now reduced to just 140 lbs CO2e annually, and the “pay back” time for the battery is now just 1.5 years.
Over the 5 years I owned the Fusion, I estimate my emissions at about 41,000 lbs CO2e. I expect the Tesla to be a third of that. Automobiles have a lifetime of about 200,000 miles. Over 200,000 miles the Ford will emit 165,000 lbs CO2e. And if I own the Tesla that long? 15,000.
Your numbers will vary, but the calculation is not hard to do. And no matter how you do the numbers, there simply is no case that the environmental impact of EV battery manufacture outweighs the benefit of not burning gasoline to run a vehicle.
There are two broad approaches to pricing carbon that are in common use today. These are carbon taxes, and emissions trading systems.
Carbon taxes are consumption taxation models. They encourage consumers to choose products that are more emissions efficient by levying a tax on those that aren’t. Need a litre of fuel? Maybe it will cost an additional 15% in tax. The taxing jurisdiction promises to put that money back into energy efficient or climate transition projects, further accelerating the transition to a decarbonized economy. In some jurisdictions (British Columbia, Canada for example) the carbon tax collected is offset by a reduction in other taxes. The promise is that the carbon tax will be revenue neutral, which satisfies at least some of the folks who object to new taxes.
Emissions trading systems (sometimes called “Cap and Trade” systems) use a different approach to driving emissions reductions. Emissions trading systems price the emissions directly. The government sets a cap on the total emissions permissible in a given period, and then allocates emissions quotas to companies that need them. Stiff penalties are imposed for exceeding the quota. Companies can then choose to become more emissions efficient, or continue to emit. If they continue to emit, they can purchase unused quota from another emitter who may be more efficient or pay the penalty. Over time, the government reduces the cap which creates pressure to be more efficient.
Sometimes emissions trading systems are also connected with an auction, as I wrote about Nova Scotia last week. When an auction is used, the quota allocation is done via auction rather than through some other scheme, which should lead to more optimal outcomes. An auction also has the benefit that it raises money for the government to spend on climate transition or energy efficiency projects, just as a carbon tax does.
Which is better?
So why choose one over the other? There are some major differences.
Carbon taxes are easy, broad, blunt tools. If you’re buying fuel, they make a lot of sense. But how do you tax the carbon content of a new home, a car, a pair of jeans, or even a carrot? Each will have differing Scope 1,2, and 3 emissions depending on the efficiency of the producers supply chain. To tax the carbon content of a consumer product accurately, you need to know the contributions at each stage of the manufacturing process. We can’t do that accurately today. Emissions trading systems overcome that limitation. Each company in the supply chain has a quota for emissions, and has to live within the quota. (note: in today’s early stage emission trading systems it’s common to only make the largest emitters comply. Hopefully that will change.)
Carbon taxes may also not be an accurate reflection of the true carbon emissions cost of a given product or service. They are simply implemented as a percentage of the end retail price. An emissions trading scheme allows the market to set the price. To return to the Nova Scotia example from last week, the government set a reserve price of $21 per ton, but the actual price paid was 74% higher, reflecting market demand.
Carbon taxes are also impractical to implement across borders. How should we tax two vehicles, one made in China in a factory powered by coal/electric, and the other made in Detroit? One of China’s competitive advantages has been their willingness to use cheap, and dirty, coal power to power industry. Again, emissions trading schemes make this easier, since they target the emitters directly.
And finally, carbon taxes do not create direct incentives to reduce emissions because there is no cap on emissions. With a carbon tax, you could conceivably have a rapidly growing economy with growing emissions. So long as the rate of growth is high enough, then the emissions tax is simply another tax. In a cap and trade emissions market, the government sets the amount of carbon allowed, and reduces that allowance each year, which creates incentives for companies to emit less.
For those reasons, emissions trading systems are preferable to carbon tax systems. Your thoughts?
Getting to a zero carbon footprint, globally, is a hard concept to wrap your mind around. The scale of what’s required is intimidating!
Today’s post is about a carbon accounting concept called emissions scope. Emissions scope helps businesses to account for where emissions occur in supply chains. Then they can focus on where improvements are possible. Businesses that want to perform carbon accounting use these concepts, but we as individuals can also use this them as a framework to think about decarbonizing our own lives.
Scope 1 emissions are from the direct operation of the business, and the assets that the business owns or controls. Scope 1 emissions include the operation of facilities, manufacturing plants and more. They can also include emissions from fuel combustion used to run operations.
Scope 2 emissions are from energy purchased to run the business. Buying power or heat from a utility creates scope 2 emissions.
Scope 3 emissions come in two categories: upstream and downstream. Upstream emissions are from the inputs needed to run the business — the raw materials used to build products, the capital expenditures to buy equipment, and even the transport of those supplies to the business. Downstream emissions are created after the outputs of the business leave the business — the emissions from the transport of the products to market, the usage of the sold products, and even the disposal of those products.
When world leaders talk about getting to zero, they are talking about decarbonizing these supply chains. Commitments like the NDCs, and individual country level regulatory actions are fairly blunt tools. They create a framework for businesses to operate within, but ultimately businesses face the hard work of gathering scope level emission data, building governance and reporting into processes, and delivering sustainable products. It’s a daunting transformation. The good news is that these kinds of transformations appear to be achievable with very little impact on the final price for products that we consumers pay. According to World Economic Forum Net Zero Supply Chain analysis, many businesses can get to a net zero supply chain with an impact of between 1% and 4% on final consumer price.
As individuals, and families, we can also apply the same kind of thinking. Scope 2 emissions would be emissions from the energy we purchase to use in our day to day lives. Scope 3 emissions would be from the things we buy, and the things that we throw away. And if you heat or cook with wood, oil or natural gas, or run a creative business like woodworking from your home, these are the actions which are creating scope 1 emissions.
So what can we as individuals do? Here are two suggestions:
We can assess our own carbon footprints. Our scope 1 emissions are likely to be small, because most of us don’t build products ourselves. But we all have scope 2 emissions. All of us consume energy at home. So what are the emissions associated with our own lives? How can we reduce them? Can we buy clean energy instead?
We can make choices about scope 3 emissions in our lives. When we purchase products — cars, houses, computers, food — we can choose to look at the emissions content of the products we are buying. For example, buying locally grown food creates fewer emissions than buying fruits and vegetables out of season from distant countries, which then have to be transported to us. Choosing to bring reusable shopping bags to carry our purchases home reduces plastic waste, and hence emissions. Those are easy and obvious. But the next time you go to make a major purchase, look at the sustainability of the products you are buying, and the commitment of the company to sustainability. More companies are starting to publish reports like this one from Microsoft. More and more, business is responding to customers who “vote” at the cash register for a cleaner future.
Getting to Carbon Zero is a huge task for human society. We all have a role. Let’s not leave it to government, or to business alone. Let’s also reduce at home, and shift our purchasing dollars to companies that value sustainability.
Have you wondered how to reduce your household carbon footprint? It turns out that it’s not hard to do.
First, start by getting a baseline. What do you use today? There are any number of websites that make this easy for you to calculate. For this example, I’ve used the EPA’s carbon footprint calculator. You’ll need your monthly heat and electricity bills, plus the mileage on your car if you want to do this yourself.
The EPA calculator starts by asking about your household, and how you heat. We’re a two-person household, heat with electricity, and use an average of 1,465 kWh each month. According to the EPA calculator, that equates to 14,890 lbs of CO2e annually. That’s 36.4% higher than the average in our zip code, which is 10,910 lbs. Ouch! The calculator makes some suggestions, like switching to ENERGY STAR lighting and appliances, but we’ve already done many of those things.
Next the calculator ask about driving habits. We have two vehicles. I drive about 10,000 miles annually, and Joanne around 2,500. The calculator also wants to know what the fuel mileage for your vehicle is. If you don’t know it yourself, the Department of Energy maintains a handy site at fueleconomy.gov where you can look it up. The DOE rates my Tesla Model Y at 125 mpg, and Joanne’s Audi at 30 mpg, which equates to another 3,245 lbs of CO2e. That moves us to 18,135 lbs of CO2e annually, but now we’re ahead. The average household in our zip code clocks in at a whopping 31,878 lbs annually! Apparently, they drive big gas guzzling vehicles…
“Wait, wait”, I hear you saying. “Isn’t your Tesla an EV? Why is it rated in mpg?”. Yes, it is. However the DOE rates it at 125 mpg because there is a cost to generating the electricity that powers it. They use a fairly crude measure, which is the amount of gasoline required to deliver the same kWh of energy used by the Tesla to drive a specific distance. More on that in a minute.
The last part of the EPA calculator is to give you credit for recycling. The average two-person household in our area sends waste to the landfill equivalent to 1,383 lbs of CO2e annually. We recycle aluminum, glass and paper but not all plastic, so they give us a credit of 511 lbs, meaning our waste CO2e is reduced to 872 lbs. We’d like to recycle more plastic, but Recology restricts the types we can recycle.
The calculator produces us a report like the one below. It shows our emissions at 19,007 lbs of CO2e annually, primarily from household electricity consumption. Note that I haven’t taken any of the suggested “planned actions”. Most of them, like replacing old appliances and lightbulbs, we’ve already done.
Next, try to reduce your footprint. You could use the EPA calculator suggestions, but as I mentioned above, we’ve already done most of them. Given that the bulk of our CO2e footprint comes from electricity consumption, it makes sense to try and focus on making the electricity we use cleaner. The answer is renewable energy. Alas, we live in a condo and it would require other owners to all agree in order to install solar panels on the roof of our complex. Plus, we live in the Pacific Northwest which has prolonged periods of cloud cover in the winter, which might make solar less efficient. However, it turns out that Puget Sound Energy provides us the option, for an extra $.01/kWh, to buy “Green” energy. This is 95% generated by wind and solar, and 5% from biogas.
So we did this, with dramatic results. It costs us less than $15/mo on the electricity bill, and basically eliminates the CO2e footprint for our home, and for the Tesla. Returning to the EPA calculator, I calculate that we have now reduced our annual household CO2e footprint to just 3,352 lbs. That’s 10% of the average CO2e footprint of similar households in our neighborhood. Sweet!
This method is imperfect. The EPA calculator only calculates household impacts. It doesn’t take into account things like food or air travel, and it uses assumptions about average households that probably will vary somewhat for most individuals. But it’s a good start.
So what’s your household carbon footprint? Grab your utility bills, head over to the EPA website to find out. Can you reduce it? Tell us how you did, below.