Gas station without pumps

2016 July 30

Average annual power use

Filed under: Uncategorized — gasstationwithoutpumps @ 00:47
Tags: , , , , ,

I just got my “True Up” bill from PG&E—it has been about a year since the solar panels were installed. During that time, the panels generated about 2.63MWh of electricity (7.2kWh/day): 77kWh more than we used during the year. PG&E reimbursed me $2.11 for the extra electricity, but wiped out the $106 of Net Energy Metering credits that we had accrued from generating electricity during peak time and using electricity during off-peak times.

Next year, we’ll be facing a minimum delivery charge of about $120 for the year. If we follow the same peak/off-peak usage, that means that we could use about another $226 worth of electricity without increasing our bill (other than losing the $2.11 credit). That would be about 1.5MWh off-peak, or only 660kWh peak consumption. What that translates to for us is that I will be buying a dehumidifier for our house, to reduce the condensation on the walls. Current Energy Start rated dehumidifiers remove about 1.85 liters of water per kWh used, and I don’t think we need to remove 2775 liters of water a year (7.6 l/day) from our house, so the dehumidfier will add nothing to our electricity bill.  Based on reviews (in Consumer Reports and on Amazon), we’re looking at the 30-pint Whynter RPD-321EW Energy Star Portable Dehumidifier, is it has good performance in cool rooms (our house gets quite cool in winter, especially when we’re both at work) and is relatively easy to empty (we don’t have a convenient way to rig up a drain hose).

We are fairly light users of electricity by US standards. We used about 2.63MWh a year, but the US average is 10.932 MWh/year, and the California average is 6.744MWh/year [https://www.eia.gov/tools/faqs/faq.cfm?id=97&t=3].  PG&E also reports what people in our area use: similar houses use 6.042MWh/year, and efficient similar houses use 3.262MWh/year [https://pge.opower.com/ei/app/myEnergyUse].

Part of the reason we use so little electricity is that we rely on natural gas for heating, hot water, cooking, and clothes drying, using about 433 therms a year.  Here we are not particularly efficient: PG&E reports that similar houses use 548 therms/year, but efficient similar houses use only 293 therms/year [https://pge.opower.com/ei/app/myEnergyUse]. Shorter showers and setting up a clothes line would probably reduce our usage, but heating is the biggest chunk, and our house is already as cool as we are willing to live in.  We’ve invested in insulation over the years, but there is only so much you can do with a poured-concrete house for sane amounts of money.

A therm is about 29.3001 kWh, so our natural gas use is about equivalent to 12.7MWh—much more energy usage than our electricity!

We’ve been planning to buy carbon offset credits for our energy usage this year (see previous estimates in Solar lies).  Nothing for electricity of course, since we had a slight surplus there.  According to PG&E, natural gas produces about 6.1 kg CO2 per therm (and their electricity generation is about 238 g/kWh, only slightly more than the 208g for the same amount of energy from natural gas) [http://www.pge.com/includes/docs/pdfs/about/environment/calculator/assumptions.pdf].

I calculate approximately the following CO2 production from our various uses this year:

My wife and I have considered taking another trip this year, to Boston, which would add another 4.9MT. Note that flying is by far the most energy intensive thing we do—reducing travel is probably the only way we could significantly reduce our carbon footprint.  As carbon offsets, we’re considering projects like https://www.cooleffect.org/content/project/efficient-cookstove-project/, which cost $6–$10 per MT.  Do any of my readers know of good carbon offsets that aren’t scams or just enabling polluters?

 

4 Comments »

  1. Interesting data! We cook with electricity instead of gas. We use an induction stove. It’s more efficient than other electrics, and like many chefs, I think it gets better results than gas or other electrics. You just can’t match the temperature control. Of course, we don’t have gas going to the kitchen, so gas wasn’t an option.

    Comment by whatisron — 2016 July 30 @ 10:06 | Reply

    • It is not difficult to add a gas line to a room if you have a crawlspace (or, rare for this area, basement). If your house is on a concrete slab, though, it is very difficult to change the infrastructure. We added a gas line out to our garage when we converted half of it into a home office (which we call the book room, since one wall is floor-to-ceiling bookcase).

      We can compare summer and winter usage to see how much of the natural gas usage is heating. Our year-round load is about 0.6 therm/day or 222 therm/year, and our total usage is about 433 therms, so heating alone is around 211 therms/year. (Actually, probably somewhat less, as we may do a bit more clothes drying and cooking in the colder, wetter months.) I don’t know how to split the year-round load among cooking, hot water, and clothes drying, but I suspect that hot water is the biggest chunk.

      We like gas burners for the range top, both for the high output and the quick response to adjustments. We can also still cook when the power goes out, which happens a lot more often than the natural gas pipelines fail.

      For a lot of purposes, it isn’t the temperature that matters (boiling water is a fixed temperature), but the rate of heat transfer. For an oven, the tighter control of temperature in an electric oven would be nice, but the gas oven does well enough.

      Comment by gasstationwithoutpumps — 2016 July 30 @ 16:59 | Reply

      • We’re on slab so gas wasn’t a realistic option. That said, I’m pretty sure no typical gas burner can compete with induction re: output. I can boil water probably 3-4 times faster than a typical gas stove… and then pick the pot off the stove and put my hand on the burner without getting burnt (because there’s not enough time for the pot to conduct heat back to the surface since boiling happened so fast — the induction heats the pan quite rapidly). While that’s a cool parlor trick, my favorite part of induction comes from the ease of accurately reproducing cooking process. For example, I know that after my rice water boils, I can just set it to 3.5 and a perfect simmer will ensue without boil over. Scrambled eggs cook great at 6.5, and pancakes come out perfect, from the first to the last (though I’d have to look up the number I use :-) ). But you can find discussions by chefs far more serious than I about why they prefer induction.

        Comment by whatisron — 2016 July 30 @ 20:39 | Reply

  2. […] Average annual power use, I […]

    Pingback by Dehumidifier | Gas station without pumps — 2016 September 5 @ 00:05 | Reply


RSS feed for comments on this post. TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Blog at WordPress.com.

%d bloggers like this: