Monday, December 22, 2008

Consumer Economics of the EEStor EESU

I sat down recently to tackle the goal of gaining a better understanding of the economic benefits of having a home based EEStor EESU. I decided to focus on 3 main areas of possible payback:

1) Moving from non-electric to fully electric (or hybrid) vehicles
2) Moving from peak to off-peak energy costs
3) Introducing home based solar and/or wind energy generation

[note: there will be at least 2 parts to this article series]

The plan is to summarize my current consumption, calculate energy cost deltas and factor in capital outlays to produce overall economic benefit statements. The guiding principle of this exercise is to use as little math as possible to make a plain English, cocktail-party-type value statement for why items 1-3 would be valuable for consumers. A remote goal of this amateur study is to find a conceptual foundation upon which one could better understand the value of the EEStor EESU to businesses of various types.

Confession: my attention span often lets me down when it comes to even small amounts of basic math. Secondly, I'm not an accountant, but I can say with some certainty that this exercise will go better for you if you start by keeping separate operating vs capital costs. Bundling it all together is best saved for the last step since it builds upon having some basic concepts arranged appropriately.

Current Consumption
I started with my latest electrical energy bill to learn that for the 12 months ended Sept 30, 2008, my household consumed 16,000kWh at a cost of $1070. My house could certainly benefit from some updated windows & insulation but the analysis justifying that is out of scope here.

16000kWh/yr =
1333kWh/month =

$1070/yr =
$88/month =

To make this article more interesting, I set aside the actual energy/cost requirements of my daily commute in favor of a scenario I think may be more interesting to "people like me." Assume with me, that I have 2 SUV's each getting 15mpg and having 20 mi one way commutes (40mi round trip--yes, probably not typical).

2.67gal/day/vehicle x 2vehicles =

Today, gas in my area costs $2/gal x 5.33 gal/day.

$10.66/day x 5 days/wk = $53.3/wk x 52wks/yr =
$2771/fuel costs for 2SUV's.

Switching from Gas to Electricity

If I switched to an EESU based solution (eg, cityZenn) and accept the specs offered with a 52kWh EESU, I would get 300 miles on a full charge.


For (2) 40mi commutes, one would need 80mi/5.77mi/kWh=13.9kWh/day. At my current electrical cost, that 13.9kWh/day x .0668c/kW = $0.93. With gasoline, the 2 SUV's require $10.66/day. With electrical energy, that drops to 0.93c/day. Carry it out .93/day x 5days/wk = $4.64/wk x 52wks = $241/yr. Again, compare $2771 in fuel costs to $241 in electrical energy costs for a net savings of $2771-$241 = $2530/yr. (Additional savings comes from using off-peak electricity. See below.)

Switching from Peak to Off-Peak Electricity
In my area, off-peak electricity rates are approximately (but not quite) half the cost of peak rates. My regular household electricity requirements are 43.84kWh where as my commuting requirements were 13.9kWh.


The cost of that much electricity is $3.86/day or $1408/yr. By charging the EESU at night with off-peak energy, the overall electricity cost reduces by half (for easy math).


Time to put a few calculations together to grab a new rough net reduction in operating costs. At peak, my house electricity is $1070/yr + $2771/yr for gasoline = $3841. By using off-peak electricity for both, my cost goes down to $655.



By switching from gas to electric vehicle and moving from peak to off-peak electrical energy, my operating savings would be $3186/yr when gasoline is at $2/gallon. Obviously at $4/gas, it would be a hell of a lot more.

Switching from Grid to Solar & Wind

To start the analysis of reducing my dependency on the grid for electricity, let me restate that I need 16000kWh per year for my home and 3614kWh per year for my commute for a total of 19614kWh/yr.

19,614kWh/yr =
1634kWh/month =


This is a good place to end part 1. Looking forward to feedback on what we've got here so far.

To comment, visit