Wednesday, April 12, 2017

Less meat and more miles or More meat and less miles?

This post is because of this report. It summarizes a study on on the environmental impacts of conversion of mangroves for agricultural uses -  raising cattle and shrimp farms. It quotes ""On a personal scale, this means a typical steak and shrimp cocktail dinner produced through mangrove conversion would burden the atmosphere with 1,795 pounds of carbon dioxide," said J. Boone Kauffman, an ecologist at Oregon State University who led the study. ... This is approximately the same amount of greenhouse gases produced by driving a fuel-efficient automobile from Los Angeles to New York City." "

Let's first dispense with the obvious. Of course the answer to the question is neither as less meat and less driving is the more sustainable choice. To me sustainability is more about  like Haile Gebrselassie rather than Usain Bolt i.e.,  winning a marathon rather than a 100m dash. So let's focus on making one adjustment at a time.

There is a neat paper co-authored by the late Dr. Lee Schipper, who made great contributions to transportation sustainability. And some of the most telling number from his study is the picture below

As someone whose single biggest impact comes from air travel, I felt better that the airline industry has made great strides in reducing the GHG intensity. If you read the paper, this is attributed to fuel economy, and regulatory changes and higher occupancy per flight. Also rail travel is getting better but in terms of the passenger miles traveled in the US it's absolute impacts are likely smaller relative to road and air travel.

But let's just focus on grub and gas (I mean gasoline, not the product of the former).  So while the statement that a single meal involving steak and shrimp might have more impact than driving a car several thousand miles is striking, most people are not considering driving from LA to New York, which is about 2800 miles. So let me interpret this as equal to about a fourth of the annual miles the average american drives each year.

Now, let us crunch some numbers to compare the effectiveness of reducing meat vis a vis reducing vehicle miles traveled from a greenhouse gas perspective. I am using the assumptions below for protein, which come from this study. Emissions per mile of auto use are based on EPA reported fuel economy (harmonic mean of 50% city and 50% highway miles)

A few additional assumptions about the base line relative to which some adjustments will be compared:
Protein intake
Daily protein requirement for adult: 60 grams (gm)/day
Baseline protein mix:  45 gm of beef protein + 15 gm of chicken/milk protein + 0 gm legumes
Average annual vehicle miles (U.S.) - 12000 miles/year
Automobile for the base case - Ford F150

Below is the effectiveness of four different adjustments relative to the baseline

Reducing beef protein intake by 10% is as effective as driving 5% less miles using a F150. Switching to a Camry is four times as effective as each of the other adjustments shown. It is for oneself to decide which of these adjustments is easier. Of course bigger adjustments, combining more than one type of adjustments or different baseline assumptions will all affect the calculations.

Bottomline: There are any number of calculators to estimate your energy, water, CO2 footprint etc. But I have not come across a calculator that combines our various activities and various types of burdens and gives information about the effectiveness (say, on a % emissions basis) of adjustments along different fronts (food, travel, housing, etc.) and in terms of changing the equipment (or capital stock) vs usage and let the consumer make better informed decisions.

Monday, April 10, 2017

Comparing apples and oranges - a life cycle assessment perspective

I am excited about my large LCA class this year. I am not sure if it was the subject matter itself, my teaching or my grading last year, that lead to an almost 20% jump in the demand for my 2017 spring LCA class from around 55 last spring to 67 this time around. Assuming a few people drop out by Week 2, which again I cannot tell whether it was the subject matter, my teaching style or the painful HW1 which I handed out, I think it will settle at 60. This would still be a 17% increase from the 51 students that stuck with me for all 10 weeks last spring. I do feel bad that I could not accommodate several more students who wanted to enroll and might have stayed on.

In any case, I introduced some noise into the above calculations because, I changed my introductory lecture. Keeping with my resolve to make sustainability more fun, I started off by talking about food, movies and sports, things I love to no end. Yes, I am an academic but I am not ashamed to admit it is not math, science or reading books that really keep me up! I hope my colleagues who are going to be voting to give me a permanent job and my references who are going to be writing me letters of support read just my academic work rather than my blog! But if they do, I hope they see that my perspective on sustainability research is that it needs a new perspective, one that moves it away communicating it as being morally and ethically right to also being an exciting and enjoyable pursuit. But this blog is just for myself, my students, broader public (wishful thinking!), and some day my family. 

You are not sitting in my class and so before you click away, I really should get to the point of this post. I began the first lecture by talking about nutrition labels and what is good, bad and confusing about them. The basic point I was trying to make is that doing an LCA is like trying to come up with a nutrition label, except that it is dominated all by the bad things associated with consuming a product. I was quick to clarify that the students will not merely become good label makers at the end of the quarter but have picked up on really interesting insights when it comes to designing an LCA study and using the information derived to make important decisions. However, in between comes the really important yet painful task of accounting. (Talking of accounting, I spent my entire weekend doing my taxes. I must say it was painful but in the end I am happy I determined my effective average and marginal tax rates at the federal and state-level. If only there was Kayak like comparison one could do with your tax that compares 10 different sites. I know that might be crazy, more on it on a separate blog post perhaps!)

I keep getting distracted, back to the point about the proverbial apples vs oranges comparison that is used and abused. I say abused because, apples and oranges are  really not that different if you look at their nutrition content. Check this out. But I found this out just as I am writing this blog and I ended up abusing the comparison anyway. Next year will be different. However, the fundamental point about LCA I wanted to get across that it is really important is that before we start comparing choices from a sustainability standpoint, we really need to be sure what it is that we are comparing. And when you look closely, the problem is nightmarishly complex. There is hardly anything that we consume that is a like for like comparison. In class we discussed, how it is hard to compare a bowl of rice vs corn, a gasoline and electric car, plastic vs paper bag, nuclear vs hydro power, etc. After that I threw in a question about how does one compare golf and football (I mean the real football, but it doesn't matter). 

A fundamental technical concept of LCA is the notion of a functional unit. We really want to be comparing substitutes that are "functionally equivalent". What I mean is, that we consume goods to meet certain needs, which are the functions that the good serves. From this perspective, one might say the function of a bowl of cereal is to provide calories, for a car it is taking you places, the function of a bag is to help carry stuff, the function of an electric power plant is to supply electricity. However, it is not so simple, and thankfully so, because otherwise, my job would be so much more boring. Here's why. Cereals or any food for that matter not only provide calories but also proteins, vitamins, fats etc. as well, and no two substitutes seem to have the same proportion of each. Likewise, a gasoline and electric car differ in their driving range and so are not directly comparable, at least not today! Paper and plastic bags are not comparable unless you normalize them for their differential capacity in terms of volume or weight carrying capacity, reusability, conformability or ability to carry wet products. Finally, nuclear and hydro power plants both produce electricity but hydro power might not have the same reliability as nuclear in dry years! You get the drift. 

Now to some fun thought questions. At the risk of making my life harder by revealing important exam questions, how might one go about comparing the following if asked which is more sustainable
1. DVD vs Netflix vs Cinema
2. Home vs restaurant meal
3. Jean vs polyester trousers
4. Starbucks vs Peet's coffee stores (a comparison of the stores itself and not simply a cup of coffee)

A hint about the last comparison, which are two places I frequent. My local stores of each appear considerate of  the poor, and likely, homeless people who come hang out (indeed, some of them do buy a drink or food) and this is really heartening for me to see, but the former seems to attract and tolerate more of such people. That said, I am a patron of both places. So the coffee stores from my perspective functions as a place to eat, drink, and hang out, in some case the only nice place for the poor. If a place was less kind to the poor then perhaps I will want to take my business to a place that is more considerate!

If you think these are mere academic comparisons and the simple answer we need variety and so need a mix of products, you are absolutely right. But still there is the question, if I had to consume one more unit of each, what would that be! In the time, chew on whether apples and oranges are that different!