I finally was able to reduce my flying this year to just two flights to visit family for the holidays. My partner still points out that I take long showers so I should get off my high horse. I've decided to fix that.

A little math

I found several calculations of the amount of carbon dioxide produced by a shower. This varies by energy source so I tried a quick calculation for my own residence.

Assuming 2.5 gallons/minute of shower, and that I'm heating the water by about 60 degrees, we can use this equation to calculate the power needed.

2.5 gallon/minute x 8 lbs/gallon x 1 BTU/lbºF x 60ºF = 1200 BTU/minute

I heat it using electricity,and it seems that electric water heaters are generally considered to be around 90% efficient. So I'm actually using 1200/0.9 = 1333 BTU/minute.

California's PG&E power mix says it is only 15% fossil fuel (probably mostly natural gas). According to the US EIA, natural gas releases ~50 kg of CO2 for every million BTU or equivalently 0.05 g/BTU. So at this point it seems every minute of shower is 1333 BTU/minute * 0.15 * 0.05 gCO2/BTU = 9 gCO2/minute.

For perspective, I used this online flight carbon calculator to calculate that I released 0.29 metric tons of carbon (or 290000 grams) to visit my family in Tuscon this Thanksgiving. So that one trip was equivalent to showering for 22 days straight.

Shortening my showers

So showers are a drop in the bucket (pun intended) compared to flights, but I still figured I could make a change. I take about a 12 minute shower every day. I figured I could drop that to 2 minutes if I try. That 10 minutes would save 90 grams of CO2 a day, and if I could keep it up for a year, that'd be about 32kg. That's equivalent to an 80 mile car ride. But no one will ride in the car with me because I'd be smelly.

Anyway, I'll be setting a timer to try to get down to 2 minutes by January 1, and after I'll see if I can go the whole year. Please leave a comment if you see something off in my calculations.

Update: I forgot that part of the reason for showering was to actually get clean. As it turns out, after a month of showering for 2 minutes I started to get a little gross. So I'm moderating my usage, but no longer limiting to 2 minutes. Oh well, worth it while it lasted.