Sunday, February 15, 2009

My energy consumption

I was an oil and gas analyst for 2 ½ years, and then a consultant to end-consumers of oil and gas for another two years. I helped my clients hedge huge amounts of energy, but I did not have a true sense of just how much consumption those numbers represent.

So, I decided to try and determine how much energy I personally use. The main drivers of my consumption are obviously the power and heat that I use in my apartment, and the gasoline I use in my car. I also often take the bus to school and spend a good bit of time on campus in general, but my share of these public goods is difficult to calculate, so I made rough estimates of my share of use.

The easy way to figure out my natural gas and electricity consumption would be to simply look at my utility bills. Indeed, I did that, but I also tried to figure out how much power each of my appliances consumes by looking at the power ratings on the identification tags, or by looking up consumption ratings on the producers’ websites. Once I found the energy rating, I multiplied it by my estimate of how much I use the appliance each day to get total power used in watt-hours and kilowatt-hours. The results were fairly intuitive; here is what I found (the numbers in yellow were provided by the government required “Energy Guide”):

My stacked washing machine/dryer that came with my apartment uses the most power, then my refrigerator, followed by lighting. Surprisingly, my TV doesn’t consume much electricity even thought it consumes power while on standby, but this is largely because I don’t watch more than an hour of TV a day. Everything else combined consumes less than the nine incandescent bulbs that I use for three hours per day. When I compare the total amount of power I consume with this method (7.5 KWH per day) to the amount of power that Austin Energy says I use, my estimate seems to be almost 3.5 KWH per short.

I figure, however, that this difference is likely due to the fact that I averaged the summer and winter usage data from Austin Energy. When I compare my monthly estimate of 225 KWH (which does not include an estimate for power consumed for air conditioning) with Austin Energy’s number of 274 KWH for January the difference is much smaller. Still, I am using 10.9 KWH of power each day, which is equivalent to leaving on 4.5 incandescent bulbs (100 watt) for 24 hours a day… every day!

My consumption of natural gas is 0.46 Ccf per day, which is equivalent to almost 1.5 MMBTUs per month. More than a million BTUs is a lot, but the firms I used to hedge for consume about 10 million times more! These firms are building product manufacturers, drug makers, and other large industrial firms. So, while I don’t directly consume a huge amount of energy, I often don’t consider how much energy I consume indirectly.

As for gasoline consumption, I primarily ride the bus or walk, so it takes me almost a month to get through a 17.1 gallon tank of gas. Since I ride the bus a good bit though, I actually I tried to calculate my portion of Capital Metro’s daily diesel consumption based on data posted in its 2008 budget report. I came up with 0.001 gallons (rounded up) per day, and I have a feeling that is probably a significant overestimate.

So, based on my calculations I have concluded that if I want to save energy, then I should: consolidate laundry loads, ride the bus, and only use the lights I need and replace them with more efficient ones. As for the fridge… I don’t know… I’m not real fond of the idea of giving up cold beer.


Ideamotor said...

Congrats on completing this project. I am curious about which companies you used to consult. I was unaware about the Energy Guide. Does that take into account how many times your drier is used or the temperature you set your fridge? It seems like those figures may range dramatically.

Michael E. Webber, Ph.D. said...

Franklin, great tally. Thanks for pulling it together. But we should just get smart meters in place, along with smart markets, and then you wouldn't have to go to this trouble. Instead, your meter would tell you exactly which appliances consumed which energy on a minute-by-minute interval. Just imagine how much more efficient everyone would be if they had that information handy.

Oh, and congratulations for only watching 1 hour of TV per day. I tell my kids that watching TV turns their brains into applesauce--I just made that up to scare them, but at the same time, it might be true.